The Study On Effects Of Humic Acid And Paddy-upland Rotation On Biological Characteristics Of Oryza Sativa L.

In order to investigate the effects of humic acid and paddy-upland rotation interaction on rice growth physiology and brown rice quality in cadmium contaminated soil, it was Conducted that 0,0.1,1 and 10g m-2 humic acid were applied into the soil in the randomized block design of pot or field experiments. The soil of paddy-upland rotation were continuous cropping paddy soil and garden soil of a year xerophilous vegetable reformed from continuous cropping paddy soil, which was contaminated with class I cadmium content, The rice variety used for pot test was Xiangzaoxian 45 in rain shelter. The rice variety used for field experiment material was Jinjianyueyou 518. The samples were respectively collected at the seedling stage, tillering stage, booting stage, heading stage and maturity stage. The main results were as follows:Under the paddy-upland rotation conditions of pot cultivation and the same humic acid level, plant height and thousand kernel weight of Xiangzaoxian 45 under garden soil were higher than those under paddy soil at tillering stage, booting stage, heading stage and maturity stage.Under the condition of pot cultivation, humic acid and paddy-upland rotation increased net photosynthetic rate, intercellular CO2 concentration, stomatal conductance, transpiration rate and SPAD value in leaves at all growth stages, and increased the grain essential elements of Cu, Fe, Mn, Zn, S, K, P, Mg and Ca contents in the pot experiment. The correlation between the net photosynthetic rate of flag leaf and Zn、Mn、Ca、P and (Cu+Fe+Mn+Zn) contents was found to be a polynomial positive correlation.Humic acid significantly increased rice yield under the field condition, humic acid at 0.1,1 and lOg m-2 increased the yield by 10.24%,12.50% and 7.79% respectively, and increased rice grain essential elements of Fe, Zn, Mg and Ca content. The correlations between the yield and P, yield and Mg, yield and (Cu+Fe+Mn+Zn) were found to be linear positive correlations.The cadmium content in brown rice and soil cadmium absorption coefficient at garden soil were less than those at poddy soil, but the content of rice nutrient microelements iron, zinc, magnesium and calcium were increased. Paddy-upland rotation reduced the cadmium content in brown rice but increased the contents of microelements.