Effect Of Enhanced UV-B Radiation On Growth, Productivity And Quality Of Rice

As the decreasing of stratospheric ozone layer,subaerial ultraviolet(UV-B)radiation arriving the earth's surface becomes stronger,whose effect on biology and the ecology effect has become focus of people issues to concern.The effects of enhanced UV-B radiation on the growth,physiological response,yield and quality of two rice cultivars (ShenNong 6014 and ShenNong 265)are studied in potted method.There are three treatments which is natural light(TCK),enhanced 5%UV-B radiation(T1)and enhanced 10%UV-B radiation(T2).The results show that:1 Effects on growth and output of rice:Enhanced UV-B radiation decreases leaf age, tiller numbers,dry weight and yield components of rice,but increases leaf thickness,plant height,and makes leaf area first increased after reduce,and also Changes the proportion of dry weight of rice.The effects of T2 is higher than T1.Change of leaf age,tiller numbers, dry weight and yield components office is:TCK＞T1＞T2,then the change of plant height and leaf thickness is:TCK＜T1＜T2,the highest inhibitory action on leaf area is in booting stage,the change situation of dry weight fraction of rice in mature stage is:fringe dry weight proportion＞stem dry weight proportion＞leaf dry weight prportion.The resistance of ShenNong6014 which displays to the UV-B radiation enhancement is strong in the growth and the output aspect.2 Effects on physiological response of rice:Enhanced UV-B radiation decreases chlorophyll a,chlorophyll b,ch1 a/b,net photosynthetic rate,PAR,soluble protein and nitrate reductase activity,but increases the content of carotenoid,POD activities,makes soluble sugar,SOD,CAT activities first increased after reduce.The effects of T2 is higher than T1.The change of chlorophyll a,chlorophyll b and chl a/b is TCK＞T1＞T2,content of carotenoid is TCK＜T1＜T2,the tread of increased amplitude is first increased after reduce,the highest increased amplitude is in heading stage,net photosynthetic rate,PAR, change of soluble protein and nitrate reductase activity is TCK＞T1＞T2,content of soluble sugar before heading stage is TCK＜T1＜T2,and is TCK＞T1＞T2 in filling stage and mature stage,the biggest and smallest increased amplitude of SOD,CAT activities appear in jointing stage and mature stage.The resistance of ShenNong6014 which displays to the UV-B radiation enhancement is strong in physiological response aspect.3 Effects on grain quality of rice:Enhanced UV-B radiation increases protein content and amylose content,but decreases the percentage of brown rice,head rice rate,the rate of white rice,grain area,length to width ratio,whiteness,fatty acid contents and eating quality of rice.The effects of T2 is stronger than T1 and the resistance of ShenNong265 which displays to the UV-B radiation enhancement is strong in grain quality aspect.