橡胶树籽苗期根系的几项生理参数——兼论与籽苗芽接成活的关系

PHYSIOLOGICAL PARAMETERS OF HEVEA ROOTS IN RELATION TO BUDDING SUCCESS OF SEED—SEEDLINGS

不同物候期橡胶籽苗根系的几项有关生理参数存在明显的差异。在正常供水条件下,籽苗根系的呼吸速率,以去氢酶为指标的根系活力以及抗坏血酸含量都以伸长期的为最大,展叶期的次之,变色期的最小;细胞过氧化产物丙二醛含量、过氧化物酶比活性及相对透性则反之,以伸长期的为最小,展叶期和变色期的相近。经0.15 mol/L 甘露醇溶液模拟水分胁迫处理后,不同物候期籽苗间的各生理参数同样存在明显差异,且各参数的大小(含量或活性)顺序,益显得分明。本实验结果说明:籽苗在不同生长发育阶段,由于种子贮藏营养物质的不断消耗枯竭,致使根系存在生理上的差异,变色期籽苗表现生理活性相对较差,因此影响了对地上部水分的充分供应,这可能是变色期橡胶籽苗芽接成活率低的根系力面的原因之一。

Roots of seed-seedlings of Hevea brasiliensis were examined physiologically at different phenophases to give a general picture of the relationship between budding success and root physiology.The results show marked differences In some related parameters of roots.Under normal water supply conditions the respiration rate, dehydrogenase activities(indicating root vigor),and ascorbic acid content were maximum in the roots at the extension stage,then at the leaflet colouring stage.The content of malonaldehyde(peroxidatic derivatives of the cells),peroxidase activitives, and relative permeability were,on the contrary,minimun at the extension stage, but similar at the other two stages.Simulated water-stress treatment by using 0.15 tool/L mannitol solution also manifests distinct differences among the parameters obtained at various phenophases.Our experiment demonstrates that seed-seedling varied physiologically in roots at different development and growth stage due to their continuous consumption of the stored nutrients In the seeds.They were rather poor in physiological activities at the colouring stage,affecting the water supply to the aerial parts.This may be one of the factors contributing to low budding success of seed seedlings at the colouring stage.