常绿木兰科植物的抗寒性研究

连续4个冬季,对16种常绿木兰科植物进行了田间受冻程度观察,用电导法追踪了抗冻崩溃点温度的变化,并调查了这些树种在自然分布区北缘和垂直分布上缘30a内经历的最低气温,发现3者的种间差异相当一致。同时发现各树种的崩溃点温度最低值与它的生态分布北缘和上缘的常年最低气温接近,由此提出了生态分布最低温度的概念。它能较准确地指示植物的最大抗寒能力,从而有可能避免引种和推广工作中的盲目性。 文章还根据上海近100余年的低温资料,对这16个树种在今后越冬和春季萌发时可能受冻的前景做了预测。

STUDY ON COLD HARDINESS OF EVERGREEN MAGNOLIACEAE

In the Yangtze basin where is in the north of everygreen magnolia family living area,the study on frost injuries and the measurement of inflection point temperatures of electrolyte leakage from 16 everygreen magnolias leaves were carried outin successive four winters. A mathematical model for plant cold acclimation was established in the former paper 25] according to the linear relationship between the inflection point temperatures of over winter leaves of tangerine and minimum air temperatures of the day before sampling. Potential limits of cold acclimation of those magnolias(Tp) were calculated from the model. The most north, and highest altitude sites of natural distribution were investigated thoroughly on literatures, therefore the extreme minimum air temperatures over 30 years at those sites (TV) were also deduced from the local meteorological records.Tes of those magnolias were found coincided well with their field frost injuries and Tps. As the lowest values of inflection point temperatures were close to Tes,a concept of lowest temperature of ecological distribution was suggested as an ecological index. This concept could be used to describe maximum frost hardiness of plant more precisely and to guide plant introduction.The probablities of frost injury in winter and early spring of those species were also forecasted according to the meteorological records over 100 years in Shanghai.