Effects Of Different Oxygen Supply On Growth Characteristics And Yield Formation Of Rice (Oryza Sativa L.)

Although rice (Oryza sativa L.) originate in swampland, the oxygen is indispensable for its growth. The investigators have regarded the improvement of aeration for paddy field and the incretion of oxygen content of rhizosphere as research focuses of rice cultivation. Previous researches on dry-wet alternate irrigation, moistening irrigation and intermittent irrigation to improve the aeration of paddy field achieved good results such as promoting the rice development, enhancing the stress resistance, increasing the yield and improving the grain quality. But the effects of above irrigations adopted in the rice-farmers'fields were poorer than in the experiment fields, because of weather, field position and irrigation facility and so on.Field and solution culture experiments were conducted with Liangyoupeijiu, Zhongzheyou 1(indica hybrid rice), Yongyou 9 (indica-japonica hybrid rice) and Xiushui 09 (inbred japonica rice) to study the effects of different oxygen environment on the growth characteristics of shoot and root, photosynthesize ability, yield and senescence in rice. The super micro bubbles generator and other aerated technique were used to elevate oxygen content of rice rhizosphere. The relationship between aerobic environment and rice growth were invesitigated. The main results showed as follow:1. The primary experimental results showed that the super micro bubbles aerated irrigation increased tillering rate and shoot growth rate significantly, and then resulted in higher leaf area index of rice. Moreover, the super micro bubbles aerated irrigation increased the content of chlorophyll, soluble protein, soluble sugar, synthesis and accumulation of photosynthate, capacity of delaying senescence and functional period of leaves. The method of application nitrogen fertilizer with irrigation water enhanced the beneficial effects of super micro bubbles aerated irrigation, which was showed as greater growth vigor and photosynthetic capacity in whole stage.2. The results of aerated solution culture experiment showed that the total root length, total root surface area, root dry weight, average root length and root volume were increased under three aerated treatments, but the average root diameter and the number of root tips were decreased. The root vigor,absorbing surface area and active absorbing surface area of roots were enhanced by the oxygen aeration, and the intermittent aerated treatment and super micro bubbles aerated treatment were more significant than other treatments. The root bleeding quantity, soluble sugar and free amino acid content of bleeding sap under super micro bubbles aerated treatment were higher than non-aerated treatment at full heading stage. Further more, all the aerated treatments also increased the root POD activity at full heading stage.3. The grain yield of rice increased significantly when application nitrogen fertilizer with aerated irrigation water. The higher effective panicles, total spikelets in the population and seed setting were the major factors resulting in higher yield. The photosynthetic rate, stomatal conductance and transpiration rate of rice when application nitrogen fertilizer with aerated irrigation water were higher than other treatments, but the intercellular CO2 concentration was lower than other treatments. Correlation analysis showed that the grain yield were significantly positive correlated with photosynthetic rate, stomatal conductance and transpiration rate, and dramatically negative correlated with intercellular CO2 concentration at full heading stage.4. The senescence process of rice under three aerated treatments was delayed in late growth stage. The SOD activity, POD activity and soluble protein content of intermittent aerated treatment were the highest in four treatments, while the lowest occurs under non-aerated treatment from flowering to 21 days after flowing. The decrease of SOD and POD activity was the slowest under super micro bubbles treatment, but decrease of soluble protein was the slowest under intermittent aerated treatment. The increases of MDA content in first 7 days after flowering were lower than subsequent 7 days. The highest increase of MDA content occurs under non-aerated treatment.