[目的]研究不同程度干旱胁迫对油茶叶片结构的影响,了解其干旱适应机理.[方法]以7年生'长林4号'油茶为试验材料,设置土壤含水率分别为15%20%(重度干旱胁迫)、20%25%(中度干旱胁迫)、25%30%(轻度干旱胁迫)和自然状况(对照),通过制作石蜡切片、临时切片、光学显微镜观察及测定叶片外部形态特征、叶片下表皮气孔特征、叶肉和叶脉显微结构.[结果]表明:干旱胁迫下,油茶单叶鲜质量、单叶干质量和单叶饱和质量均随着胁迫程度的增加呈下降趋势,叶片厚度、叶片大小显著降低;叶片下表皮气孔面积、气孔周长、气孔开度、气孔器大小均显著减小,气孔密度先减小后增大;随着干旱程度的增强,叶片上表皮、下表皮厚度显著减小,上角质层厚度、下角质层厚度显著增加,栅栏组织厚度、栅海比显著降低,海绵组织厚度变化差异不显著;叶片主脉厚度与主脉突起度随着胁迫程度的加强而显著增加,木质部厚度在中度干旱胁迫下及维管束短径在中度干旱胁迫、重度干旱胁迫下显著低于对照,不同干旱处理对韧皮部厚度的影响差异不显著.[结论]油茶叶片结构的变化均是油茶应对干旱胁迫的适应特征,油茶植株能够根据水分亏缺程度调整叶片结构以维持生存和生长,对干旱胁迫具有较强的适应性.%[Objective]To study the effects of different drought stress on leaf structure of Camellia oleifera,in order to understand the mechanism of drought adaptation.[Method]7-year-old C.oleifera'Changlin-4'forests were test-ed by applying four levels of drought stress which soil moisture contents were kept as 15%-20% (severe drought stress),20%-25% (moderate drought stress),25%-30%(mild drought stress)and the control (natural con-dition).The leaf external morphological characters,stomatal characters of leaf lower epidermis,microstructure of mesophyll and main vein were measured by making paraffin sections,temporary sections and microscopic observa-tion system.[Result]The results showed that the leaf fresh weight,leaf dry weight,and saturated weight of C.ole-ifera declined with the decreasing of soil moisture,the drought stress significantly reduced the leaf thickness and leaf size,the stomatal area,perimeter,aperture,apparatus length and width of leaf lower epidermis also decreased sig-nificantly,the stomatal density decreased at first and then increased.As the drought stress became more intense, the thickness of leaf upper and lower epidermis decreased significantly,the upper and lower cuticle thickness in-creased significantly,the thickness of palisade tissue and the ratio of the palisade tissue and spongy tissue decreased significantly.As drought stress intensified,the thickness of the main veins of the leaves and the midrib protuberant degree increased significantly,the thickness of xylem under moderate drought stress and short diameter of vascular bundle under moderate and severe drought stress were significantly lower than that of the control,different treat-ments of drought stress had no significant effect on the thickness of phloem.[Conclusion]All of these changes in the leaf structure of C.oleifera were ecological adaptations to drought stress.C.oleifera could adjust the leaf struc-ture to maintain their survival and growth based on the water deficit,indicating that C.oleifera has strong adaptabil-ity to drought stress.
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