Effects Of SO₂ On Injury Reaction, Physiological And Biochemical Change Of Crops

In this paper twenty important vegetables,grain crops, and herbages were studied.The study focused on the injury symptoms, dose reactions, injury threshold value and influential factors of pollutant SO2 on various crops, and also on the dynamic transformations of cell membrane osmosis,SOD,POD, CAT, MDA, chlorophyll and soluble protein of resistant and sensitive crops.The relations among these physiological biochemical transformations and crop resistant ability were analyzed. Meanwhile, the protective roles of the five compounds to crops were also studied. The results were listed as the following: 1. Injury reactions: (1)The outer symptoms caused by SO2 were obviously different on various crops, and injury symptoms first appeared on leaves. The symptoms on the leaves of the twenty crops could be classified into the four types:gray spots between veins, yellow spots along veins, curl along leaf tips and leaf edges and syndrome. The treated doses affected the symptom types, occurrence time, injury degrees, spots distribution, spots spread and color changes directly;.(2)The sensitivity of various crops to SO2 differeed with growth periods. The resistant ability to SO2 in cotyledon period was higher than in real leaves period. The ability between two real leaves and four real leaves won't be different. The sensitivity of crop seedlings to SO2 could be used as an identified basis;(3)There were siginificant differences among various crops in the injury degrees of diverse treated times of SO2 to crops. The same as various doses of the same crops. With the raise of treated times, the injury degrees of crops also increased, but the increased extents were obviously less than the injury degree resulted from the dose accession;(4)The injury degrees of SO2 on crops were functions of the exposure time and SO2 concentration. The injury degrees of crops increased with the raise of SO2 concentration, and the increased extents were higher than the injury degrees resulted from the exposure time accession. The SO2 concentration was the major factor to the injury degrees of crops;(5)The crops were relatively sensitive in two leaves period. So we can use the dose reactions to SO2 in two leaves period as the injury threshold values to classify resistant ability types. According to the injury threshold values in two real leaves period, the supplied crops divided into four types: 1) the extremely sensitive types,their injury threshold values≤0.3ppm×4h; 2) the relatively sensitive types,their injury threshold values 0.3ppm×4h~0.4ppm×3h; 3)the relatively resistant types, their injury threshold values 0.4ppm×4h~0.5ppm×4h; 4)the extremely resistant types, their injury threshold values≥0.5ppm×4h.