Deeper rooting 1 (Dro1) and Deeper rooting 2 (Dro2) are the QTLs that contribute considerably to root growth angle assisting in deeper rooting of rice plant. In the present study, a set of 348 genotypes were shortlisted from rice germplasm based on root angle study. Screening results of the germplasm lines under drought stress identified 25 drought tolerant donor lines based on leaf rolling, leaf drying, spikelet fertility and single plant yield. A panel containing 101 genotypes was constituted based on screening results and genotyped using Dro1 and Dro2 markers. Structure software categorized the genotypes into four sub-populations with different fixation index values for root growth angle. The clustering analysis and principal coordinate analysis could differentiate the genotypes with or without deeper rooting trait. The dendrogram constructed based on the molecular screening for deep rooting QTLs showed clear distinction between the rainfed upland cultivars and irrigated genotypes. Eleven genotypes, namely Dular, Tepiboro, Surjamukhi, Bamawpyan, N22, Dinorado, Karni, Kusuma, Bowdel, Lalsankari and Laxmikajal, possessed both the QTLs, whereas 67 genotypes possessed only Dro1. The average angle of Dro positive genotypes ranged from 82.7° to 89.7°. These genotypes possessing the deeper rooting QTLs can be taken as donor lines to be used in marker-assisted breeding programs.

较深的生根1（Dro1）和较深的生根2（Dro2）是QTL，它们对根系生长角度的贡献很大，有助于水稻植株更深的生根。在本研究中，基于根角研究从水稻种质中筛选出一组348个基因型。根据叶片滚动，叶片干燥，小穗育性和单株产量，筛选了干旱胁迫下的种质系，鉴定出25个耐旱的供体系。根据筛选结果组成一个包含101个基因型的面板，并使用Dro1和Dro2进行基因分型标记。结构软件将基因型分为四个亚群，这些亚群的根系生长角度的固定指数值不同。聚类分析和主坐标分析可以区分具有或没有较深生根特征的基因型。根据分子筛对深根QTL进行构建的树状图显示了雨养高地品种和灌溉基因型之间的明显区别。共有11个基因型，分别是Dular，Tepiboro，Sunjamukhi，Bamawpyan，N22，Dinorado，Karni，Kusuma，Bowdel，Lalsankari和Laxmikajal，均具有QTL，而67个基因型仅具有Dro1。Dro的平均角度阳性基因型范围为82.7°至89.7°。这些具有更深生根QTL的基因型可以用作供体，用于标记辅助育种程序。