模拟冬季低温和夜间退潮对无瓣海桑幼苗的协同作用

利用人工控制手段,模拟冬季低温和夜间低潮对无瓣海桑幼苗的影响,分析气温-水温协同作用下无瓣海桑幼苗的低温适应机制.结果表明:低温显著抑制了无瓣海桑幼苗株高和基径的增长,而提高水温5℃对其的缓解作用分别达41.2％和44.6％;低气温(15℃)显著降低了叶片的最大光化学效率(Fv/Fm)值,进而影响叶片的光合能力,而提高水温未能显著缓解其损伤;低气温时,提高水温能促进幼苗叶片脯氨酸的积累,增加可溶性糖含量,缓解低温对叶片的伤害.极端低温发生时,夜间高潮对幼苗起到较好的保温作用,缓解了低温对幼苗生长和叶片的生理伤害,提高了无瓣海桑幼苗的成活率.

Synergistic effects of low temperature in winter and ebb tide at night on Sonneratia apetala seedlings growth and key eco-physiological traits

By setting up a set of simulated tidal systems with different air- and water temperature and tidal flood conditions, this paper studied the synergistic effects of low temperature in winter and ebb tide at night on the growth and key eco-physiological traits of Sonneratia apetala seedlings. Low air temperature depressed the seedlings growth, but the reduction in the seedling height and basal stem diameter was compensated 41.2% and 44.6%, respectively by a 5 degrees C increase of water temperature. Low air temperature (15 degrees C) reduced the leaf Fv/Fm significantly, indicating a dramatic reduction in the leaf photosynthetic capacity, whereas the flooded tide with higher water temperature could not compensate this damage. The flooded tide with high air temperature increased the proline and soluble sugar contents in mature leaves, which could protect the mature leaves from cold damage. When extreme cold events occurred, the flooded tide at night worked as a heat storage medium, which alleviated the cold damage on the seedlings growth and leaf physiological traits, and promoted the survival rate of S. apetala seedlings.