不同密度下抗性与敏感稗草对水稻氮素水平和光合作用的影响

Effects of different densities of resistant and sensitive barnyardgrass on nitrogen content and the photosynthesis in rice

以遗传背景一致的抗二氯喹啉酸型和敏感型稗草为供试材料,分析了水稻与稗草以不同密度(4:1和4:2)共生的条件下,稗草种群对水稻氮素水平和光合作用的影响。结果显示,水稻-稗草共生并未影响穗分化始期的水稻株高;但造成了水稻分蘖数的显著降低,抗性稗草处理后水稻分蘖数的降低幅度与敏感稗草处理后的差异不显著。水稻与稗草以高密度(4:2)共生,水稻的根长及植株鲜重均显著下降;而此密度下抗性与敏感稗草对水稻根长和植株鲜重的影响无显著差异。稗草与水稻共生导致了水稻干物质积累量和植株全氮含量的降低,高密度(4:2)的敏感稗草共生条件下水稻的干物质积累量最低。同一密度下,敏感稗草影响下水稻植株的全氮含量略高于抗性稗草。抗性稗草的净光合速率显著高于敏感稗草。抗性稗草以不同密度与水稻的共生导致了水稻胞间CO2浓度的显著降低,稗草对水稻光合作用的影响主要是通过增强水稻的蒸腾速率、降低其气孔导度来实现的。

Taking quinclorac-resistant and sensitive barnyardgrass with the same genetic background as the test material, the effect of different barnyardgrass populations on nitrogen level and photosynthesis of rice under the different densities symbiosis between rice and barnyardgrass(4:1 and 4:2) were analyzed. The results showed that the rice-barnyardgrass symbiosis did not affect the rice height at the beginning of panicle differentiation period;instead, the tiller number of rice were decreased significantly, and there was no significant difference between the reduction of tiller number after resistant barnyardgrass treatment and that after sensitive barnyardgrass treatment. When the density of rice and barnyard grass was 4:2, the root length and fresh weight of rice were decreased significantly. There was no significant difference between resistance and sensitive barnyardgrass on root length and fresh weight of rice under the density of 4:2. The decrease of dry matter accumulation and total nitrogen content of rice were resulted in the relationship of symbiosis between rice and barnyardgrass, and the lowest of the dry matter accumulation of rice was under the high density(4:2) with sensitive barnyardgrass symbiosis. The total nitrogen content in rice plants was affected by sensitive barnyardgrass, which was slightly higher than that of resistant barnyardgrass at the same density. The net photosynthetic rate of resistant barnyardgrass was significantly higher than that of the sensitive barnyardgrass. The symbiosis of resistant barnyardgrass with rice at different densities resulted in a significant decrease in the intercellular CO2 concentration of rice. The effect of barnyardgrass on photosynthesis of rice was mainly affected by increasing transpiration rate and reducing stomatal conductance of rice.