干旱胁迫对茉莉3个品种叶片光合特性和超微结构的影响

Effect of Drought Stress on Photosynthetic Characteristics and Ultrastructure of Mesophyll Cells in Three Cultivars of Jaminum sambac

摘要:

为探讨植物光合作用和叶肉细胞超微结构对干旱胁迫的响应,研究了茉莉(Jaminum sambac)3个品种在干旱胁迫下的光合作用相关生理指标和叶肉细胞超微结构的变化。结果表明,在轻度干旱胁迫下, 单瓣茉莉和多瓣茉莉净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和胞间CO₂浓度(Ci)呈下降趋势,但叶肉细胞超微结构仅受轻微影响。在中度干旱胁迫下,多瓣茉莉Pn、Tr、Gs持续降低,而Ci随干旱胁迫的增加反而上升,单瓣茉莉Pn、Tr、Gs和Ci继续呈下降趋势,两品种叶绿体超微结构发生明显变化并出现伤害症状。在重度干旱胁迫下,Pn、Tr、Gs降幅明显,与对照差异极显著(P<0.01),Ci持续上升,叶绿体超微结构发生巨大变化,特别是叶绿体发生严重损伤。双瓣茉莉Pn、Tr、Gs、Ci随干旱胁迫的加重也呈现逐渐下降的趋势,但降幅较小,叶肉细胞超微结构无明显变化。因此,与单瓣茉莉和多瓣茉莉相比较,双瓣茉莉对干旱胁迫的耐受力较强。

Abstract:

In order to understand the response of photosynthesis and ultrastructure of mesophyll cells to drought stress, three cultivars of Jaminum sambac, including ‘Unifoliatum', ‘Bifoliatum' and ‘Trifoliatum', were cultured in pots experiment in greenhouse under different drought treatments (mild drought, moderate drought, severe drought), The effects of drought stress on photosynthetic characteristics and ultrastructure of mesophyll cells in J. sambac were studied. The results showed that the net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs) and intercellular CO₂ concentration (Ci) in J. sambac ‘Unifoliatum' and ‘Trifoliatum' decreased under mild drought stress, and the ultrastructure of mesophyll cells was only slightly affected. Under moderate drought stress, Pn, Tr, Gs and Ci of ‘Unifoliatum' and ‘Trifoliatum' decreased continuously except Ci of ‘Trifoliatum' increased, while chloroplast structure changed obviously and occurred damage. Under severe drought stress, Pn, Tr and Gs of ‘Unifoliatum' and ‘Trifoliatum' had singnificant decrease compared to those of control (P<0.01), and Ci increased, while chloroplast structure changed tremendously and occurred serious damage. The Pn, Tr, Gs and Ci of ‘Bifoliatum' decreased slightly with increment of drought stress, and ultrastructure of mesophyll cells of ‘Bifoliatum' had not obvious changes. Therefore, the tolerance ability to drought of J. sambac ‘Bifoliatum' is stronger than that of ‘Unifoliatum' and ‘Trifoliatum'.