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探讨喜马拉雅紫茉莉叶片的光合特性及其影响因子,为指导喜马拉雅紫茉莉人工种植和提高产量提供依据。该研究选择一年生、二年生和三年生喜马拉雅紫茉莉植株,在开花期利用LI-6400光合仪测定植株叶片的光合-光响应曲线及光合日进程。结果表明:喜马拉雅紫茉莉叶片的光响应曲线与非直角双曲线方程拟合度较高(R2≥0.98)。三年生植株的最大光合速率和光能利用效率均大于一年生和二年生个体。喜马拉雅紫茉莉叶片的净光合速率和气孔导度日变化曲线呈双峰曲线(一年生除外),存在明显的“午休”现象,其原因是由气孔限制造成的;而蒸腾速率呈单峰曲线,中午高蒸腾速率是植物减少高温伤害的一种自我保护机制。相关分析表明,光合有效辐射和空气温度与净光合速率呈显著正相关。这说明喜马拉雅紫茉莉为阳生植物,种植时应选择光照充足的地块,并适当延长生长年限以提高产量。
To study the photosynthetic characteristics of leaves and its influencing factors in Mirabilis jalapa in Himalayas and provide the basis for the artificial cultivation and the increase of yield of Mirabilis jalapa in Himalayas. In this study, annual, biennial and three-year-old Mirabilis jalapa plants were selected to study their photosynthetic-light response curve and photosynthetic daily process at flowering stage with LI-6400 photosynthesis system. The results showed that the fitting degree of light response curves and non-rectangular hyperbolic equations of Mirabilis jalapa was high (R2≥0.98). The maximum photosynthetic rate and light use efficiency of three-year-old plants were higher than those of annual and biennial individuals. The net photosynthetic rate and stomatal conductance curve of leaves of Mirabilis jalapa in Himalayas showed a bimodal curve (except for one year), and the phenomenon of “lunch break” was obvious, which was caused by the stomatal limitation. The transpiration rate showed a single peak curve , Noon high transpiration rate is a self-protection mechanism of plants to reduce high temperature damage. Correlation analysis showed that there was a significant positive correlation between photosynthetic active radiation and air temperature and net photosynthetic rate. This shows that the Mirabilis hygroscopicus in the Himalayas is a sun-grown plant. When planting, it should choose a well-lit area and prolong the growth period to increase the yield.