Publications by authors named "Daniel I Leskovar"

4 Publications

  • Page 1 of 1

Direct Seeding and Transplanting Influence Root Dynamics, Morpho-Physiology, Yield, and Head Quality of Globe Artichoke.

Plants (Basel) 2021 Apr 29;10(5). Epub 2021 Apr 29.

Texas A&M AgriLife Research and Extension Center, Texas A&M University, Uvalde, TX 78801, USA.

The objective of this two-year field study was to assess the influence of stand establishment methods (direct seeding or transplanting) on root growth dynamics, shoot morphology, leaf physiology, yield, and quality of globe artichoke (). Three artichoke cultivars were evaluated, 'Green Globe Improved' (GGI), 'Imperial Star' (IS), and 'Romolo' (ROM). Plants established with the transplanting method had higher mean root length intensity (a), root length, and root surface area as compared to plants established by direct seeding. The topsoil (0-20 cm) had on average higher a, root length, and root surface area than deeper soil profiles. Transplanted plants had higher plant shoot width and leaf area index (LAI) chlorophyll content index (SPAD) than direct seeded plants at the vegetative stage in 2015. The improvement of root and shoot growth in transplants (compared to direct seeding) also resulted in higher ( < 0.05) marketable yield (21.1 vs. 19.9 ton ha in 2015 and 18.3 vs. 13.7 ton ha in 2016). Additionally, 46-50% of the total yield occurred during the first 30 days of harvest in the transplanting method compared to 13-38% for direct seeding. No significant differences were found between planting methods or cultivars in leaf-level gas exchange (photosynthesis, stomatal conductance, and transpiration) and cynarin concentration in the marketable heads. Although chlorogenic acid was similar in both establishment methods in 2015, direct seeding had higher concentration in 2016. Comparing cultivars, GGI had higher root length, surface area, root volume, and earlier and higher marketable yield than ROM. However, ROM had higher mean root length intensity (a; total root length per specific area in soil profile) than GGI in both growing seasons. This study showed significant and consistent improvements in root and shoot traits, and yield for transplants as compared to direct seeded plants.
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http://dx.doi.org/10.3390/plants10050899DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8145455PMC
April 2021

Exploring Morpho-Physiological Variation for Heat Stress Tolerance in Tomato.

Plants (Basel) 2021 Feb 12;10(2). Epub 2021 Feb 12.

Texas A&M AgriLife Research and Extension Center, Texas A&M University, Uvalde, TX 78801, USA.

Texas tomato production is vulnerable to extreme heat in the spring-summer cropping period, which is exacerbated by the lack of superior genetic materials that can perform well in such environments. There is a dire need for selecting superior varieties that can adapt to warm environments and exhibit high yield stability under heat stress conditions. This research aimed at identifying heat-tolerant varieties under heat-stress conditions in controlled and open-field environments and was carried out in three stages. For the first experiment, 43 varieties were screened based on yield responses in natural open-field environment. From those, 18 varieties were chosen and exposed to control (greenhouse: 26/20 °C) and constant heat-stress (growth-chamber: 34/24 °C) conditions for three months. Measurements were done for chlorophyll fluorescence, chlorophyll content (SPAD), plant height, stem diameter and heat injury index (HII). The last experiment was conducted in an open field with a pool of varieties selected from the first and second experiments. Leaf gas exchange, leaf temperature, chlorophyll fluorescence, SPAD value, electrolyte leakage, heat injury index and yield were assessed. From the combined studies, we concluded that heat-tolerant genotypes selected by using chlorophyll fluorescence and HII in controlled heat-stress conditions also exhibited heat-tolerance in open-field environments. Electrolyte leakage and HII best distinguished tomato varieties in open-field environments as plants with low electrolyte leakage and HII had higher total yield. 'Heat Master,' 'New Girl,' 'HM-1823,' 'Rally,' 'Valley Girl,' 'Celebrity,' and 'Tribeca' were identified as high heat-tolerant varieties. Through trait correlation analysis we provide a better understanding of which traits could be useful for screening and breeding other heat-tolerant tomato varieties.
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http://dx.doi.org/10.3390/plants10020347DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7918821PMC
February 2021

Stability of yield and its components in grafted tomato tested across multiple environments in Texas.

Sci Rep 2020 08 11;10(1):13535. Epub 2020 Aug 11.

Department of Horticultural Sciences, Texas A&M University, College Station, TX, 77845, USA.

Grafting with vigorous rootstocks could offer tomato growers in Texas sustainable and efficient option to achieve reliable yield across a range of production systems and locations. Genotypes (G) of grafted and non-grafted tomato were grown in different environments (E) in the 2017 and 2018 spring seasons. The objectives of the study were to (i) evaluate the effects of production system and grafting on tomato yield traits, (ii) determine the size of genotypic and genotype by environment interaction (G × E) variance components, and (iii) evaluate the relative stability of tested genotypes for yield and its components across production environments. In 2017, genotypes were non-grafted 'TAMU Hot Ty' (TAM) and 'Tycoon' (TY) and each grafted on commercial tomato rootstocks 'Estamino' (TAM/ES, TY/ES) and 'Multifort' (TAM/MU, TY/MU) while in 2018, TAM and 'HM1823' (HM) were grafted on 'Estamino' (TAM/ES, HM/ES) and 'Multifort' (TAM/MU, HM/MU). Testing environments were high tunnel (HT) and open-field (OF) in Uvalde in 2017 while in 2018, these were HT and OF in Lubbock (LU-HT, LU-OF), Overton (OV-HT, OV-OF), Uvalde (UV-HT, UV-OF), and Weslaco (WE-HT, WE-OF). Total and marketable yields, fruit number per plant, and average fruit weight were significantly affected by E, G, and G × E interaction. Environmental component contributed 71-86% to the total variation for all these traits, while genotype explained 1.5-10.8%, and the contribution of G × E ranged between 4.3 to 6.7%. Estimation of the univariate statistic parameters and genotype plus genotype × environment (GGE) biplot analysis indicated that HM/MU and HM/ES were the most stable graft combination with the highest total and marketable yields, while TAM/ES was very unstable for yields across test environments. TAM/MU was stable but with yield lower than the grand mean. These results suggest that high tomato yields could be consistently achieved with grafted combination (HM/MU and HM/ES) especially under high tunnel production system across the regions of Texas.
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http://dx.doi.org/10.1038/s41598-020-70548-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7419296PMC
August 2020

Genetic diversity and interrelationship among Indian and exotic melons based on fruit morphology, quality components and microsatellite markers.

Physiol Mol Biol Plants 2020 May 17;26(5):985-1002. Epub 2020 Apr 17.

1Department of Vegetable Science, Punjab Agricultural University, Ludhiana, Punjab 141004 India.

Seventy melon ( L.) accessions comprising of landraces, inbred lines, cultivars, wild relatives and exotic populations were characterized using fifteen fruit traits and 30 SSR markers. Overall, aim of this study was to investigate the genetic relatedness across origins, horticultural groups and accession categories. Significant differences were observed for days to first fruit maturity, fruit weight, fruits per vine, yield per plant, flesh thickness, fruit shape index, total soluble solids, β-carotene, ascorbic acid and titrable acidity. Twenty-four polymorphic SSRs detected 67 distinct alleles with moderate polymorphic information content (0.43) and genetic diversity (0.44). Observed heterozygosity (0.53) was higher than expected heterozygosity (0.48) which can be attributed to out-cross nature of melons. Neighbor joining tree based on SSRs diverged 70 accessions into six clusters independent of geographic sites of collections. and accessions formed distinct clusters, with some exceptions. Intermixing of landraces, modern cultivars and exotic accessions belonging to different taxa and geographic regions indicated genetic resemblance with each other. Hybridization among exotic and indigenous genetic resources can be utilized for genetic enhancement and introgression of new traits in modern melon cultivars.
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http://dx.doi.org/10.1007/s12298-020-00814-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7196569PMC
May 2020