不同氮素施肥方法对尾巨桉苗期生长和光合生理特性的影响

Effects on Growth and Photosynthetic Physiological Characteristics of Different Nitrogen Fertilization Methods of Eucalyptus urophylla × E. grandis Seedlings

采用3种不同的氮素施肥处理(平均施肥、直线施肥和指数施肥)对尾巨桉苗木进行施肥处理,结果显示:指数施肥获得的苗木苗高和地径均大于其他施肥处理;指数施肥下尾巨桉苗木的叶、茎、根和地上部分干质量和整株生物量均显著大于其他施肥处理,指数施肥获得了更多的苗木生物量;3种施肥处理下,指数施肥的苗木净光合速率Pn、气孔导读Gs和蒸腾速率Tr均为最大值,且显著大于其他处理。因此,3种施肥方法中,指数施肥方法最利于尾巨桉苗木的生长和光合作用。

The effects of nitrogen fertilization of Eucalyptus urophylla × E. grandis seedlings by three different methods （mean fertilization, linear fertilization and exponential fertilization plus a control involving no applied fertilizer） were examined in this study. The height and ground diameter of seedlings given exponential fertilization were larger than those fertilized by the mean and linear methods whilst growth of seedlings that received no fertilization was markedly poorer than all fertilized seedlings. Leaf dry weights, stem dry weights, root dry weights, shoot dry weights and whole plant biomass of exponential fertilized seedlings were significantly higher those fxom other fertilization methods. Under the 3 fertilization methods, the net photosynthesis ratio （Pn）, stomatal conductance （Gs） and transpiration rate （Tr） were similar and significantly higher than those of seedlings with no fertilization. Exponential fertilization generally proved the best method for E. urophylla × E. grandis seedlings as it gave the highest growth of the 3 fertilization methods and matched the other methods on photosynthetic and physiological indicators.