干旱是影响森林植物天然更新的重要因子,但干旱如何阻碍云南蓝果树天然更新的机制尚不清楚。试验采用室内受控的方法,研究干旱可能导致的水分需求限制和自毒效应加剧对云南蓝果树种子萌发这一关键环节的影响。结果表明: PEG 6 000浓度、浸提液浓度和浸提液来源器官(根、茎和叶)对云南蓝果树种子萌发均产生极显著的影响,且随着处理水平浓度的提高,云南蓝果树的发芽率和发芽势呈降低趋势,但是12.5 g /L和25 g /L浸提液浓度之间、10%与15%PEG 6 000浓度之间的差异不显著;建立的二元线性回归方程表明,浸提液浓度的标准化影响系数的绝对值都低于PEG 6 000浓度的标准化影响系数的绝对值,说明干旱导致的水分缺失对云南蓝果树种子萌发的影响要强于干旱导致的自毒效应加剧的影响。因此,综合原始生境的改变,气候变化引起的干旱胁迫通过水分缺失和自毒效应加剧两种作用方式,共同影响了云南蓝果树的种子萌发,从而阻碍其天然更新。研究结果阐明了干旱对云南蓝果树种子萌发的影响机制,初步揭示了云南蓝果树濒危的原因和机理,为云南蓝果树的有效保存提供了科学理论依据。
英文摘要:
For many plants,drought is an important factor affecting the natural regeneration of forest plants.However, the mechanisms by which drought affects natural regeneration of Nyssa yunnanensis are not well known.In this experiment,controlled experiments were conducted to study the effects of drought on water demand limitation and autotoxity on seed germination and early seedling growth of N.yunnanensis.The results showed that the concentration of PEG 6000, the concentration of extract solution and the source of extract organs (roots and leaves) had significant effects on seed germination and early seedling growth index of N.yunnanensis. Morever, the seed germination rate,germination vigor, root length and seedling length decreased with the increase of the concentrations of PEG 6000 and extract solution.However, there was no significant difference between the concentration of 12.5 g /L and 25 g /L extract,and between 10% and 15% PEG 6000 concentration. Established linear regression equation of two variables demonstrated that the absolute value of standardized influence coefficient of leaching solution is lower than that of PEG 6000 concentration,suggesting that the effects of water loss caused by PEG was more important than that caused by drought on seed germination. Therefore,water deficiency and aggravating autotoxicity caused by drought,which was induced by the change in original habitat and climate change,had jointly affected the seed germination and early seedling growth of of N. yunnanensis, thus hindering its natural regeneration.The results would illuminate impacts of drought on the natural generation of N. yunnanensis and their mechanisms.Conclusions made from natural regeneration difficulties might partly help reveal endangered reasons of N. yunnanensis,which would provide scientific and theoretic basis for its effective conservation.