Effects of Low Light Density Stress on Yield and Physiological Characteristics of Different Growth Stages of Tomato

This experiment is to investigate effects of low light density stress on yield and physiological characteristics during different growth stages of 4 stable inheriting tomato strains by simulating low light environment.The result is that percentage of fruit setting,average fruit weight and average plant yield of 4 tomato strains decrease under low light stress,the decreased extent in strains 1 and 2 is lower than that in strains 3 and 4.In functional leaves at different tomato growth stages chlorophyll content,especially chlorophyll b of strains 1 and 2,increases,and soluble sugar decreases.The relative value of soluble sugar content in strain 4 at seedling stage is 30% of that of the control.Soluble protein decreases and SOD,POD(or CAT) activities increase at the earlier stages of growth,and they are the contrary at the later stages.The relative value of every index in strains 1 and 2 at different growth stages is higher than that in strains 3 and 4(POD excluded).