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为了揭示苜蓿的补偿生长相关的光合生理补偿机制,以大田单株筛选、扦插扩繁的抗蓟马苜蓿无性系R-1和感蓟马苜蓿无性系I-1为材料,以相邻老苜蓿田自然发生的蓟马作为虫源,任其持续危害,于现蕾期和初花期通过模拟有效光辐射和固定CO2浓度,测定R-1和I-1的光合特性和水分利用特性。结果表明:(1)在现蕾期,R-1受害后叶片叶绿素含量显著增加,净光合速率(net photosynthetic rate,Pn)显著增大,光补偿点(light compensation point,Lcp)和暗呼吸速率(dark respiration rate,Rd)均显著降低(P<0.05);而I-1叶片叶绿素含量显著降低(P<0.05),植株净光合速率(Pn)与对照差异不显著(P>0.05),且在低于正常光照强度时,受害I-1植株Pn相对健株下降,同时,其光补偿点(Lcp)和暗呼吸速率(Rd)均显著升高(P<0.05);R-1和I-1受害后植株胞间CO2浓度(intercellular CO2concentration,Ci)、蒸腾速率(transpiration rate,Tr)和气孔导度(stomatal conductance,Gs)均显著升高(P<0.05),水分利用效率(water use efficiency,WUE)均显著降低。(2)在初花期,在较强的光照条件下,受害I-1植株Pn显著增大(P<0.05);在弱光下受害R-1植株Pn增大,而受害I-1植株Pn显著降低(P<0.05),其他指标变化同现蕾期。结果说明,抗蓟马无性系R-1对蓟马的危害具有显著的补偿光合作用;而感蓟马无性系的补偿光合作用滞后于初花期发生,且需要较高的光强条件,这种滞后发生的补偿光合作用对于苜蓿产量的补偿贡献意义不大。
In order to reveal the photosynthetic physiological compensation mechanism of alfalfa’s compensatory growth, the anti-thrips R-1 and I-1 of the thrips of Thripsimnus albus Field natural occurrence of thrips as a source of insects, their continued harm, in the budding and early flowering through the simulation of effective light and CO2 concentration fixed measured R-1 and I-1 photosynthetic characteristics and water use characteristics. The results showed that: (1) At the budding stage, the leaf chlorophyll content of R-1 increased significantly and the net photosynthetic rate (Pn) increased significantly. The light compensation point (Lcp) and dark respiration rate (P <0.05). However, the chlorophyll content of I-1 was significantly decreased (P <0.05) and the photosynthetic rate (Pn) of plant was not significantly different from that of the control (P> 0.05) At lower than normal light intensity, the relative Pn of I-1 plants decreased, and the light compensation point (Lcp) and dark respiration rate (Rd) were significantly increased (P <0.05); R-1 and I -1, intercellular CO2concentration (Ci), transpiration rate (Tr) and stomatal conductance (Gs) were significantly increased (P <0.05), water use efficiency efficiency, WUE) decreased significantly. (2) In the early flowering stage, under high light conditions, the Pn of I-1 plants significantly increased (P <0.05); the Pn of R-1 plants damaged in low light intensity increased, but Pn Significantly decreased (P <0.05), other indicators of change with budding period. The results showed that anti-thrips R-1 harm of thrips has a significant compensatory photosynthesis; and compensatory photosynthesis of thrips sensitive to thrombosis occurs at the beginning of flowering, and the need for high light conditions, this The compensatory photosynthesis that occurs after lag is of little significance for the compensation of alfalfa yield.