田间小气候对水稻产量的影响

Effect of field microclimate on rice yield

在中科院桃源农业生态试验站,选择了3个不同类型水稻品种(常规稻、一般杂交稻和超级杂交稻)为材料,利用稻田中部(距稻田边界6 m)和近边界(距稻田边界1 m)小气候的差异,研究了田间小气候对水稻产量和生物量的影响。稻田中部与近边界相比,在光合盛期(10:00-14:00),CO2含量低10～15μmol.mol-1,日平均温度低0.081℃,日平均相对湿度高10%。近边界水稻产量和生物量均显著高于稻田中部。稻田中部和近边界0.081℃的温度差异对光合速率的影响微小。稻田中部较高的相对湿度有利于缓解光合"午休",促进光合作用。因此,温度和湿度差异均不是近边界水稻产量和生物量均显著高于稻田中部的原因。通过Li-6400光合仪测定发现水稻叶片光合速率与250～400μmol.mol-1的CO2含量内成线性正相关。在1 200μmol.m-2.s-1光强下,如果CO2含量增加10～15μmol.mol-1,水稻光合速率将增加0.652 3～0.978 5μmol.m-2.s-1。所以CO2含量差异是近边界产量和生物量高于稻田中部的主要原因。最后建议通过一些栽培措施,改善群体通风状况,增加冠层内CO2含量,从而增加水稻产量和生物量。

Based on the microclimate difference between central-field （6 meters from field boundary ） and near-boundary area （1 meter from field boundary）, we analyzed the effect of field microclimate on the rice yield and biomass in Taoyuan Station of Agro-ecology Research, Chinese Academy of Science. We chose 3 rice varieties including conventional, hybrid and super hybrid rice. In central-field, compared with those in near-boundary area, CO2 content was 10 - 15 ttmol.mol-1 lower during high photosynthetic rate duration （10：00-14：00）, daily average temperature was 0.081 ~C lower, and daily average relative humidity was 10% higher. Both rice yield and biomass production in near-boundary area were significantly higher than those in central-field. The temperature difference of 0.081 ℃ had little effect on the photosynthetic rate. Higher relative humidity in central-field contributes to photosynthesis for reducing the midday depression of photosynthesis. So the temperature and relative humidity differences were not the reason for higher yield and biomass in near-boundary area. Leaf photosynthetic rate under different CO2 content was determined by Li-6400 portable photosynthesis system. There was a linear positive correlation between photosynthetic rate and CO2 content within 250 - 400 μmol·m-2·s-1. Under 1 200 μmol·m-2·s-1 photosynthetic photon flux density, If CO2 content increased 10 - 15 μmol·m-2·s-1, photosynthetic rate would increase 0.652 3- 0.978 5 μmol·m-2·s-1. Therefore, CO2 content difference was the main reason that led to higher yield and biomass production in near-boundary area than those in central-field. Some cultivation measures should be taken to better air diffusion, improve CO2 content in canopy, thus to increase rice production.