Horticulturae

18 pages, 4638 KiB

Open AccessEditor’s ChoiceArticle

Genome-Wide Characterization of Cucumber (Cucumis sativus L.) GRAS Genes and Their Response to Various Abiotic Stresses

by Caixia Li, Shaoyun Dong, Xiaoping Liu, Kailiang Bo, Han Miao, Diane M. Beckles, Shengping Zhang and Xingfang Gu

Horticulturae 2020, 6(4), 110; https://doi.org/10.3390/horticulturae6040110 - 21 Dec 2020

Cited by 7 | Viewed by 3058

Abstract

The GRAS (gibberellic acid insensitive, repressor of GAI, and scarecrow) proteins are a family of plant-specific transcription factors that regulate plant growth, development, and stress response. Currently, the role of GRAS transcription factors in various abiotic stress responses has [...] Read more.

The GRAS (gibberellic acid insensitive, repressor of GAI, and scarecrow) proteins are a family of plant-specific transcription factors that regulate plant growth, development, and stress response. Currently, the role of GRAS transcription factors in various abiotic stress responses has not been systematically studied in cucumber (Cucumis sativus L.), a popular vegetable crop. Here, we provide a comprehensive bioinformatics analysis of the 35 GRAS genes identified in the cucumber genome. In this study, cucumber genotypes, i.e., “CG104”, which is stress-tolerant, and genotype “CG37”, which is stress-sensitive, were examined to provide insight on potential differences in the GRAS-regulated abiotic stress pathways. Transcriptional analysis by RNA-seq or qRT-PCR of these two genotypes revealed common and divergent functions of CsGRAS genes regulated by low and high temperatures, salinity, and by exposure to the phytohormones gibberellin (GA) and abscisic acid (ABA). Notably, CsGRAS2 (DELLA) and CsGRAS26 (LISCL) were regulated by all abiotic stresses and hormone treatments, suggesting that they may function in the biological cross-talk between multiple signaling pathways. This study provides candidate genes for improving cucumber tolerance to various environmental stresses. Full article

(This article belongs to the Section Biotic and Abiotic Stress)

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14 pages, 1784 KiB

Open AccessEditor’s ChoiceArticle

Improvement of Growth and Morphology of Vegetable Seedlings with Supplemental Far-Red Enriched LED Lights in a Plant Factory

by Hyunseung Hwang, Sewoong An, Byungkwan Lee and Changhoo Chun

Horticulturae 2020, 6(4), 109; https://doi.org/10.3390/horticulturae6040109 - 21 Dec 2020

Cited by 19 | Viewed by 4935

Abstract

Although light-emitting diode (LED) lamps have been broadly applied in horticultural production to improve plant yield and quality, compared to natural light there is a disadvantage in the lack of far-red light in the LED spectrum. Far-red light has been studied widely to [...] Read more.

Although light-emitting diode (LED) lamps have been broadly applied in horticultural production to improve plant yield and quality, compared to natural light there is a disadvantage in the lack of far-red light in the LED spectrum. Far-red light has been studied widely to control plant growth and development. Therefore, this study aimed to find the effect of supplemental far-red-enriched LED lights to control the growth of tomato, red pepper, cucumber, gourd, watermelon and bottle gourd seedlings. The treatments were cool white LED:far-red LED at ratios of 5:0, 5:1, 5:2 and 5:3. The growth of tomato and red pepper seedlings, including hypocotyl length, was correlated to far-red light and light intensity. The phytochrome photostationary state (PSS) value of maximum hypocotyl length by supplemental far-red-enriched light ranged from 0.69 to 0.77 in tomato and red pepper seedlings. Although hypocotyl lengths of cucumber and watermelon were greatly affected by PSS, the PSS value for maximum hypocotyl length was lower than for tomato and red pepper. These results show that manipulating supplemental far-red enrichment can be used to control vegetable seedling growth with some variation among plant species. Full article

(This article belongs to the Section Vegetable Production Systems)

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16 pages, 5457 KiB

Open AccessArticle

Improvement of Phenylpropanoid Production with Elicitor Treatments in Pimpinella brachycarpa Nakai

by Nam Su Kim, Dae Hui Jung, Chung Ryul Jung, Kwon Seok Jeon, Hong Woo Park and Sang Un Park

Horticulturae 2020, 6(4), 108; https://doi.org/10.3390/horticulturae6040108 - 17 Dec 2020

Cited by 5 | Viewed by 2422

Abstract

Pimpinella brachycarpa Nakai, known as cham-na-mul in Korea, is a popular edible herb and vegetable. Phenolic compounds are recognized as a vital group of plant secondary metabolites that provide innumerable, valuable therapeutic properties. Elicitors are biofactors or chemicals from diverse sources that can [...] Read more.

Pimpinella brachycarpa Nakai, known as cham-na-mul in Korea, is a popular edible herb and vegetable. Phenolic compounds are recognized as a vital group of plant secondary metabolites that provide innumerable, valuable therapeutic properties. Elicitors are biofactors or chemicals from diverse sources that can trigger morphological and physiological responses in the target organism. This study examined the effect of methyl jasmonate (MeJA), salicylic acid (SA), and chitosan treatment on the accretion of phenolic compounds in P. brachycarpa Nakai. This plant was harvested under different concentration of elicitor treatment for time course. Eight phenolic compounds including were detected in response to elicitor using HPLC. While the untreated controls showed the lowest phenolic content, treatment with 0.3% chitosan, 0.1 mM SA, and 0.1 mM MeJA resulted in 1.43-, 1.39-, and 1.35-fold increase in the phenolic content, respectively. The highest content of most of the individual phenolic compounds followed a similar trend according to treatment type, with chitosan treatment showing the highest content, followed by SA and then MeJA treatments. Thus, we demonstrate that the treatment with optimal concentrations of these elicitors for an optimal period of time increases the production of phenolic compounds in P. brachycarpa Nakai. Full article

(This article belongs to the Special Issue Production and Quality of Medicinal and Aromatic Plants)

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11 pages, 2747 KiB

Open AccessEditor’s ChoiceArticle

Indices for the Assessment of Glycoalkaloids in Potato Tubers Based on Surface Color and Chlorophyll Content

by Shimeles Tilahun, Hee Sung An, Tifsehit Solomon, Min Woo Baek, Han Ryul Choi, Hee Cheol Lee and Cheon Soon Jeong

Horticulturae 2020, 6(4), 107; https://doi.org/10.3390/horticulturae6040107 - 16 Dec 2020

Cited by 3 | Viewed by 2813

Abstract

Glycoalkaloids (GAs) are toxic to humans at higher concentrations. However, studies also suggest the health benefits of GAs depending on the dose and conditions of use. Methods that have been used to determine GA content in potato tubers are destructive and time-consuming and [...] Read more.

Glycoalkaloids (GAs) are toxic to humans at higher concentrations. However, studies also suggest the health benefits of GAs depending on the dose and conditions of use. Methods that have been used to determine GA content in potato tubers are destructive and time-consuming and require skilled personnel and high-performance laboratory equipment. We conducted this study to develop indices for the prediction of the level of total GAs in potato tubers at different greening stages based on surface color readings and chlorophyll (Chl) development. Color values (Hunter L*, a*, b*, a*/b*), Chls (Chl a, Chl b, and total Chls) and GA (α-solanine, α-chaconine, and total GAs) content were measured from tubers of ‘Atlantic’ and ‘Trent’ potato cultivars at three-week intervals in up to six greening stages during the storage at room conditions (22 °C, 12-h shift of light-dark cycles). The results have revealed that greening, Chls, and GA content significantly increased for the two cultivars as the stage proceeded. The toxic level of GAs (>200 mg kg⁻¹ FW) was accumulated at the late greening stages, accompanied by the highest Chl content. Finally, indices were developed based on surface color and Chl content for estimation of the safe GA levels for the consumption of the two commercially and commonly used potato cultivars. Moreover, the developed indices could be used as basic information to adapt to other potato cultivars. Full article

(This article belongs to the Special Issue Nutritional and Antioxidant Value of Horticulturae Products)

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10 pages, 5984 KiB

Open AccessFeature PaperArticle

Qualitative Assessment of the Economic Impacts of Horticulture Research and Extension at MSU Coastal Research and Extension Center

by Benedict Posadas, Patricia Knight, Eric Stafne, Christine Coker, Eugene Blythe, Gary Bachman, James DelPrince and Scott Langlois

Horticulturae 2020, 6(4), 106; https://doi.org/10.3390/horticulturae6040106 - 16 Dec 2020

Cited by 2 | Viewed by 2775

Abstract

This paper summarizes opinions on the economic impacts of horticulture research and extension at the Mississippi State University, Coastal Research and Extension Center. More than 8400 horticulture producers, master gardeners, research and extension staff, and nonprofit organizations participated in horticulture events during the [...] Read more.

This paper summarizes opinions on the economic impacts of horticulture research and extension at the Mississippi State University, Coastal Research and Extension Center. More than 8400 horticulture producers, master gardeners, research and extension staff, and nonprofit organizations participated in horticulture events during the last five years. Qualitative assessments of horticulture research and extension performed by the faculty and staff were solicited during voluntary surveys. Full article

(This article belongs to the Section Outreach, Extension, and Education)

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13 pages, 839 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Influences of Postharvest Storage and Processing Techniques on Antioxidant and Nutraceutical Properties of Rubus idaeus L.: A Mini-Review

by Ermes Lo Piccolo, Leani Martìnez Garcìa, Marco Landi, Lucia Guidi, Rossano Massai and Damiano Remorini

Horticulturae 2020, 6(4), 105; https://doi.org/10.3390/horticulturae6040105 - 16 Dec 2020

Cited by 9 | Viewed by 3353

Abstract

The growth of agricultural mechanization has promoted an increase in raspberry production, and for this reason, the best postharvest storage and processing techniques capable of maintaining the health beneficial properties of these perishable berry fruits have been widely studied. Indeed, raspberries are a [...] Read more.

The growth of agricultural mechanization has promoted an increase in raspberry production, and for this reason, the best postharvest storage and processing techniques capable of maintaining the health beneficial properties of these perishable berry fruits have been widely studied. Indeed, raspberries are a rich source of bioactive chemical compounds (e.g., ellagitannins, anthocyanins, and ascorbic acid), but these can be altered by postharvest storage and processing techniques before consumption. Although there are clear differences in storage times and techniques, the content of bioactive chemical compounds is relatively stable with some minor changes in ascorbic acid or anthocyanin content during cold (5 °C) or frozen storage. In the literature, processing techniques such as juicing or drying have negatively affected the content of bioactive chemical compounds. Among drying techniques, hot air (oven) drying is the process that alters the content of bioactive chemical compounds the most. For this reason, new drying technologies such as microwave and heat pumps have been developed. These novel techniques are more successful in retaining bioactive chemical compounds with respect to conventional hot air drying. This mini-review surveys recent literature concerning the effects of postharvest storage and processing techniques on raspberry bioactive chemical compound content. Full article

(This article belongs to the Special Issue Feature Papers in Horticulturae)

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13 pages, 1020 KiB

Open AccessFeature PaperArticle

Stimulatory Effect of Seed Priming as Pretreatment Factors on Germination and Yield Performance of Yard Long Bean (Vigna unguiculata)

by Md. Naziul Karim, Md. Nasir Hossain Sani, Jasim Uddain, Md Obyedul Kalam Azad, Md. Sazzadul Kabir, Mohammed Saifur Rahman, Ki Young Choi and Most Tahera Naznin

Horticulturae 2020, 6(4), 104; https://doi.org/10.3390/horticulturae6040104 - 15 Dec 2020

Cited by 10 | Viewed by 4024

Abstract

Seed priming is a technique that can potentially facilitate rapid and consistent germination and subsequent plant growth. The present study investigates the effect of different seed priming treatments and processing times on germination and growth efficiency for the effective cultivation of Yard-long bean. [...] Read more.

Seed priming is a technique that can potentially facilitate rapid and consistent germination and subsequent plant growth. The present study investigates the effect of different seed priming treatments and processing times on germination and growth efficiency for the effective cultivation of Yard-long bean. Thirteen different primings were used to determine the stimulatory effect on the germination and yield performance of the Yard-long bean. The priming treatments included control (without priming); hydro priming for 12, 18, 24, and 30 h; halo priming (1% CaCl₂) for 12, 18, 24, and 30 h; and halo priming (2% KNO₃) for 12, 18, 24, and 30 h. Studies showing the highest level of germination (86.66%), germination index (35.69), seedling vigor index (1833.80), number of branches (7.20), and pod yields per plant (1836.00 g) were recorded from halo priming with 1% CaCl₂ at 12 h treatment. Halo priming with 1% CaCl₂ at 12 h is thus considered to be a compatible priming technique for the germination of seeds and a higher yield of Yard-long bean. Full article

(This article belongs to the Section Propagation and Seeds)

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15 pages, 1717 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Correlations among Quality Characteristics of Green Asparagus Affected by the Application Methods of Elevated CO₂ Combined with MA Packaging

by Li-Xia Wang, In-Lee Choi and Ho-Min Kang

Horticulturae 2020, 6(4), 103; https://doi.org/10.3390/horticulturae6040103 - 14 Dec 2020

Cited by 4 | Viewed by 2983

Abstract

This research investigated the effects of continuous elevated CO₂ (20%, (v/v)) application or a 3 day CO₂ pretreatment followed by modified atmosphere (MA) or micro-perforated (MP) packaging on the postharvest quality of asparagus. The combination of CO₂ pretreatment with MA packaging [...] Read more.

This research investigated the effects of continuous elevated CO₂ (20%, (v/v)) application or a 3 day CO₂ pretreatment followed by modified atmosphere (MA) or micro-perforated (MP) packaging on the postharvest quality of asparagus. The combination of CO₂ pretreatment with MA packaging (Pre-MA) inhibited the yellowing of asparagus and fresh weight loss (FWL), whereas stem firmness slightly increased with all elevated CO₂ treatments. CO₂ pretreatments increased antioxidant activity in the stem, but not in the tip, in contrast to the continuous flow CO₂ (Flow-CO₂) treatment. The phenolic and flavonoid contents increased in the elevated CO₂ pretreatments and Flow-CO₂ treatment. The elevated CO₂ treatments, especially Flow-CO₂, inhibited the development of microorganisms, and the treated asparagus did not decay. Pre-MA and Flow-CO₂ treatments were more effective in maintaining the visual quality and retarding the off-odor of asparagus. Furthermore, significant correlations between sensory quality characteristics and physiological-biochemical attributes were recognized; three principal components were extracted and they explained 86.4% of asparagus characteristics. The results confirmed the importance of visual quality, off-odor, firmness, color parameters, SSC and total phenolic content. In conclusion, elevated CO₂ pretreatment followed by MA packaging (Pre-MA) was beneficial for extending asparagus cold storage shelf life, and Flow-CO₂ was the best treatment for inhibiting postharvest decay. Full article

(This article belongs to the Special Issue Managing the Product Quality of Vegetable Crops under Abiotic Stress)

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8 pages, 423 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Efficacy of Orange Essential Oil and Citral after Exposure to UV-C Irradiation to Inhibit Penicillium digitatum in Navel Oranges

by Mohammad M. Rahman, Ron B. H. Wills, Michael C. Bowyer, John B. Golding, Timothy Kirkman and Penta Pristijono

Horticulturae 2020, 6(4), 102; https://doi.org/10.3390/horticulturae6040102 - 14 Dec 2020

Cited by 6 | Viewed by 2565

Abstract

The effect of UV-C irradiation on antifungal properties of orange essential oil (EO) against Penicillium digitatum in inoculated Navel oranges was examined. The UV-C irradiation of orange EO resulted in a 20% loss of the major constituent, limonene, and the generation of three [...] Read more.

The effect of UV-C irradiation on antifungal properties of orange essential oil (EO) against Penicillium digitatum in inoculated Navel oranges was examined. The UV-C irradiation of orange EO resulted in a 20% loss of the major constituent, limonene, and the generation of three hydroperoxide oxidation products, (2S,4R)-p-mentha-6,8-diene-2-hydroperoxide,(1S,4R)-p-mentha-2,8-diene-1-hydroperoxide, and (1R,4R)-p-mentha-2,8-diene-1-hydroperoxide. The P. digitatum growth in oranges dipped in non-irradiated orange EO at 1000–4000 µL L⁻¹ was not significantly different to control the fruit. Dipping in UV-C treated orange EO inhibited the growth of P. digitatum with 4000 µL L⁻¹ having the greatest effect. No phytotoxic injury to the rind was observed at any concentration. Citral, as a known antifungal chemical, was included for comparison. The non-irradiated citral (1000 µL L⁻¹) was more effective than irradiated orange EO, but elicited rind phytotoxicity. The irradiated citral was less effective in inhibiting P. digitatum growth with the loss of citral, but not hydroperoxide formation. These results suggest UV-C irradiated orange EO as a potential alternative to synthetic fungicides to inhibit P. digitatum decay. The source of orange EO could be waste flavedo generated by the orange juice processing industry. Full article

(This article belongs to the Special Issue Explorations in Postharvest Diseases of Fruits and Vegetables)

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13 pages, 705 KiB

Open AccessReview

Advances in Research and Application of Male Sterility in Brassica oleracea

by Jialei Ji, Jianxin Huang, Limei Yang, Zhiyuan Fang, Yangyong Zhang, Mu Zhuang, Honghao Lv, Yong Wang, Yumei Liu, Zhansheng Li and Fengqing Han

Horticulturae 2020, 6(4), 101; https://doi.org/10.3390/horticulturae6040101 - 14 Dec 2020

Cited by 7 | Viewed by 3795

Abstract

Brassica oleracea is an important vegetable species which belongs to the genus Brassica and the mustard family Brassicaceae Burnett. Strong heterosis in B. oleracea is displayed in yield, quality, disease resistance, and stress tolerance. Heterosis breeding is the main way to improve B. [...] Read more.

Brassica oleracea is an important vegetable species which belongs to the genus Brassica and the mustard family Brassicaceae Burnett. Strong heterosis in B. oleracea is displayed in yield, quality, disease resistance, and stress tolerance. Heterosis breeding is the main way to improve B. oleracea varieties. Male sterile mutants play an important role in the utilization of heterosis and the study of development and regulation in plant reproduction. In this paper, advances in the research and application of male sterility in B. oleracea were reviewed, including aspects of the genetics, cytological characteristics, discovery of genes related to male sterility, and application of male sterility in B. oleracea. Moreover, the main existing problems and prospect of male sterility application in B. oleracea were addressed and a new hybrids’ production strategy with recessive genic male sterility is introduced. Full article

(This article belongs to the Section Propagation and Seeds)

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22 pages, 1617 KiB

Open AccessArticle

Interrelation of Ecophysiological and Morpho-Agronomic Parameters in Low Altitude Evaluation of Selected Ecotypes of Sweet Potato (Ipomoea batatas [L.] Lam.)

by Esteban Burbano-Erazo, Carina Cordero, Iván Pastrana, Laura Espitia, Evelin Gomez, Alfredo Morales, Jazmín Pérez, Leonardo López and Amparo Rosero

Horticulturae 2020, 6(4), 99; https://doi.org/10.3390/horticulturae6040099 - 10 Dec 2020

Cited by 4 | Viewed by 3101

Abstract

Sweet potato is a crop with a wide capacity to adapt to adverse conditions. To study the tolerance of the sweet potato to a low-altitude environment, 34 genotypes comprising three groups from different altitude conditions ranging from 18–599, 924–1298, 1401–2555 meters above sea [...] Read more.

Sweet potato is a crop with a wide capacity to adapt to adverse conditions. To study the tolerance of the sweet potato to a low-altitude environment, 34 genotypes comprising three groups from different altitude conditions ranging from 18–599, 924–1298, 1401–2555 meters above sea level were evaluated. These genotypes were evaluated through ecophysiological parameters: net photosintetic rate (Pn), stomatal conductance (G_S), transpiration (E), leaf internal CO₂ (ICO₂), vapor pressure deficit (VPD) and leaf internal temperate (LT). sSubsequently, water use efficiency (WUE) and carboxylation efficiency index (CEI) were estimated. Simultaneously, morpho-agronomic characterization of the genotypes was conducted including descriptors and morpho-colorimetric parameters. A wide ecophysiological variability was found among genotypes from high, intermediate and low altitudes, when those were evaluated under low altitude conditions. The genotypes that presented major soil coverage efficiency and leaf size showed greater Pn, WUE and CEI, and Low VPD and E, aspects that benefited the ability to form roots the under low-altitude environment. The altitudinal origin of the genotypes influenced the ecophysiological response under low altitude conditions. The capacity of certain sweet potato genotypes to tolerate low altitude conditions were due to to different mechanisms, such as certain morphoagronomic traits that allowed them to adjust their physiological processes, especially those related to photosynthesis. Full article

(This article belongs to the Section Developmental Physiology, Biochemistry, and Molecular Biology)

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18 pages, 1854 KiB

Open AccessEditor’s ChoiceArticle

Molecular Characterization and Positive Impact of Brassinosteroids and Chitosan on Solidago canadensis cv. Tara Characteristics

by Iman M. El-Sayed, Rasha G. Salim, Eman F. El-Haggar, Rasha A. El-Ziat and Dina M. Soliman

Horticulturae 2020, 6(4), 100; https://doi.org/10.3390/horticulturae6040100 - 10 Dec 2020

Cited by 14 | Viewed by 2640

Abstract

Although goldenrod (Solidago canadensis) is considered an invasive plant in many countries, it is a global cut-flower species. In addition, demand for goldenrod has increased significantly in recent years. Thus, the present study aimed to evaluate the response of Solidago canadensis [...] Read more.

Although goldenrod (Solidago canadensis) is considered an invasive plant in many countries, it is a global cut-flower species. In addition, demand for goldenrod has increased significantly in recent years. Thus, the present study aimed to evaluate the response of Solidago canadensis cv. Tara to brassinosteroids (BRs) at levels of 0.10⁻³, 10⁻⁶, and 10⁻⁸ M, and chitosan at 0, 100, 150, and 200 mg/L as a foliar application to increase the quality and quantity of production, and its polyphenolic compounds. Moreover, antibacterial activity and genetic polymorphism for both untreated and the optimally treated goldenrod were investigated. The results showed that the highest mean of growth characteristics was found when plants were treated with BRs at 10⁻⁸ M, whereas the longer vase life was obtained using 200 mg/L chitosan. Furthermore, higher pigment values, N, P, K, and total phenolic content, antioxidant capacity, chlorogenic acid, and rutin content were detected on plants treated with 200 mg/L chitosan. In addition, foliar application with 200 mg/L chitosan caused higher antibacterial activity among the control and BRs. The optimal treatment of BR at 10⁻⁸ M (89%) showed a low genetic similarity, based on sequence-related amplified polymorphism (SRAP) analysis, comparable with the control and 200 mg/L chitosan. BR at 10⁻⁸ M and 200 mg/L chitosan showed a significant enhancement of growth parameters. As a result, it can be concluded that goldenrod, as a herb extract, shows significant promise as a natural preservative in pharmaceutical, food, and cosmetic products. Full article

(This article belongs to the Section Developmental Physiology, Biochemistry, and Molecular Biology)

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11 pages, 2452 KiB

Open AccessFeature PaperArticle

Augmenting Nutrient Acquisition Ranges of Greenhouse Grown CBD (Cannabidiol) Hemp (Cannabis sativa) Cultivars

by Jennifer Kalinowski, Keith Edmisten, Jeanine Davis, Michelle McGinnis, Kristin Hicks, Paul Cockson, Patrick Veazie and Brian E. Whipker

Horticulturae 2020, 6(4), 98; https://doi.org/10.3390/horticulturae6040098 - 09 Dec 2020

Cited by 7 | Viewed by 5476

Abstract

There is a growing interest in the production of hemp for the extraction of cannabidiol (CBD) due to reported therapeutic benefits. Recent policy reform has permitted state hemp pilot programs, including the land grant research institutions, the ability to investigate the potential of [...] Read more.

There is a growing interest in the production of hemp for the extraction of cannabidiol (CBD) due to reported therapeutic benefits. Recent policy reform has permitted state hemp pilot programs, including the land grant research institutions, the ability to investigate the potential of growing and harvesting Cannabis sativa plants (≤0.3% tetrahydrocannabinol) for these purposes in the U.S. There are vast gaps of knowledge regarding the fertility requirements of hemp cultivars grown in a horticultural production setting for floral attributes such as the cannabinoid constituents. Foliar tissue analysis provides an avenue to determine adequate ranges for nutrient uptake and estimating fertilizer requirements prior to visual symptoms of deficiency or toxicity. To facilitate a survey range of elemental nutrient acquisition in hemp cultivars propagated for CBD production, foliar analysis was executed using the most recently mature leaves (MRML) of mother stock plants. All plants were maintained in the vegetative stage for twelve weeks, prior to initiation of cutting for clone harvesting. A total of thirteen cultivars were utilized to broaden previously reported baseline survey ranges. Significant differences were found among all thirteen cultivars in accumulation of both micro and macro essential nutrients, widening the range of the fertility requirements of Cannabis plants grown in this production model for CBD harvesting. Full article

(This article belongs to the Section Plant Nutrition)

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10 pages, 538 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Impact of Grafting on Watermelon Fruit Maturity and Quality

by Pinki Devi, Penelope Perkins-Veazie and Carol Miles

Horticulturae 2020, 6(4), 97; https://doi.org/10.3390/horticulturae6040097 - 08 Dec 2020

Cited by 14 | Viewed by 6223

Abstract

Watermelon (Citrullus lanatus) grafting has emerged as a promising biological management approach aimed at increasing tolerance to abiotic stressors, such as unfavorable environmental conditions. These conditions include environments that are too cold, wet, or dry, have soil nutrient deficiency or toxicity [...] Read more.

Watermelon (Citrullus lanatus) grafting has emerged as a promising biological management approach aimed at increasing tolerance to abiotic stressors, such as unfavorable environmental conditions. These conditions include environments that are too cold, wet, or dry, have soil nutrient deficiency or toxicity and soil or irrigation water salinity. Studies to date indicate that fruit yield and quality may be positively or negatively affected depending on rootstock-scion combination and growing environment. Growers need information regarding the general effect of rootstocks, as well as specific scion-rootstock interactions on fruit maturity and quality so they can select combinations best suited for their environment. This review summarizes the literature on watermelon grafting with a focus on abiotic stress tolerance and fruit maturity and quality with specific reference to hollow heart and hard seed formation, flesh firmness, total soluble solids, and lycopene content. Full article

(This article belongs to the Special Issue Managing the Product Quality of Vegetable Crops under Abiotic Stress)

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12 pages, 1980 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Soil Nitrogen and Weed Biodiversity: An Assessment under Two Orchard Floor Management Practices in a Nitrogen Vulnerable Zone in Italy

by Md Jebu Mia, Elga Monaci, Giorgio Murri, Francesca Massetani, Jacopo Facchi and Davide Neri

Horticulturae 2020, 6(4), 96; https://doi.org/10.3390/horticulturae6040096 - 07 Dec 2020

Cited by 18 | Viewed by 3187

Abstract

Nowadays, understory vegetation along the tree row is considered a vital source of agroecosystem services and functional biodiversity improvement in the fruit orchard. Hence, current orchard floor management systems encourage practicing a more sustainable approach that supports vegetation cover rather than keeping bare [...] Read more.

Nowadays, understory vegetation along the tree row is considered a vital source of agroecosystem services and functional biodiversity improvement in the fruit orchard. Hence, current orchard floor management systems encourage practicing a more sustainable approach that supports vegetation cover rather than keeping bare soil herbicide use, or tillage. A two-year field trial was conducted using two different ground management techniques; integrated mowing (mower and brush or disc) and herbicide (glyphosate) in two commercial apple and peach orchards in a nitrogen vulnerable zone (NVZ) of the Marche region, Italy. This study aimed to evaluate the effects of these practices on soil N status, weed abundance, percent of soil cover, and dry weed biomass production. Weed management systems had no significant effect on soil organic matter and N availability; however, an improvement was noticed under integrated mowing when compared to the one treated with herbicides. Integrated mowing had a significant effect on species richness, soil coverage, and weed biomass production, which was approximately 2-times higher than in the herbicide-treated plots. The overall results showed that integrated mowing maintained a balance in the soil N status of both orchards, while supporting above-ground weed biodiversity and soil protection. Full article

(This article belongs to the Special Issue Fertilization Management of Horticultural Crops)

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16 pages, 1387 KiB

Open AccessArticle

Effects of Water Stress on Vegetative Growth and ‘Merlot’ Grapevine Yield in a Semi-Arid Mediterranean Climate

by Juan L. Chacón-Vozmediano, Jesús Martínez-Gascueña, Francisco J. García-Navarro and Raimundo Jiménez-Ballesta

Horticulturae 2020, 6(4), 95; https://doi.org/10.3390/horticulturae6040095 - 03 Dec 2020

Cited by 19 | Viewed by 3707

Abstract

Water stress is considered to be the most influential type of abiotic stress to which plants may be exposed. In grapevines (Vitis vinifera L.), it is a common practice to keep plants under water stress at different stages of the season with [...] Read more.

Water stress is considered to be the most influential type of abiotic stress to which plants may be exposed. In grapevines (Vitis vinifera L.), it is a common practice to keep plants under water stress at different stages of the season with the aim of reducing yield and improving the composition of the fruit. The objective of this study was to evaluate foliar development and yield of ‘Merlot’ grapevines grown in the field when they are subjected to different levels of water stress in a semi-arid Mediterranean climate. Four treatments with different levels of water stress were applied during two phenological intervals (flowering-veraison and veraison-maturity) to 128 grapevines for a period of two consecutive years. The levels of water stress were none-light, light-moderate, moderate-intense, and intense-intense for the flowering-veraison and veraison-maturity intervals, respectively. The results revealed that the total leaf area, the exposed leaf area, and the yield all decreased as the degree of water stress increased. The weight of the berry was a decisive factor in determining yield. The least restrictive water regime treatment gave the heaviest berries and bunches and, as a result, the highest yields. Full article

(This article belongs to the Special Issue Grape Responses to Abiotic and Biotic Stresses)

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9 pages, 192 KiB

Open AccessFeature PaperArticle

High Tunnel Production of Tomatoes for Season Extension in Southeast Alabama

by Bradley Reeder, Wheeler Foshee, Eugene Blythe, Raymond Kessler, Joseph Kemble, Edgar Vinson, William Dozier and Larry Wells

Horticulturae 2020, 6(4), 94; https://doi.org/10.3390/horticulturae6040094 - 01 Dec 2020

Cited by 2 | Viewed by 1890

Abstract

A series of experiments was conducted to evaluate variety selection and planting date for spring and fall season extension of tomato (Solanum lycopersicum L. (syn.: Lycoperisicon esculentum Mill.)) production in high tunnels in southeast Alabama. ‘BHN 640’, ‘Florida 91’, ‘Sun Leaper’, and [...] Read more.

A series of experiments was conducted to evaluate variety selection and planting date for spring and fall season extension of tomato (Solanum lycopersicum L. (syn.: Lycoperisicon esculentum Mill.)) production in high tunnels in southeast Alabama. ‘BHN 640’, ‘Florida 91’, ‘Sun Leaper’, and ‘Carolina Gold’ were evaluated for early spring production in 2004. These varieties did not differ in total yield of marketable fruit; however, ‘BHN 640’ and ‘Sun Leaper’ produced higher early yields compared with the other varieties. ‘BHN 640’ and ‘Florida 91’ were evaluated for late-season extension in fall 2004. ‘BHN 640’ produced higher yields of large, medium, total marketable, and unmarketable fruit grades than ‘Florida 91’. In a study conducted in early 2005, higher yields of marketable fruit were produced from the first planting date (31 January) compared with the final of four planting date (25 Mar.). In summary, results indicated that season extension of tomato production in high tunnels was possible, with harvests three weeks earlier in the spring and 12 weeks later in the fall compared with typical field harvest dates. These early yields can command prices from $3.30 to $4.40US per kg of fruit. Full article

(This article belongs to the Section Vegetable Production Systems)

20 pages, 2149 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Effects of Foliar Application of Gibberellic Acid on the Salt Tolerance of Tomato and Sweet Pepper Transplants

by Alessandro Miceli, Filippo Vetrano and Alessandra Moncada

Horticulturae 2020, 6(4), 93; https://doi.org/10.3390/horticulturae6040093 - 28 Nov 2020

Cited by 11 | Viewed by 3856

Abstract

Seed germination and early seedling growth are the plant growth stages most sensitive to salt stress. Thus, the availability of poor-quality brackish water can be a big limiting factor for the nursery vegetable industry. The exogenous supplementation of gibberellic acid (GA₃) [...] Read more.

Seed germination and early seedling growth are the plant growth stages most sensitive to salt stress. Thus, the availability of poor-quality brackish water can be a big limiting factor for the nursery vegetable industry. The exogenous supplementation of gibberellic acid (GA₃) may promote growth and vigor and counterbalance salt stress in mature plants. This study aimed to test exogenous supplementation through foliar spray of 10⁻⁵ M GA₃ for increasing salt tolerance of tomato and sweet pepper seedlings irrigated with increasing salinity (0, 25, and 50 mM NaCl during nursery growth. Tomato and sweet pepper seedlings suffered negative effects of salinity on plant height, biomass, shoot/root ratio, leaf number, leaf area, relative water content, and stomatal conductance. The foliar application of GA₃ had a growth-promoting effect on the unstressed tomato and pepper seedlings and was successful in increasing salinity tolerance of tomato seedlings up to 25 mM NaCl and up to 50 mM NaCl in sweet pepper seedlings. This treatment could represent a sustainable strategy to use saline water in vegetable nurseries limiting its negative effect on seedling quality and production time. Full article

(This article belongs to the Special Issue Feature Papers in Horticulturae)

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11 pages, 5738 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Effect of Phytosanitary Irradiation Treatment on the Storage Life of ‘Jiro’ Persimmons at 15 °C

by John B. Golding, Penta Pristijono and Baogang Wang

Horticulturae 2020, 6(4), 92; https://doi.org/10.3390/horticulturae6040092 - 26 Nov 2020

Cited by 3 | Viewed by 2622

Abstract

Irradiation is becoming a more accepted phytosanitary market access treatment for some international horticultural trades. However, there is little information on the effects of phytosanitary irradiation treatment on persimmon fruit quality. ‘Jiro’ persimmon fruit were treated with an average of 769 Gray (Gy) [...] Read more.

Irradiation is becoming a more accepted phytosanitary market access treatment for some international horticultural trades. However, there is little information on the effects of phytosanitary irradiation treatment on persimmon fruit quality. ‘Jiro’ persimmon fruit were treated with an average of 769 Gray (Gy) at a commercial phytosanitary irradiation X-ray facility to examine the effect of this market access treatment on fruit quality during storage. After treatment, fruit were stored in air at 15 °C for up to three weeks. The results showed that, in general, there was no effect of irradiation treatment on fruit weight loss, calyx appearance, fruit firmness (objective and subjective), total soluble solids (TSS), titratable acidity (TA), internal appearance, and ethylene production rate. There were some treatment differences in fruit respiration rates and some aspects of fruit appearance and colour, where irradiated fruit had higher respiration rates and were slightly darker with higher levels of skin blemish, although these measured differences were not commercially significant. This study showed the promise of using low dose irradiation as a phytosanitary treatment for ‘Jiro’ persimmons, but more work is required to test other persimmon cultivars and other storage and marketing environments. Full article

(This article belongs to the Special Issue Propagation and Post-harvest of Fruit Crops)

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13 pages, 936 KiB

Open AccessArticle

The Relationship between Fruit Size and Phenolic and Enzymatic Composition of Avocado Byproducts (Persea americana Mill.): The Importance for Biorefinery Applications

by Igor Trujillo-Mayol, Guillermo Badillo-Muñoz, Carlos Céspedes-Acuña and Julio Alarcón-Enos

Horticulturae 2020, 6(4), 91; https://doi.org/10.3390/horticulturae6040091 - 25 Nov 2020

Cited by 16 | Viewed by 3367

Abstract

Avocado byproducts are a rich source of health-promoting biomolecules. The purpose of this work is to study three groups of statistically different avocado fruit sizes (Persea americana Mill.) (small (S), medium (M), and large (L)), and their relationship with total phenolic and [...] Read more.

Avocado byproducts are a rich source of health-promoting biomolecules. The purpose of this work is to study three groups of statistically different avocado fruit sizes (Persea americana Mill.) (small (S), medium (M), and large (L)), and their relationship with total phenolic and flavonoid contents (TPC and TFC, respectively), DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging capacity and individual phenolics, and the activities of phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), and polyphenol oxidase (PPO) in avocado peel extract (APE). The results indicated that TPC, TFC, and antioxidant and enzymatic activities were higher in the APE of the S group (p < 0.05). The flavonoids (flavanols and flavonols) and phenolic acids were also significatively concentrated in S group’s APE. Overall, the phenolic content was significantly lower in the L group. Positive correlations (p < 0.0001 and p < 0.05) were observed between TPC, TPF, DPPH, and enzymatic activity, and negative correlations resulted for avocado weight and volume. The outstanding phenolic content and enzymatic activity of avocado peels from low-cost avocado byproducts are ideal for biorefinery applications, thereby increasing the bioeconomy of the avocado industry. Full article

(This article belongs to the Section Fruit Production Systems)

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16 pages, 3977 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Salinity-Induced Physiological Responses of Three Putative Salt Tolerant Citrus Rootstocks

by Lamiaa M. Mahmoud, Manjul Dutt, Christopher I. Vincent and Jude W. Grosser

Horticulturae 2020, 6(4), 90; https://doi.org/10.3390/horticulturae6040090 - 25 Nov 2020

Cited by 17 | Viewed by 4581

Abstract

Our study aimed to evaluate the physiological responses following salinity treatment of three putatively salt-tolerant Citrus rootstocks recently developed by the University of Florida’s Citrus breeding program. Four-month-old seedlings from each of the three rootstocks (HS1, HS17, and HC15) were irrigated with 0, [...] Read more.

Our study aimed to evaluate the physiological responses following salinity treatment of three putatively salt-tolerant Citrus rootstocks recently developed by the University of Florida’s Citrus breeding program. Four-month-old seedlings from each of the three rootstocks (HS1, HS17, and HC15) were irrigated with 0, 60, 80, and 100 mm NaCl solution. The seedlings were evaluated together with the salt-tolerant Cleopatra mandarin as a positive control, Volkamer lemon as a moderately salt-tolerant rootstock, and the salt-sensitive Carrizo rootstock as a negative control. Our results demonstrated that chlorophyll content, net CO₂ assimilation rate (A), transpiration rate (E), and stomatal conductance (g_sw) significantly decreased in response to salinity. Na⁺ and Cl⁻ levels were higher in leaf tissues than in the roots. Relatively little damage to the cellular membrane was recorded in HC15 and Cleopatra rootstocks under the 100 mm NaCl treatment, along with high accumulation of total phenolic content (TPC), while HS17 had the highest proline levels. Our results indicate that HC15 and HS17 rootstocks exhibited salt tolerance capacity via different strategies under salt stress and could be suitable replacements to the commercially available, salt-tolerant Cleopatra rootstock. Full article

(This article belongs to the Special Issue Advances in Citrus Horticulture)

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15 pages, 1213 KiB

Open AccessArticle

Effects of Metamitron under Different Relative Humidity Conditions on the Fruit Abscission of Malus domestica Borkh. Cultivars

by Nídia Rosa, Wim Verjans, Glória Àvila, Joaquim Carbó, Joan Bonany, José Cochicho Ramalho, Luís Asín and Cristina Moniz Oliveira

Horticulturae 2020, 6(4), 89; https://doi.org/10.3390/horticulturae6040089 - 23 Nov 2020

Cited by 2 | Viewed by 2114

Abstract

Metamitron is an apple (Malus domestica Borkh.) fruit thinner that acts by reducing the photosynthetic capacity of trees. Relative humidity may influence thinning efficacy; however, the broadness of this effect is not yet fully understood. Trials were set in Sint-Truiden (Belgium) in [...] Read more.

Metamitron is an apple (Malus domestica Borkh.) fruit thinner that acts by reducing the photosynthetic capacity of trees. Relative humidity may influence thinning efficacy; however, the broadness of this effect is not yet fully understood. Trials were set in Sint-Truiden (Belgium) in 2018 and Lleida and Girona (Spain) in 2019, using 4-year-old cvs. Braeburn and Elstar trees in Belgium, and 16-year-old cv. Golden Reinders trees in Spain. Four treatments were implemented at the stage of 12–14 mm fruit diameter: (a) CTR—control, trees under natural environmental conditions; (b) HH—high humidity, trees submitted to artificially increased air relative humidity applied for 3 h prior to the beginning of the experiment; (c) MET—trees sprayed with 247.5 mg/L metamitron; (d) MET + HH—trees submitted to the combination of increased humidity (HH) and metamitron (MET) application. In Belgium, metamitron absorption by leaves was greater than in Spain. This might be related to morphological characteristics of the leaves which developed under greater natural relative humidity levels in Belgium than in Spain. Compared to MET alone, ‘Braeburn’ and ‘Elstar’ demonstrated significantly greater metamitron absorption, 59% and 84%, respectively, under MET + HH, accompanied by declines in leaf net photosynthesis (10% and 32%, respectively) and sucrose (31% and 26%, respectively). At harvest, MET + HH treatment reduced yield by 24% and 32% in ‘Braeburn’ and ‘Elstar’, respectively, when compared with MET alone. A large reduction (considered over thinning) in the yield of ‘Elstar’ occurred. In contrast, metamitron absorption by ‘Golden Reinders’ using MET alone was similar to MET + HH; however, there was a slight foliar sugar reduction in the latter treatment. In addition, both treatments enhanced shoot growth and increased fruit abscission with similar improvements in fruit weight and size. In this study, high relative humidity enhanced fruit thinning efficacy under certain circumstances, such as age or genetic predisposal, which left the tree more susceptible to a negative carbohydrate balance. For instance, ‘Braeburn’ and ‘Elstar’ were easier to thin when compared to ‘Golden Reinders’. In addition, this study raises a question that requires further research regarding the impact of HH before and after spraying as well as its effect in combination with higher temperatures. Full article

(This article belongs to the Section Fruit Production Systems)

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13 pages, 1897 KiB

Open AccessFeature PaperReview

Advances in Watermelon Grafting to Increase Efficiency and Automation

by Pinki Devi, Scott Lukas and Carol Miles

Horticulturae 2020, 6(4), 88; https://doi.org/10.3390/horticulturae6040088 - 20 Nov 2020

Cited by 20 | Viewed by 7283

Abstract

Grafting watermelon (Citrullus lanatus) onto resistant rootstocks is an effective technique in the management of biotic and abiotic stresses. Since the first reported grafting of watermelon for disease resistance in 1927, adoption of the practice has been steadily increasing up to [...] Read more.

Grafting watermelon (Citrullus lanatus) onto resistant rootstocks is an effective technique in the management of biotic and abiotic stresses. Since the first reported grafting of watermelon for disease resistance in 1927, adoption of the practice has been steadily increasing up to 95% in Japan, Korea, Greece, Israel and Turkey. However, for grafting to be further adopted in the United States and other regions of the world with high labor costs and high plant volume demands, the watermelon grafting method must be more time and labor efficient as well as suitable for automation. To accomplish these goals, recent advances have been achieved in splice grafting of watermelon, where both cotyledons are removed from the rootstock. This review provides a summary of the new discoveries regarding watermelon grafting and an overview of the anatomy of cucurbit stems and the physiological processes that occur at the time of grafting and during the healing process in order to enhance the understanding of the complex nature of the cucurbit vascular system, which limits grafting success. This review article further provides insights to guide future research and technology development that will support the expansion of watermelon grafting. Full article

(This article belongs to the Section Fruit Production Systems)

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13 pages, 2447 KiB

Open AccessEditor’s ChoiceArticle

Phylogenetic Analysis and Molecular Diversity of Capsicum Based on rDNA-ITS Region

by Kumpei Shiragaki, Shuji Yokoi and Takahiro Tezuka

Horticulturae 2020, 6(4), 87; https://doi.org/10.3390/horticulturae6040087 - 20 Nov 2020

Cited by 14 | Viewed by 5464

Abstract

The genus Capsicum is comprised of 5 domesticated and more than 30 wild species. The region of nuclear ribosomal DNA internal transcribed spacers (rDNA-ITS) has widely been used for species identification, but has rarely been used in Capsicum. In this study, the [...] Read more.

The genus Capsicum is comprised of 5 domesticated and more than 30 wild species. The region of nuclear ribosomal DNA internal transcribed spacers (rDNA-ITS) has widely been used for species identification, but has rarely been used in Capsicum. In this study, the evaluation of genetic diversity and a phylogenetic analysis were conducted using rDNA-ITS of 28 Capsicum accessions, including five domesticated and two wild species. We surveyed six conventional keys of domesticated species and another five traits in Capsicum accessions. Specific morphological characteristics were found in C. annuum, C. baccatum, and C.pubescens. Three subclones of each accession were sequenced, and rDNA-ITS polymorphisms were detected in all accessions excluding C. annuum, suggesting that incomplete concerted evolution occurred in rDNA-ITS of Capsicum. The genetic diversity was evaluated using nucleotide polymorphism and diversity. C. annuum had the lowest genetic diversity of all species in this study. The phylogenetic tree formed a species-specific clade for C. annuum, C. baccatum, and C. pubescens. The C. chinense clade existed in the C. frutescens clade, implying that it was a cultivated variant of C. frutescens. C. chacoense likely belonged to the C. baccatum complex according to its morphologic and genetic features. This study indicated that the rDNA-ITS region can be used for simple identification of domesticated Capsicum species. Full article

(This article belongs to the Section Genetics, Genomics, Breeding, and Biotechnology (G2B2))

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19 pages, 3242 KiB

Open AccessEditor’s ChoiceArticle

Evaluation of the Crop Water Stress Index as an Indicator for the Diagnosis of Grapevine Water Deficiency in Greenhouses

by Chen Ru, Xiaotao Hu, Wene Wang, Hui Ran, Tianyuan Song and Yinyin Guo

Horticulturae 2020, 6(4), 86; https://doi.org/10.3390/horticulturae6040086 - 20 Nov 2020

Cited by 43 | Viewed by 5016

Abstract

Precise irrigation management of grapevines in greenhouses requires a reliable method to easily quantify and monitor the grapevine water status to enable effective manipulation of the water stress of the plants. This study evaluated the applicability of crop water stress index (CWSI) based [...] Read more.

Precise irrigation management of grapevines in greenhouses requires a reliable method to easily quantify and monitor the grapevine water status to enable effective manipulation of the water stress of the plants. This study evaluated the applicability of crop water stress index (CWSI) based on the leaf temperature for diagnosing the grapevine water status. The experiment was conducted at Yuhe Farm (northwest China), with drip-irrigated grapevines under three irrigation treatments. Meteorological factors, soil moisture contents, leaf temperature, growth indicators including canopy coverage and fruit diameter, and physiological indicators including SPAD (relative chlorophyll content), stem water potential (

φ_{s}

), stomatal conductance (g_s), and transpiration rate (E) were studied during the growing season. The results show that the relationship between the leaf-air temperature difference (T_c-T_a) and the plant water status indicators (

φ_{s}

, g_s, E) were significant (P < 0.05), and the relationship between g_s, E and T_c-T_a was the closest, with R² values ranging from 0.530–0.604 and from 0.545–0.623, respectively. CWSI values are more easily observed on sunny days, and it was determined that 14:00 BJS is the best observation time for the CWSI value under different non-water-stressed baselines. There is a reliable linear correlation between the CWSI value and the soil moisture at 0–40 cm (P < 0.05), which could provide a reference when using the CWSI to diagnose the water status of plants. Compared with the T_c-T_a value, the CWSI could more accurately monitor the plant water status, and above the considered indictors, g_s has the greatest correlation with the CWSI. Full article

(This article belongs to the Special Issue Grape Responses to Abiotic and Biotic Stresses)

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25 pages, 653 KiB

Open AccessReview

Chemical Element Concentrations of Cycad Leaves: Do We Know Enough?

by Benjamin E. Deloso, Murukesan V. Krishnapillai, Ulysses F. Ferreras, Anders J. Lindström, Michael Calonje and Thomas E. Marler

Horticulturae 2020, 6(4), 85; https://doi.org/10.3390/horticulturae6040085 - 19 Nov 2020

Cited by 8 | Viewed by 5190

Abstract

The literature containing which chemical elements are found in cycad leaves was reviewed to determine the range in values of concentrations reported for essential and beneficial elements. We found 46 of the 358 described cycad species had at least one element reported to [...] Read more.

The literature containing which chemical elements are found in cycad leaves was reviewed to determine the range in values of concentrations reported for essential and beneficial elements. We found 46 of the 358 described cycad species had at least one element reported to date. The only genus that was missing from the data was Microcycas. Many of the species reports contained concentrations of one to several macronutrients and no other elements. The cycad leaves contained greater nitrogen and phosphorus concentrations than the reported means for plants throughout the world. Magnesium was identified as the macronutrient that has been least studied. Only 14 of the species were represented by data from in situ locations, with most of the data obtained from managed plants in botanic gardens. Leaf element concentrations were influenced by biotic factors such as plant size, leaf age, and leaflet position on the rachis. Leaf element concentrations were influenced by environmental factors such as incident light and soil nutrient concentrations within the root zone. These influential factors were missing from many of the reports, rendering the results ambiguous and comparisons among studies difficult. Future research should include the addition of more taxa, more in situ locations, the influence of season, and the influence of herbivory to more fully understand leaf nutrition for cycads. Full article

(This article belongs to the Special Issue Feature Papers in Horticulturae)

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15 pages, 1925 KiB

Open AccessEditor’s ChoiceArticle

Effect of High CO₂ Treatment and MA Packaging on Sensory Quality and Physiological-Biochemical Characteristics of Green Asparagus (Asparagus officinalis L.) during Postharvest Storage

by Li-Xia Wang, In-Lee Choi and Ho-Min Kang

Horticulturae 2020, 6(4), 84; https://doi.org/10.3390/horticulturae6040084 - 19 Nov 2020

Cited by 9 | Viewed by 2973

Abstract

Green asparagus is vulnerable to thrips that carry microorganisms and cause deterioration in quality. The effects of 60% CO₂ treatment, which is used to kill thrips, combined with perforated (P) or modified atmosphere (MA) packages during cold storage, on the sensory quality [...] Read more.

Green asparagus is vulnerable to thrips that carry microorganisms and cause deterioration in quality. The effects of 60% CO₂ treatment, which is used to kill thrips, combined with perforated (P) or modified atmosphere (MA) packages during cold storage, on the sensory quality and physiological–biochemical characteristics of asparagus were investigated. MA packaging yielded an asparagus shelf-life five days longer than P packaging. The 60% CO₂ treatment for 48 h at 4 °C packaged with MA film (CO₂-48 h-4 °C-MA) showed a lower number of aerobic bacteria, yeast, and mold. Yellowing of asparagus was retarded, as shown by higher hue angle and chlorophyll content and lower chlorophyllase activity. Also, CO₂-48 h-4 °C-MA treatment inhibited the reduction of soluble solids content in asparagus. Likewise, all high CO₂ treatments showed lower electrolyte leakage (EL), with CO₂-48 h-4 °C-MA demonstrating the minimum EL. The effectiveness of high CO₂ on maintaining sensory qualities was observed, with a score higher than 3.0. In conclusion, CO₂-48 h-4 °C-MA treatment during cold storage was effective for maintaining post-harvest sensory qualities and physiological–biological traits of asparagus, and provided strong inhibition of microflora growth during the storage period. Full article

(This article belongs to the Section Postharvest Biology, Quality, Safety, and Technology)

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16 pages, 3510 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Implementation of the Circular Economy Concept in Greenhouse Hydroponics for Ultimate Use of Water and Nutrients

by Angeliki Elvanidi, Cinthya Marilu Benitez Reascos, Elissavet Gourzoulidou, Alexander Kunze, Johannes F. J. Max and Nikolaos Katsoulas

Horticulturae 2020, 6(4), 83; https://doi.org/10.3390/horticulturae6040083 - 13 Nov 2020

Cited by 22 | Viewed by 5131

Abstract

The circular economy in agriculture aims to reduce waste while also making best use of residues by using economically viable processes and procedures to increase their value. In this study a two-level cascade cultivation system was set up under greenhouse conditions. The research [...] Read more.

The circular economy in agriculture aims to reduce waste while also making best use of residues by using economically viable processes and procedures to increase their value. In this study a two-level cascade cultivation system was set up under greenhouse conditions. The research was focused on the identification of crop species as secondary crops and the development/iterative optimization of cultivation practices. For this purpose, different crop-combinations with a primary and different secondary crops were investigated using different system-layouts. Measurements were carried out during two cultivation periods. During the 1st Period a combination of cucumber (Cucumis sativus) as primary crop, with rosemary (Rosmarinus officinalis), basil (Ocimum basilicum), and peppermint (Mentha piperita) as secondary crops, was evaluated. In the 2nd Period the drainage of tomato (Solanum lycopersicum) plants was re-used to irrigate spearmint (Mentha spicata), dill (Anethum graveolens), celery (Apium graveolens) and parsley (Petroselinum crispum) plants. In both periods, different fertigation management strategies based on the drainage solution of the primary crop were employed. The use of the cascade hydroponic system improved both crop water and nutrient use efficiency. Notably, the NO₃ disposal was about 40% less as compared to a monoculture. Average fresh water consumption of secondary crop plants irrigated with diluted drainage solution was reduced by 30% in comparison to plants irrigated with fresh water. Full article

(This article belongs to the Special Issue Transformation toward Sustainability in Controlled Environment Agriculture)

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19 pages, 3117 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Spring Freeze Damage of Pecan Bloom: A Review

by Amandeep Kaur, Louise Ferguson, Niels Maness, Becky Carroll, William Reid and Lu Zhang

Horticulturae 2020, 6(4), 82; https://doi.org/10.3390/horticulturae6040082 - 13 Nov 2020

Cited by 6 | Viewed by 4112

Abstract

Pecan is native to the United States. The US is the world’s largest pecan producer with an average yearly production of 250 to 300 million pounds; 80 percent of the world’s supply. Georgia, New Mexico, Texas, Arizona, Oklahoma, California, Louisiana, and Florida are [...] Read more.

Pecan is native to the United States. The US is the world’s largest pecan producer with an average yearly production of 250 to 300 million pounds; 80 percent of the world’s supply. Georgia, New Mexico, Texas, Arizona, Oklahoma, California, Louisiana, and Florida are the major US pecan producing states. Pecan trees frequently suffer from spring freeze at bud break and bloom as the buds are quite sensitive to freeze damage. This leads to poor flower and nut production. This review focuses on the impact of spring freeze during bud differentiation and flower development. Spring freeze kills the primary terminal buds, the pecan tree has a second chance for growth and flowering through secondary buds. Unfortunately, secondary buds have less bloom potential than primary buds and nut yield is reduced. Spring freeze damage depends on severity of the freeze, bud growth stage, cultivar type and tree age, tree height and tree vigor. This review discusses the impact of temperature on structure and function of male and female reproductive organs. It also summarizes carbohydrate relations as another factor that may play an important role in spring growth and transition of primary and secondary buds to flowers. Full article

(This article belongs to the Section Biotic and Abiotic Stress)

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12 pages, 911 KiB

Open AccessArticle

Effects of the Biofertilizer OYK (Bacillus sp.) Inoculation on Endophytic Microbial Community in Sweet Potato

by Ahsanul Salehin, Md Hafizur Rahman Hafiz, Shohei Hayashi, Fumihiko Adachi and Kazuhito Itoh

Horticulturae 2020, 6(4), 81; https://doi.org/10.3390/horticulturae6040081 - 12 Nov 2020

Cited by 5 | Viewed by 2923

Abstract

Sweet potato (Ipomoea batatas L.) grows well even in infertile and nitrogen-limited fields, and endophytic bacterial communities have been proposed to be responsible for this ability. Plant-growth-promoting bacteria are considered eco-friendly and are used in agriculture, but their application can interact with [...] Read more.

Sweet potato (Ipomoea batatas L.) grows well even in infertile and nitrogen-limited fields, and endophytic bacterial communities have been proposed to be responsible for this ability. Plant-growth-promoting bacteria are considered eco-friendly and are used in agriculture, but their application can interact with endophytic communities in many ways. In this study, a commercial biofertilizer, OYK, consisting of a Bacillus sp., was applied to two cultivars of sweet potato, and the effects on indigenous endophytic bacterial communities in field conditions were examined. A total of 101 bacteria belonging to 25 genera in 9 classes were isolated. Although the inoculated OYK was not detected and significant plant-growth-promoting effects were not observed, the inoculation changed the endophytic bacterial composition, and the changes differed between the cultivars, as follows: Novosphingobium in α-Proteobacteria was dominant; it remained dominant in Beniharuka after the inoculation of OYK, while it disappeared in Beniazuma, with an increase in Sphingomonas and Sphingobium in α-Proteobacteria as well as Chryseobacterium and Acinetobacter in Flavobacteria. The behavior of Bacilli and Actinobacteria also differed between the cultivars. The Shannon diversity index (H) increased after inoculation in all conditions, and the values were similar between the cultivars. Competition of the inoculant with indigenous rhizobacteria and endophytes may determine the fates of the inoculant and the endophytic community. Full article

(This article belongs to the Section Plant Nutrition)

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