施磷对紫花苜蓿光合作用及抗蓟马的影响

Effects of phosphorus application on alfalfa photosynthesis and resistance to thrips (Thysanoptera:Thripidae)

为了明确施磷对苜蓿抗蓟马的影响及其相关的光合机制,本试验以西北广泛种植的感蓟马苜蓿品种‘甘农3号’和抗蓟马苜蓿品种‘甘农9号’为材料,在大田蓟马为害高峰期,调查评价了不同施磷水平下苜蓿的受害指数、生长指标和蓟马虫口数量,测定了不同施磷水平下苜蓿的光合气体交换参数、可溶性糖含量。结果表明:施磷后,‘甘农3号’和‘甘农9号’苜蓿的受害指数均显著降低,株高和产量显著增加,蓟马虫口数量无显著变化;净光合速率(Pn)和水分利用率(WUE)显著升高,蒸腾速率(Tr)和气孔导度(Gs)显著降低;苜蓿心叶可溶性糖含量显著升高,但可溶性糖含量与蓟马虫口密度间无相关性,而与受害指数之间存在极显著的负相关关系。施磷有效地增强了苜蓿的光合作用,进而增强了苜蓿对蓟马的耐害性。在大田条件下,通过增施磷肥来控制苜蓿蓟马的危害是一种经济有效的绿色防控措施。

The aim of this research was to investigate the effects of phosphorus application on the mechanism of photosynthesis in the alfalfa Medicago sativa and its resistance to thrips. Two alfalfa varieties were chosen for this study: ‘Gannong No.3’(thrip-susceptible) and ‘Gannong No.9’(thrip-resistant). During the peak period of thrips infection, the damage index, thrips’ number and growth index of alfalfa at different phosphorus levels were investigated and evaluated, and the photosynthetic gas exchange parameter and the content of soluble sugars were determined. The results showed that the damage index was significantly reduced, but the plant height and yield were significantly increased with the increase of phosphorus level. There was no significant change in the number of thrips. The photosynthetic rate(Pn) and efficiency of water application(WUE) were significantly increased but the transpiration rate(Tr) and stomatal conductance(Gs) were reduced with the increase of phosphorus level. The soluble sugar content in the heart leaves was significantly increased with the increase of phosphorus level. There was no correlation between soluble sugar content in the heart leaves and the density of insect population, but there was a highly significant negative correlation between soluble sugar content and the damage index. The alfalfa photosynthesis and its tolerance to thrips were enhanced after the application of phosphorus. It is an economical and effective ecological control measure against thrips to apply phosphorus fertilizer in the field.