沙芥幼苗叶片解剖结构和光合作用对干旱胁迫的响应

Effect of drought stress on anatomical structure and photosynthesis of Pugionium cornutum (L.) Gaertn. leaves in seedling

为了了解干旱胁迫对植物光合作用和叶片结构的影响,明确植物光合作用和结构对干旱胁迫的响应,本研究以沙生植物、中国特有种---沙芥为材料,采用Li-6400光合仪和常规石蜡切片法,研究了干旱胁迫下沙芥光合参数、叶片解剖结构的变化,结合前期对沙芥叶片内活性氧物质含量变化的研究,试图阐述沙芥叶片应对干旱胁迫的机制,揭示沙生植物—沙芥在干旱环境中的生存策略,为植物耐旱性提供理论依据。结果表明:随着土壤含水量下降,净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、叶片厚度、上表皮厚度、下表皮厚度呈下降趋势;海绵组织厚度呈先下降后上升的趋势;胞间二氧化碳浓度(Ci)呈上升的趋势;气孔限制值(Ls)、水分利用率(WUE)、栅栏组织和栅栏组织/海绵组织和叶片组织结构紧密度(CTR)呈先先上升后下降的趋势;且在土壤含水量大于39%WHC时沙芥光合和结构受影响较小,在土壤含水量低于39%WHC时,沙芥光合作用受到抑制,而叶片紧密度变大,能够较好的抵御干旱环境。结果表明干旱胁迫下沙芥幼苗叶片光合作用的下降是非气孔因素造成的,且其叶片结构的变化会影响光合作用,光合作用通过产生活性氧对结构也有影响。说明沙芥能够很好的适应中度干旱以上的环境,在重度干旱环境中沙芥通过调节叶片结构以适应环境,这可能是沙芥能够在沙漠地区生存繁殖的原因之一。

The effect of drought stress on anatomical structrue and photosynthesis of chinese specie, Pugionium cornutum（L.） Gaertn. Leaves in seedling were obeserved by conventional paraffin sectioning and Li-6400 photosynthetic apparatus respectively. Which would help us to find out how to the P. cornutum （L.） Gaertn. dealed with the drought stress and the survival strategy in arid environment in seedling, and which would provide theoretical basis for plant drought resistance.The results showed that： The net photosynthetic rate（Pn）, transpiration rate（Tr）, stomatal conductance （Gs）, upper and lower epidermis thickness of P. cornutum（L.） Gaertn. leaves decreased with the soil water content decreasing under drought stress, to the contrary, the carbon dioxide concentration incresed, and the thickness of spongy tissue decresed at first and then incresed, howere, the stomatal limitation （Ls）, water use efficiency （WUE）, palisade tissue, palisade tissue/spongy tissue and leaf structure closely degrees （CTR） incresed at first and then decresed. There were lillte affect on the anatomical structure and photosynthesis of P. cornutum（L.） Gaertn. Leaves when the soil water content were more than 39% WHC, however, the photosynthesis were restrained and the Leaf blade tightness incresed when the soil water content were less than 39% WHC, and P. cornutum（L.） Gaertn. could faced up the drought stress. The ability of photosynthesis ofP. cornutum（L.） Gaertn. leaves in seedling was mainly induced by non-stomatal factors, and the structure change of leaves would affect the photosynthesis, at the same time, the photosynthesis would affect the strcture of leaves by the production of reactive oxygen. P. cornutum（L.） Gaertn. could grow well in morderate even more soil drought stress, and it would grow in serious soil drought stess by changing the strcture of leaves, which possiblely were the one of reasones that P. cornutum（L.） Gaertn. could survived and reproducted in desert.