摘要
摘要:由于人类大量开采使用石油、煤炭、天然气等化石燃料，使大气CO₂浓度升高，这不但加速全球变暖，还将影响地球上动植物的生存和分布，从而对整个生态系统产生深远影响。为探明CO₂浓度升高与豌豆蚜（Acyrthosiphon pisum）虫口密度对紫花苜蓿（Medicago sativa）叶片内化学物质的影响，明确CO₂浓度升高和蚜虫密度在紫花苜蓿生理生化中的作用，试验在CO₂光照培养箱内设置380 μL·L^-1（对照）、550 μL·L^-1和750 μL·L^-1 3个CO₂浓度培育苜蓿幼苗并接入10日龄成蚜10头·株^-1、20头·株^-1、30头·株^-1，并以0头·株^-1作为空白对照，1周后测定植物体内营养物质和次生代谢物质含量。结果表明，随CO₂浓度升高，蚜虫密度为30头·株^-1时紫花苜蓿可溶性蛋白、可溶性糖以及淀粉含量均上升，在750 μL·L^-1 CO₂浓度下分别比CK上升11.62倍、0.49倍和0.24倍；黄酮、总酚和简单酚含量也显著上升。随蚜虫危害程度加重，同一CO₂浓度下紫花苜蓿淀粉、简单酚含量先上升后下降，高CO₂浓度蚜虫密度为30头·株^-1时比0头·株^-1时可溶性糖、总酚以及单宁含量上升1.66倍、1.49 mg·g^-1和1.09 mg·g^-1，差异均显著（P < 0.05）。说明具有固氮作用的豆科植物更易于适应CO₂浓度升高的变化，从而在受到刺吸胁迫后增强自身诱导抗虫性以抵御害虫为害。
Abstract:Due to massive exploitation and use of fossil fuel such as petroleum, coal and natural gas, atmospheric CO₂ concentration has been increasing, which not only accelerated global warming, but also affected the survival and distribution of animals and plants on the earth with far-reaching impacts on the ecosystem. This research was carried out to explore the effects of elevated CO₂ concentration and pest population density of Acyrthosiphon pisum on chemical substances in the leaves of Medicago sativa. The objective was assessed the effects of elevated CO₂ concentration and pea aphid density on the physiology and biochemistry of M. sativa. The nutrients and secondary metabolites in M. sativa leaves were determined by cultivating M. sativa seedlings attacked by 10-day old pea aphids of 10 head·plant^-1, 20 head·plant^-1, 30 head·plant^-1 and 0 head·plant^-1 (CK) for one week under three CO₂ concentrations[380 μL·L^-1 (CK), 550 μL·L^-1 and 750 μL·L^-1] in CO₂ gradient chamber. The results indicated that the contents of soluble protein, soluble carbohydrate and starch increased after aphid sucking of 30 head·plant^-1 with increasing CO₂ concentration. At 750 μL·L^-1 CO₂ concentration, they were respectively 11.62 times, 0.49 times and 0.24 times higher than those under CK, respectively. Also the contents of flavone, total polyphenols and simple phenols increased significantly. Furthermore, the contents of starch and simple phenols increased and then decreased with increasing degree of damage under the same CO₂ concentration. Comparatively, contents of soluble carbohydrate, total polyphenols and tannin were significant differences between aphid densities of 30 head·plant^-1 and 0 head·plant^-1, which increased by 1.66 times, 1.49 mg·g^-1 and 1.09 mg·g^-1 (P < 0.05) compared with those of CK under the highest level of CO₂ concentration. The results indicated that nitrogen fixing legume plants were more likely to adapt to increased CO₂ concentration and thereby enhanced self-induced resistance to insect pests.



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