Mass screening and cluster analysis for tolerance to stress of hybrid rice variety under field conditions

Using 2 high-yield hybrid rice varieties (the 3-line hybrid rice variety “Shanyou 63” and 2-line hybrid rice variety “Liangyoupeijiu”) as the control (CK), selected growth and physiological parameters including chlorophyll content, dry-weight, Fv/Fm, stem bleeding and nitrate reductase activity (NRA) of 48 rice materials (sz744~sz791) were measured at flowering stage in a one-year field experiment to determine the material’s tolerance to high light intensity, low light intensity, drought, high nitrogen application and early aging. Seed-setting rates of the rice plants were also observed after harvesting. The results show different tolerance performances to above mentioned stresses of the tested materials. Clustering analysis on different performance combinations of the rice to the stresses classifies the materials into 5 types. Based on the indices, the correlation coefficient of seed-setting rate to change in chlorophyll content under high light intensity, leaf NRA at heading stage, and chlorophyll content of flag leaf at booting stage are respectively 0.426^**, 0.295^* and 0.566^**. Rice seed-setting rate in one year may also be an important eurytropic adaptability index.