Venkateshwarlu Challa, Kole Paresh Chandra, Paul Pronob J, Singh Arun Kumar, Singh Vikas Kumar, Kumar Arvind
International Rice Research Institute (IRRI), South Asia Hub, Patancheru, India.
Institute of Agriculture, Viswa Bharati University, Sriniketan, India.
Front Plant Sci. 2022 Feb 14;13:814774. doi: 10.3389/fpls.2022.814774. eCollection 2022.
Drought is one of the most predominant abiotic stresses in this century, leading to a drastic reduction in the yield of rainfed rice ecosystems. Breeding of drought-resilient rice varieties is very much in demand for sustainable rice production in drought-prone rainfed ecology. An experiment was designed under irrigated non-stress and drought-stress situations involving an exotic drought-tolerant landrace (Chao Khaw) and a high-yielding aromatic rice cultivar (Kasturi), and an F derived population of 156 breeding lines was developed at IRRI South Asia Hub, Hyderabad. The objective of the study was to assess the genetic variability, drought tolerance behavior, and identify promising breeding lines for different rice ecologies and drought breeding programs. Restricted maximum likelihood (REML) analysis using the mixed model approach revealed a considerable genetic variation in the population for yield and yield contributing traits in non-stress and drought-stress conditions. We observed very high heritability for all the selected traits under stress 2015 WS (73.8% to 85.3%) and 2016 WS (72.4% to 93.5%) and non-stress 2015 WS (68.2% To 92.9%) and 2016 WS (61.4% to 92.6%) environments, indicating possible selection for grain yield under drought stress and non-stress with the same precision level. None of the secondary traits except harvest index and biomass included in our study showed a positive association with grain yield, indicating indirect selection's ineffectiveness in improving yield under drought. A total of 48 promising breeding lines were found to have a better yield than donor Chao Khaw (up to 38% advantage) and popular drought-tolerant cultivars Shabhagidhan (up to 48% advantage) in stress conditions and recommended for rainfed upland ecology, 34 breeding lines under the well-watered condition suited for rainfed lowland ecology. Overall, the study found 21 common breeding lines that showed their superiority in non-stress and under drought stress situations, fitting best in rainfed lowland ecology with occasional drought occurrence. The large genetic variation found in this population can be exploited further to develop a few forward breeding high-yielding lines with better drought tolerance ability and used as drought donors in drought breeding programs.
干旱是本世纪最主要的非生物胁迫之一，导致雨养水稻生态系统的产量大幅下降。为了在易干旱的雨养生态环境中实现水稻的可持续生产，培育具有抗旱能力的水稻品种迫在眉睫。在灌溉非胁迫和干旱胁迫条件下设计了一项试验，涉及一个外来耐旱地方品种（Chao Khaw）和一个高产香稻品种（Kasturi），并在位于海得拉巴的国际水稻研究所南亚中心培育了一个由156个育种系组成的F代群体。本研究的目的是评估遗传变异性、耐旱行为，并为不同的水稻生态环境和干旱育种计划鉴定有前景的育种系。使用混合模型方法的限制最大似然（REML）分析表明，在非胁迫和干旱胁迫条件下，该群体在产量和产量构成性状方面存在相当大的遗传变异。我们观察到，在2015年雨季胁迫（73.8%至85.3%）、2016年雨季胁迫（72.4%至93.5%）以及2015年雨季非胁迫（68.2%至92.9%）和2016年雨季非胁迫（61.4%至92.6%）环境下，所有选定性状的遗传力都非常高，这表明在干旱胁迫和非胁迫条件下，以相同的精度水平选择籽粒产量是可行的。在我们的研究中，除收获指数和生物量外，没有一个次要性状与籽粒产量呈正相关，这表明在干旱条件下通过间接选择提高产量是无效的。在胁迫条件下，共发现48个有前景的育种系产量高于供体Chao Khaw（优势高达38%）和流行的耐旱品种Shabhagidhan（优势高达48%），推荐用于雨养旱作生态环境；在水分充足条件下，有34个育种系适合雨养低地生态环境。总体而言，该研究发现21个共同的育种系在非胁迫和干旱胁迫条件下均表现出优势，最适合偶尔发生干旱的雨养低地生态环境。该群体中发现的大量遗传变异可进一步用于培育一些具有更好耐旱能力的正向育种高产系，并用作干旱育种计划中的干旱供体。
