Effects Of High Temperature On Light Allocation And Antioxidant Activities In Common Bean Seedlings

Common bean(Phaseolus vulgaris) is a genus phaseolus fabaceae annual herbaceous vegetable. It originates in Argentina and Mexico in America, and been introduced into China in the late sixteenth century. It’s one of the most popular vegetables.This bean is suitable for planting in high altitudes of temperate and tropical, and it’s a kind of yoshimitsu cold cross-pollinated crops. Its optimum growth temperature is25℃-30℃. Common bean will be subjected to high temperatures hurt under the high temperature environment above35℃, which will lead to seriously affect its yield and quality. Exploring the common bean’s response mechanism under high temperature stress should provide a theoretical basis for its breeding and cultivation in the future. In this study, we consider common bean seedlings as test material, analysis the high lethal temperature of different kinds of common bean seedlings, and explore the Index, electrolyte penetration, chlorophyll content, chlorophyll fluorescence parameters and antioxidant enzyme activity of varieties heat damage that high temperature stress on common bean of different resistance. The main results are on the following:First, the heat resistance of22bean varieties that consider semi-lethal temperature as a screening indicator identification. The results show that,’ZI HUA DAO DOU’’s high lethal temperature is low, so it’s a heat-sensitive variety, and’LI YUN I’ is a Heat-resistant variety, which is consistent with the result of heat injury index.Second, at the beginning under heat stress at38℃/26℃(day/night), PS Ⅱ photochemical quenching coefficient (qP), quantum efficiency of the photosynthetic electron transport (Φ PS Ⅱ) and chlorophyll a (Chla) content, chlorophyll b (Chlb) all show a decreasing trend, and the decline of ’ZI HUA DAO DOU’, which is a heat-sensitive variety, is greater than that of’LI YUN I’.This indicates that, after heat stress, the Pigment content of common bean’s seedling leaves will decline, the activity of PS Ⅱ will be inhibited, and the extent of injury is larger compared the heat-sensitive variety,’ZI HUA DAO DOU’, with’LI YUN I’Third, the relative electrolyte leakage will be increasing under heat stress and that of the heat-sensitive variety,’ZI HUA DAO DOU’, is larger than’LI YUN I’, which shows that the damage of cellular membranes of the heat-sensitive variety,’ZI HUA DAO DOU’, is larger than that of’LI YUN I’after heat stress. The content of common bean’seedling leaves’MDA declines, superoxide dismutase (SOD)、catalase (CAT), ascorbate peroxidase (APX) all decrease significantly (P<0.05).The activity of APX and POD of the heat-sensitive variety, ZI HUA DAO DOU’shows a greater decline than’LI YUN I’.The recovery rate of the heat-resistant variety,’LI YUN I’, is larger than that of’ZI HUA DAO DOU’after relieving the stress, which shows that there are different effects to the antioxidant system of different common bean’s seedlings under heat stress:In the early phase of treatment, resistant variety shows a lower decline and a greater recovery rate, which is useful to remove the surplus reactive oxygen species.