Effects of low phosphorous stress on the morphologies and physiological indices of different sorghum cultivars at seedling stage

The effects of low P stress on the morphologies and physiological indices of sorghum were investigated with 14 sorghum cultivars at seedling stage. The results show, 1) Different P supply levels significantly affect the morphologies of sorghum seedlings (P0.01). P supply level of 0.25 mmol/L was found to be the proper P level for screening P-tolerance cultivars; 2) Low P stress decreases the P content of shoot, and negatively influences morphological development of sorghum seedlings, especially on plant dry weight accumulation. Therefore shoot P content and above ground dry weight were recommonded as screening indices for low P-tolerance cultivars at sorghum seedling stage; 3) Different cultivars responded differently to lowP stress. Bayueqi was a lowP tolerance cultivar, while Nong858 was a low-P sensitive cultivar through cluster analysis; 4) P deficiency leads to low chlorophyll and soluble protein contents, high MDA content and high SOD and POD activities in sorgum seedlings. Except soluble protein, relative variations in the tested indices were small in low-P tolerance cultivars, high in low-P sensitive cultivars.