接种中华根瘤菌SD101和避光对紫花苜蓿固氮和光合作用的影响

Effects of Sinorhizobium SD101 Inoculation and Shading on Nitrogen Fixation and Photosynthesis of Medicago sativa L.

为了研究光合和氮素互作对紫花苜蓿自身生长和光合作用的影响,以紫花苜蓿品种WL319为试验材料,通过接种中华根瘤菌SD101和避光处理相结合,测定接种中华根瘤菌SD101紫花苜蓿在非避光、避光和复光条件下的生长情况和光合指标。研究结果表明,非避光条件下,接种中华根瘤菌SD101能够显著提高紫花苜蓿的地上生物量、叶片中叶绿素含量和紫花苜蓿的光合能力;避光条件下,受气孔导度和非气孔等因素的影响,中华根瘤菌SD101不能发挥其与紫花苜蓿共生固氮的优越性,光合速率比不接种中华根瘤菌SD101对照低。恢复光照后,接种中华根瘤菌SD101的紫花苜蓿光合作用恢复程度没有不接菌对照好。由此可见,紫花苜蓿与中华根瘤菌SD101的共生固氮作用需要在适宜的光照下才能促进紫花苜蓿生长和光合作用。

Plant growth and photosynthetic indexes in alfalfa（Medicago sativa L. WL319） were investigated after inoculation with Sinorhizobium fredii SD101 under shaded and subsequent recovered conditions in order to study the interactive effects of shading and nitrogen supply on plant growth and photosynthetic physiology. The results showed that under non-shading conditions, plant biomass, chlorophyll contents and photosynthetic capacity all significantly increased by inoculating with Sinorhizobium fredii SD101 as compared to the control alfalfa. Under shading condition, photosynthetic rate of the inoculated alfalfa decreased compared to the non-inoculated control alfalfa due to the influences of stomatal and non-stomatal factors, which lead the inoculated rhizobia not to play the role in alfalfa nitrogen fixation. After the restoration of light, the photosynthetic parameters were not recovered to the degree as the non-inoculated control. It could be inferred that only under suitable illumination condition symbiotic nitrogen fixation between alfalfa and Sinorhizobium fredii SD101 could promote the plant growth and photosynthesis.