Horticulturae, Volume 8, Issue 7 (July 2022) – 109 articles

People have an ancient and strong bond to flowers, which are known to have a positive effect on the mood. During the COVID-19 pandemic, sales of ornamental plants increased, and many turned to gardening, possibly as a way to cope with ubiquitous increases in negative mood following lockdowns and social isolation. The nature of the special bond between humans and flowers requires additional elucidation. To this means, we conducted a comprehensive online mixed methods study, surveying 253 individuals (ages 18–83) from diverse ethnic backgrounds and continents, regarding their thoughts and feelings towards photos of flowers, nature scenes and flower drawings. We found that looking at pictures and drawings of flowers, as well as nature scenes induced positive emotions, and participants reported a variety of positive responses to the images. More specifically, we found associations of flowers with femininity, and connotations to particular flowers that were affected by geographical location. While nature scene photos induced positive reactions, flower photos were preferred, denying a mere substitution of nature by flowers and vice versa. Drawings of flowers elicited less positive emotions than photos, as people related more to the art than to the flower itself. Our study reveals the importance of ornamental flowers and nature in our life and well-being, and as such their cultivation and promotion are essential. Full article

Chinese olive (Canarium album), a characteristic fruit tree in tropical and subtropical areas, suffers greatly from low-temperature stress (LTS). The regulatory roles of microRNA (miRNA) in plant LTS responses have been confirmed in many plant species but not in C. album. In this study, a cold-tolerant cultivar ‘Rui’an 3′ (RA) and a susceptible cultivar ‘Qinglan 1’ (QL) treated at 25 °C (control, CK) and −3 °C (cold temperature treatment, CT) were subjected to small RNA (sRNA) and transcriptome sequencing for the exploration of the cold responses of C. album. Comparative sRNA sequencing analysis identified much fewer LTS-responsive, differentially expressed miRNAs (DEMs) in RA (4 DEMs) than in QL (23 DEMs). Cal-miR482-22 was found to be specifically induced by LTS in RA. Cal-miR397-3 was upregulated, while cal-miR398_2-3 and cal-undef-190 were downregulated after LTS only in QL. However, when compared with QL, a higher basic expression of cal-miR397-3, and lower expression of cal-miR398_2-3 and cal-undef-190 were found in RA, suggesting that they may contribute to the cold tolerance of RA. Comparative transcriptome analysis showed that the number of LTS-responsive differentially expressed genes (DEGs) identified in QL was larger than that in RA, and some DEGs were also predicted as the target genes of the identified DEMs, forming multiple differentially expressed miRNA–target gene pairs, such as cal-miR397-3_laccase 2, 4, 17, cal-miR482-22_suppressor of npr1-1, etc. Quantitative real time PCR results showed that the expression changes of DEGs and DEMs in different samples were generally consistent with the sequencing results. Our study indicated that the basic expression levels of some miRNAs (especially the cal-miR397-3, cal-miR398_2-3, and cal-miR482-22), and their target genes contribute greatly to the cold-tolerance characteristics of C. album. Our study is helpful for understanding the roles of miRNAs in the cold resistance and responses of C. album. Full article

Accurate surface defect extraction of apples is critical for their quality inspection and marketing purposes. Using multi-band images, this study proposes a detection method for apple surface defects with a combination of machine vision and deep learning. Five single bands, 460, 522, 660, 762, and 842 nm, were selected within the visible and near-infrared. By using a near-infrared industrial camera with optical filters, five single-band images of an apple could be obtained. To achieve higher accuracy of defect extraction, an improved U-Net was designed based on the original U-Net network structure. More specially, the partial original convolutions were replaced by dilated convolutions with different dilated rates, and an attention mechanism was added. The loss function was also redesigned during the training process. Then the traditional algorithm, the trained U-Net and the trained improved U-Net were used to extract defects of apples in the test set. Following that, the performances of the three methods were compared with that of the manual extraction. The results show that the near-infrared band is better than the visible band for defects with insignificant features. Additionally, the improved U-Net is better than the U-Net and the traditional algorithm for small defects and defects with irregular edges. On the test set, for single-band images at 762 nm, the improved U-Net had the best defect extraction with an mIoU (mean intersection over union) and mF1-score of 91% and 95%, respectively. Full article

Biostimulants are agronomic products that have become highly important in agriculture, as they are formulated with substances capable of stimulating physiological and biochemical processes in plants that help them adapt to different detrimental environmental conditions such as drought, salinity, high temperatures, nutritional deficiencies, etc. in such a way that the crops, under these conditions, maintain a good agronomic yield and quality of harvest. Every two years, the International Congress on Biostimulants is held with the aim of publicizing the most innovative and recent advances in every relevant type of product: new active ingredients, modes of action, cultivation protocols, test platforms and phenotyping, use of analytical omics tools, etc. In December 2021, the 5th World Congress on Biostimulants was held in Miami (Florida, USA). This publication summarizes the most relevant results that were presented at this congress, in which biostimulants formulated with algae extracts and amino acids stood out in a number of presentations. The various studies presented were carried out on diverse crops such as apple, blackberry, carrot, celery, cherry, corn, grape (table and wine), olive, pear, pepper, potato, rapeseed, spinach, sunflower, soybean, tomato, and wheat. The future lines of the new generation of biostimulants were also marked. Full article

Foliar fertilization makes it possible to quickly provide plants with essential nutrients, mainly micronutrients, which can significantly improve the quality of yields. The aim of this study was to evaluate the effect of foliar fertilization with fertilizers containing calcium and microelements on yielding and fruit quality of highbush blueberry (Vaccinium corymbosum L.). A two-year study was carried out in western Poland in an experimental highbush blueberry production plantation. During the growing season the bushes were treated several times with the following foliar fertilizers: Armurox, BioCal, and Stymjod. The experiment assessed bush growth vigor, yield, fruit quality characteristics, sugar, organic acid, and health-promoting substance content. It was found that as a result of fertilizing highbush blueberry bushes with foliar fertilizers, the leaf blade area and plant yield increased significantly. The fruits collected from those bushes were characterized by a higher mass, firmness, and TSS content. This also applies to blueberry fruit after storage. Foliar fertilization had no significant effect on the content of chlorophyll a and b in the leaves of northern highbush blueberry, on fruit coloration, the content of sugars, ascorbic and citric acids, and the phenolic compounds in them. Full article

Water stress negatively impacts the physiology of plants, affecting their growth and development. It is considered among the most important environmental factors responsible for reduced crop production. In this regard, biofertilizers may be considered significant for their reparative properties to increase stress tolerance in crop plants. We studied the effects of water stress on the morphological and biochemical characteristics of onion plants with AMF (Funneliformis mosseae) and potassium silicate application. The water stress significantly affected all the studied traits, each with minimum recorded levels. Plants that received combined treatments of AMF and potassium silicate showed maximum percent increments in all the studied characteristics, e.g., plant height (156.7%), weight of bulb (416.8%), antioxidant activity (224.0%), membrane stability index (74.5%), relative water content (87.3%), and total soluble solids (63.71%). Therefore, the study demonstrated that all the investigated variables were affected negatively by water stress. However, bio-fortification of onion plants with silicates and AMF inoculation may be considered useful for functional food production, with numerous health promoting properties. Full article

Positive stress or essential and nonessential elements can improve nutritive values (biofortification) of edible plants. In the present study, we evaluate (i) the effect of moderate salinity on lettuce biofortification, evaluated as nutritional bioactive compound accumulation, and (ii) the role of iodine in enhancing salt tolerance by increasing photorespiration and the content of antioxidants in lettuce. Physiological (gas exchange and chlorophyll fluorescence emission) and biochemical (photosynthetic pigment and bioactive compound) analyses were performed on lettuce plants grown under moderate salinity (50 mM NaCl alone or 50 mM NaCl in combination with iodine, KIO₃). Our results show that NaCl + iodine treatment improves the nutritional value of lettuce in terms of bioactive compounds acting as antioxidants. More specifically, iodine enhances the accumulation of photosynthetic pigments and polyphenols, such as anthocyanins, under salt but does not improve the salt tolerance. Our findings indicate that iodine application under moderate salinity could be a valid strategy in plant biofortification by improving nutritional bioactive compound accumulation, thus exercising functional effects on human health. Full article

Recently there have been new trends in global consumption toward fresh foods that are sources of healthy bioactive compounds, as is the case with pitaya. However, pitaya cultivation is a relatively recent phenomenon and little is known about its management. The objective of this work is to determine the most appropriate annual fruiting pruning method for pitaya in order to obtain a regular annual yield of quality fruit and an intense shoot renewal that guarantee future production. This study compared the response of Hylocereus undatus to spur, cane, and combined pruning. As control plants, we left some plants where only sanitary pruning was performed. The results indicate that spur pruning greatly reduced flowering (seven times less than controls) and did not promote intense vegetative growth. Cane pruning, on the contrary, allowed greater flowering which is compatible with a higher number of new shoots (8% more than controls). The vigor of the new shoots was equal in all treatments. Fruit size and quality did not differ either among treatments. Spur pruning only seems applicable as a rejuvenation pruning. Combined pruning gave an intermediate response and seems of no interest given the good shoot renewal provided by cane pruning. Performing sanitary pruning alone may be an interesting option, but only in the first years of cultivation. Full article

Potassium is among the three essential macronutrients for tea plants, along with nitrogen and phosphorous, and plays important roles in growth and stress response. Potassium is absorbed by plants in larger amounts than any other mineral element except nitrogen and, in some cases, calcium. At present, more than 59% of China’s tea gardens are in a state of potassium deficiency, which negatively affects tea quality and yield. This paper reviews the effects of potassium deficiency on tea plant growth and stress response, details factors affecting potassium supply and demand in tea gardens, examines the interactions between potassium and other elements in soils, and provides strategies for optimizing potassium levels in soils. Potassium is positively correlated with the elements nitrogen, copper, and zinc. Sufficient potassium dramatically improves the yield and quality of tea: it accelerates metabolism, promotes synthesis of catechins, and strengthens biotic and abiotic resistance by activating and regulating different enzymes. Moderate application of potassium fertilizers, along with potassium-solubilizing bacteria, can regulate the ratio of different forms of potassium and increase available potassium in soils of tea gardens. We suggest that research on potassium occurring in soils and its interaction with other elements be strengthened, so as to improve the efficient use of potassium fertilizers in tea gardens and maintain the balance of elements in soils. Full article

Cross-pollination can improve the fruit set and quality of blueberry (Vaccinium spp.) for growers and consumers. However, the xenia effect in southern highbush blueberry remains unclear. Therefore, we selected eight cultivars of southern highbush blueberry (Vaccinium corymbosum L., interspecific hybrids) and applied pollination treatments (i.e., artificial self-pollination, artificial pollination with mixed pollen, or artificial pollination with individual cultivar pollen) to explore the xenia effects on the fruit set and quality of ‘O’Neal’ and ‘Emerald’. Pollen viability tests indicated that all of the cultivars are capable of fertilization. The highest fruit set came from ‘Bluerain’ pollen for ‘O’Neal’, while ‘Gulfcoast’ pollen increased fruit set the most in ‘Emerald’. Principal component analysis revealed that the cross combinations ‘Emerald’ × ‘Gulfcoast’ and ‘O’Neal’ × ‘Gulfcoast’ optimized the external and interior quality of the fruit. SSR was applied to determine which pollen source yielded the most seedlings. Results indicated that ‘Emerald’ × ‘Gulfcoast’ and ‘O’Neal’ × ‘Bluerain’ increased seedling production. Our results demonstrate that the xenia effects of ‘Gulfcoast’ pollen may increase ‘Emerald’ yields and promote fruit quality, while pollen from ‘Bluerain’ or ‘Jewel’ can improve ‘O’Neal’ fruit quality and seed number. Hence, these cross combinations may be utilized in blueberry production to increase fruit set, yield, and quality. Full article

Null alleles are alleles that are recessive to codominant markers without any effect on the phenotype. In SSR assays, there are several reasons for the lack of amplification at a locus: the primer does not bind well, longer fragments do not amplify due to imperfections in the PCR reaction, or the amount of DNA in the sample is insufficient. In microsatellite studies, null alleles are mostly used in pedigree analysis and population genetics calculations such as diversity estimation. Null alleles in pedigree analysis can cause rejection of the true parent; if not recognized while in population genetics they distort the results in underestimating diversity. In this review, the effects caused by null-alleles in viticultural research and its possible solutions were summarized. Full article

Apple (Malus x domestica) fruit size is dependent on cell division and cell expansion, processes that are subsequently regulated by plant hormones such as auxins, gibberellins, and cytokinins. In this study, we investigated the role of cell division and cell expansion in apple growth and identified which of the two was more deterministic of final fruit size. Three cultivars of different sizes were selected, namely, “Twenty Ounce” (large-sized), “Royal Gala” (medium-sized), and “Crabapple” (small-sized). Gene expression and cell size analyses were conducted over the course of two consecutive seasons. The expression patterns of three classes of genes were markedly similar across all cultivars. Two cell division markers, namely MdCDKB2;2 and MdANT2, were discovered to be correlatively expressed, as both displayed initially high expression levels, which gradually declined from the early to late stages of the growth time course. For cell expansion markers, MdEXP3 was upregulated as the cells expanded, while MdARF106 was expressed in both the cell division and expansion stages. Meanwhile, the ripening-related gene MdACO1 was expectedly expressed only during the ending stages associated with ripening. Interestingly, the cell measurements taken regularly from each cultivar throughout the same experimental timespan showed that cell sizes were unaltered and remained constant from initial pollination at the zeroth Day After Pollination (DAP) to ripening at 120 Days After Full Bloom (DAFB). Full article

TCP transcription factors are a unique transcription family in higher plants, and play important roles in plant development, responses to environmental stresses and phytohormones. Radish is an important crop and widely cultivated worldwide. However, genome-wide identification and expression analysis of TCP family in radish has not been reported yet. In this study, 32 RsTCP genes were identified from the whole genome. Phylogenetic analysis showed that the RsTCP family can be divided into two major groups and three subgroups, namely Class I (PCF), Class II (CIN), and Class II (CYC/TB1). Chromosome mapping showed that 32 genes were distributed on all nine chromosomes of radish. Transcriptome data indicated that the transcription of RsTCP genes differed between tissues and developmental stages. Multiple phytohormone-related cis-acting elements in the promoter region of RsTCPs and several post-translational modification sites in RsTCP protein sequences were identified. The real-time quantitative PCR (RT-qPCR) analysis indicated that several RsTCP genes changed significantly in response to the treatments, including low temperature, drought, salt, gibberellin (GA₃), and abscisic acid. Among them, RsTCP16 showed significantly higher levels in leaves than in other radish tissues, and the transcription of RsTCP16 was significantly upregulated under the five treatments, especially during low temperature, salt shock, and GA₃ response, suggesting that RsTCP16 could be involved in the development of radish leaves and the response to stress. In summary, these results provided a basis for further exploring the molecular mechanism of RsTCP genes in radish. Full article

Cut roses are grown throughout the four distinct seasons of spring, summer, autumn, and winter in Korea. Especially in the very hot or cold seasons of summer or winter, the temperature and light environments inside a greenhouse cause abiotic stress on the growth of horticultural crops. In a greenhouse where shade cultivation is performed in summer, the temperature is high and the light intensity is low, whereas in winter when shade cultivation is not performed, both temperature and light intensity are low. This experiment investigated the year-round growth and yield changes of cut roses grafted onto three rootstocks. The root activity of rootstocks was generally higher than that of the scion. The stomata of the grafted cut roses showed morphological changes according to the seasons. Compared with the scion, the stomata of grafted cut roses became smaller and their number increased in summer, whereas only the stomata size increased in winter. The grafted cut roses had characteristics of high photosynthetic efficiency such as photosynthesis rate, stomatal conductance, transpiration rate from rootstocks under harsh environmental conditions including temperature and light intensity, and thus the photosynthetic efficiency was higher than that of the scion. There was no significant change in the yield of grafted cut roses, but flower quality parameters such as the stem height, stem thickness, and weight of grafted cut roses were improved according to the rootstocks compared with those of the scion. In particular, in cut roses grafted with R. multiflora cv. Natal Briar and Rosa indica ‘Major’ rootstocks, the weight increased as the stem lengthened and thickened in spring, autumn, and winter. Therefore, grafting is effective in improving the quality of cut roses grown under abiotic stress caused by harsh temperature and light intensity conditions during winter. Full article

Bois noir, an economically important disease of grapevine yellows that causes significant economic losses in wine production, is associated with ‘Candidatus Phytoplasma solani’ and transmitted to grapevines by cixiids Hyalesthes obsoletus and Reptalus panzeri. Polyphagous planthopper Dictyophara europaea, commonly found in natural habitats, harbors phytoplasmas from distinct groups and is an alternative vector in the open epidemiological cycles of the Flavescence dorée phytoplasma in grapevine in European vineyards. This study addresses the role of D. europaea in the transmission cycle(s) of ‘Ca. P. solani’ among wild habitats, natural reservoir plants, and the vineyard agroecosystem using MLSA and transmission trials with naturally infected adults to grapevine and Catharanthus roseus. The infection rates of D. europaea ranged from 7% to 13% in diverse locations, while reservoir herbaceous plants were infected in the amount of 29%. A total of 13 CaPsol MLSA genotypes were detected in D. europaea (7) and plants (8). Nine of them corresponded to previously identified genotypes. Two new genotypes were found in D. europaea (tuf-b1/S1/V14/Rqg50-sv1 and tuf-b1/S18/V14/Rqg50-sv1) and one in Convolvulus arvensis (tuf-b1/S1/V2-TA/Rqg31-sv1), whereas one was shared by two hosts, Crepis foetida and Daucus carota (tuf-b1/S1/V2-TA/STOL-sv1). Naturally infected D. europaea successfully transmitted the tuf-b1/S1/V2-TA/STOL type to five grapevines and six periwinkles, tuf-b1/S1/V2-TA/Rqg31 to one grapevine, and tuf-b1/S1/V2-TA/Rqg50 to one periwinkle, indicating that D. europaea is an intermediate vector in CaPsol epidemiological cycles. Full article

Common ice plant (Mesembryanthemum crystallinum L.) is a novel edible plant with a succulent and savory flavor emerging as new crop for greenhouse and plant factory growers. Currently very limited information is available on the response of ice plant to photoperiod and to daily light integral (DLI). The objective of this study was to determine the impact of photoperiod/DLI on the growth of ice plant for indoor vertical production. Four-week old seedlings of ice plant were transplanted into vertical hydroponic systems and given five photoperiod/DLI treatments: 8/6.3, 12/9.5, 16/12.7, 20/15.8, and 24/19.0 h/mol·m⁻²·d⁻¹. Sequential destructive harvests to determine plant growth occurred 14, 21, and 28 days after lighting treatments began. Plants performed better with increasing photoperiod/DLI from 8 h/6.3 mol·m⁻²·d⁻¹ to 20 h/15.8 mol·m⁻²·d⁻¹. By day 28, shoot fresh weight increased from 160 g to 639 g as the photoperiod/DLI increased from 8 h/6.3 mol·m⁻²·d⁻¹ to 20 h/15.8 mol·m⁻²·d⁻¹. The continuous lighting treatment, 24 h/19 mol·m⁻²·d⁻¹, showed a negative effect on the plant fresh weight (FW) and dry weight (DW). Light treatment did not have obvious effects on shoot:root ratio and macronutrient uptake except that potassium (K) uptake decreased slightly with increased photoperiod/DLI. Plants receiving higher photoperiod/DLI showed the same number of leaves (indicating the same development stage) but had smaller, thicker, and darker green leaves compared to lower photoperiod/DLI treatments. Leaf water content was not affected by light treatment up to 20 h/15.8 mol·m⁻²·d⁻¹ but decreased at 24 h/19 mol·m⁻²·d⁻¹. Further research is needed to separate the physiological response of increasing/continuous photoperiod from the response of increasing DLI. Full article

The use of extracts derived from different plants has gained popularity as an alternative option to manage weeds and support phenological development in plants. One of the main problems facing agricultural production is the intensive application of chemical fertilizers that harm the environment. This study investigated the biostimulant effects of the aqueous extracts of Verbesinasphaerocephala and Verbesinafastigiata on the germination and growth of tomato (Solanum lycopersicum) and American cucumber (Cucumis sativus) seedlings. The aqueous extracts of both species of Verbesina were tested at concentrations of 0.5 and 1%. Seed germination and seedling development under nursery conditions were evaluated. The seed germination percentage was reduced in all treatments with the extracts of both Verbesina species when compared to that of the control treatment, which was considered an allelopathic effect. However, seedling growth in pots showed different behavior, with the extracts beneficially affecting certain agronomic variables, such as root and leaf length. The results suggest potential uses for V. sphaerocephala and V. fastigiata extracts, although a greater range of action may be experienced through the effects of certain molecules on weed growth. Additional studies with chemical approaches are necessary to better direct the uses and applications of Verbesina biomolecules, as they also functioned as growth promoters. Full article

Various abiotic stresses, particularly salinization, restrict plant growth and yield around the world. Lipoxygenases play essential functions in coping with various stresses. In the present study, we found an apple (Malus domestica) homolog of Arabidopsis lipoxygenase3, named MdLOX3. MdLOX3 has a typical conserved lipoxygenase domain. MdLOX3 was expressed in all tissues of apple and was highly expressed in the root and flesh tissues by a qRT-PCR analysis. In addition, the promoter of MdLOX3 consists of multiple response elements. Various abiotic stresses and ABA treatment can induce the expression of MdLOX3. The overexpression of MdLOX3 in apple calli enhanced the ability to tolerate salt stress, and the heterotopic expression of MdLOX3 in Arabidopsis elevated salt stress tolerance via enhancing the ability of scavenging ROS. Furthermore, the overexpression of MdLOX3 in transgenic plants significantly reduced the sensitivity to ABA. Through the above, this work demonstrated that MdLOX3 played an active position in salt resistance and decreased the sensitivity to ABA, providing a theoretical reference for studying the role of MdLOX3 in abiotic stresses in apple. Full article

Studying the changes of carotenoids in the taproot of carrots under salt treatment is helpful to probe the salt stress response mechanism of carrots. The carotenoid concentration and the expression profiles of 10 carotenoid-related genes were determined in two carrot cultivars with different taproot colors. Under salt stress, the biosynthesis of carotenoids in the taproot of both ‘KRD’ and ‘BHJS’ was activated. RT-qPCR manifested that the expression levels of DcPSY1, DcPSY2, DcZDS1, DcCRT1 and DcCRT2 increased significantly in both ‘KRD’ and BHJS’ under salt stress, but DcCHXE transcripts decreased and DcPDS transcripts maintained a basal level compared to that of the control. In the taproot of ‘KRD’, the expression level of DcLCYB, DcLCYE and DcCHXB1 climbed dramatically. However, there was no significant change in the taproot of ‘BHJS’. The study showed that salt stress can stimulate the biosynthesis of carotenoids. The accumulation of lutein in the taproots of ‘KRD’ and ‘BHJS’ may be mainly attributed to the variation in DcLCYE and DcCHXB1 transcripts. The increase in β-carotene accumulation is speculated to increase salt tolerance. Full article

‘Yunnan’ quince (Cydonia oblonga Mill.) is used as the dwarfing rootstock for pear (Pyrus spp.). Here, we reported that the sugar contents in mature ‘Zaosu’ pear fruit grafted on ‘Yunan’ quince (Z/Q) were higher than that in ‘Zaosu’ pear fruit grafted on ‘Duli’ (Pyrus betulifolia) (Z/D). To investigate the underlying mechanism, the leaf photosynthetic capacity and the leaf-to-fruit assimilate transport capacity were initially analyzed. The leaf photosynthetic capacity was similar between Z/Q and Z/D, but the assimilate transport capacity was greater for Z/Q than for Z/D. Sugar transporters mediate the distribution of assimilates; therefore, changes in PbSWEET transcriptional patterns were examined. PbSWEET6 was highly expressed in Z/Q fruit. Thus, the PbSWEET6 function related to assimilate transport was further verified. Sucrose and glucose contents increased in transgenic tomato fruit and pear fruit calli overexpressing PbSWEET6. Taken together, these results suggest that ‘Yunnan’ quince positively regulated fruit sugar contents by influencing the flow of PbSWEET6-involved assimilates in the scion. Full article

Edible coatings are an appropriate way to preserve the quality of horticultural crops and reduce post-harvest losses. In this study, treatments with proline (Pro), chitosan (CTS) and proline-coated chitosan nanoparticles (CTS-Pro NPs) to maintain quality and reduce the decay of strawberry fruit were examined during storage at 4 °C for 12 days. The strawberries were treated with Pro 1 and 5 mM, CTS at 0.1% (w/v), CTS-Pro NPs at 0.1% (w/v) and distilled water (control) at 20 °C for 5 min. Following 3, 6, 9 and 12 days of cold storage, the fruits were removed from refrigeration, and some traits were evaluated one day after storage under shelf-life conditions. The results indicated that the fruit coated with CTS and CTS-Pro NPs showed reduced malondialdehyde and hydrogen peroxide content and less decay and weight loss compared to control and proline. CTS-Pro NPs also preserved fruit quality by conserving higher levels of ascorbic acid, total soluble solids, total phenolic content, and antioxidant capacity and enzymes. These results confirmed the benefit of using chitosan and CTS-Pro NP coatings to maintain fruit quality and increase the shelf life of strawberries by enhancing their antioxidant system and their ability to eliminate free radicals under cold storage. Full article

Sustainable nutrient and water management are critical for optimizing the quality and subsequent landscape performance of nursery plants. In this 2-year study, we investigated the influence of different nitrogen (N) rates [N-free fertilizer (0 N) or N-free fertilizer plus 7 (0.5 N) or 14 (1.0 N) mg N per day from NH₄NO₃] and irrigation frequencies and volumes [once daily to 50% or 100% container capacity (CC) or twice daily with the same total amount of water as 100% CC] on plant growth, flowering, and nutrient uptake of three rhododendron cultivars, including one deciduous cultivar, Rhododendron ‘Gibraltar’ and two evergreen cultivar, Rhododendron ‘P.J.M.’ and Rhododendron ‘Catawbiense Album’. In each case, the plants were grown in soilless media in year 1 and transplanted to soil in year 2. Increasing the N rate in year 1 increased plant biomass and N content in both years and improved flowering performance the following year. Furthermore, in year 1, irrigation once daily to 50% CC or twice daily to 100% CC enhanced the uptake of several nutrients in each cultivar and the growth of the evergreen cultivars. Plants that were irrigated more frequently during year 1 performed better in the landscape the following year, while those irrigated to 50% CC only performed better in the deciduous cultivar. In the evergreen cultivars, lower irrigation volume altered nursery plant qualities, resulting in a trade-off between flower production and growth in year 2. Our results indicate that manipulating N rates and irrigation frequency and volume can be used to alter nursery stock qualities and improve subsequent performance in the landscape. Full article

Phytophthora cinnamomi causes one of the most important diseases in avocado crop and its chemical management represents 25% of the production cost per year. Induction of plant defense responses by elicitors is a promising strategy that is compatible with sustainable agriculture. This study aimed to evaluate the effect of curdlan application on the induction of defense responses in avocado plants against P. cinnamomi. The trials were conducted under greenhouse conditions, and curdlan leaf spraying was performed one day before the inoculation of the pathogen. The results showed that the application of elicitor significantly increased the protection of avocado plants against P. cinnamomi, decreasing the injury and wilting. The Curd + Phy treatment improved the defenses of plants by increasing the enzymes peroxidase (POD) and polyphenol oxidase (PPO) in the first 3 h after inoculation and increasing the enzymes superoxide dismutase (SOD) and phenylalanine ammonium lyase (PAL) 144 h after inoculation (p < 0.05). Also, chlorophyll and carotenoid content increased or remained stable in Curd + Phy treatment. Therefore, these results suggest that curdlan increases the protection against P. cinnamomi and its protection could be due to an increase in the activity of the enzymes related to the phenylpropanoid pathway as well as the effect on chlorophyll and carotenoids. Full article

The aim of the present study was to evaluate the effects of three biostimulant products (Nomoren (N), Twin Antistress (TW), x-Stress (XS) and control treatment (C: no biostimulants added)) on the nutritional value, chemical composition and bioactive properties of greenhouse tomato fruit grown under full (W+: 100% of field capacity) and deficit irrigation (W–: 70% of field capacity) conditions. Fat content was the highest for the fully irrigated plants that received no biostimulants (CW+), while proteins and carbohydrates and energetic value were the highest in the XSW+ treatment. The content of the main detected sugars (fructose, glucose and trehalose) varied depending on the irrigation and biostimulant treatment. The highest amounts of individual and total organic acids and tocopherols were recorded in fully irrigated plants treated with Twin Antistress (TW), whereas the lowest overall values were observed under deficit irrigation for plants that received the XS treatment. The most abundant fatty acids were palmitic (27.5–36.0%) and linoleic acid (27.4–35.4%), followed by oleic (9.2–21.2%), linolenic (5.4–13.1%) and stearic acid (5.3–6.8%). Moreover, the highest values of β-carotene and lycopene were recorded for the CW- and NW+ treatments, respectively. The TWW+ showed the highest antioxidant activity for both assays tested (TBARS and OxHLIA). Most of the tested extracts showed lower antibacterial activity against the tested bacteria compared to the positive controls. On the other hand, CW+, XSW+ and XSW- treatments showed higher antifungal activity (MIC values) than positive controls. In conclusion, each biostimulant product had a different effect on the determined characteristics depending on the level of irrigation. Therefore, more research is needed to better identify the mechanisms of action and the physiological processes, after which the tested biostimulants may be used to standardize the application of such products in tomato cultivation. Full article

Maintaining uniform photon irradiance distribution above the plant canopy is a fundamental goal in controlled environment agriculture (CEA). Spatial variation in photon irradiance below the light saturation point will drive differences in individual plant development, decreasing the economic value of the crop. Plant growth is also affected by the spectral composition of light. So far, little attention has been paid to the quantification of the spatial variability in horticultural lighting applications. This work provides a methodology to benchmark and compare lighting installations used in indoor cultivation facilities. We measured the photon irradiance distributions underneath two typical grow light installations using a 10 × 10 measurement grid with 100 mm spacing. We calculated photon irradiance values for each grid point for 100 nm-wide blue, green, red and far-red wavebands covering the 400–800 nm range. We showed that the generally used uniformity metric defined as the minimum to average ratio of PPFD is not appropriate for the characterization of light uniformity in horticultural lighting applications. Instead, we propose to normalize photon irradiance to the maximum, analyze the histograms constructed from relative photon irradiance values and consider the light response of the cultivated crop while comparing the performance of CEA grow systems. Full article

High CO₂ treatment is a widely used deastringency technology that causes the accumulation of acetaldehyde which precipitates the astringent soluble tannins from persimmon fruit, making them more attractive to consumers. The identification of DkADH1 and DkPDC2 (the key genes for acetaldehyde accumulation) and their regulators (e.g., ERFs), has significantly advanced our understanding of the fruit deastringency mechanism, but other TFs are also involved in the high CO₂ response. Here, 32 DkDofs genes were identified from ‘Gongcheng-shuishi’ persimmon, with nine of them shown to differentially respond to high CO₂ treatment. Dual luciferase assay indicated that DkDof3 and DkDof6 could repress the promoters of DkADH1 and DkPDC2, respectively. EMSA assay showed that DkDof3 and DkDof6 physically interacted with probes containing T/AAAAG elements from the DkADH1 promoter, whereas they failed to recognize similar elements from the DkPDC2 promoter. The expression of DkDof3 and DkDof6 was also found to be repressed in different persimmon cultivars in response to high CO₂ treatment. It is proposed that DkDof3 and DkDof6 were involved in fruit deastringency by regulating the expression of DkADH1 and DkPDC2 in different persimmon cultivars. Full article

In this study, we analyzed and compared the concentrations of selected metals/metalloids and the antioxidant response of Salix alba L. (white willow) bark in the highly polluted area around the Kosovo A and B thermal power plants. The antioxidant capacity of Salix alba bark was evaluated in terms of the total phenolics, flavonoids, chlorophylls, and carotenoids, while the metal content in the soil and willow bark was analyzed by ICP-OES (inductively coupled plasma optical emission spectroscopy). For total antioxidant level assessment, FRAP, DPPH, and CUPRAC assays were conducted. The mean concentrations of selected elements in soil and willow dry mass range from 15,698.4 mg kg⁻¹ dry mass (soil) to 371.1 mg kg⁻¹ (willow bark) for Al; 37.676 mg kg⁻¹ (soil) to <2 ppb (willow bark) for As; 14.8 mg kg⁻¹ (soil) to 0.62 mg kg⁻¹ (willow bark) for Cd; 24.2 mg kg⁻¹ (soil) to 1.2 mg kg⁻¹ (willow bark) for Cr; 58.8 mg kg⁻¹ (soil) to 9.1 mg kg⁻¹ (willow bark) for Cu; 16,975.68 mg kg⁻¹ (soil) to 385.4 mg kg⁻¹ (willow bark) for Fe; 95.0 mg kg⁻¹ (soil) to 7.9 mg kg⁻¹ (willow bark) for Ni; 185.2 mg kg⁻¹ (soil) to <1 ppb (willow bark) for Pb; and 226.7 mg kg⁻¹ (soil) to 87.7 mg kg⁻¹ (willow bark) for Zn. Additionally, the Salix alba bark samples presented mean values of 12,191.6 mg kg⁻¹ for Ca, 1306.0 mg kg⁻¹ for Mg, and 123.1363 mg kg⁻¹ for Mn. The mean phenolic content was 39.292 mg GAE g⁻¹ DW, being 28.222 mg CE g⁻¹ DW for flavonoids, 38.099 mg g⁻¹ FW for CHLa, 49.240 mg g⁻¹ FW for CHLb, and 94.976 mg g⁻¹ FW for CAR. The results of this study indicate that the bark of Salix alba contains significant amounts of phenolic compounds, and strong positive and moderate negative correlations are revealed between total phenolic compounds and iron, and total phenolics and nickel and manganese, respectively. Full article

Black cardamom (Amomum tsao-ko Crevost & Lemarié) is a spice plant of great commercial value in Vietnam, but with limited propagation ability. Its seeds are characterized by a thick and hard seed coat, a small endosperm, and a small embryo, which are the causes of the physical dormancy of the seeds and low germination. Attempts in this study to improve the germination rate and achieve uniform germination included mechanical scarification, immersion in hot or cold water, acid scarification, and the application of plant growth regulators. Although immersion of seeds in cold water and application of plant growth regulators (PGRs) (gibberellic acid (GA₃) and 1-naphtaleneacetic acid (NAA)) showed positive effects on seed germination and subsequent seedling growth, mechanical scarification provided the highest germination rate of black cardamom seeds (68.0%) and significantly shortened germination time (53.7 days) compared to control (16.0% and 74.7 days). On the other hand, an efficient micropropagation protocol has been established using shoot tip explants derived from in-vitro-grown seedlings. Murashige and Skoog (MS) medium supplemented with 4.0 mg/L 6-benzylaminopurine (BAP) + 0.5 mg/L NAA proved to be most suitable for rapid multiplication and rooting, providing a mean of 5.4 shoots per explant, 6.8 cm shoot length, and 16.2 roots per explant after 7 weeks of culture. Well-rooted black cardamom plantlets have been successfully adapted to ex vitro conditions. “Fasco” bio-soil was more suitable for acclimatization, with a 48.9% survival rate, 23.3 cm plant length, and 5.7 leaves per plant after 3 months of planting. Improved germination and multiplication protocols can be used to improve propagation performances and to develop elite of black cardamom planting material. Full article

Drought-tolerant plant growth-promoting rhizobacteria (PGPR) may promote plant development under limited water supply conditions, when plant’s water demand is not completely satisfied under rain-fed conditions or when irrigation water availability is limited. The aim of this study was to examine the effects of two inoculation treatments (B2: Alcaligenes sp. 3573, Bacillus sp. BAR16, and Bacillus sp. PAR11 strains and B3: Pseudomonas sp. MUS04, Rhodococcus sp. BAR03, and Variovorax sp. BAR04 strains) and compare those to a control (B0) without artificial inoculation on chlorophyll fluorescence, leaf chlorophyll content (SPAD value), canopy temperature, and the yield of the processing tomato cultivar H-1015 F1 grown under field conditions. The young seedlings of the hybrid tomato variety H-1015 F1 were immersed in 1% of B2 or B3 products (BAY-BIO, Szeged Hungary) for 5 min. Inoculated and untreated seedlings were grown under three irrigation treatments [regular irrigation (RI), deficit irrigation (DI), and no irrigation (I0)], to reveal the effect of PGPR under different levels of water stress. In the dry year (2018), higher canopy temperature and chlorophyll fluorescence (Fv/Fm) were measured during flowering in plants treated with bacteria than in untreated plants. In the stage of flowering and fruit setting, the B3 treatment led to a significant decrease in the Fv/Fm value, canopy temperature remained high, and the SPAD value was statistically the same in all treatments. Under limited water supply, in most cases, PGPR led to a significantly greater total yield but more unripe green berries compared to untreated plants. Under moderate water shortage (dry year + deficit irrigation), the B3 treatment resulted in 26% more ripe, marketable fruit and 49% less unripe fruit compared to the B2 treatment. On the other hand, in the wet year (2020), the bacterial treatments generally did not affect physiological properties, though the B2 treatment produced a higher marketable yield while the amount of green and diseased fruits did not differ statistically, compared to the B3 treatment under deficit irrigation. Based on our study, we recommend the application of the B3 PGPR product as it positively affected key physiological processes, leading to a higher marketable yield particularly under water shortage. Full article

In the present study, the chemical profile and bioactive properties of the roots of turnip-rooted parsley (Petroselinum crispum spp. tuberosum) germplasm were evaluated. For this purpose, plants from seventeen parsley cultivars were grown in 6 L pots, and the obtained roots were analyzed in terms of nutritional value, chemical composition (tocopherols, sugars and organic and fatty acids) and bioactive content (antioxidant activity, phenolic compound composition and antimicrobial properties). Our results showed great variability in terms of the chemical composition and bioactive properties of root parsley germplasm. A higher fresh root yield was recorded for the common “Root parsley” common variety (164 g/pot), followed by the varieties “Osborne” (109 g/pot), “Sonata” (104 g/pot), “Kaśka” (104 g/pot) and “Halblange Berlinska” (103 g/pot), whereas the lowest yield was recorded for the “Hanacka” variety (69 g/pot). A significant variation was also observed in the nutritional value parameters: the roots of the “Sonata” genotype showed the highest fat content; “Arat”, “Osborne” and “Olomuńcka” had the highest ash content; the “Alba” cultivar contained significantly higher amounts of carbohydrates; and the “Vistula” cultivar showed the highest energetic value. The only detected isoforms of vitamin E were α- and δ-tocopherols; content varied depending on the cultivar, although α-tocopherol was the most abundant compound in most cultivars, especially in the “Arat” cultivar. Sucrose was the most abundant free sugar detected, especially in the “Sonata” cultivar (16.96 g/100 g dw), followed by apiose (2.93–5.55 g/100 g dw), glucose (1.3–3.47 g/100 g dw) and fructose (1.37–3.03 g/100 g dw). Moreover, malic acid was the most abundant organic acid in most of the tested cultivars. Twenty-one individual fatty acids were identified in all the studied cultivars, with linoleic (47.9–57.1%) and palmitic acid (20.66–20.5%) being the most abundant. Nineteen individual phenolic compounds were tentatively identified, including three phenolic acids, fourteen flavonoids and two hydrolyzable tannins, while apigenin-O-pentoside-O-hexoside was the most abundant. The antioxidant activity differed between the tested assays (TBARS and OxHLIA), and the most effective cultivars for the TBARS assay (“Root parsley (common variety)” and “Berlinski Halblange Springer”) were those with the lowest antioxidant activity for the OxHLIA assay after 120 min. Finally, in most cases, the root extracts were more efficient or similarly effective compared to the positive controls against the tested bacteria and fungi. In conclusion, our results provide information regarding the chemical characterization and the bioactivities of the roots of turnip-rooted parsley germplasm that could be further exploited in sustainable and diversified agro-ecosystems through the introduction of this species as a novel/complementary crop in the traditional farming systems of the Mediterranean basin. Full article