Identification of Drought Resistance and Variety Screening of Next Generation Dryland Rice at Different Growth Stages

Purpose This study aimed to establish an indicator system for evaluating drought resistance in next generation dryland rice (NGDR) based on yield and its component factors, to reveal the differences in drought resistance among different varieties (lines) of NGDR, and to screen varieties (lines) with superior comprehensive drought resistance performance.

Methods Using four types and 28 rice varieties (lines) as materials, with the drought-sensitive variety IR64 and the drought-resistant variety Hanyou 73 as the drought-stress control materials, two water management regimes, drought stress and conventional irrigated cultivation were established. Drought stress experiments were implemented at four growth stages: seedling, tillering, booting, and flowering-filling stages, to investigate the effects of drought stress at different stages on yield and its component factors of each variety (line). Principal component analysis (PCA) and cluster analysis were employed to comprehensively evaluate the drought resistance of each variety (line).

Results Under drought stress, the seedling emergence rate, survival rate under repeated drought, tiller number, plant height, panicle length, effective panicle number, grains per panicle, seed-setting rate, 1000-grain weight, and yield per plant of the tested varieties (lines) were inhibited. The effective panicle number, grains per panicle, filled grains per panicle, seed-setting rate, and 1000-grain weight were extremely significantly positively correlated with yield per plant (P<0.01 or P<0.001). Eight varieties (lines), namely H479B, DH45B, C210, DHY918, DHY211, DHY220, DHY221, and DHY223, exhibited relatively strong drought resistance.

Conclusion The emergence rate, repeated drought survival rate, effective panicle number, grains per panicle, filled grain number per panicle, seed-setting rate, 1000-grain weight, and yield can served as the core indices for drought resistance assessment of NGDR. Five japonica hybrid rice varieties, DHY918, DHY211, DHY220, DHY221, and DHY223 can be used as preferred varieties for demonstration and promotion of NGDR, while the three varieties, H479B, Dianhe 45B, and C210 can serve as backbone parents for drought resistance breeding in NGDR.