Drought resistance identification and drought resistance indexes screening of Tibetan hulless barley resources at adult stage

Abstract

<p id="C3">Drought is one of the main factors affecting the production of hulless barley in the Qinghai-Tibet Plateau. Identification of drought resistance of hulless barley germplasm resources at adult stage and screening of reliable drought resistance indexes can provide basis for breeding drought resistant varieties. In the present study, a total of 238 hulless barley germplasms were used as materials, and two treatments of normal irrigation and drought stress in the field conditions were conducted in Zhangye of Gansu Province in 2019 and 2020, respectively. Seven indexes, such as the plant height, spike number per plant, biomass per plant, grain weight per spike, spike length, 1000-grain weight, and yield were determined. The drought resistance comprehensive evaluation value (<italic>D</italic>-value), comprehensive drought resistance coefficient (CDC-value), and weight drought resistance coefficient (WDC-value) were used to identify drought resistance at adult stage of hulless barley germplasms. The results showed that the effects of drought stress on all indexes were extremely significant, and the correlation analysis showed that the yield was significantly positively correlated with plant height and 1000-grain weight at<italic> P </italic>&lt; 0.01, and significantly positively correlated with the grain weight per panicle at <italic>P</italic>&lt;0.05. Frequency analysis showed that the sensitivity of seven indexes to drought stress was plant height, yield, biomass per plant, grain weight per ear, number of ears per plant, ear length and 1000-grain weight, respectively. The ranks of drought resistance of germplasms based on the <italic>D</italic>-value, CDC-value, and WDC-value were similar. Grey correlation degree analysis showed that the correlation degree between DC-value and <italic>D</italic>-value was in the order of yield, biomass per plant, grain weight per spike, plant height, number of spikelets per plant, ear length and 1000-grain weight, which was basically consistent with the close degree between DC-value and WDC-value of each index. Stepwise regression analysis showed that yield, plant height, panicle number per plant, 1000-grain weight and biomass per plant could be used as reliable indexes for drought resistance identification of hulless barley in adult stage. <italic>D</italic>-value was determined as the appropriate method for drought resistance identification. Based on <italic>D</italic>-value, the tested hulless barley germplasms were divided into five drought resistance grades, and 38 germplasms were classified in grade I, such as Ziyanwoqingke, Liulengqingke, Ziqingke, ZDM8125, Tuhuluqingke, etc. These results provided important basic materials and theoretical reference for the breeding of drought-resistant varieties and the study of drought-resistant mechanism of hulless barley.