Horticulturae, Volume 10, Issue 2 (February 2024) – 87 articles

Among halophyte plants, Salicornia species (also known as glasswort or sea asparagus) are increasingly grown in open fields and greenhouses for edible or non-edible purposes. Their salinity tolerance makes it possible to irrigate Salicornia plants with saline waters and even seawater, which cannot be used by other crop species. In this work, S. europaea (L.) was cultivated in pots under the typical climatic conditions of the fall season in the Mediterranean region and irrigated with non-saline standard nutrient solution (SNS) or saline wastewater discharged from a greenhouse semi-closed hydroponic (substrate) culture of tomato or a saltwater recirculating aquaculture system (RAS) with Gilthead sea bream (Spaurus aurata L., which was used as such or after dilution (50:50) with SNS. Plant growth was not significantly affected by the composition of irrigation water, while higher antioxidant capacity (measured using the DPPH assay) and concentration of photosynthetic pigments, phenols, flavonoids, and ascorbic acid were found in the shoots of SNS plants than in those of plants irrigated with wastewater. The level of lipid peroxidation and H₂O₂ production significantly increased in the SNS plants, which also showed higher activity of superoxide dismutase and lower activity of catalase. These results suggest that S. europaea can be cultivated using wastewater with moderate to high salinity discharged from greenhouse hydroponic crops or RASs, and that salt is not strictly required for the growth of this species. Using non-saline nutrient solution can result in moderate oxidative stress that improves the shoot quality of S. europaea. Full article

The Phyllanthus genus exhibits a broad distribution spanning across the majority of tropical and subtropical regions. Due to their ability to synthesize medicinal bioactive compounds such as lignans, they have been utilized historically in traditional medicine to treat a wide range of ailments. This review discusses the current knowledge on the potency of lignans for medicinal purposes, the benefit of lignans for plants, various lignans produced by Phyllanthus, and how lignan synthesis could be increased through biotic and abiotic elicitation. Finally, we present a set of connected hypotheses to explain how signaling crosstalk between endophytic microbes and drought stress responses regulates lignan production. Although the mechanisms of lignan synthesis in Phyllanthus are not fully explored, this review strongly supports the view that endophytic fungi and drought stress can increase lignan production in plants belonging to the genus Phyllanthus. The medicinal plant–endophyte–drought stress relationship helps to improve the lignan yield of Phyllanthus, which is crucial for human health and can be optimized under in vitro and in vivo conditions. Full article

Short-term modified-atmosphere storage with an adjusted CO₂ and/or O₂ concentration could recover blueberry fruit infested with the larvae of quarantine pests. However, this could significantly affect the fruit quality. In our experiment we investigated the performance of highbush blueberry ‘Bluecrop’ fruit (firmness, peel color, individual phenolics, sugars, and organic acids) under four short-term storage regimes: (1) a regular atmosphere with 0.03% CO₂, 21% O₂, and 78% N₂ at 22 °C, i.e., the control; (2) a regular atmosphere with 0.03% CO₂, 21% O₂, and 78% N₂ at 2 °C; (3) a modified atmosphere with 10% CO₂, 5% O₂, and 85% N₂ at 2 °C; and (4) a modified atmosphere with 100% CO₂ at 2 °C. Fruit sampling took place after 24 h, 48 h, and 72 h. Fruit firmness was not significantly altered by storage regime or duration, while some significant, but minor, changes were detected in the color parameters. Regarding the primary metabolites, the sugar/organic acid ratio stagnated in the first 48 h in all storage regimes. The content of the majority of the individual phenolics was significantly higher in the fruit stored under control conditions. From our results, we can conclude that the short-term storage of highbush blueberry ‘Bluecrop’ fruit for 24 h in a cold atmosphere does not affect the phenolic content, and storage for 48 h does not affect the total sugar/organic acid ratio, regardless of the atmosphere composition. Full article

Cinnamon (Cinnamomum sp.) essential oil microcapsules, oregano (Origanum sp.) essential oil microcapsules, and oregano–thyme (Thymus sp.) essential oil microcapsules are rarely used in the postharvest preservation treatment of okra (Abelmoschus esculentus L.). The mechanism of these three essential oil microcapsules on the postharvest preservation of okra is also not yet well understood. In this study, fresh okra was preserved by three kinds of essential oil microcapsules (cinnamon essential oil microcapsules, oregano essential oil microcapsules, and oregano–thyme essential oil microcapsules). The effect of essential oil microcapsules on the postharvest storage quality of okra was discussed. We also used RNA-Seq to preliminarily explore the mechanism of oregano–thyme essential oil microcapsules on the pre-harvest storage quality of okra. The results showed that the three kinds of essential oil microcapsules could maintain the high sensory evaluation quality and firmness of okra, slow down the increase in respiratory intensity, slow down the total number of colonies on the fruit surface, and slow down weight loss. Through analysis, it was found that the effect of oregano–thyme essential oil microcapsules was remarkably better than that of cinnamon essential oil microcapsules and oregano essential oil microcapsules. The preservation mechanism of oregano–thyme essential oil microcapsules on postharvest okra was preliminarily elucidated by RNA-Seq. This study provides a certain basis for a follow-up study of essential oil microcapsules in the preservation of okra. Full article

Blueberry (Vaccinium corymbosum) leaves have a positive influence on health because of their phenolic contents, including anthocyanins. Phytohormone abscisic acid (ABA) promotes anthocyanin accumulation, but the underlying mechanisms are unclear in blueberry leaves. In this study, we found that exogenous ABA promotes anthocyanin accumulation in blueberry leaves and we explored the global molecular events involved in these physiological changes by treating in vitro-grown blueberry seedlings with ABA and performing transcriptome deep sequencing (RNA-seq). We identified 6390 differentially expressed genes (DEGs), with 2893 DEGs at 6 h and 4789 at 12 h of ABA treatment compared to the control. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to plant hormone signal transduction and phenylpropanoid and flavonoid biosynthesis were significantly enriched at both stages of the ABA treatment. Analysis of DEGs in plant hormone signal transduction pathways revealed that exogenous ABA affected the expression of genes from other plant hormone signaling pathways, especially brassinosteroid, auxin, and gibberellin signaling. To elucidate the mechanism driving anthocyanin biosynthesis in blueberry in response to ABA treatment, we screened anthocyanin biosynthesis structural genes (ASG) from the phenylpropanoid and flavonoid biosynthetic pathways, MYB transcription factor genes from R2R3-MYB subgroups 5, 6, and 7 and ABRE-binding factor (ABF) genes from the ABA signal transduction pathway. Pearson’s correlation coefficient (r) analysis indicated that the ABFs, MYBs, and structural genes form a network to regulate ABA-induced anthocyanin biosynthesis and MYBA1 is likely to play an important role in this regulatory network. These findings lay the foundation for improving anthocyanin biosynthesis in blueberry leaves. Full article

The Sugars Will Eventually be Exported Transporter (SWEET) is a class of bidirectional sugar transporter that is involved in critical physiological processes such as plant growth and development, and its response to biotic and abiotic stresses. Currently, there are few reports on the SWEET gene family in strawberry. In this study, we mined the SWEET gene family members in Fragaria × ananassa ‘Camarosa’ and carefully analyzed their molecular features and expression patterns. The results showed that 77 FanSWEET genes existed in the F. × ananassa ‘Camarosa’ genome, and the phylogenetic analysis classified them into four sub-groups. Analysis of gene structure, conserved structural domains, and conserved motifs showed that FanSWEETs were highly conserved during the evolutionary process. Expression profiling of the 11 FanSWEET genes revealed that three members were highly expressed in strawberry fruits, which were presumed to be involved in sugar transport during strawberry fruit ripening. In addition, based on the exogenous sugar-spraying treatment and quantitative real-time PCR analysis, we found that different members responded to different sugar treatments in different response patterns, and their functions in sugar transport need to be further explored. The present study provides a reference for further analysis of the functions of the SWEET gene in strawberry. Full article

The recognition of pollen and pistil in the self-incompatibility process is generally determined by the interaction between the pollen S gene and pistil S gene located at the S locus. However, the regulatory mechanism of self-incompatibility in goji remains unknown. In this study, we used the self-compatible strain ‘13–19’ and self-incompatible strain ‘xin9’ from Ningxia as parents to create an F1 hybrid population. Reciprocal cross-pollination was performed within the same plant to evaluate the self-compatibility of the parents and F1 progeny. The parents and progeny were subjected to whole-genome resequencing, and mixed pools of DNA were constructed using 30 self-compatible and 30 self-incompatible individuals. Association analysis using the SNP-index method and Euclidean distance was employed to identify the key candidate region of the S locus. The candidate region was further annotated using the Swiss-Prot database to identify genes within the region. Additionally, transcriptome sequencing data from different organs/tissues, as well as from pistils of self-compatible and self-incompatible strains at control (0 h), short (0.5 h), medium (8 h), and long (48 h) time points after self-pollination and cross-pollination, were analyzed to assess differential gene expression and screen for self-compatibility-related loci. Specific primers were designed for PCR amplification to determine the S-RNase genotypes of the extreme parents. The results revealed that the S locus in goji is located within a 32.2 Mb region on chromosome 2 that contains a total of 108 annotated genes. Differential expression analysis showed that ten genes, including Lba02g01064, were specifically expressed in stamens, with four of them annotated as F-box genes, potentially serving as determinants of self-compatibility in stamens. Lba02g01102 was exclusively expressed in pistils and annotated as an S-RNase gene, likely involved in self-compatibility. The expression of Lba02g01102 in pistils decreased after self-pollination and cross-pollination. Six candidate genes exhibited significant changes after self-pollination and cross-pollination. Both parents and progeny carried two S-RNase alleles, and the S-RNase genotypes showed a significant correlation with self-compatibility, with the self-compatible progeny containing the S8-RNase allele. The identification of the S locus in goji provides molecular markers for future marker-assisted breeding and offers genetic resources for studying the mechanism of self-incompatibility in goji, thus contributing to the improvement of goji varieties. Full article

Osteospermum ecklonis DC. NORL. is native to South Africa and is fully adapted to the Mediterranean climate. The aim of the study was to elucidate morphological and developmental changes in O. ecklonis plants associated with drought resistance in response to low doses of UV-C. Growth responses under three levels of drought stress (NW: normal watering, MD: moderate drought stress and SD: severe drought) were recorded. The results showed that 1 kJ m⁻² UV-C significantly (p < 0.05) increased resistance to water stress without affecting growth and development or damaging photosystem II. Fresh weights of the upper parts and the root system of the irradiated plants were maintained at similar levels to those of the non-irradiated control plants. Fv/Fm values in the irradiated plants ranged from 0.73 to 0.82 depending on the stress level, while in the non-irradiated plants, the values ranged from 0.69 to 0.83. Differences between UV-C irradiated and non-irradiated plants were recorded in electrolyte leakage (EL), in malondialdehyde (MDA) and in relative water content (RWC) at all drought levels. The EL percentage of the non-irradiated plants at SD was 19.7%, while in the irradiated plants, it was 17.8%. RWC rates in the irradiated plants ranged between 60.6 and 76.4%, while in the non-irradiated plants, they ranged from 54.2 to 63.6%. Superoxide dismutase (SOD) and catalase (CAT) activities increased with UV-C irradiation, suggesting that antioxidant responses were induced and protected cell membranes from lipid peroxidation and damage. The results of the present study showed that UV-C irradiation at 1 kJ m⁻² alleviated the drought symptoms of O. ecklonis by reducing oxidative stress and membrane lipid peroxidation. Full article

Litchi (Litchi chinensis Sonn.) is considered one of the most important sub-tropical fruits of the world. In the western part of Odisha, India, litchi growers are facing problems of unstable and lower marketable yield and inferior quality due to a higher incidence of fruit cracking, fruit drop, low sugar content, and higher fruit acidity. Keeping in mind the positive effects of nutrients and bioregulators, the current study was conducted to elucidate their impact on fruit yield and quality in the farmers’ field of Jamankira block in Sambalpur district of Odisha, which is under the care of Odisha University of Agriculture and Technology, India. For this study, eight-year-old litchi trees were selected. With 12 treatments, the experiment was set up in a Randomized Block Design replicated thrice, as follows: T₁: spray treatment with Borax—0.5%; T₂: spray treatment with Borax—0.3%; T₃: spray treatment with ZnSO₄—0.75%; T₄: spray treatment with ZnSO₄—0.5%; T₅: spray treatment with CaCl₂—0.5%; T₆: spray treatment with CaCl₂—0.1%; T₇: spray treatment with humic acid—1.5%; T₈: spray treatment with humic acid—1%; T₉: spray treatment with seaweed extract—0.5%; T₁₀: spray treatment with seaweed extract—0.1%; T₁₁: foliar spray with NAA—20 ppm; and T₁₂: control (Water Spray). The current study compared foliar feeding treatments comprising different nutrient and bioregulators, which were applied during the first week of December, just after the completed formation of new leaves and the untreated control. The highest total number of fruits per plant was recorded in plants sprayed with 0.5% ZnSO₄ (T₄) followed by those treated with 1% humic acid (T₈). The highest total fruit yield was recorded in plants subjected to foliar feeding with 0.3% Borax (T₂) which was found to be statistically similar to plants treated with 0.1% seaweed extract (T₁₀) and 0.5% seaweed extract (T₉). Among the treatments, a better response, i.e., a higher number of marketable fruits and marketable yield, was recorded in litchi plants treated with 0.3% Borax (T₂) followed by 0.5% zinc sulphate (T₄), 1% humic acid (T₈), and 0.1% CaCl₂ (T₆). The application of 1% humic acid (T₈) followed by 1.5% humic acid (T₉) enhanced fruit setting (%) and fruit retention rates (%) and reduced the fruit drop rate (%). The enhanced fruit size (fruit length and fruit width) and higher fruit weight was obtained in litchi plants treated with 0.3% Borax. The foliar application of 0.3% Borax (T₂) also resulted in a higher TSS, total sugars, reducing sugar content, lower acidity, the highest aril weight, and lower seed weight in litchi cv. Bombai. In this research, among the five principal components, only PC1 demonstrated approximately 45.14% variability within the influential axes. PC1 contributed the highest proportion (48.9%) to the overall variability, followed by PC2 with 29.1%, PC3 with 11.9%, PC4 with 0.59%, and PC5 with 0.20%. Consequently, the outcomes of the principal component analysis indicate the presence of extensive variability among treatments. Full article

The aim of this study was to determine the changes in chemical composition of fresh red raspberry ‘Willamette’ fruits caused by the presence of raspberry leaf blotch emaravirus (RLBV). In three experimental orchards of ‘Willamette’ raspberry, fruits were harvested from RLBV-free and RLBV-infected plants in 2019 and 2020. Fruits were collected at appropriate maturity stages and further analyzed in terms of total phenolics, total anthocyanins, and selected individual phenolics. In all three experimental orchards, the phenolic profiles of the infected and uninfected fruit samples were considerably different during both studied years. Nonetheless, the intensity of the modifications varied greatly depending on the location and harvest year. Statistical analysis revealed that the influence of RLBV infection on the studied features was undeniable, although the influences of weather conditions and soil composition outweighed the influence of RLBV. Taking into consideration all the experimental and statistical data, it can be concluded that RLBV had an impact on the phenolic profile of raspberry ‘Willamette’ fruits, while sensitivity to environmental conditions and soil composition is emphasized. Full article

Understanding the diverse environmental influences on seedling growth is critical for maximizing yields. The need for a more comprehensive understanding of how various environmental factors affect seedling growth is required. Integrating sensor data and image processing techniques offers a promising approach to accurately detect stress symptoms and uncover hidden patterns, enhancing the comprehension of seedling responses to environmental factors. The objective of this study was to quantify environmental stress symptoms for six seedling varieties using image-extracted feature characteristics. Three sensors were used: an RGB camera for color, shape, and size information; a thermal camera for measuring canopy temperature; and a depth camera for providing seedling height from the image-extracted features. Six seedling varieties were grown under controlled conditions, with variations in temperature, light intensity, nutrients, and water supply, while daily automated imaging was conducted for two weeks. Key seedling features, including leaf area, leaf color, seedling height, and canopy temperature, were derived through image processing techniques. These features were then employed to quantify stress symptoms for each seedling type. The analysis of stress effects on the six seedling varieties revealed distinct responses to environmental stressors. Integration of color, size, and shape parameters established a visual hierarchy: pepper and pak choi seedlings showed a good response, cucumber seedlings showed a milder response, and lettuce and tomato seedlings displayed an intermediate response. Pepper and tomato seedlings exhibited a wide range of growth stress symptoms, at 13.00% to 83.33% and 2.96% to 70.01%, respectively, indicating considerable variability in their reactions to environmental stressors. The suggested classification approach provides valuable groundwork for advancing stress monitoring and enabling growers to optimize environmental conditions. Full article

Fresh Codonopsis pilosula is highly susceptible to fungus contamination during post-harvest storage, which not only compromises the quality of C. pilosula but also contributes mycotoxin contamination, posing a significant threat to human health. Studies have indicated that ozone treatment can inhibit post-harvest diseases in fruits and vegetables. The impact of ozone treatment on the disease incidence, disease severity index, and weight loss rate of the fresh C. pilosula infected with Actinomucor elegans was investigated through the spray inoculation of A. elegans on C. pilosula tissues. Changes in the main active ingredients of C. pilosula after ozone treatment were analyzed, and the effects of ozone treatment on the integrity of cell membranes in C. pilosula tissue and reactive oxygen species (ROS) metabolism were studied. The results showed that ozone treatment had a significant inhibitory effect on the A. elegans-induced mucor rot in C. pilosula, significantly reducing the incidence of the disease. Compared with the control group, the ozone-treated group maintained the effective components of C. pilosula well. Furthermore, ozone treatment reduced the cell membrane permeability and Malondialdehyde (MDA) content in C. pilosula, significantly increased the activity of antioxidant enzymes in the ROS metabolism pathway, prevented oxidative stress caused by the accumulation of ROS in C. pilosula tissues, and maintained the integrity of cell membranes. Full article

Scab, caused by Venturia inaequalis, is the most destructive fungal disease of apple worldwide. Apple scab incidence was studied in apple orchards in the south and southeast of Kazakhstan, including the Almaty, Zhambyl, and Turkestan regions, during 2022 and 2023. Disease incidence was higher in the Zhambyl region than in the Turkestan and Almaty regions in both years. The field evaluation suggested that 19 genotypes showed resistance to apple scab. Molecular screening was carried out using eight gene-specific molecular markers (AM19, CH05e03, OPL19, Hi07f02, AL07, K08, HB09, and CH02f06). The results of the molecular screening revealed that in 38 of the 45 studied cultivars, which included 11 Kazakh cultivars and 34 foreign cultivars, the Rvi (Rvi2, Rvi4, Rvi5, Rvi6, Rvi8, Rvi9, Rvi11, Rvi14, and Rvi15) resistance genes were amplified. Resistance genes such as Rvi2, Rvi4, Rvi6, and Rvi9 are still useful for breeding, but their use is recommended only in extended pyramids of multiple resistance genes. Several cultivars will be strong candidates for further breeding programs against apple scab and for the pyramiding of scab resistance genes in new cultivars. Full article

The composition of the essential oil depends on the duration and conditions under which the distillation of the plant material is carried out. In this study, one sample without fractionation and eight fractions (each after 15 min of steam distillation) of the essential oil of cultivated H. italicum were analysed by gas chromatography-mass spectrometry (GC-MS). The steam conditions for all samples were as follows: flow rate 800 L/h, temperature 104 °C, and pressure 0.4 bar. The test of the antimicrobial activity was performed with the modified Kirby–Bauer method (disc diffusion method) on non-selective nutrient media (blood agar) using the reference bacterial and fungal strains. A total of 75 different components were found in the essential oil samples obtained. A shorter distillation time makes the oil richer in monoterpenes and more suitable for the perfume and cosmetics industry. On the other hand, prolonged distillation leads to the essential oil being enriched with sesquiterpene oxides, which can have a negative effect on the fragrance of the essential oil. The essential oil of H. italicum showed antimicrobial activity only against Staphylococcus aureus ATCC 25923, and the best activity was shown by the sixth fraction. Full article

Kandelia obovata (Rhizophoraceae) is the most cold-tolerant mangrove species and has been widely used in coastal wetland ecological restoration due to its specific viviparous phenomenon, beautiful shape, and unique floral pattern. Due to long-term adaptation to their local environment, the phenotypic characteristics and stress resistance of widely distributed plants of the same species often differentiate across different locations. The capacity for cold resistance is closely linked to the physiological and structural characteristics of plants. Herein, we explored the temporal variations in the leaf structure and physiological status of K. obovata under −5.5 °C from different areas such as Jiulongjiang Estuary (JLJ, 24°25′ N), Fujian Province, and Longgang City (LG, 27°34′ N) and Jiaojiang District (JJ, 28°67′ N), Zhejiang Province. The morphological variations implied that the cold resistance of K. obovata obviously strengthened after the northward migration and acclimatization, in the following order: LG > JJ > JLJ. More specifically, after exposure to a sustained low temperature, the relative conductivity (REC), an index widely used to evaluate the degree of plant damage, remarkably increased from 33.62 ± 2.39 to 63.73 ± 3.81, 31.20 ± 1.63 to 49.48 ± 1.12, and 23.75 ± 0.13 to 54.24 ± 1.45 for JLJ, LG, and JJ, respectively (p < 0.05). Additionally, the palisade-to-spongy tissue ratio (P/I) of JLJ and JJ decreased from 0.78 ± 0.05 and 0.75 ± 0.03 to 0.5 ± 0.04 and 0.64 ± 0.02 (p < 0.05), whereas no significant changes were found in LG (p > 0.05). The SOD activity of LG significantly kept increasing, with values increased from 352.49 ± 10.38 to 477.65 ± 1.78 U·g⁻¹, whereas no apparent changes in JLJ and JJ were observed with the sustained low temperature. The results of this study improved our understanding of the response of K. obovata to freezing stress, which could provide a sound theoretical foundation for cultivating cold-resistant varieties, as well as expanding mangrove plantations in higher latitudes. Full article

In recent years, Italy’s craft beer industry has seen remarkable growth, fostering the local production of key ingredients, notably hops. However, a research gap exists in exploring open-field hop productivity in typical Mediterranean climates using low-trellis systems. This study addressed this gap by evaluating the productive performances of “Cascade” and “Chinook” hop varieties on “V” trellis systems at different heights (2.60, 3.60, and 4.60 m above ground) in inner Sicily’s Mediterranean climate and soil conditions. The results highlighted the significant impact of trellis height on various parameters, with Cascade displaying exceptional adaptability to low-trellis farming. Key factors like stem and leaf weight emerged as crucial drivers of cone yield, emphasizing their significance in hop cultivation. The distinct responses of Cascade and Chinook varieties to varying trellis heights underscored the need for tailored approaches, offering valuable insights for optimizing hop cultivation practices in semi-arid climates. Full article

Citrus peels are an important by-product of citrus processing industries, but a large part is considered waste. There has been increased attention in the last five years on these industrial by-products, especially those containing residual essential oils (EOs). Lemon, orange, and mandarin peels from Egypt were subjected to hydro-distillation to obtain EOs, which were analyzed via mass spectrometry (GC/MS) and by building Global Natural Products Social Molecular Networking (GNPS-MN) for the purpose of visually exploring the volatile components of citrus species. The constructed MN revealed that D-Limonene, α-pinene, and β-pinene are the dominant volatile constituents in the three Egyptian citrus species. The EOs from three citrus peels exhibited promising activities as antioxidants using two tested methods: 1,1-diphenyl-2-picryl-hydrazil (DPPH) and nitric oxide (NO) compared with vitamin C. Lemon EO proved excellent antimicrobial activity against Gram-positive and negative bacteria. Additionally, the three citrus EOs showed good activities against the yeast Candida albicans. Regarding the anti-inflammatory assay, the three citrus EOs showed promising activities as COX-1 and COX-2 inhibitors. This study concludes that EOs extracted from citrus peel waste can be valorized as an innovative strategy for food preservation or may be incorporated in cosmetics and pharmaceutical formulations in alignment with circular economy principles. Full article

Apples are one of the most valuable fruits worldwide. ‘Honeycrisp’ is the top sales-producing cultivar in the US. Lack of red skin coloration and increased preharvest fruit drop significantly reduce the market value for cultivars such as ‘Honeycrisp’. The use of reflective groundcovers has been shown to enhance apple skin coloration. While the use of plant growth regulator AVG reduces fruit drop, it negatively affects skin coloration. Studies on the impacts of these practices in mid-Atlantic US-grown apples are limited. In this work, for two years, we compared differences in the light environment, fruit drop, internal ethylene concentration (IEC), physicochemical parameters, and skin coloration of ‘Honeycrisp’ apples in the lower third of the canopy. Apples were submitted to four treatment combinations of reflective groundcover (Extenday) and AVG (130 mg L⁻¹). Assessments occurred throughout three ripening stages. Our results demonstrated that Extenday significantly promoted skin coloration (>75% blush) via the increased reflectance of photosynthetic photon flux density and UV radiation, and increased IEC, while also advancing fruit maturity, i.e., overripening. Conversely, AVG significantly minimized fruit drop and decreased EIC, delaying fruit maturity but drastically reducing red coloration (30–48% blush). The combined use of Extenday and AVG had a synergistic effect by decreasing fruit drop while enhancing fruit with >50% blush, without promoting overripening. Combining Extenday and AVG can boost the market value for ‘Honeycrisp’ apples in the mid-Atlantic US. Full article

Camellia chekiangoleosa is an economically important woody plant from the Genus Camellia in Theaceae, and its seed kernels are rich in edible oils of high health value. Yet, little is known about the molecular regulation of growth and development in C. chekiangoleosa. In this study, we characterized the MYB (Myeloblastosis) gene family that was widely involved in plant development and stress responses, and identified 235 members from the C. chekiangoleosa genome. Based on transcriptomic analysis of multiple tissues, we obtained tissue-specific expression profiles of the MYB genes. We found that 37 MYB genes were highly expressed during seed development, and among them, CcMYB33 (GAMYB) was specifically expressed in the seed coat, suggesting that it may be an important regulator. We cloned full-length sequences of the CcMYB33 gene and further analyzed its sequence characteristics and expression pattern. Our results indicated that CcMYB33 is an R2R3-type MYB transcription factor that is closely related to GAMYB genes of Arabidopsis thaliana. We showed that ectopic expression of CcMYB33 in Arabidopsis lines caused pleiotropical developmental defects, including abnormal leaves, fused stamen, and early flowering, among other things. This work identified important MYB regulators in the regulation of development and growth in C. chekiangoleosa, providing support for further molecular and genetic studies. Full article

Citrus tangerines are famous fruits worldwide, and monitoring the water content of citrus leaves is highly important for citrus production. However, there are still challenges in quantitatively estimating the water content of citrus leaves using hyperspectral technology, and the random noise generated during spectral acquisition and the overlapping peaks in the sensitive band of the citrus leaf water content will affect estimation accuracy. To solve these problems and further explore the roles of the continuous wavelet transform (CWT) and fractional-order derivative (FOD) in the estimation of citrus leaf water content, this study intends to use of CWT and FOD to decompose the original spectrum, and then compare the correlation between the original spectrum and leaf water content to explore whether the decomposition treatment has improved the correlation between spectrum and leaf moisture content. Then, the successive projections algorithm (SPA) was used to select feature bands and combine spectral vegetation indices. Partial least squares regression (PLSR) was used to construct water-content inversion models for citrus leaves, and the inversion accuracies of two commonly used spectral preprocessing methods were compared. The results indicate that (1) the CWT can improve the sensitivity of the spectrum to the citrus leaf water content to a certain extent, and the inversion accuracy of the CWT is approximately 5% greater than that of the FOD. (2) On the basis of the CWT and FOD methods, the inversion accuracy of the citrus leaf water content based on SPA screening increased by 9.61% and 9.29%, respectively, compared with the original spectrum. (3) Under CWT decomposition, Scale4 of the Gaus1 wavelet was screened by the SPA, and the inversion model of citrus leaf water content was constructed by combining the spectral vegetation index NDVI with the best results. The R-squared (${\mathrm{R}}^2$) and root mean square error (RMSE) values were 0.7491 and 0.0284, respectively, which were both 0.0138 greater than those of the best inversion model for the FOD ${\mathrm{R}}^2$. In conclusion, the CWT-SPA combined with the spectral vegetation index can improve the sensitivity of the spectrum to the citrus leaf water content, eliminate a large amount of redundant data, and enhance the prediction ability and stability of the citrus leaf water content. Full article

(1) Background: Table grapes are often subjected to thermal stress during the growing season, affecting their production. Shading nets utilization has been proposed as an alternative to face this problem, but there is little available information about their effectiveness in hyperarid conditions. INIA-G2 vines were covered with kristall-colored mesh of 8% shade, and their ecophysiological responses were compared to uncovered vines during the daily cycle of two days with contrasting thermic conditions. (2) Methods: Net assimilation rate (A_N), stomatal conductance (g_s), transpiration (E), instantaneous water use efficiency (WUE: A_N E⁻¹), stem water potential (Ψ_s), air temperature (Ta) and vapor-pressure deficit (DPV) were determined in daily cycles (from 06:00 to 20:00 hrs) on two thermally contrasting days (330 DOY at 29.4 °C and 345 DOY at 22.6 °C) on grapevines without water restriction. (3) Results: The Ψ_s was not affected by treatment and day of measurement; nevertheless, A_N and g_s were statistically lower during 330 than 345 DOY (31% and 44% decrease, respectively). The covered vines presented less restrictive climatic conditions in terms of DPV in both DOY, reaching higher WUE values at 10, 12 and 14 h, which was associated with a decrease in E. (4) Conclusions: These results suggest that the use of shading nets can be an interesting alternative to cope with high temperatures in viticulture, improving the water use efficiency of vines. These are the first published results about the viticultural performance of the INIA-G2 variety. Full article

Olives (Olea europaea L.) are an important crop in the Mediterranean Basin, but it is not well-known that they have also been grown in other areas, such as Galicia in northwestern Spain. Although commercial production ended long ago in this peripheral growing region, it remains home to olive resources that are well-adapted to the prevailing environmental conditions, providing a valuable but largely undocumented source of genetic variation. Following a survey of Galicia to locate examples of centuries-old olive trees, those detected were subjected to molecular characterization using a set of microsatellite markers, as well as full botanical characterization using the features established by the International Union for the Protection of New Varieties of Plants, along with others proposed by the present authors. These procedures allowed 11 undescribed varieties to be identified, which are new genetic resources that might be of use in olive improvement programs or studies of how the species adapts to different climates. The trees also underwent preliminary health checks, allowing disease-free specimens of each variety to be propagated. The addition of this material to the Community Plant Variety Office’s register of commercial varieties is underway. Full article

Contrarily to chronic stresses, acute (i.e., fast and dramatic) changes in environmental factors like temperature, radiation, concentration of toxic substances, or pathogen attack often lead to DNA damage. Some of the stress factors are genotoxic, i.e., they damage the DNA via physical interactions or via interference with DNA replication/repair machinery. However, cytotoxic factors, i.e., those that do not directly damage the DNA, can lead to secondary genotoxic effects either via the induction of the production of reactive oxygen, carbon, or nitrogen species, or via the activation of programmed cell death and related endonucleases. The extent of this damage, as well as the ability of the cell to repair it, represent a significant part of plant stress responses. Information about DNA damage is important for physiological studies as it helps to understand the complex adaptive responses of plants and even to predict the outcome of the plant’s exposure to acute stress. Single cell gel electrophoresis (Comet assay) provides a convenient and relatively inexpensive tool to evaluate DNA strand breaks in the different organs of higher plants, as well as in unicellular algae. Comet assays are widely used in ecotoxicology and biomonitoring applications; however, they are still relatively rarely used in physiological studies. In this review, we provide an overview of the basic principles and of useful variations of the protocols of Comet assays, as well as of their use in plant studies, in order to encourage plant physiologists to include this tool in the analysis of plant stress responses. Full article

Apocynum venetum L. is a natural fiber and medicinal plant species with significant economic value. Jasmonic acid is an endogenous growth regulatory substance present in higher plants that participate in plant growth, development, and defense. As important endogenous single-stranded RNA molecules, microRNA (miRNA) plays an important role in the post-transcriptional regulation of plant genes. A combination of miRNA and mRNA sequencing techniques was used to systematically identify the methyl jasmonate miRNAs and mRNAs in A. venetum. Up to 135 conserved and 26 species-specific miRNAs have been identified in A. venetum. These miRNAs mainly target genes that encode transcription factors and enzymes. The expression levels of 23 miRNAs, including miR398 and miR482, significantly changed after MeJA treatment. A total of 1778 genes were differentially expressed under MeJA treatment, of which 825 were upregulated and 953 were downregulated. The main biological processes enriched in these differentially expressed genes were redox balance, secondary metabolism, photosynthesis, and plant hormone signal transduction. Joint analysis of the miRNAs and mRNA revealed that MeJA-responsive miRNAs function by forming regulatory modules, including miR398-CSD, miR482-NBS-LRR, miR156-SPL10, and miR164-NAC056, which further regulate multiple biological processes, including redox balance, disease resistance, and morphogenesis in A. venetum. This study provides important information to understand the biological roles of miRNAs in A. venetum. Full article

Extreme weather and the declining organic matter content of soils cause serious sustainability problems in agriculture. Therefore, soil conditioner composites (chicken manure, bentonite and super absorbent polymer) were developed and tested in an integrated apple orchard characterized by poor nutrient and water management to study their effects on soil, leaf and fruit attributes. Composites with higher doses of additives increased soil organic carbon by 4–9 g/kg, and organic nitrogen by 1.8–2.8 g/kg compared to the control (p < 0.05). Similarly, soil nitrate content steadily increased from 8–10 mg/kg to 30–38 mg/kg by composites. Composites effectively elevated leaf N, K, Ca, and Mg while not affecting the leaf P (p < 0.05). Treatments significantly enhanced the yields by 14–63% on average compared to the control. Treatments with bentonite improved the fruit weight by 2% and 24% compared to the chicken manure. On average, composite treatments increased the titratable acidity of fruits by 26–43% compared to the control and 0.5–10% compared to the treatment containing solely chicken manure. Overall, the developed organic-based composites are able to cope with changing circumstances that could help mitigate the negative effects of climate change, especially in arid areas, thus contributing to sustainable nutrient management. Full article

Bulblets, as the main reproductive organ of lilies, have a tremendous impact on the reproductive efficiency of lilies. Cytokinin is known to promote the formation of lily bulblets, but little is known about the mechanisms involved. In this study, a combination of full-length transcriptome and high-throughput RNA sequencing (RNA-Seq) was performed at the leaf axils of LA lily ‘Aladdin’ to characterize the transcriptional response to 6-BA treatment during the critical period of stem-to-bulblet transition. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that 6-BA treatment caused significant changes in starch and sucrose metabolism and plant hormone balance. In particular, the high expression of SUS1 and TPS6 in the 6-BA-treated group suggests that sucrose may act as a key signal to promote bulblet initiation. Furthermore, the induction of elevated expression of genes associated with cytokinin and auxin transport and signaling is crucial for initiating bulblet emergence and stimulating growth. WGCNA analysis revealed that hub TFs such as BLHs, ARFs, HD-ZIPs, AP2/ERFs, and SBPs were significantly overexpressed with genes involved in carbohydrate metabolism and phytohormone signaling, which warranted more in-depth functional studies. This study enriches the understanding of plant hormone-related genes, sugar metabolism-related genes and various transcription factors in the regulation of plant organ development, and lays the foundation for further studies on the molecular mechanisms of lily stem bulblet formation. Full article

Heat stress is one of the most critical environmental abiotic stresses that can negatively affect plant growth. This article investigates the role of a plant growth promoter (Benzylaminopurine) in tomato fields in regard to its ability to withstand high-temperature conditions resulting from greenhouse gas emissions and climate changes. Three genetically different tomato cultivars (Castlerock, GS 12-F1, and Fayrouz F1) were sprayed with 2% 6-Benzylaminopurine (BAP) at 300 and 600 ppm; then, growth and yield components, physio-biochemical characteristics, and antioxidant enzyme activities were determined. The results showed that the highest BAP concentration (600 ppm) enhanced the ability of tomato plants to withstand high temperatures and the maximum dose of BAP improved chlorophyll (71.7 spad units) in GS 12 leaves, while the same dose enhanced proline contents (24.91 mg/100g FW), total antioxidants (83.35 µmol Trolox/g dw), total phenolics (20.99 mg/g dw), Superoxide dismutase (33.74 U/g), peroxidase (46.30 U/g), and polyphenol oxidase (64.10 U/g) in Fayrouz F1 leaves. Application BAP on tomatoes moderately improved fruit quality, such as ascorbic acid and maturity degree, while BAP applications reduced TSS and acidity. In this investigation, taste index was not affected by Benzylaminopurine application but by tomato genotype. The highest number of fruits/plant (45.7), fruit yield/plant (3.98 kg), and total yield (103 tons/ha) were obtained from the GS 12 genotype. Full article

Yellowstriped armyworm (YSAW), Spodoptera ornithogalli, is a polyphagous pest that infests various crops, including cotton, cabbage, corn, blackberry, grape, etc. We documented egg clusters, larvae and adults of YSAW in pecan orchards in Georgia. Until now, there have been no reports of YSAW infesting pecan and its suitability as a host. To investigate the survival, development, and reproduction of YSAW on pecan, we used the age-stage, two sex life table. The YSAW successfully completed its lifecycle on pecan with an 82% preadult survival rate. The preadult duration and mean fecundity were 47.84 d and 1212.55 offspring per female. The population parameters, including intrinsic rate of increase (r), finite rate of increase (λ), net reproduction rate (R₀), and mean generation time (T) were 0.1184 d⁻¹, 1.1257 d⁻¹, 430.67 offspring/female, and 51.05 d, respectively. This study confirms that pecan, Carya illinoinensis, is a potential host plant of YSAW and perhaps more widespread damage could be observed. Full article

The continued increase in human populations and use of chemical fertilizers remain a threat to the health and stability of human–ecological systems worldwide. To ameliorate this problem and achieve long-term food security, a variety of ecofriendly technologies have been developed, including the production of cyanobacteria-based biofertilizers. This technology can be optimized through experiments that assess how plant growth is enhanced under different biofertilizer concentrations (g L⁻¹). In this study, the biofertilizer capabilities of various concentrations of sonicated biomass (0, 2.5, 5, 10, 20, and 40 g L⁻¹) derived from the cyanobacteria Arthrospira maxima on the growth of basil (Ocimum basilicum, Lamiaceae) were assessed, comparing their effectiveness with that of a positive control, a commercial biofertilizer (OptiMar Algas Marinas^®) administered at 4 mL L⁻¹. Generally, increased concentrations led to enhanced growth parameters; however, discernible differences from the negative control (0 g L⁻¹) were often observed only when concentrations exceeded 5 g L⁻¹. Surprisingly, the negative and positive controls often yielded similar results. A chemical composition analysis of A. maxima revealed high concentrations of the phytohormones, macronutrients, and essential amino acids that likely explain how our A. maxima sample enhanced growth in basil. Further research is required to determine how other crop plants respond to different concentrations of A. maxima. Additionally, assessing the feasibility of creating an economically accessible product with a higher concentration of A. maxima is crucial for practical applications. Full article

This study investigated the impact of fertilization treatments on mature, forty-year-old, fully productive olive trees (Olea europaea L. cv. Koroneiki) in two non-irrigated orchards featuring contrasting soil types: non-calcareous–acidic and calcareous–alkaline. Over three years (2019–2021), seven distinct treatments were applied, involving inorganic soil fertilizers (traditional strategy) and foliar applications of a liquid organic product containing fulvic and humic acids. Fertilization significantly influenced physiological parameters, such as mineral nutrition, photosynthetic pigments of olive leaves, fruit yield, and oil production per tree, revealing noteworthy effects influenced by soil types and their interactions with treatments. Statistical analysis highlighted specific treatments, indicating that the foliar application of the organic product once a year in alkaline soil or biannually in acidic soil resulted in the highest observed fruit yield and oil production per tree. Indeed, contrary to the control–unfertilized trees, specific fertilization strategies resulted in an average increase of up to 47% and 73% in fruit yield per tree and up to 96% and 100% in oil production per tree in acidic and alkaline soil, respectively. Furthermore, consistently high yields were correlated with constant high values of the chlorophyll a/chlorophyll b ratio (2.3–3.3 in August for acidic soil) and leaf chlorophyll a concentration (55–66 mg/100 g f.w. in August for alkaline soil). This novel finding underscores the crucial role of these factors as prerequisites for achieving superior fruit production. Our results emphasize the potential of integrating foliar organic fertilization as a complementary strategy to traditional soil-based approaches. This is particularly relevant under non-irrigated/rainfed cultural conditions, emphasizing the significance of considering alternative fertilization practices for optimized olive orchard management. Full article