About

Dr. Daniel Leskovar is the Center Director and Professor of Vegetable Physiology at the Texas A&M AgriLife Center at Uvalde. His research program focuses on vegetable physiology, production, and quality, with an emphasis on understanding plant adaptation mechanisms to abiotic stresses such as water limitation, drought, and heat stress. The program aims to develop sustainable cropping systems for high-value crops in the challenging environmental conditions of south Texas, including water-limited areas and less fertile soils. Key research areas include seed and transplant physiology, soil amendments and health, tomato grafting in high tunnel and field production systems, organic systems focusing on soil health and phytochemicals, hydroponics for leafy vegetables, and the integration of genetic, environmental, and management factors for stress tolerance, yield, and quality. His work on seed and transplant physiology has demonstrated practical methods to improve onion crop establishment and performance, while studies on soil amendments have shown the benefits of humic substances in enhancing plant root growth and soil microbial activity under water deficit stress. Dr. Leskovar's research on tomato grafting has revealed significant yield improvements when combining grafting with protected environment systems, and his investigations into organic and conventional production systems have provided insights into optimizing soil and crop quality in globe artichoke. Additionally, his hydroponics research has contributed to water and nitrogen management strategies for leafy vegetables, promoting efficient resource use. Collaborating with breeders, Dr. Leskovar integrates production strategies with advanced sensing methods to select superior germplasm with traits such as high root vigor, improved canopy growth, and enhanced nutritional quality, aiming to create new branded products and increase market opportunities for Texas growers.

Research topics

• Biology
• Horticulture
• Agronomy
• Environmental science
• Ecology
• Agroforestry
• Statistics
• Materials science
• Soil science
• Medicine
• Chemistry
• Animal science
• Mathematics
• Biochemistry
• Botany

Selected publications

• Net radiation estimation using the Brunt equation for clear-sky emissivity and air and canopy temperatures for longwave radiation in well-watered crops

  bioRxiv (Cold Spring Harbor Laboratory) · 2026-04-03

  articleOpen access

  Abstract Net radiation (R n ) can be estimated using models that apply the Brunt equation for the incoming longwave radiation and air temperature (T air ) for the outgoing longwave radiation under reference conditions. This study aimed to estimate R n using two previously regionally calibrated Brunt model, thereby eliminating the need site-specific calibration, and to assess whether T air can be used as a substitute for canopy temperature (T c ) under well-watered crop conditions. Measurements were conducted in sesame and cotton fields during the first year and in a cotton field during the second year. Canopy temperature was measured during the second year, and the calculations were performed at hourly and daily time scales. Regardless of the method used to estimate sky emissivity or whether T c or T air was used, errors were greater at hourly time scale. The overall RMSE, MAE, Bias and KGE values at the daily time scales were 11.88, 9.13, 2.53, and 0.91, in the first year, and 13.45, 10.56, 0.10 and 0.74, in the second year, respectively. When using both regionally calibrated Brunt model, R n simulation performance was superior to that of the Allen/FAO method. The comparison between R n estimated using T air and T c , indicated statistical differences. Nevertheless, linear regression and error metrics showed that these differences were modest, especially at daily time scale. Thus, for practical purposes both regionally calibrated Brunt equations can be used to calculate clear-sky emissivity and improve R n estimations, and T air can be used as a substitute for T c at the daily time scale under well-watered conditions.

  PublisherOA PDFDOI

• System design shapes resource use efficiency and yield trade-offs in lettuce-freshwater prawn aquaponics

  Agricultural Water Management · 2026-03-17

  articleOpen accessSenior author
  PublisherDOI

• Texas A&M Tomato Genotypes Exhibit Superior Yield and Physiological Responses under Heat Stress While Maintaining Fruit Quality Traits

  HortScience · 2026-02-24

  articleOpen accessSenior author

  Tomato production in South Texas has been constrained by high temperatures, particularly in open-field systems, with growers primarily relying on winter greenhouse cultivation because of the high cost of summer cooling. This study evaluated the yield and physiological responses of eight commercial and 13 Texas A&M–developed tomato genotypes during summer production in Uvalde, TX, and reevaluated the high-yielding selections for thermotolerance and fruit quality in the second year. Five-week-old seedlings were transplanted into open-field clay loam soil in Spring 2024 and 2025, with fruits harvested through midsummer under average daily maximum temperatures of 32.8 and 33.3 °C, respectively. Two-year average yields of ‘TAM-C6’ and ‘TAM-C9’ exceeded ‘Supersweet 100’ among cherry types, whereas ‘TAM-FLW2’ and ‘TAM-FLW3’ exceeded ‘Celebrity Plus’ among slicer types. Key physiological traits associated with high yield included high pollen viability in ‘TAM-FLW2’ and ‘TAM-FLW3’, high leaf antioxidant capacity in ‘Hot-Ty’, and efficient photosynthate allocation in ‘TAM-C9’. In contrast, the low-yielding cultivars ‘Amish Paste’ and ‘Cherokee Purple’ had the highest lipid peroxidation and lowest transpiration rate, respectively. Fruit yield–quality trade-offs were observed, as ‘TAM-C6’ and ‘TAM-C9’ had lower fruit antioxidant compounds and/or total soluble solids (TSS) than ‘Supersweet 100’, whereas ‘TAM-FLW2’ and ‘TAM-FLW3’ showed lower TSS than ‘Celebrity Plus’. The slicer genotype ‘Hot-Ty’ demonstrated performance comparable to or superior in yield, flavor quality, and antioxidant content relative to ‘Celebrity Plus’. In conclusion, the Texas A&M genotypes ‘TAM-C6’, ‘TAM-C9’, ‘TAM-FLW2’, ‘TAM-FLW3’, and ‘Hot-Ty’ could offer strong potential for summer tomato production in hot climates, despite minor trade-offs in flavor and nutraceutical traits.

  PublisherDOI

• Lectio "Horticultura y Resiliencia". Discurso pronunciado por el Dr. D. Daniel Ivan Leskovar en su Ceremonia de Investidura como Doctor “Honoris Causa” por la Universidad Politécnica de Cartagena, 2026

  Digital Repository (Polytechnic University of Cartagena) · 2026-01-28

  otherOpen access1st authorCorresponding

  La ‘Horticultura’ no es sólo una ciencia: implica arte, historia, espiritualidad y una relación directa con el medio ambiente y las personas. En muchas festividades tradicionales se incluyen en la preparación de alimentos los cultivados de manera local; y el diseño de jardines suele reflejar estilos artísticos propios de la cultura de cada lugar. A través de la historia, los huertos y jardines han sido espacios de encuentro espiritual, social y político fortaleciendo el sentido de pertenencia y relevancia de nuestras acciones. ¿Qué haríamos sin ella? No es exagerado decir que la palabra "horticultura" se asocia con comida, tradiciones y comunidad, independientemente de creencias étnicas o religiosas.

  Publisher

• Metabolomic Profiling of Novel Muskmelon Cultigens Reveals Regional Variations in Fruit Composition Across Four Distinct U.S. Growing Locations

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• Humic Substances and LED Lighting Improved Tomato Transplant Growth, with Limited Carryover Effects on Fruit Yield and Quality

  HortScience · 2025-03-07 · 2 citations

  articleOpen accessSenior author

  Humic substances (HS) and light-emitting diode (LED) light applications have shown beneficial effects on plant growth, nutrition, and yield in various vegetable crops. However, their carryover effects on fruit yield and quality, when applied to the growing media before transplanting, have not been widely explored in tomatoes. This study evaluated tomato transplant growth in response to the application of solid HS (1% v/v, control) and varying LED light qualities [10 blue (B):90 red (R), 50B:50R, 100B, and fluorescent] in growth chamber conditions (25/19 °C, 16-hour days/8-hour nights, 100 µmol·m –2 ·s –1 photosynthetic photon flux density, 60% relative humidity), followed by a post-transplant study assessing fruit yield and quality. Round-type ‘Celebrity’ and cherry-type ‘Chadwick’ tomato seedlings were transplanted into 16-L pots 5 weeks after sowing (WAS), and fruit were harvested for 10 weeks. Transplant growth components measured at 5 WAS were significantly greater in seedlings treated with HS compared with control plants, including improved shoot and root dry weight, stem diameter, leaf area, and total root length and surface area. Seedlings grown under 50B:50R light showed a greater increase in shoot and root growth when treated with HS compared with other light treatment groups, whereas plants grown under 10B:90R light exhibited the greatest growth without HS. However, the enhanced seedling growth under HS and specific LED light treatments did not translate fully into increased fruit yield and quality after transplanting. There were no significant increases in fruit yield in response to HS application, except for ‘Chadwick’ under 50B:50R and 100B light. No clear correlation was observed between high-quality transplants and tomato quality traits, such as total soluble solids and secondary metabolites, although the 100B light treatment increased lycopene and total phenolic content. In conclusion, the application of HS to the transplant growing media, combined with specific LED wavelengths, particularly 50B:50R, enhanced shoot and root growth significantly in young tomato seedlings. However, these benefits largely diminished after transplanting and did not result consistently in increased fruit yield or quality.

  PublisherDOI

• SiO2 and ZnO nanoparticles and salinity stress responses in hydroponic lettuce: selectivity, antagonism, and interactive dynamics

  Frontiers in Plant Science · 2025-09-26 · 2 citations

  articleOpen accessSenior authorCorresponding

  Salinity stress negatively affects plant growth but can also act as a eustressor, enhancing nutraceutical quality. Nanoparticles (NPs) have unique physical and chemical properties that can impact crop growth and abiotic stress responses in both beneficial and detrimental ways. This study investigated the potential of SiO 2 and ZnO NPs to alleviate salinity stress or enhance nutraceutical quality by synergizing with the eustressor effects of salinity in hydroponically grown lettuce. Two-week-old lettuce seedlings ( Lactuca sativa cv. Green Forest) were transplanted into a 5-L deep water culture system and grown for four weeks in a customized growth chamber set at 25 °C with 230 µmol/m 2 /s photosynthetic photon flux density (PPFD). The nutrient solution was maintained at an electrical conductivity (EC) of 1.5 dS/m and pH 5.8, and replenished weekly. A factorial design was employed with four salinity treatments (non-saline, 50 mM NaCl, 33.3 mM CaCl 2 , and 25 mM NaCl + 16.6 mM CaCl 2 ) and three nanoparticle treatments (no-NP control, 100 ppm SiO 2 , and 100 ppm ZnO). Overall, NPs improved lettuce growth under non-saline conditions. Specifically, SiO 2 NPs increased shoot and root biomass, root system architecture, and antioxidant enzyme activities (superoxide dismutase-SOD and glutathione reductase-GR) compared to controls, while ZnO NPs improved root biomass and architecture, and leaf chlorophyll content. Under CaCl 2 stress, SiO 2 NPs enhanced root growth, non-enzymatic antioxidant capacity, and antioxidant enzyme activities (catalase-CAT, ascorbate peroxidase-APX, and GR), while these improvements were not observed under NaCl and NaCl + CaCl 2 stress. ZnO NPs caused greater physiological damage under CaCl 2 and NaCl + CaCl 2 stress compared to NaCl alone, suggesting that the interaction between ZnO NPs and CaCl 2 impaired root development and water uptake, ultimately reducing PSII efficiency through oxidative damage. The synergistic effect between NPs and salinity stress was limited, observed only between SiO 2 NP and CaCl 2 stress in total flavonoid content. Overall, both NPs benefited hydroponic lettuce under non-saline conditions, with SiO 2 NPs enhancing tolerance under CaCl 2 stress, though their interaction with salinity as a eustressor was limited. These results suggest that SiO 2 NPs enhance salinity tolerance in hydroponics, whereas ZnO NPs should be used with caution under saline conditions.

  PublisherOA PDFDOI

• Enhancing Hydroponic Organic Tomato Resilience through Grafting and Bioprotection Strategies

  HortScience · 2025-02-12 · 2 citations

  articleOpen accessSenior author

  The infestation of major greenhouse pests such as whiteflies, leafminers, and thrips and hot and humid conditions pose significant challenges in controlled environment horticulture, particularly for organic tomato production. Low tomato productivity is attributed to pests and inadequate stress tolerance of existing cultivars, which hinder the ability to optimize fruit set and yield. Although the individual effects of bioprotection and grafting strategies of conventional production systems have been extensively studied, their combined effects in controlled environments have been less explored. This study aimed to assess the efficacy of grafting (‘Maxifort’ × ‘Valdeon RZ’) and bioprotection strategies (yellow sticky traps, Spinosad, and Bacillus thuringiensis ) on the mitigation of greenhouse pest infestation and enhancement of the yield of organically grown hydroponic tomatoes in adverse environmental conditions in Qatar. The experimental design used a strip plot with grafted ‘Valdeon RZ’ and nongrafted ‘Valdeon RZ’ as the main plot treatments; Yellow sticky traps, Spinosad, and Bacillus thuringiensis were randomly assigned to the subplots. Tomato cultivar Valdeon RZ grafted on Maxifort exhibited superior seedling quality, as evidenced by increased stem diameters and improved root attributes. Grafted ‘Valdeon RZ’ plants treated with Spinosad demonstrated an enhanced net assimilation rate (27%) and stomatal conductance (17%), as well as reduced transpiration loss (22%) and electrolyte leakage (18%); however, the intercellular CO 2 concentration was maintained. Flowering of grafted ‘Valdeon RZ’ plants treated with Spinosad occurred 4 days earlier than that of untreated and nongrafted counterparts. Compared with the control plants, grafted plants treated with Spinosad exhibited superior fruit sets (22%) and pollen viability (18%), as well as fewer incidences of flower drops (28%). Grafted ‘Valdeon RZ’ plants treated with ‘Spinosad’ outperformed the control in terms of marketable fruit yields, with a significantly higher yield (26%). Additionally, fruits collected from grafted plants demonstrated superior postharvest quality, including firmness, soluble solids content, acidity, and color dynamics. Among the bioprotection strategies, Spinosad exhibited superior pest control efficiency, followed by Bacillus thuringiensis and yellow sticky traps. Spinosad-treated plants showed a 40% reduction in leafminer, 28% reduction in whitefly, and 22% reduction in thrips compared with untreated control plants. Our findings can lead to practical strategies that minimize greenhouse pest infestations while improving tomato yield in an organic hydroponic system within a protected environment.

  PublisherDOI

• Metabolomic profiling of novel muskmelon cultigens reveals regional variation in fruit composition across four U.S. growing locations

  Journal of Food Composition and Analysis · 2025-03-13

  article
  PublisherDOI

• Foliar gas exchange, morphology, and cannabinoid contents of three hemp varieties in southwest Texas

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-03-13

  preprintOpen access

  In the US, a high level (≥ 0.3%) of intoxicating Δ-9-tetrahydrocannabinol (THC) threatens farm-scale production of industrial of Hemp ( Cannabis sativa L. ssp. sativa ), but the linkage between THC and major physiol-morphological traits of hemp is not well-known. This study aims to characterize the variations in physiological and/or morphological parameters and cannabinoid contents of three hemp varieties, i.e., Berry Blossom, Painted Lady, and Skipper. Diurnal foliar gas exchange, chlorophyll fluorescence, water potential, and canopy temperature were measured on five clear days in the 2022 growing season, and cannabinoids were measured at peak flowering using high-performance liquid chromatography. Allometric equations were developed to use easily measured biomass or morphological variables to predict variables that are more difficult to measure. The diurnal foliar gas exchange of the three hemp varieties was largely unaffected by the high temperatures of southwest Texas, with Berry Blossom and Skipper showing the highest and lowest photosynthesis, respectively, and Painted Lady having the most efficient stomatal control of gas exchange. Although the rooting depth of Berry Blossom was shallower than that of the two other varieties, there was no evidence showing the effect of rooting habit on the physiology of the studied hemp varieties, which was presumably due to the lack of water stress in our experiment. Nor were there significant differences in the cannabinoid contents in relation to environmental and varietal responses, as the measured THC contents of all three varieties were under 0.3%. Overall, the three hemp varieties showed different behavior strategies in southwest Texas.

  PublisherOA PDFDOI

Frequent coauthors

• Giovanni Piccinni

  101 shared

• Kevin M. Crosby

  Texas A&M University

  96 shared

• Thomas Marek

  Amarillo College

  57 shared

• John L. Jifon

  Texas A&M University

  48 shared

• Charles S. Vavrina

  University of Florida

  46 shared

• Daniel J. Cantliffe

  University of Florida

  42 shared

• Penelope Perkins‐Veazie

  42 shared

• Leonard M. Pike

  Texas A&M University

  38 shared

Labs

• Vegetable Physiology, Production, QualityPI

Education

• B.S., Horticulture (Agricultural Engineer)

  Universidad Nacional del Comahue

• M.S., Vegetable Crops

  University of California, Davis

• Ph.D., Vegetable Crop - Physiology

  University of Florida