Browsing by Author "Sanchez, Jacobo"
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Item Analysis of genetic and physiological factors governing water deficit and chilling stress effects on yield penalty in model cereal species(2022-05) Sanchez, Jacobo; de los Reyes, Benildo G.; Emendack, Yves; Laza, Haydee; Shim, Rosalyn; Ritchie, Glenn; Hayes, ChadDeveloping crops with abiotic stress tolerance has moved ahead for many years by targeting the improvement of what could be considered survival traits. While important to plant growth, these traits have seldom proven to be good biological markers for the selection of lower yield penalty under abiotic stress. A major reason could be that these traits usually have a wide reaction norm while that of the complex trait that is being selected for, i.e. reproduction, typically does not. Reproductive transition requires that the intense cellular signaling that is characteristic of this stage of development not be perturbed. The cell differentiation processes that lead to floral organ formation are on very strict spatial and temporal programs. Therefore, improving the yield retention of food and fiber crops, while under reproductive stage stress, will require a better understanding of the physical and molecular processes that are tightly intertwined during reproductive differentiation. Therefore, current and future studies in food crop improvement should focus on characterizing the effects of suboptimal environments on the physical structures that undergird fruit formation (reproductive architecture) and on the molecular signals governing these processes. The literature on these types of studies is lacking but some researchers are realizing that the next generation of crops will have to be built (ideotype breeding) purposefully for reproductive resilience and not necessarily for survival. Our studies in rice and sorghum found that the reproductive stage of growth was critical for assessing tolerance to abiotic stress (chilling and water-deficit) with respect to yield penalty. Specifically, in rice, our findings showed that a gene network anchored by the DECUSSATE gene was pivotal for initiation of flowering (beginning at booting) before source strength became severely limited. In sorghum, our findings indicated that the panicle differentiation stage was sensitive to chilling stress with the later stages (SB1 and SB4) being the most sensitive as shown by the large grain yield penalties. These later stages represented differentiation of spikelet, spikelet pair, and floral meristems. Together, these case studies revealed the importance of reproductive stage resilience to abiotic stressors for lowering associated yield penalties.Item Liquid Organic Fertilizer Effects on Growth and Biomass of Lettuce Grown in a Soilless Production System(2022) Shaik, Azeezahmed; Singh, Hardeep; Singh, Sukhbir; Montague, Thayne; Sanchez, JacoboDemand for locally produced, organically grown leafy greens is increasing throughout the United States. However, due to lack of efficient organic fertilizers (OFs) for soilless substrates, organic greenhouse production of leafy greens may be challenging. Therefore, a greenhouse study was conducted to analyze the effects of six liquid OFs on growth and development of lettuce in a soilless system. Two experiments were conducted using a randomized block design, and treatments included six fish- or plant-based OFs: OF1 (5N–1P–1K), OF2 (2N–5P–1K), OF3 (3N–1P–1K), OF4 (2N–2P–2K), OF5 (4N–1P–1K), and OF6 (3N–3P–2K); one inorganic fertilizer treatment (IF, 24N–8P–16K); and one unfertilized control treatment. Fertilizer solutions were prepared at 2 dS m–1 and applied at 100 mL/plant. In Expt. 1, fresh biomass for IF-treated plants was 12% to 38%greater than OF treatments, whereas this difference ranged from 25% to 57% in Expt. 2. Similarly, leaf area values of IF-treated plants were 5% to 40% greater than OF treatments in Expt. 1, and the difference ranged from 28% to 90% in Expt. 2. A possible explanation could be greater availability of nutrients in the IF treatment compared with OF treatments. There was no significant difference among fertilized treatments for number of leaves and stem diameter. Based on the index-based ranking, fish-based (OF1) and fish- and plant-based (OF2 and OF6) performed well among different liquid OFs used in the study. Although the yield under OFs was less compared with that under IF, there is potential to reduce this yield gap by optimized fertility management of these fertilizers. Future research is needed to investigate the impact of optimized rate, timing, different placement, and additional nitrogen (N) sources of OFs on the soilless production of lettuce.Item Seed-to-seed early-season cold resiliency in sorghum(2021) Emendack, Yves; Sanchez, Jacobo; Hayes, Chad; Nesbitt, Matthew; Laza, Haydee (TTU); Burke, JohnEarly planted sorghum usually experiences cooler day/night temperatures, which may result in delayed growth, floral initiation, and infertile pollen, limiting productivity in high altitudes and temperate regions. Genetic variability for cold tolerance in sorghum has been evaluated by characterizing germination, emergence, vigor, and seedling growth under sub-optimal temperatures. However, the compounded effect of early season cold on plant growth and development and subsequent variability in potential grain yield losses has not been evaluated. Agro-morphological and physiological responses of sorghum grown under early-, mid-, and standard planting dates in West Texas were characterized from seed-to-seed. A set of diverse lines and hybrids with two major sources of tolerance, and previously selected for seedling cold tolerance were used. These were evaluated with a standard commercial hybrid known for its seedling cold tolerance and some cold susceptible breeding lines as checks. Variabilities in assessed parameters at seedling, early vegetative, and maturity stages were observed across planting dates for genotypes and sources of cold tolerance. Panicle initiation was delayed, and panicle size reduced, resulting in decreased grain yields under early and mid-planting dates. Coupled with final germination percent, panicle width and area were significant unique predictors of yield under early and mid-planting dates. Significant variability in performance was observed not only between cold tolerant and susceptible checks, but noticeably between sources of cold tolerance, with the Ethiopian highland sources having lesser yield penalties than their Chinese counterparts. Thus, screening for cold tolerance should not be limited to early seedling characterization but should also consider agronomic traits that may affect yield penalties depending on the sources of tolerance.Item Selection for seedling cold vigor in grain sorghum(2017-05) Sanchez, Jacobo; Ritchie, Glen L.; Burke, John J.; Emendack, Yves Y.Sorghum is the fifth most widely grown cereal grown in the world, but one limitation to sorghum production is the restriction of cool temperatures on crop growth and development. The primary objective of the current study was to validate five previously identified markers of cold tolerance in sorghum by deriving a recombinant inbred line population from a cross between BTx623, a warm season elite sorghum line, and Hong Ke Zi, a Chinese sorghum landrace with increased cold tolerance. We conducted controlled environment screening testing of 307 recombinant inbred lines (RILs), followed by field-based phenotypic testing early-planted sorghum for 31 selected lines. Genotyping of the 31 F4 RILS using the KASP genotyping technology indicated that only two of the five markers tested showed segregation for the HKZ, BTx623, and the heterozygous genotype. Using the genotype data obtained, the genotype of each of the 31 RILS was compared to the various growth parameters measured by performing a one-way ANOVA analysis. Significant separation of the three genotypic groups (homozygous for HKZ allele, homozygous for BTx623 allele, and heterozygous for both alleles) was seen with the root biomass per plot (RBM/plot) phenotype only. That is, RILS that contained the homozygous HKZ (cold-tolerant) allele had significantly more root biomass than did RILS that were homozygous for the BTx623 allele or heterozygous for both alleles (Table 3.2). This result indicates that the two markers tested could be potential candidates in selecting for the seedling cold vigor trait using marker assisted selection (MAS). Though this result is promising, the markers need to be tested against a larger pool of diverse individuals to observe if the markers are truly viable as a selection tool.