Objective Effects of broadcasting density and seedling strengthen agent on physiological characteristics of rice seedling were studied.

Method By conventional dry nursery using an aromatic rice cultivar Nongxiang18 as material, four broadcasting densities, which were 30, 60, 90, 120 g·plate^-1, respectively, were designed, and whether seedling strengthen agent was applied or not.

Result and conclusion The results showed that leaf area and rice seedling dry mass(leaf dry mass, stem dry mass, root dry mass and dry mass per height) significantly decreased with the increase of broadcasting density when broadcasting density was in the range of 30-120 g·plate^-1.The values of leaf area and rice seedling dry mass (leaf dry mass, stem dry mass, root dry mass and dry mass per height) were higher in the broadcasting density of 30 g·plate^-1 than those of other treatments whether seedling strengthen agent was applied or not.Compared with the treatment of no seedling strengthen agent, the seedling strengthen agent could increase SPAD value, leaf area, rice seedling dry mass (leaf dry mass, stem dry mass, root dry mass and dry mass per height) and specific leaf mass.And superficial area, average diameter and volume of roots remarkably increased.Furthermore, the activities of superoxide dismutase (SOD) and peroxidase (POD) of rice seedling significantly increased, too.However, the plant height and malondialdehyde (MDA) concentration of rice seedling remarkably decreased.Principal component analysis showed that stronger stem (heavier stem dry mass, bigger width of stem and dry mass per height) and bigger value of root to shoot and heavier leaf dry mass may be considered as better rice seedling qualities rapidly and accurately at the growth stage of rice seedling.