檫木苗期光合特性及水分利用效率研究

Study on Photosynthetic Characteristics and Water Use Efficiency at Seedling Stage of Sassafras tsumu Hemsl.

利用LI-6400便携式光合作用测定仪对2年生檫木幼苗光合速率、蒸腾速率及水分利用效率进行研究。结果表明:檫木在晴天条件下光合速率日变化为双峰曲线,分别在10:00和16:00时达到峰值,而在12:00时达到谷底,表现出"午休"现象,相关分析表明其影响因子主要是气孔导度;檫木蒸腾速率日变化呈双峰曲线,分别在10:00和14:00时达到峰值,而在12:00时达到谷底;檫木水分利用效率日变化为倒单峰曲线变化;檫木叶片光饱和点为996.78μmol/(m^2·s),光补偿点为10.51μmol/(m^2·s)。研究结果表明檫木是一种较耐荫的阳性植物,研究结果为檫木苗期管理奠定理论依据。

Using Li-6400 portable photosynthesis system,the characteristics of photosynthesis,transpiration and water use efficiency( WUE) of 2 year old seedlings of Sassafras tsumu Hemsl. were studied. The results showed as follows: Under a fair weather condition,there was a typical two peak variation( 10: 00 and 16: 00 at peak)with an obvious phenomenon of noontime repose( 12: 00 at bottom) in leaf photosynthesis of Sassafras tsumu Hemsl. And correlation analysis showed that the dominant affecting factor was stomatal conductance; There was also a two peak variation( 10: 00,14: 00 at peak and 12: 00 at bottom) in leaf transpiration of Sassafras tsumu Hemsl.; There was a one-peak variation in water use efficiency( WUE); Light saturation point( LSP) of Sassafras tsumu Hemsl was 996. 78μmol/( m^2·s),and light compensation point( LCP) was10. 51μmol/( m^2·s). The results also showed that Sassafras tsumu Hemsl. was a kind of heliophilous plant with shade-resistant ability,which laid a theoretical basis for the seedling management of Sassafras tsumu Hemsl.