乙烯刺激割胶对巴西橡胶树PR107树皮结构的影响

Effects of ethylene on the bark structure of rubber tree(Hevea Brasiliensis Muell.Arg.)of clone PR107

树干树皮中的次生乳管及其周围的组织是巴西橡胶树天然橡胶生产的结构基础.施用乙烯能明显增加橡胶树PR107的胶乳产量,但对其树皮结构的影响鲜有报道.本文以橡胶树PR107为试验材料,研究了乙烯利和乙烯气刺微割采胶对树皮光学显微结构的影响以及乙烯利刺激后短期(2天、4天和7天)树皮超微结构的变化.结果显示,乙烯利和乙烯气体长期刺激都会导致水囊皮(有功能韧皮部)厚度减少,筛管直径缩小,表明其输导能力明显减弱;树皮中出现膨大乳管以及积累单宁,石细胞位置内移,表现出早衰,其中乙烯利诱导单宁细胞、石细胞的作用更强,而乙烯在增强细胞的分裂增生且纵向影响上则更深远.高浓度乙烯利短期处理后,筛管中积累大量P-蛋白以及胼胝体,筛分子的连通受到阻碍;薄壁细胞中膜代谢异常,与蛋白质合成、能量代谢相关的细胞器也发生明显的变化.本研究旨在为制定合理的刺激割胶制度提供解剖学上的依据.

Secondary laticifers and their surrounding cells in the bark of the rubber tree form the structural basis for natural rubber production.The impact of ethylene application on the rubber tree of clone PR107 could significantly increase the latex yield,but its effect on the structure of bark is rarely reported.In this paper,the microstructure of the bark of the rubber tree(clone PR107)treated with ethrel was observed,followed by the effect of micro-cut tapping with ethylene gas.Additionally,the ultrastructure of the bark treated with ethrel for 2,4,and 7 days was also observed.Regular tapping with ethrel and micro-cut tapping with ethylene gas for a long time resulted in a reduction of water sac skin(conducting secondary phloem)thickness and sieve tube size,which led to significantly decreased transportation ability of sieve tubes in the phloem.The swollen and disarrayed secondary laticifers,tannin accumulation in parenchyma cells and the stone cells near the cambium were observed,exhibiting premature aging.By comparison,ethrel strongly induced tannins and stone cells,while ethylene enhanced the cell division and proliferation,showing a more profound longitudinal impact.After short-term treatment with high-concentration ethrel,P-protein and callosum accumulated largely in sieve tubes,further hindering the connection between molecular sieves.Ethrel showed a significant effect on the ultrastructure due to abnormal membrane metabolism in parenchyma cells and changes in organelles responsible for protein synthesis and energy production.This study provides an anatomical basis for the development of reasonably exploitative techniques for rubber production.