Effects Of Soil Cr Concentration On Grain Yield Of Rice (Oryza Sativa L.) And Analysis Of Its Causes

In order to investigate the effects of soil Cr concentration on grain yield of rice and analyze its causes, Pot experiments were carried out in Yangzhou, China in 2003, and with 20 rice cultivars of various types from different years, origins and backdrop of descendiblity as materials. The cultivars were clustered into 3 types by biomass, grain yield, root dry weight, panicle number, respectively, using hierarchical cluster method. The difference of yield formation, dry matter production and distribution, nitrogen uptake and utilization at maturity between different types were studied and causes of the differences were analyzed by investigating the relationship between biomass, grain yield, root dry weight, panicle number. The purpose of this study is to provide valuable bases for selecting and breeding rice varieties in area which is polluted by Cr. Results showed as follows:1. Significant difference of the response of yield among cultivars to soil Cr Concentrations was observed. Compared with CK ,among the 20 rice cultivars, soil Cr Concentrations resulted in significant increases in the yield to the CK among 6 rice cultivars, which including Zaofen 9, Fengyouxiangjing, IR8, Aizizhan, Ribenqin, Huangjinqin(an average yield increase of 20.8% ) , There is no significant increase in yield to the CK among 7 rice cultivars, which including Nanjing11, Teqing, Guichao2, Lianjing3, Wuxiangjing14, Wuyunjing7, Wuyujing3(an average yield increase of 0.56%) , There is an significant decreases in yield to the CK among 7 rice cultivars, which including Yangdao6, IR24, Liangyoupeijiu , Shangyou63, Nongken57, Zhengdao88, Yanjing2(an average yield decrease of 19.25%).2. The basic characters of the varieties that the yield added significantly under Cr treatment were as follows: seed setting percentage increased significantly, panicle number pot spike and sink potential increased slightly, spikelet number per panicle and 1000-grain weight decreased slightly; The basic characters of the varieties that the yielddecreased significantly under Cr treatment were as follows: sink potential decreased significantly, panicle number pot spike and spikelet number per panicle decreased obviously, seed setting percentage and 1000-grain weight decreased slightly; The basic characters of the varieties that the yield influenced slightly under Cr treatment were as follows: sink potential decreased slightly, panicle number pot spike and seed setting percentage increased slightly, spikelet number per panicle and 1000-grain weight decreased slightly.3. The basic characters of the varieties that the yield added significantly under Cr treatment were as follows: Economic co-efficient and the ratio of panicle dry matter to total biomass of rice at maturity decreased obviously, biomass increased slightly, all the ratio of the root> stem and sheath > leaf dry matter to total biomass of rice at maturity decreased slightly; The basic characters of the varieties that the yield decreased significantly under Cr treatment were as follows: biomass of rice at maturity decreased significantly, Economic co-efficient decreased slightly, all the ratio of the root> panicle dry matter to total biomass'of rice at maturity decreased significantly, all the ratio of the stem and sheath and the leaf dry matter to total biomass of rice at maturity increased obviously or significantly; The basic characters of the varieties that the yield influenced slightly under Cr treatment were as follows: biomass decreased significantly, Economic co-efficient increased slightly, the ratio of the root dry matter to total biomass of rice at maturity decreased significantly, all the ratio of the stem and sheath - panicle and the leaf dry matter to total biomass of rice at maturity increased slightly.4. The basic characters of the varieties that the yield added significantly under Cr treatment were as follows: all the nitrogen uptaken nitrogen use for grain output and nitrogen harvest index increased significantly, The basic characters of the varieties that the yield decreased s...