Effett Of Rhizosphere Oxygen Statues On Rice Nutrient Accumulation And Yield Formation

Rhizosphere oxygen statue as an important factor significantly affected rice growth and yield. It’s of great value to characterize the growth, yield formation and nutrient accumulation and utilization of rice under different rhizosphere oxygen statues, further to improve high-yield theory and the oxygen nutrient control techniques. In this research three experiments were conducted:(1) Hydroponic experiment was conducted to study the effect of rhizosphere oxygen concentration on yield formation and nitrogen accumulation and utilization with IR45765-3B(deepwater rice), Zhongzheyou-1(ZZY-1, rice) and Zhonghan221(ZH221, upland rice) as plant materials.Four rhizosphere oxygen concentration levels were set in this experiment: ie, 1.0 mg/L(T1, hypoxia),3.0 mg/L(T2),5.5 mg/L(T3) and 7.5 mg/L(T4, saturated oxygen concentration),respwctively;(2) IR45765-3B(deepwater rice) and Zhongzheyou-1(ZZY-1, rice) were chosen to detect the growth, grain yield and nitrogen utilization of rice under different root aeration methods in rainfall proof trough cultivation. Four methods were used in this experiment: ie, calcium peroxide applied(Ca O2), micro-nano bubble water irrigation(MBWI), alternate wetting and drying(AWD) and control(waterlogging, WL);(3). Using IR45765-3B(deepwater rice) and Zhongzheyou-1(ZZY-1, rice) as materials to probe the effect of rhizosphere oxygen statues on P and K uptake of rice under hydroponic and rainfall proof trough cultivation. The main results in this study were as follows:1. Rhizosphere oxygen concentration significantly affected yield and dry matter accumulation of rice. The order of yield and dry matter accumulation of three varieties among the four treatments was followed as T2>T1>T3>T4. The variances between the treatments were significant. The significant impacts on grains/panicle and seed setting contributed to the variance on yield in IR45765-3B and ZH221 among the treatments. In case of ZZY-1, the effect of treatments on grains/panicle, seed setting and effective panicles accounted for the difference of yield.2. T1 and T2 enhanced N accumulation of rice during early stage of growth. Aeration behavior(T2)could increase N accumulation of plant during later grain filling stage, but suppression of excessive oxygen concentration(T3,T4) on N transportation to grain was also examined in hydroponic experiment. In addition, the top nitrogen utilizationefficiency(NUE) values of three varieties were achieved in T2, which increased by 6.9%( IR45765-3B),12.8%(ZZY-1) and 13.8%(ZH221) than that in T1, while rhizosphere aeration promoted N dry matter production efficiency(NDMPE) during vegetative stage.3. Under rainfall proof trough cultivation, rhizosphere aeration significantly enhanced rice growth and yield relative to waterlogging control. At fully tillering stage, rhizosphere aeration treatments could increasenumber of tillers by 10.7%-33.6% of IR45765-3B, but rhizosphere aeration treatments with Ca O2 increased significantly it by 11.6% of ZZY1 compared with waterlogging control. The significant promotion of rhizosphere aeration on dry matter accumulation of IR45765-3B was observed from transplant to full heading stage, and little difference was found after full heading stage, but that of ZZY1 was significantly increased after full heading stage, particularly under Ca O2 and MBWI treatments. Compared with waterlogging control, yield of IR45765-3B and ZZY-1 increase by 26.3%( Ca O2)、21.8%( MBWI)、10.7%( AWD) and 51.0%( Ca O2)、52.2%( MBWI)、29.68%( AWD) respectively.4. In rainfall proof trough cultivation, rhizophere aeration enhanced N absorption and utilization of rice. Compared with control the Npartial factor productivity(NPFP) of IR45765-3B and ZZY-1 under Ca O2, MBWI and AWD increased by 26.3%, 21.7%, 10.7% and 51.0%, 52.2%, 29.5% respectively. The N transport efficiency(NTE) and N transport contribution rate(NTCR) of two varieties were reduced under Ca O2 and MBWI treatments, but its N absorption and accumulation after full heading stage were increased by 73.4%, 128.7% in IR45765-3B and 119.2%, 106.5% in ZZY-1, respectively.5. Under hydroponic conditions, The phosphorus(P) and potassium(K) accumulation of rice were increased with the increase of oxygen concentration and reached the peak at 3.0mg/L(T2) of oxygen concentration compared with other treatments, the absorption of P and K were significant lower at 5.5mg/L(T3) and 7.5mg/L(T4) than that at 3.0mg/L. Moreover, rhizosphere aeration significantly enhanced the accumulation of P, K during growth duration stages of rice under rainfall proof trough cultivation. No difference on the absorption of P and K was found in the three treatments during tillering stage, however, during grain filling and mature stage, the absorption of P and K were observed significantly higher under Ca O2 and MBWI than under AWD treatment.In conclusion, oxygen level at 3.0mg/L was suitable for the growth, grain yield, absorption and utilization of N, P and K of rice. Under the rainfall proof trough cultivation, rizosphere aeration significantly promoted the rice formation of panicles, grain yield and NUE, and the mprovement of rizosphere aeration on rice were better under Ca O2 and MBWI than that under AWD.