Abstract:

The biomass allocation, productivity, nitrogen cycle of clone PR107 in XiLian, XiQing, and CATAS farm state, DanZhou, Hainan province, were compared study by selecting the similar stands in stand structure, site and management practices, but different stand ages, from 2 to 28-year-old. The results showed that the 2a to 28a rubber trees were significantly different in biomass allocation, productivity allocation, nitrogen accumulation, fallitter, nitrogen return and nitrogen use efficiency (NUE). The rubber trees of different ages had showed different nutrient biological traits. (i) The nitogen amount in different organs was relative to age of trees and season. The order of nitrogen percentage in organs’ was: leaf>branch>root>bark>trunk>latex. However, it’s accumulation and allocation was: trunk>branch>leaf>bark>root>latex. Nitrogen accumulation in 28yr growth period of PR107 was 5639.12 kg/hm2, in which nitrogen was 1606.13 kg/hm2, and 28.84%. (ii) Along with age growth of rubber tree, the total fallitter, nitrogen return amount to soil and return ratio of nitrogen from fallitter were increased, of which 0.295～11.08t/hm2 of fallitter and 13.44~431.4kg/hm2 of nutrition be returned by fallitter per one year, including 5.28～162.62kg/hm2 of nitrogen. (iii) The NUE was varied among different age trees and organs, which was higher at younger trees, and then lower gradually along with age growth. The order of NUE in different organs was: trunk>bark>latex>branch>root>leaf. Keywords: rubber tree, clone PR107, nutrient cycle, nitrogen