Drought Stress Tolerance Screening of Elite American Breeding Rice Genotypes Using Low-Cost Pre-Fabricated Mini-Hoop Modules

Abstract

Drought is a major abiotic stress factor affecting the growth and development of plants at all stages. Developing a screening tool for identifying drought stress tolerance during seedling establishment is important in the deployment of rice varieties suited to water-limited growing environments. An experiment was conducted to evaluate 100 rice genotypes, mostly belonging to the tropical japonica subspecies, for drought stress tolerance using low-cost, pre-fabricated mini-hoop structures. The rice seedlings were subjected to two different soil moisture regimes- control pots managed at 100% and drought pots at 50% field capacity, from 12 to 30 days after sowing (DAS). Several morpho-physiological parameters including root traits were measured to assess the response of genotypes to drought stress. Significant moisture stress × genotype interactions were found for most of the parameters measured. A cumulative drought stress response index (CDSRI) was developed by adding the individual response indices of all cultivars. Based on CDSRI and standard deviation values, 5 and 28 genotypes were identified as highly sensitive and sensitive to drought, respectively, and 45 as moderately sensitive. On the other hand, 16 and 6 genotypes were classified as tolerant and highly tolerant to drought, respectively. Cheniere, a released cultivar, and RU1402174, an experimental breeding line, were identified as the least and most tolerant to drought among the 100 genotypes tested. Significant linear correlation coefficients were obtained between CDSRI and root growth parameters (R2 = 0.91, n = 100) and CDSRI with shoot growth parameters (R2 = 0.48, n = 100), revealing the importance of root traits in studying and identifying drought tolerant lines during the seedling establishment stages in rice. The tolerant rice genotypes identified will be valuable for rice scientists in studying the mechanism for early season drought as well as for rice breeders for developing new genotypes best suited under growing environments prone to early-season drought.

Genome-Wide Association Mapping of Seedling Drought Tolerance in Winter Wheat

“…The ratio of variable fluorescence (F v ) to maximum fluorescence (F m ) is used to estimate the potential quantum efficiency of photosystem (PS) II maximum efficiency under abiotic stress conditions (Sayed, 2003;Rachmilevitch, 2006). This technique has been used as one of the stress-tolerance screening tools in different crop species including wheat (Yang et al, 2007;Kumar et al, 2012;Maulana et al, 2018), sorghum (Sayyad-Amin et al, 2016;Sukumaran et al, 2016), rice (Oryza sativa L.) (Lone et al, 2019), barley (Hordeum vulgare L.) (Li et al, 2006), and maize (Zea mays L.) (Song et al, 2018). Generally, a low F v /F m value indicates low photosynthetic efficiency, whereas greater F v /F m values under stress conditions show better tolerance to stress (Kumar et al, 2012).…”

Screening of Rice Accessions for Tolerance to Drought and Salt Stress Using Morphological and Physiological Parameters

“…In view of the enormous yield losses in rice caused by drought and salt stresses and the ongoing climate change issues, there is need to develop more upland rice lines that are tolerant to drought and salt. Although several rice lines tolerant to drought or salt have been identified worldwide [1] [6] [16]- [27], many landraces, newly improved varieties and hybrids are yet to be screened for tolerance to these abiotic stresses, especially in Nigeria. The present study assists in this direction by screening rice varieties cultivated in Nigeria for tolerance to drought and salt stresses using morphological and physiological parameters.…”

Response of U.S. Rice Cultivars Grown under Non-Flooded Irrigation Management

“…Despite these benefits, a major concern for producing commercial rice under reduced irrigation is GY penalties ranging from 13% to 32% when compared to conventional flood irrigation, but genetic variation in rice germplasm may serve to correct this concern [24,26,27] by deploying alleles through breeding that result in effective use of water and crop resiliency to abiotic stress [17,28]. There has been worldwide interest in evaluating rice germplasm for production under reduced irrigation systems, particularly in areas where access to irrigation resources is limited and/or incidence of drought is expected to increase [29][30][31][32]. However, such efforts have been more limited in the U.S. where rice research has historically been focused on achieving higher yield potential without production constraints [26,30].With the availability of whole genome sequencing there is a greater understanding of the genetic population structure found in cultivated rice [33,34].…”

“…There has been worldwide interest in evaluating rice germplasm for production under reduced irrigation systems, particularly in areas where access to irrigation resources is limited and/or incidence of drought is expected to increase [29][30][31][32]. However, such efforts have been more limited in the U.S. where rice research has historically been focused on achieving higher yield potential without production constraints [26,30].With the availability of whole genome sequencing there is a greater understanding of the genetic population structure found in cultivated rice [33,34]. Most U.S. cultivars trace to the tropical japonica (TRJ) subpopulation [35], whereas most global rice acreage is planted with cultivars derived from the indica sub-population [36].…”

“…There has been worldwide interest in evaluating rice germplasm for production under reduced irrigation systems, particularly in areas where access to irrigation resources is limited and/or incidence of drought is expected to increase [29][30][31][32]. However, such efforts have been more limited in the U.S. where rice research has historically been focused on achieving higher yield potential without production constraints [26,30].…”