The Influence of High Temperature and Drought on the Growth, Nodulation and Nitrogen-Fixation of Alnus cremastogyne in Different Kinds of Soils

Ivestigations were conducted during the drought and after the drought on the growth, nodulation and nitrogen-fixation of Alnus cremastogyne Burk planted in local soils of three typical categories. The results showed: 4-year-old or over 4-year-old A. cremastogyne had fairly high drought-resistance, but A. cremastogyne of three years old or younger are sensitive to drought. The trees damaged by the drought the most in river alluvial deposit soil, the second in hangh red soil, the third in gully fen aging red soil. Drought killed many trees of A. cremastogyne, the nitrogen content in leaves of the survivors decreased. Leaves, roots and nodules of the survivors partly withered. Drought also made nitrogen-fixation activity of root nodules dropped down to zero. After drought at least two months are needed for A. cremastogyne to recover. Although A. cremastogyne which grew in gully fen aging red soil didn't suffer much from drought during drought period, whereas in raining season when the soil was filled with water the growth of roots and nodules of A. cremastogyne stopped. Therefore from July to November the growth and nitrogen-fixation amount of A. cremastogyne cultivated in local soil were far less than that grew in the original place.