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通过水培试验,采用前期以根系耐性指数为指标从12个白菜[Brassica campestris L.ssp.chinensis(L.)Makino]品种中筛选的两个对Cd耐性不同的白菜品种‘上海青’(Cd敏感型)和‘杭油冬’(Cd耐性)为试材,研究硅(Si,1.5mmol·L-1)对镉(Cd,5.0mg·L-1)胁迫下白菜生长、Cd含量、光合参数、叶片叶绿体超微结构的影响。结果表明:在Cd胁迫下,‘上海青’和‘杭油冬’与各自对照相比,地上部和地下部生物量显著降低了33.8%,30.6%和33.0%,12.0%,地上部和地下部Cd含量增加了55.2%,85.7%和73.2%,42.1%;叶片光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和叶绿素含量均下降,细胞间隙二氧化碳浓度(Ci)增加;叶片的叶绿体结构明显受到损伤,叶绿体膨胀,叶绿体的基质片层结构破坏,片层方向紊乱。施硅后与单独Cd处理相比,两品种地上部和地下部生物量显著增加了24.9%,41.1%和31.9%,43.5%;地上部Cd含量显著降低了15.1%和26.3%,而地下部Cd含量显著增加了24.7%和33.6%;叶片的光合作用能力增强,而且叶片叶绿体超微结构变得完整。说明施硅减少了Cd从地下部向地上部的运输,提高了光合作用效率。这种缓解效应在耐Cd型品种‘杭油冬’中表现的效果更加显著。
Two hydroponic cultivars, ’Shanghai Qing’ (Cd), which had different tolerance to Cd, were screened from 12 cabbage [Brassica campestris L.ssp.chinensis (L.) Makino] (Cd, Cd-tolerant) and Cd tolerant (Cd tolerant) were used as experimental materials to study the effects of Si (1.5 mmol·L -1) on the growth, The Effect of Parameters on the Ultrastructure of Chloroplast in Leaves. The results showed that under Cd stress, the biomass of above-ground and below-ground parts of ’Shangqing’ and ’Hangyoundong’ significantly decreased by 33.8%, 30.6%, 33.0% and 12.0% Cd increased by 55.2%, 85.7%, 73.2% and 42.1%, respectively. The photosynthetic rate, Tr, stomatal conductance and chlorophyll content of leaves decreased and the intercellular CO2 concentration increased The chloroplast structure of leaves was obviously damaged, the chloroplast was expanded, the structure of chloroplast stroma lamellae was destroyed, and the lamellar direction was disordered. Compared with Cd alone, the biomass of shoots and shoots of two cultivars significantly increased by 24.9%, 41.1% and 31.9% and 43.5%, respectively. Cd content in shoots decreased significantly by 15.1% and 26.3% The contents of Cd increased significantly by 24.7% and 33.6%, respectively. The photosynthetic capacity of leaves increased, and the ultrastructure of leaf chloroplasts became intact. The results showed that Si application reduced the transport of Cd from underground to aboveground and increased the photosynthesis efficiency. This mitigation effect was more pronounced in the Cd-tolerant cultivar ’HangYingDong’.