Horticulturae

Cyclic diguanylate (c-di-GMP) affects bacterial physiological and biochemical functions like biofilm, motility, virulence, and bacterial secretion systems. GGDEF/EAL-domain proteins, participating in c-di-GMP synthesis and degradation, are widely present in Pseudomonas, with various structures and functions. Pseudomonas glycinae MS82 is a rhizosphere bacterium that protects mushroom against the pathogenic fungi. Although 14 genes encoding GGDEF/EAL-domain proteins have been identified in the genome of MS82, c-di-GMP regulation is poorly understood as a facilitator or repressor of physiological phenotypes. Here, PafQ and PafR, encoding the proteins with the tandem GGDEF/EAL domain, were functionally analyzed and found to regulate antifungal activity. Individual deletion mutants of PafQ and PafR were constructed in P. glycinae MS82 through biparental conjugation and homologous recombination. Subsequently, antifungal activity, biofilm formation, motility, and expression of the genes related to antifungal substance synthesis were examined and contrasted with those of wild-type P. glycinae MS82. Most phenotypes of physiological activities were significantly reduced after knocking out PafQ or PafR. In other members of the genus Pseudomonas, homologous genes of PafQ and PafR possess different functions in c-di-GMP regulation. In P. glycinae, the positive regulation of PafQ and PafR on fungistatic substance synthesis, biofilm formation, and motility is crucial in the biocontrol of mushroom diseases. Full article

In order to investigate the impact of peach branch derived fertilizer (PB), cow manure derived fertilizer (CM) and silicon liquid fertilizer (Si) on the growth and Cd uptake of the Spinacia oleracea L. in the Cd contaminated soil, a pot experiment was conducted. The fertilizers were applied with low (L), medium (M) or high (H) levels, leading to nine treatments and a control group (CK). As a result, compared to CK, PB increased shoot dry mass by 15 to 46% and reduced shoot Cd by 19 to 56%; CM increased shoot dry mass by 6.1 to 162% and reduced shoot Cd by 38 to 55%; Si showed no effect on plant biomass but significantly reduced the root Cd bioconcentration factor. The CMM and CMH significantly reduced soil-available Cd by 6.5 and 7.5%, respectively, compared to CK. The CM enhanced the plant biomass dilution of Cd and decreased soil-available Cd, but led to higher total shoot Cd accumulation. PB led to simultaneous decline of the shoot Cd and total shoot Cd accumulation, indicating a stronger plant Cd “rejection” effect, independent from biomass accumulation. Si reduced plant root Cd with the sacrifice of biomass accumulation. Full article

One of the major challenges that global society is facing nowadays is finding sustainable and safe methods for crop growth and development. Besides the traditional crops cultivated worldwide (tomatoes, potatoes, lettuce, strawberries, etc.), there is a general trend in the exploitation of polyvalent plants. Mulberry (Morus spp.) faced no exception; with its undeniable proprieties, it became suitable not only to be used in the sericulture industry, but in the food chain, the pharma industry, and environmental safety. Spare parts of the plants can be used in a very wide range, starting from introducing mulberry leaves in supplements to increase the protein content of a meal to extracting biologically active compounds from fruits and roots to be used in phytotherapy. However, the outstanding proprieties of this plant come with some requirements related to space availability and watering; requirements that can be easily surpassed by using vertical farming methods, such as hydroponic, aeroponic, or aquaponic systems. The present paper aims to evaluate vertical farming techniques’ applicability to mulberry propagation in a controlled environment and their prospects for a more sustainable and safer agricultural practice. Full article

Picking robots have become an important development direction of smart agriculture, and the position detection of fruit is the key to realizing robot picking. However, the existing detection models have the shortcomings of missing detection and slow detection speed when detecting dense and occluded grape targets. Meanwhile, the parameters of the existing model are too large, which makes it difficult to deploy to the mobile terminal. In this paper, a lightweight GA-YOLO model is proposed. Firstly, a new backbone network SE-CSPGhostnet is designed, which greatly reduces the parameters of the model. Secondly, an adaptively spatial feature fusion mechanism is used to address the issues of difficult detection of dense and occluded grapes. Finally, a new loss function is constructed to improve detection efficiency. In 2022, a detection experiment was carried out on the image data collected in the Bagui rural area of Guangxi Zhuang Autonomous Region, the results demonstrate that the GA-YOLO model has an mAP of 96.87%, detection speed of 55.867 FPS and parameters of 11.003 M. In comparison to the model before improvement, the GA-YOLO model has improved mAP by 3.69% and detection speed by 20.245 FPS. Additionally, the GA-YOLO model has reduced parameters by 82.79%. GA-YOLO model not only improves the detection accuracy of dense and occluded targets but also lessens model parameters and accelerates detection speed. Full article

Michelia crassipes is a great ornamental plant, the flowers of which have high economic value. In this study, we employed headspace solid-phase microextraction (HS–SPME) combined with gas chromatography high-resolution mass spectrometry (GC–HRMS) for the first time to identify the volatile compounds emitted from different organs of M. crassipes flowers at different flowering stages. M. crassipes flower odor comprises 69 volatile compounds that are dominated by terpenes constituting 84% of collected volatiles. It was found that α-guaiene, β-caryophyllene and germacrene B had the highest relative amounts, while ethyl 3-methyl valerate, methyl benzoate and β-damascone had the highest odor activity values (OAVs). This contributed to the complex fruity, woody and floral aromas of M. crassipes. Total odor emission increased along the flower blooming, which was most abundant in the pistil followed by tepals and stamens. Paraffin sections of M. crassipes flower organs showed the highest density of oil secretory cells in the pistil at the full flowering stage, which was positively correlated with total odor release. The scent of the pistil and tepals was characterized by terpenes, whereas stamens was characterized by benzenoids. We suggest that the benzenoids in stamens might contribute to pollinator attraction in M. crassipes. Full article

Sustainable agriculture is the most desired solution to ensure food security for the growing world population and to face climate change. Furthermore, sustainable agriculture seeks alternatives to harmful pesticides and chemical fertilizers. This review presents an overview of recent scientific research and potential applications of volatile organic compounds (VOCs) as pest biocontrol and disease management during pre- and postharvest, along with possible limitations in scalability at the agricultural level. According to the information reviewed, bacteria, fungi, yeast, and plants are the principal organisms that produce VOCs with biotechnological potential. The main applications reported for VOCs are enhanced resistance/tolerance to abiotic stressors, such as drought, cold, and salinity, and an enhanced defense response against biotic stressors, such as viruses, bacteria, fungi, nematodes, and insects. Some VOCs in particular present an antimicrobial effect on a wide range of plant and human pathogens. Therefore, VOCs are considered a promising, sustainable biocontrol strategy that can replace pesticides and fertilizers. However, future research needs to promote collaboration with farmers and the development of applications for VOCs at the industrial level. Full article

In order to provide early selection indicators for the breeding of plants used for producing tea seed oil or harvesting tea, we investigated the relationships between flower morphology and fruit yields in tea plants. We analyzed 106 tea varieties to determine the relationships between flower morphological traits and fruit yields. Notably, the homogeneity of flower traits within the same tea plant variety was found to be very high. The average length and width measurements of certain phenotypic traits of tea plants, including pistil length, stamen length, stamen bundle inner width, stamen bundle outer width, and stigma width, were 11.8, 10.9, 2.5, 15.0, 3.7 mm, respectively. In this study, the flower traits that affect fruit yield appear to be related to the difficulty of pollination by insects (e.g., bees), in terms of their contacting the stigma. In 2013, three phenotypic trait variables showed significant effects on yield; namely, the stamen bundle outer width (negative), stigma width (positive), and stigma width minus the stamen bundle inner width (positive). In 2015, only the stamen bundle outer width had a significant negative effect on yield. Regarding pollen viability, in the TTC (2,3,5-triphenyl tetrazolium chloride) staining test, about 84% of the considered tea varieties presented pollen viability exceeding 70%. This indicates that most tea pollen has the ability to germinate normally after contact with the cross-pollinated stigma. The yields of all of the tea varieties exhibited a positively skewed distribution in 2013 and 2015. Although our results indicate that flowers in the anther superior group tend to produce fewer fruits than flowers in the stigma superior group in 2013, in the analysis of the effect of traits on yield, there were no significant differences in the relative positions of stigmas and anthers. In conclusion, we determined that the main trait affecting fruit yield is stamen bundle outer width, while the secondary trait affecting fruit yield is stigma width. However, the efficacy of the stigma width may also be affected by the position of the stigma relative to the anther and the stamen bundle inner width. These two traits have the potential to be used as reference indicators for early selection in future breeding programs. Full article

Pleurotus ostreatus is one of the most cultivated mushrooms worldwide. It is a lignocellulolytic fungus cultivated on different substrates, whose more common raw material is straw. The present study investigated the biological efficiency of Pleurotus ostreatus as affected by the different age of straw and the growing media preparation process in four production cycles. The content of organic carbon significantly decreased during the growing media preparation, while the content of total nitrogen, moisture, and ash, as well asthe pH value, showed an opposite trend. The first production cycle was characterized by the highest total and soluble sugar content. A dramatic reduction in soluble sugars was recorded at the end of the preparation of the growing media, regardless of the production cycle, while the total sugars were slightly reduced during the production cycle. The microbial population was significantly influenced by the growing media preparation, while only bacteria were slightly influenced by the straw’s age. In contrast, cellulase activity significantly increased in the old straw, while an opposite trend was observed for pectinase activity. The β-glucosidase activity was influenced only by the growing media preparation. As expected, cluster analysis showed that the microbial community changed in each phase of growing media preparation. Finally, the biological efficiency of Pleurotus ostreatus decreased from 26.28% to 15.49% with increasing age of the straw, which may presumably be ascribed to the higher content of sugars in fresh straw compared to the older ones. Therefore, fresh straw should be used to prepare the growing media of Pleurotus ostreatus in order to increase its biological efficiency. Full article

The plant growth regulator ethylene influences rachis browning in grape (Vitis vinifera L.). Although the ethylene signaling pathway is well defined, there is limited knowledge on its mode of action during rachis browning. Here, we show that an ethylene response factor (VvERF111) positively regulates chlorophyll degradation in rachis by binding to a DRE motif in the promoter of VvCLH1. The expression of VvERF111 and VvCLH1 in rachis was induced by ethylene and inhibited by 1-methylcyclopropene (1-MCP). VvERF111 belongs to the ERF IX subfamily of the APETALA2/ethylene responsive factor (AP2/ERF) superfamily, shows transcriptional activity in yeast, and is localized in the nucleus and membrane. The transient overexpression of VvERF111 or chlorophyllase (VvCLH1) in grape leaves accelerated chlorophyll degradation. In VvERF111-overexpressing leaves, transcript levels of VvCLH1 were also increased. Our findings offer a deeper understanding of the transcriptional regulation of chlorophyll degradation during the rachis browning of grape. Full article

Citrus are one of the most important fruit crops in the world, and the citrus hybrid cv. Beni-Madonna (BM) is widely cultivated in Xiangshan County in China because of its profitability. However, due to the lack of technical guidance and management, nutritional unbalances of trees occur frequently and are a major constraint for fruit quality and yield. In this study, the soil and fruit nutritional status of 62 citrus orchards in three diverse landforms (mountain, flat, and coastal saline–alkali land) located in Xiangshan County has been investigated. Higher pH, calcium, and magnesium content but lower soil organic matter, nitrogen, iron, and boron content were observed in orchards of the coastal saline–alkali land compared with the mountain and flat lands. Compared to Citrus x unshiu, another major hybrid citrus cultivar in Xiangshan county, the Fe deficiency in fruits of BM in coastal saline–alkali lands was more severe, leading to chlorosis symptoms. In addition, long-term cultivation under plastic housing increased soil salinization and affected the absorption of Fe and other nutrients by BM. In conclusion, organic fertilizers, acidic fertilizers, and micronutrient fertilizers should be applied in citrus orchards located in coastal saline–alkali lands. Especially, BM orchards should be supplemented with iron fertilizer and not rely excessively on protection with plastic films. Full article

The yield of the crop is a complex function of a number of dependent traits, which makes yield prediction a statistically difficult task. A number of work on yield prediction using morphological characters already exists in the literature. Most of the work used statistical techniques such as linear regression and crop yield models, which assume a linear relationship between yield and the morphological traits; in actual practice, such a linear relationship is seldom achieved. With the advancement in the field of machine learning techniques, these methods can provide a viable alternative for dealing with nonlinear relationships for yield prediction. Globally, apples are the most consumed fruit. In this paper, attempts have been made to predict the yield of the apple crop using morphological traits. PCA was used for selection of the significant variables. These variables were later used as input variables in the ANN model with different hidden layers for predicting crop yield. The predictive performance of the model was evaluated using standard statistical tests. Sensitivity analysis was performed to find out the individual effects of each character on the apple yield. The study contributes to a better understanding of the complex relationships between crop yield and morphological traits. Full article

Panax ginseng Meyer is an important medicinal crop; however, most ginseng farmers cultivate native species that are not genetically fixed. Although several cultivars have been developed in Korea, distribution to farmers remains insufficient given their low propagation characteristics. This study compared the efficiency of seed production and micropropagation via somatic embryogenesis. Seeds were collected from cultivars, and zygotic embryo-derived explants were inoculated and cultured in a series of media for micropropagation. Seed production and characteristics of commercial cultivars were evaluated. The number of seeds from a 4-year-old individual cultivar was 23.1–58.8, and seed characteristics varied with cultivars. The genotype had a notable effect on somatic embryogenesis and plant regeneration. The number of somatic embryos and shoots obtained from a single seed of cultivars was 71.3–100.2 and 50.7–61.3, respectively. The number of in vitro grown roots (IGRs) per a single seed was 37.1–41.1 in one year. IGRs were successfully acclimatized and sprouted normally in the field. Flow cytometry analysis suggested that micropropagated plants had no ploidy variations. The results demonstrated the utility of somatic embryogenesis in the in vitro micropropagation of P. ginseng cultivars. Our findings can enhance the distribution of cultivars among farmers in the future. Full article

The absorption and utilization of NH₄⁺ and NO₃⁻ by plant roots is closely related to soil moisture. In this study, we investigated the effect of short-time drought and rewatering on uptake and assimilation of NH₄⁺ and NO₃⁻ in 1-year-old Malus hupehensis plants, as well as transcription changes of ammonium transporters (AMTs) and nitrate transporters (NRTs). In roots, the NH₄⁺ and NO₃⁻ content and nitrate reductase activity decreased under drought and to some extent was restored after rewatering. Expression analysis indicated that most investigated AMTs and NRTs were down-regulated while MhAMT1;2 was significantly up-regulated in drought-stressed roots. Therefore, the function of MhAMT1;2 was further studied through bioinformatics analysis, tissue-specific expression, subcellular localization, and functional complementation in NH₄⁺ uptake-defective yeast and Arabidopsis mutants. Results showed that MhAMT1;2 was mainly expressed in roots and localized to the cell membrane. Moreover, MhAMT1;2 can mediate NH₄⁺ uptake in both yeast and Arabidopsis mutants, and the transport process was affected by external proton concentrations and ATP. The present study will create a basis for exploring the functional roles of plant AMT members and improving N uptake and use efficiency under drought condition in fruit trees. Full article

The species Brassica rapa includes enormous leafy vegetables with extreme leaf morphological diversity. Leaf traits such as size, shape, weight, and ratio of the leaf blade to the petiole contribute to yield, appearance, and desirability to consumers. These leaf-related traits are controlled by quantitative trait loci (QTLs). The construction of high-density bin maps using low-coverage sequencing is a powerful method for QTL fine-mapping and gene identification. In this study, we performed whole-genome re-sequencing of Wutacai ‘Zhongbaye’ and Chinese cabbage ‘HN53’ and 150 F₂ individuals to construct a high-density bin map for QTL mapping of 11 leaf-related traits. The parental lines and F₂ population were re-sequenced at 10x and 1x coverage, respectively. A map containing 565 bin markers was constructed based on parental single-nucleotide polymorphisms and a modified sliding window approach. The total map length was 944.6 cM and the average distance of the bins was 1.65 cM. In total, 60 significant QTLs controlling 11 leaf-related traits were detected. We further identified candidate genes responsible for these complex leaf-related traits. These findings suggest that this cost-effective bin-mapping approach is capable of rapid identification of QTLs and candidate genes, and will thus facilitate the dissection of the underlying molecular basis of leaf morphological variations and accelerate the improvement of B. rapa vegetable breeding. Full article

The kiwifruit [Actinidia deliciosa (A. Chev.) C.F. Liang & A.R. Ferguson] has attained significant importance for commercial cultivation in the mid-Himalayan region of the Indian subcontinent during the last three decades. The fruit quality matching international standards has remained a concern. Keeping in mind the bio-stimulatory effects of seaweed extract, a marine bioactive component in horticultural crops, the current study conducted to elucidate the impact of seaweed extract on kiwifruit growth, yield, and quality was conducted in the Department of Fruit Science’s kiwifruit block at Dr. Yashwant Singh Parmar University of Horticulture and Forestry, Nauni, Himachal Pradesh, India. For the studies, nine-year-old Allison kiwi vines of uniform size and vigor were planted at a spacing of 4 m × 6 m. With 11 treatments, the experiment was set up in a randomized block design viz, T₁: Spray treatment of 1000 ppm (seaweed extract) SWE at fruit set (FS); T₂:Spray treatment of 2000 ppm SWE at FS; T₃: Spray treatment of 3000 ppm SWE at FS; T₄: Spray treatment of 1000 ppm SWE at FS and 10 days after Fruit set (FS); T₅: Spray treatment of 2000 ppm SWE at FS and 10 days after FS (DAFS); T₆: Spray treatment of 3000 ppm SWE at FS and 10 days after FS; T₇: Fruit dip treatment of 1000 ppm SWE at 10 days after FS; T₈: Fruit dip treatment @ 2000 ppm SWE at 10 days after FS; T₉: Fruit dip treatment @3000 ppm SWE at 10 days after fruit set; T₁₀: Fruit dip treatment @ 5 ppm CPPU at 10 days after fruit set; T₁₁: Control. The current study compared several seaweed extract treatments, which were applied at various times and concentrations, to N-(2-chloro-4-pyridyl)-N-phenyl-urea (CPPU-5ppm) and untreated control. Seaweed extract (SWE) dip at 3000 ppm 10 days after the fruit set produced significant growth in fruit length and diameter in growing kiwifruit, which was non-significant with CPPU treatment and superior to control. The shape index, fruit weight, and total fruit yield were also found to be the highest with the same treatment. Fruit quality parameters, namely fruit soluble solids contents (SSC) and total sugars, were recorded at a maximum with the SWE Spray dose of 3000 ppm at FS and 10 DAFS. The SSC: Acid ratio and reducing sugars were recorded as the highest with an application of SWE dip at 3000 ppm 10 DAFS. The application of SWE dip at 2000 ppm 10 DAFS) was found to advance the harvesting maturity by 6 days and also exhibited the lowest physiological loss in weight (% PLW) with the highest ascorbic acid content. After 15 days of storage at ambient room temperature (25 ± 2 °C), the application of SWE dip at 3000 ppm 10 DAFS recorded the highest SSC acid ratio and the lowest titratable acidity. Thus, the application of seaweed extract dip at 3000 ppm 10 days after the fruit set can be recommended to the farmers as an appropriate alternative to the chemical treatment. Full article

Information on industrial hemp (Cannabis sativa) water use and water stress is sparse. We studied water stress impact in two essential-oil hemp cultivars (‘Wife’ and ‘Cherry’) prompted by anecdotal differences in growth and water use. In a greenhouse setting, we measured water relations, water use, growth, and essential oil (CBD-cannabidiol and THC-delta-9 tetrahydrocannabinol) concentrations. Water stress did not significantly affect THC and CBD concentrations, but both cultivars responded to water stress by reducing transpiration through notably different mechanisms. ‘Cherry’ had more anisohydric behavior, maintaining high stomatal conductance (Gs) and more negative leaf water potential until root zone water depletion triggered partial afternoon stomatal closure to moderate stress, resulting in lower flower and CBD yield. By contrast, water-stressed ‘Wife’ rapidly defoliated half its leaf area in balance with less applied water and so maintained high Gs and flower yield on par with well-watered plants, suggesting potential for deficit irrigation to conserve water and reduce post-harvest vegetation management. Differences in water use translated to provisionally suggested crop coefficients of 1 for ‘Cherry’ and 1.3–1.5 for ‘Wife’, but further research is needed. Because hemp is genetically diverse, and cultivar naming conventions are currently lax, further germplasm screening and research are needed to determine the extent to which either conservative ‘Cherry’ or the water-stress defoliation response of ‘Wife’ is found in the larger population of hemp cultivars. Full article

We aimed to compare the maturation and ripening characteristics of two apple cultivars, early maturation mutant ‘Beni Shogun’ and ‘Fuji’. The study revealed that both cultivars reached full bloom on the same day, but ‘Beni Shogun’ matured earlier than ‘Fuji’. In addition, differences were observed in fruit size, length, width, sweetness, acidity, and ethylene production levels. The study also examined the expression patterns of genes involved in ethylene biosynthesis and signal transduction, as well as those involved in auxin signal transduction and transcriptional regulation, to investigate the putative molecular mechanism behind the distinct fruit development, maturation, and ripening. The expression of the MdACO1 gene showed a sharp increase after the maturation date, whereas the expression of the MdACO7 gene was higher in the early and middle stages of fruit development. The clustering analysis provided insights into the correlation between the phenotypic traits and expression levels of the key genes. They were categorized into three clusters, and the third cluster consisted of six phenotypes, including fruit size, length, width, sweetness, starch content, and ethylene production, as well as the one gene MdACO1. These findings suggest that ‘Beni Shogun’ and ‘Fuji’ have distinct fruit development and ripening behaviors, with ‘Beni Shogun’ maturing earlier than ‘Fuji’. Full article

Fruit size is a major factor determining yield, quality, and consumer acceptability. fw2.2 (fruit weight-2.2) is a primary quantitative trait locus that was the first to be cloned, accounting for 30% of the variation in tomato fruit size. The various homologs of fw2.2 (fw2.2-like) have been identified in many plants and belong to a large family. To date, there has been no report that has carried out a comprehensive identification of fw2.2-like members in pear. In this study, a total of 14 fw2.2-like genes were identified in the pear (Pyrus bretschneideri Rehd) genome and designated as PbFWL1-14. All of the PbFWL genes were unevenly distributed on nine chromosomes, and each chromosome contained between one and four genes. All PbFWL proteins contained more than two conserved motifs, and PbFWL genes contained more than one intron, and the genes of the same subfamily seemed to have a similar intron gene structure. According to the neighbor-joining phylogenetic tree, a total of 78 fw2.2/CNR (cell number regulator) from five plant species, including pear, maize, tomato, peach, rice, and physalis, could be divided into seven subgroups, and PbFWL proteins were mainly distributed in subgroups 1, 3, 4, 5, and 6. The Ka/Ks analysis also revealed that the fw2.2-like gene family of pear may have been subjected to strong purifying selection pressure during its evolution. A cis-element analysis found that many cis-elements responsive to hormones and stress were discovered in promotion regions for all PbFWLs. When combining real-time quantitative PCR analysis detection results, PbFWL1/2/5 were found to be the most likely candidate genes for regulating pear fruit size. Full article

Ethylene is a gaseous phytohormone that delays flowering in Chrysanthemum morifolium Ramat. To date, however, there have been no systematic studies on genes involved in the ethylene response of this species, and the mechanism underlying ethylene-delayed flowering remains unclear. Herein, we applied RNA sequencing to characterize the ethylene response by comparing the transcriptomes of chrysanthemum cultivar ‘Jinba’ with or without ethephon treatment. Six unique RNA-seq libraries were generated. The identified differentially expressed genes (DEGs) primarily involved ethylene, auxin, and abscisic acid signaling genes; circadian clock genes; genes encoding functional proteins associated with floral transition, such as homologs of AP1/FRUITFUL-like 1 (AFL1), TERMINAL FLOWER 1 (TFL1), and so on; and genes encoding transcription factors, specifically of the MYB and bHLH families. Furthermore, quantitative RT-PCR was used to verify the DEGs identified by RNA-seq. Heterologous CmAFL1 overexpression in Arabidopsis thaliana resulted in early flowering. Our findings present a landscape of transcriptomes and reveal the candidate genes involved in the ethylene-mediated regulation of flowering time in chrysanthemum, providing useful data for further studies. Full article