The effects of three cultivation methods on amino acid content of rice grains and preliminary study on its mechanism

Rice is a low protein crop,and the protein content in rice grain is determined not only by its inherent gene,but also by environment factors(such as temperature,light and fertilization) and cultural methods.In this paper,the effects of 3 cultivation methods(high-protein and high-yield integrative cultivation method,San-zhuang-san-gao cultivation method and conventional cultivation method) on amino acid content of rice grains and preliminary study on its mechanism were conducted using the rice type of Xiangzaoxian 31(early rice) and Peiliangyou 210 combination(late rice) by means of field experiment combined with lab analysis in Langli county Changsha city 2004.Glutamicoxalacetic transaminase(GOT) activities and aspartokinase(AK) activities of leaves and grains,and the contents of protein and amino acid in brown rice were analyzed.The results showed that the activities of GOT and AK in functional leaves and grains during the middle and late filling stage,the contents of amino acid,lysine(the restrictive amino acid of protein in rice grain,the primary restrictive amino acid of pig) and methionine(the restrictive amino acid of protein in rice grain),7 kinds of essential amino acid for people(Lys,Thr,Val,Met,Leu,Ile,Phe),protein as well as protein yield in brown rice were improved significantly by high-protein and high-yield integrative cultivation method compared with conventional cultivation method.Except for protein content in early rice grains,other indices were not significant different as under high-protein and high-yield integrative cultivation method and San-zhuang-san-gao cultivation method.The contents of amino acid,7 kinds of essential amino acid for people,lysine,methionine,protein N as well as protein yield in early rice grains under high-protein and high-yield integrative cultivation method were increased over San-zhuang-san-gao method and conventional cultivation method by 4.09% and 31.92%,2.99% and 33.06%,1.95% and 18.55%,6.54% and 31.98%,6.76% and 27.57%,15.72% and 38.64%,respectively.The contents of amino acid,7 kinds of essential amino acid for people,protein N as well as protein yield in late rice grains under high-protein and high-yield integrative cultivation method were increased over San-zhuang-san-gao method and conventional cultivation method by 2.24% and 42.98%,9.20% and 58.05%,1.74% and 26.06%,2.80% and 59.42%,respectively.It is concluded that high-protein and high-yield integrative cultivation method was suitable for rice cultivation.