Mapping a Novel Gene of Cold Tolerance at Booting Stage by Using Near-Isogenic Lines in japonica Rice

Genetic analysis showed that cold tolerance at booting stage of near-isogenic lines （NILs） of Kunmingxiaobaigu was controlled by a gene with large phenotypic variance. One hundred and sixty-four simple sequence repeats （SSR） distributed over 12 chromosomes were used to screen polymorphism between Towata （recurrent parent, RP） and near-isogenic line pool （NILP）, and two SSR markers at the long arm of chromosome 5 showed polymorphism in comparison with RP genome. Of the two markers, RM31 was found possibly linked with the cold tolerance gene at booting stage through one-way ANOVA. Twelve SSR markers around RM31 were then used to detect polymorphism between RP and NIL, and only RM7452 had polymorphism. The gene of cold tolerance at booting stage was further mapped on chromosome 5 between RM7452 and RM31 with genetic distances of 4.8 cM and 8.0 cM, respectively. This gene explained 10.50% of phenotypic variance and 5.10% of phenotypic variance of fully filled grains, and was tentatively designated as Ctb（t）.

Effects of Silicon Preparation on Different Forms of Silicon in Soil and Silicon Content in Rice Plants

Rice is a typical silicon-loving crop,known as"representative of silicic acid plant".Southeast Asia and other rice-producing countries have listed silicon fertilizer as the fourth most elemental fertilizer after nitrogen,phosphorus and potassium.Therefore,improving the utilization of soil silicon and promoting the transformation of soil silicon form is of great significance to the growth of rice and the development of agriculture.In order to investigate the effects of silicon preparations on different forms of silicon in soil and silicon contenst in rice plants,a pot experiment with Dongnong 427 was carried out,spraying on rice leaves at the booting stage,and three treatment groups(Si-TG,Si-EG and Si-60G)and a control group(CK)were set up.The contents of available silicon,water-soluble silicon,amorphous silicon,active silicon in soil and plant silicon were measured at the heading stage and the maturity stage of rice,then the effect of silicon preparation on the silicon content of rice soil and plant was analyzed.The results showed that spraying silicon preparation could significantly improve the silicon content of rice plants,promote the transformation of silicon forms in soil to varying degrees,and improve the silicon supply capacity of soil.Compared with CK,the soil available silicon content increased by 7.42%-8.26%at the heading stage and 6.70%at the maturity stage.The Si-EG treatment at the heading stage had the best effect on increasing the available silicon content of the soil,which was 8.26%higher than that of CK,reaching a significant level;the Si-TG treatment at the maturity stage had the best effect on increasing the silicon content of the plant,and the silicon content of the plant was 27.17%higher than that of CK,reaching a significant level.