Sandhu Nitika, Subedi Sushil R, Yadaw Ram B, Chaudhary Bedanand, Prasai Hari, Iftekharuddaula Khandakar, Thanak Tho, Thun Vathany, Battan Khushi R, Ram Mangat, Venkateshwarlu Challa, Lopena Vitaliano, Pablico Paquito, Maturan Paul C, Cruz Ma Teresa Sta, Raman K Anitha, Collard Bertrand, Kumar Arvind
International Rice Research Institute, Los Baños, Philippines.
National Rice Research Program, Hardinath, Nepal.
Front Plant Sci. 2017 Oct 31;8:1879. doi: 10.3389/fpls.2017.01879. eCollection 2017.
Reducing water requirements and lowering environmental footprints require attention to minimize risks to food security. The present study was conducted with the aim to identify appropriate root traits enhancing rice grain yield under alternate wetting and drying conditions (AWD) and identify stable, high-yielding genotypes better suited to the AWD across variable ecosystems. Advanced breeding lines, popular rice varieties and drought-tolerant lines were evaluated in a series of 23 experiments conducted in the Philippines, India, Bangladesh, Nepal and Cambodia in 2015 and 2016. A large variation in grain yield under AWD conditions enabled the selection of high-yielding and stable genotypes across locations, seasons and years. Water savings of 5.7-23.4% were achieved without significant yield penalty across different ecosystems. The mean grain yield of genotypes across locations ranged from 3.5 to 5.6 t/ha and the mean environment grain yields ranged from 3.7 (Cambodia) to 6.6 (India) t/ha. The best-fitting Finlay-Wilkinson regression model identified eight stable genotypes with mean grain yield of more than 5.0 t/ha across locations. Multidimensional preference analysis represented the strong association of root traits (nodal root number, root dry weight at 22 and 30 days after transplanting) with grain yield. The genotype IR14L253 outperformed in terms of root traits and high mean grain yield across seasons and six locations. The 1.0 t/ha yield advantage of IR14L253 over the popular cultivar IR64 under AWD shall encourage farmers to cultivate IR14L253 and also adopt AWD. The results suggest an important role of root architectural traits in term of more number of nodal roots and root dry weight at 10-20 cm depth on 22-30 days after transplanting (DAT) in providing yield stability and preventing yield reduction under AWD compared to continuous flooded conditions. Genotypes possessing increased number of nodal roots provided higher yield over IR64 as well as no yield reduction under AWD compared to flooded irrigation. The identification of appropriate root architecture traits at specific depth and specific growth stage shall help breeding programs develop better rice varieties for AWD conditions.
减少需水量和降低环境足迹需要予以关注，以尽量减少对粮食安全的风险。本研究旨在确定在干湿交替条件（AWD）下提高水稻产量的合适根系性状，并确定在不同生态系统中更适合AWD的稳定高产基因型。2015年和2016年，在菲律宾、印度、孟加拉国、尼泊尔和柬埔寨进行了一系列23次试验，对先进育种系、流行水稻品种和耐旱系进行了评估。在AWD条件下，籽粒产量存在很大差异，这使得能够在不同地点、季节和年份选择高产且稳定的基因型。在不同生态系统中，节水率达到5.7%-23.4%，且产量无显著损失。各基因型在不同地点的平均籽粒产量为3.5至5.6吨/公顷，各环境的平均籽粒产量为3.7（柬埔寨）至6.6（印度）吨/公顷。拟合效果最佳的芬利-威尔金森回归模型确定了8个稳定基因型，其在不同地点的平均籽粒产量超过5.0吨/公顷。多维偏好分析表明根系性状（分蘖根数、移栽后22天和30天的根干重）与籽粒产量密切相关。基因型IR14L253在根系性状和跨季节及六个地点的高平均籽粒产量方面表现出色。在AWD条件下，IR14L253比流行品种IR64具有1.0吨/公顷的产量优势，这将鼓励农民种植IR14L253并采用AWD。结果表明，与持续淹水条件相比，在移栽后22-30天，10-20厘米深度处更多的分蘖根数和根干重等根系结构性状在提供产量稳定性和防止AWD条件下产量降低方面具有重要作用。与淹水灌溉相比，具有更多分蘖根数的基因型比IR64产量更高，且在AWD条件下产量无降低。确定特定深度和特定生长阶段的合适根系结构性状将有助于育种计划培育出更适合AWD条件的水稻品种。
