Preharvest irrigation cutoff to promote skin set is a common management practice in irrigated commercial sweetpotato production, but its effects on native periderm, the developmentally formed periderm of intact storage roots before harvest, are poorly understood. We evaluated anatomical, physiological, and molecular responses of native periderm to controlled short-term irrigation/fertigation withdrawal during the early storage root bulking stage (30–50 days after transplanting) in ‘Bayou Belle’, ‘Beauregard’, and ‘Orleans’ sweetpotato. Greenhouse experiments compared well-watered plants with plants subjected to 5 days of withdrawal (WD5) or 10 days of withdrawal (WD10) before harvest. Native periderm structure was characterized from transverse sections stained with phloroglucinol-HCl, and postharvest weight loss was measured for 5 weeks. The relative expressions of IbPAL , IbCCoAOMT , IbCAD , and IbACO were quantified in well-watered and WD10 roots. Withdrawal increased circularity, an index of reduced outer-boundary irregularity, and produced a more continuous native periderm with fewer expansion-associated discontinuities. Percent lignified tissue increased 1.9-fold to 3.6-fold relative to well-watered controls, depending on cultivar and treatment duration. By week 5, cumulative weight loss was 38% to 45% in well-watered roots compared with 21% to 24% after WD5 and 20% to 30% after WD10. IbPAL expression increased 1.6-fold to 3.8-fold across cultivars, whereas IbCCoAOMT , IbCAD , and IbACO responses were genotype-dependent. These coordinated responses are consistent with accelerated native periderm maturation during early bulking and support the use of greenhouse-grown roots as a controlled developmental system. Because nutrient delivery was also interrupted during irrigation withdrawal, the response cannot be attributed to the water status alone; therefore, field validation and experiments that separate water from the nutrient supply are needed.
Foliar fertilization can supplement nutrients efficiently. We screened foliar fertilizers suitable for Camellia oleifera to improve leaf photosynthetic function, and enhance fruit yield and quality. Ten-year-old C. oleifera ‘Ganshi 84-8’ trees were used as experimental material, and the effects of different combinations of potassium dihydrogen phosphate (KH 2 PO 4 ), boric acid (H 3 BO 3 ), and brassinosteroids (BRs) were evaluated. Our results show that all foliar fertilizer treatments increased fruit set rates to varying degrees. In addition, these treatments exhibited differentiated improvements in fruit yield and quality parameters. Specifically, treatment 1 (T1) and T4 increased the fresh seed kernel yield rate and yield per plant significantly, and T2 helped increase oil content and yield per plant, with increases of 7.32% and 32.20%, respectively, compared with the control. Although T3 reduced yield per plant significantly, it increased fruit longitudinal diameter notably. Treatments 5 and 7 increased the fresh fruit seed yield rate and fresh seed kernel yield rate significantly. Treatments 6, 8, and 9 increased primarily the fruit transverse and longitudinal diameters, and T8 also increased oil content by 9.63%. A comprehensive comparison indicated that T8 (2.4 g·L –1 KH 2 PO 4 + 0.8 g·L –1 H 3 BO 3 + 0.06 mg·L –1 BRs) exhibited the best overall effect, improving fruit quality and yield substantially. Our results provide a theoretical basis and scientific reference for improving the quality of C. oleifera .
For rapid determination of whether gray leaf spot disease in field-grown Welsh onion ( Allium fistulosum L.) is caused by Stemphylium vesicarium , we targeted the glycerol-3-phosphate dehydrogenase ( gapdh ) gene and designed specific primers (sv-gpdF/R) that amplify a 194-bp fragment, showing high specificity. In quantitative polymerase chain reaction (qPCR) assays, its sensitivity was 10 5 -fold higher than that of conventional PCR. The standard curve constructed showed a strong linear relationship between the cycle threshold (Ct) and the logarithm of template concentration, with a coefficient of determination ( R 2 ) of 0.9902. When this qPCR method was applied to detect S. vesicarium on inoculated Welsh onion leaves at various time points, the pathogen was detected as early as 3-h postinoculation, and it exhibited rapid proliferation between 72 and 96 h. Additionally, the alkaline lysis method allowed rapid DNA extraction from lesion sites, and subsequent PCR using the specific primers could determine whether Welsh onion plants were infected with S. vesicarium . In summary, this study established a rapid detection method for S. vesicarium , the causal agent of gray leaf spot disease in Welsh onion. This method facilitates rapid pathogen identification, enables informed selection of fungicides and provides an effective technical tool for disease prevention and control.
Tomato ( Solanum lycopersicum L.) breeding increasingly emphasizes the integration of productivity, fruit quality, marketability, and consumer-preference traits. In the present study, 39 diverse tomato genotypes representing multiple fruit types were evaluated across two field environments at Tifton, GA, during the Fall 2025 season to characterize phenotypic diversity and identify promising breeding materials. Quantitative agronomic, marketable and unmarketable yield, qualitative horticultural, and sensory traits were assessed using integrated phenotypic analyses. Significant genotype effects were observed for most quantitative traits, including plant height, flower number, marketable fruit number, marketable fruit weight, and unmarketable fruit traits, indicating substantial phenotypic variability among genotypes. Correlation analysis revealed positive associations between flower number and marketable fruit production, whereas negative relationships between marketable and unmarketable traits suggested potential trade-offs between productivity and fruit quality retention. Principal component and hierarchical clustering analyses further separated accessions based on yield, fruit morphology, and marketability-associated characteristics. Qualitative trait analysis demonstrated significant associations between fruit type and traits such as fruit color and greenback presence. Major unmarketable fruit defects included cracking, black spot, browning, blossom-end rot (BER), and zippering, with considerable variation observed among accessions for defect incidence and marketability performance. Sensory evaluation revealed substantial diversity among genotypes for sweetness, aroma, flavor balance, firmness, juiciness, acidity, and overall preference. Genotypes UGA-TOM-5, UGA-TOM-25, and UGA-TOM-26 exhibited superior sensory performance, whereas UGA-TOM-23, UGA-TOM-5, UGA-TOM-22, and UGA-TOM-3 demonstrated superior agronomic performance. Several accessions, particularly UGA-TOM-5 and UGA-TOM-23, exhibited favorable combined performance across agronomic, marketability, and sensory evaluations. The identified elite accessions provide valuable parental resources for future tomato breeding efforts integrating productivity, fruit quality, and virus resistance.
Field studies were conducted over 2 years, with one location evaluated each year, to determine the effects of plant length (25- or 38-cm) and plant orientation (horizontal or vertical) on node count, storage root number, and storage root yield by US Department of Agriculture grade of ‘Covington’ sweetpotato under four transplant–harvest timing regimes. Effects of plant length and orientation varied among timing regimes and site-year conditions. Longer plants increased US No. 1, canner, marketable, and total yields in some timing regimes, whereas horizontal orientation increased US No. 1 storage root number and yield; vertical orientation occasionally increased jumbo-grade yield. Plant length × orientation interactions were detected within individual transplant–harvest timing regimes, with horizontally oriented long plants (38-cm) generally producing the greatest US No. 1, marketable, and total yields. Although the mechanisms were not evaluated directly, differences in plant positioning and belowground node distribution may contribute to these responses. Longer plants combined with horizontal orientation may improve marketable yield under specific production conditions, but additional research across diverse environments and with methods that separate orientation effects from transplanting system effects is needed to determine the consistency of these responses.
In northern latitudes, many commercial greenhouse growers use supplemental lighting (SL) and heating to compensate for low ambient solar radiation, average daily temperature (ADT), and root zone temperature (RZT) during peak propagation months. Growers have traditionally used high-pressure sodium (HPS) lamps to deliver SL, but they are adopting light-emitting diode (LED) fixtures because of their improved energy efficacy. However, propagators have reported abnormal leaf coloration resembling nutrient deficiencies when cuttings of some species, including petunia ( Petunia × hybrida ), are rooted under LED SL. The objective of this study was to quantify how temperature (ADT and RZT) and SL (light intensity and quality during rooting) influence the nutrient concentration and coloration of petunia. Shoot-tip cuttings of petunia SureShot ‘Dark Blue’ and ‘White’ were inserted in 72-cell trays and propagated inside a greenhouse at an air ADT of 21 °C or 23 °C and an RZT of 21 °C or 25 °C. Cuttings were grown under SL delivered by HPS lamps or LED fixtures with different light qualities (low blue or moderate blue), with each providing a photosynthetic photon flux density of 60 or 120 µmol·m −2 ·s −1 for the first 6 days, and then 120 µmol·m −2 ·s −1 for the remaining 16 days. In general, cuttings of ‘Dark Blue’ grown under LED SL emitting a moderate amount of blue light had a lower leaf phosphorus concentration than that of ‘Dark Blue’ grown under HPS lamps. Cuttings of both cultivars grown under HPS lamps generally had lower leaf zinc concentrations than those of cuttings of cultivars grown under either LED fixture. Overall, cuttings of ‘Dark Blue’ propagated under LED SL had higher leaf anthocyanin concentrations and were more red and blue compared with ‘Dark Blue’ grown under HPS lamps. Across treatments, cuttings of both ‘Dark Blue’ and ‘White’ generally had higher leaf nutrient concentrations when grown at an air ADT of 23 °C than when grown at 21 °C and when grown at an RZT of 25 °C than when grown at 21 °C. Additionally, cuttings of ‘Dark Blue’ had lower anthocyanin concentrations and were less red in color when grown at an RZT of 25 °C than when grown at 21 °C. Furthermore, there was no clear association between foliage discoloration and nutrient concentration in ‘Dark Blue’. The coloration of ‘White’ was generally unaffected across treatments. These results indicate that both crop coloration and pigmentation responses to spectral differences in SL are likely cultivar-dependent, and LED SL may exacerbate undesirable responses in sensitive cultivars.
Night temperature and light intensity are crucial for off-season production of watermelon ( Citrullus lanatus ) while temperature is very low sometimes minus and lower intensity of natural light. They regulate carbon assimilation, energy conversion efficiency, and overall plant productivity. However, their interactive effects of watermelon during off-season production remain unclear. To address these issues the present study was investigated under controlled hydroponic conditions during the winter season (Off-season). A completely randomized designed was used for the evaluation of three environmental treatments: T0 [control; low temperature and low light: day/night 22.76/13.30 °C, photosynthetic photon flux density (PPFD) 492.03 μmol·m −2 ·s −1 ]; T1 (comparatively high temperature and high light: 30.30/21.66 °C, PPFD 929.71 μmol·m −2 ·s −1 ) and T2 (high daytime and low night temperature with high PPFD; 33.53/15.00 °C, PPFD 1235.57 μmol·m −2 ·s −1 ). The results revealed that among the treatments T1 had significantly higher chlorophyll content, photosynthetic rate ( Pn ), transpiration rate ( E ), and stomatal conductance ( g s ) compared with control and T2, chlorophyll a and b increased by 63% and 61% in T1 and 57% and 22% in T2, respectively. The effective quantum yield of Photosystem II (ΦPSII) and electron transport rate (ETR) also improved in T1, suggesting enhanced photochemical efficiency under elevated temperature and light conditions. Leaf Ca 2+ and Mg 2+ concentrations increased by 21.76% and 220% in T1, respectively, compared with control, suggesting enhanced nutrient assimilation. Morphological traits, including leaf area, plant height, and number of nodes, increased by up to 85% in T1, leading to earlier flowering and a higher number of female flowers. The anther dehiscence and many pollen observed in T1 like optimum growing season indicating easy pollination, which is the main obstacle during off-season cultivation. At the molecular level, rbcL gene expression, a key photosynthetic gene encoding the catalytic large subunit of Rubisco, was downregulated in control and T2 plants whereas T1 showed upregulation indicating the optimized light and temperature under T1 enhances photosynthesis. Overall, increases in temperature and light intensity synergistically promoted photosynthetic efficiency, nutrient uptake, and reproductive capacity, providing insights for optimizing off-season watermelon cultivation under controlled environments.
Marigolds (Tagetes erecta ) are culturally significant flowers throughout the world with limited production and use in the United States. Few studies have examined the effects of preharvest foliar sprays on juvenile timing and postharvest longevity in marigolds. To address this, two greenhouse studies were performed using exogenous spray applications of 2% calcium nitrate [Ca(NO 3 ) 2 ] to determine the effects on juvenile bloom period and postharvest vase life in two marigold cultivars, White Swan and Coco Gold. Marigold blooms were separated into four developmental stages, (stages 1–4) and sprayed with 20 mL 2% Ca(NO 3 ) 2 solution per bloom. Preharvest foliar application of Ca(NO 3 ) 2 was found to reduce the juvenile period in both cultivars. Notably, applying Ca(NO 3 ) 2 at stage 1 shortened the juvenile period by 6.9 days in ‘White Swan’ and by 7.2 days in ‘Coco Gold’. No significance was found regarding vase life in either cultivar, although some positive trends were observed in ‘White Swan’. These results show that preharvest foliar supplementation of Ca(NO 3 ) 2 is effective at reducing the juvenile period and may be beneficial for extending vase life in some marigolds. However, cultivar-related responses may influence these results.
Supplemental lighting is necessary to optimize plant growth and maintain year-round production of greenhouse vegetables in countries that endure cold and dark winter months. The use of energy efficient light-emitting diodes has steadily increased in crops such as tomatoes and cucumbers, but there has been little adoption in eggplants, in part due to lack of research and knowledge. Although red and blue light is more readily absorbed by the plant, a broad spectrum light, including green light, can also affect plant growth and yield. In this study, we assessed the impact of spectral quality on physiological, morphological, and yield parameters of mini eggplants cv. Jaylo during a 209-day experiment. Plants were exposed to four supplemental overhead LED lighting treatments: red-blue (95% red), pink, warm-white, and white. The progression of light treatments represents an increasing broad light spectrum. Growth under the red-blue treatment increased plant height while a broader light spectrum (i.e., pink or warm-white) increased leaf number and area. Cumulative yield during the long experiment showed a significant decrease in both total fruit number and total fruit weight with the supplemental light became broader with higher percentage of green light. It was determined that the red-blue treatment produced more fruit in early production which indicates an advantage of using supplemental narrow-band light during the initial phase of growth. This early advantage persisted throughout the production period. The ability of green light to penetrate the mini eggplant crop canopy was also assessed. Regardless of the amount of green light in the supplemental lighting treatments, green light was not observed to penetrate through the canopy better than red or blue light. These results indicate that exposing mini eggplant to red-rich (95%) red-blue supplemental light during the early stages of production may provide a competitive advantage with respect to fruit yield.
Parsley ( Petroselinum crispum Mill.) and sage ( Salvia officinalis L.) are popular herbs grown for culinary usage. As herb production in controlled environments increases, the need for leaf tissue nutrient standards specific to these production systems becomes increasingly important for troubleshooting nutrient disorders. The objectives of this study were to induce and document nutrient disorders of hydroponically grown parsley and sage and establish refined foliar nutrient interpretation ranges by expanding on the sufficiency range approach (SRA). Plants were grown in silica sand and supplied with a modified Hoagland’s solution that omitted or supplemented individual nutrients while maintaining all other nutrients at consistent concentrations. At the onset of symptoms, plants were photographed, plant tissue was collected to measure dry mass, and tissue nutrient concentrations were documented. The resulting foliar tissue data were compiled with data from analytical laboratories and research studies to create a larger dataset for parsley and sage, which were used to establish foliar nutrient interpretation ranges using a hybrid meta-analysis SRA. Normal, gamma, and Weibull distributions were compared, and the distribution of best fit was selected based on the lowest Bayesian information criterion value. Based on the best fit model, ranges for deficient, low, sufficient, high, and excessive tissue concentrations were defined for 12 essential elements. The documented symptoms of nutrient disorders and updated nutrient interpretation ranges provide valuable guidelines for nutrient management of greenhouse-grown parsley and sage.
This study examined the effects of planting density and nitrogen fertilizer rates on yield, bulb size distribution, nutrient uptake, and flavor quality of Vidalia onions ( Allium cepa ). Field experiments were conducted in 2023 and 2024 at the University of Georgia Vidalia Onion and Vegetable Research Center, using three planting densities (143,318, 214,977, and 286,636 plants/ha) and three nitrogen (N) rates (89.7, 112.1, and 134.5 kg/ha). Bulb yield, size distribution, and bolting were measured in both years, whereas plant nutrient uptake and bulb flavor quality were evaluated only in 2024. Higher planting densities increased both total marketable bulb yield and jumbo-sized bulbs; however, the highest planting density (286,636 plants/ha) also reduced the yield of colossal bulbs. Bulb weight generally increased at moderate and high planting densities, with N response varying depending on planting density and year. N and sulfur uptake in bulbs varied with planting density and N application rate, with significant interactions between these factors. Pyruvic acid (<4.83 µmol·mL −1 ) and lachrymatory factor (<2.21 µmol·mL −1 ) remained below the reported sweet onion thresholds, whereas methyl thiosulfinate concentrations exceeded the reported threshold but were not significantly affected by planting density or nitrogen rate. Among the flavor attributes evaluated, significant differences were observed only for the lachrymatory factor. Bolting was not observed in 2023 but increased significantly at the highest planting density (286,636 plants/ha) in 2024. These findings emphasize the need for optimal planting density to maximize yield and jumbo bulb production, whereas nitrogen rate recommendations may need to be adjusted based on specific growing conditions and seasonal changes.
Stomatal traits are important determinants of photosynthesis and water use; however, their variation among plant parts and cultivars and their relationships with growth and yield in strawberry remain unclear. This study characterized stomatal density and guard cell length among plant parts and across 34 cultivars and examined their associations with growth and yield. Stomata were found not only on the abaxial leaf surface but also on petioles and calyces and occasionally on the adaxial surface of leaves. Both traits varied widely among cultivars and decreased between November and May. Stomatal density was significantly negatively correlated with plant height, estimated leaf area, and total yield in both seasons, whereas guard cell length showed no significant association with these traits. These results suggest that stomatal density may be a more relevant indicator of growth and yield in strawberries and that characterizing stomatal traits across plant parts and cultivars may support breeding and cultivation research.
We studied leaf pigmentation, and several aspects of tree growth and physiology, in transgenic purple and wild-type trees in the field with the goal of evaluating leaf color and stability of color expression, and general growth and adaptation in a natural environment over several years. The transgenic trees overexpressed a MYB transcription factor gene that regulates anthocyanin biosynthesis. Thirty-six transgenic insertion lines made within the model poplar hybrid Populus tremula × alba , along with a green wild-type control of the same clone, were grown in western Oregon for three growing seasons. The color intensity and quality of purple leaf color varied widely between transgenics made with the MYB transcription factor from poplar ( Ptr MYB119 ) overexpressed under the cauliflower mosaic virus double-35S promoter vs. that from grape ( Vv MYBA1 ) that was overexpressed under the same promoter. The grape-derived MYB transgenics had far darker leaves than the poplar-derived MYB transgenics or controls, and had distinctive colorimetric, spectral, and hyperspectral profiles from laboratory and remote sensing measurements. They also had much slower growth, less efficient leaf photosynthetic parameters, and higher mortality. The grape-gene transgenics also showed a higher degree of leaf mottling and instability of leaf coloration within and between insertion events. In contrast, the poplar-gene transgenics, although having distinctly purple leaves, had growth and survival that was nearly the same as in the controls. The poplar gene–derived purple transgenics appear very well suited for use as an ornamental in temperate environments.
Nursery crops are commonly propagated from stem cuttings rooted in small-diameter containers, but weed infestations can reduce crop quality and be transferred into the production cycle. Preemergence herbicides are not labeled for use in cutting propagation, yet several products may be safe and viable alternatives to hand-weeding, which is costly and time-consuming. Optimizing the proper time for applying preemergence herbicides would provide propagators with more weed management tools. Our study (2020 and 2021) evaluated preemergence herbicide (isoxaben, isoxaben + dithiopyr, and oxyfluorfen + oxadiazon) and application timing (before, at, and after sticking cuttings) compared with an untreated control on the rooting and growth of cuttings from four ornamental plant species [butterfly bush ( Buddleja davidii ‘Nanho Blue’), hydrangea ( Hydrangea paniculata ‘Limelight’), holly ( Ilex cornuta ‘Dwarf Burford’), and crape myrtle ( Lagerstroemia indica ‘Catawba’)]. Application timing did not affect root or shoot biomass of the tested plant species except for isoxaben + dithiopyr applied at and after sticking on crape myrtle (in 2021). Isoxaben and isoxaben + dithiopyr were safe on all the other plant species except butterfly bush, for which neither product is labeled for use. Oxyfluorfen + oxadiazon was safe on all tested plant species and can be applied 2 weeks before, at, or 2 weeks after sticking stem cuttings. The results indicate certain preemergence herbicides can be applied during stem cutting propagation when used in accordance with product label restrictions.
