Effects of Humic Acid on the Photosynthetic Characteristics, Essential Elements and Yield of Oryza sativa L. and Their Correlation Analysis

In order to compare the effects of humic acid contents on the growth and physiology of rice(Oryza sativa L.), four treatments of 0, 0.1, 1 and 10 g/m2 humic acid were respectively applied into the pot and field experiments. The results showed that humic acid could increase net photosynthetic rate, intercellular CO2 concentration, stomatal conductance, transpiration rate and SPAD value in flag leaf at heading stage, and increase the contents of essential elements (Cu, Fe, Mn, Zn, S, K, P, Mg and Ca) in rice in the pot experiment. The net photosynthetic rate of flag leaf had a polynomial positive correlation with the contents of Zn, Mn, Ca, P and (Cu+Fe+Mn+Zn) in rice, and had a linear positive correlation with the S content. Humic acid significantly increased the rice yield in the field condition (P0.05), 0.1, 1 and 10 g/m2 humic acid increased the yield by 10.24%, 12.50% and 7.79%, respectively, and increased the contents of essential element (Cu, Fe, Mn, Zn, S, K, P, Mg and Ca) in rice. The yield had a linear positive correlation with and the contents of P, Mg, (Cu+Fe+Mn+Zn). The results provide the important theory and the practice basis for the application of humic acid in agriculture production.