不同遮光和施氮水平对小粒咖啡生长和光合特性的影响

【目的】探明小粒咖啡Coffea arabica幼树最佳的光照和施氮耦合模式。【方法】试验设置3个遮光水平:不遮光(S0,自然光照)、轻度遮光(S1,65%自然光照)、重度遮光(S2,30%自然光照), 3个施氮水平:无氮(N0,0 g·kg-1)、中氮(N1,0.20 g·kg-1)、高氮(N2,0.40 g·kg-1),研究不同遮光和施氮水平对小粒咖啡生长、日均光合特性和生物量累积的影响。【结果】随遮光度的增加叶绿素总量呈上升趋势。与S0处理相比,S1处理小粒咖啡叶片净光合速率、气孔导度、表观光能利用效率和总生物量分别提高13.54%、18.54%、127.77%和12.41%;S2处理总生物量减少11.55%。与N0处理相比,N1处理叶片净光合速率、气孔导度、表观光能利用效率和总生物量分别增加27.25%、20.77%、10.80%和18.47%,N2处理的上述性状分别增加14.85%、25.99%、41.65%和21.02%。与S0N0相比,随遮光度和施氮量的增加叶片蒸腾速率和表观光能利用效率增大,叶片水分利用效率呈先增后减趋势。【结论】小粒咖啡最优的遮光和施氮耦合模式为轻度遮光下高氮组合(S1N2),该组合有利于获得较高的叶片水光利用效率和生物量。

Effects of shading and nitrogen application levels on growth and photosynthesis characteristics of Coffea arabica

Objective To explore the optimal coupled management mode of light intensity and nitrogen application for Coffea arabica seedlings.Method We set three shading levels:No shade (S₀, natural light), light shade (S₁, 65% natural light) and severe shade (S₂, 30% natural light), and three nitrogen levels:No nitrogen (N₀,0 g·kg⁻¹), medium nitrogen (N₁, 0.20 g·kg⁻¹), high nitrogen (N₂, 0.40 g·kg⁻¹). The effects of shading and nitrogen levels on growth, daily photosynthetic characteristics and biomass accumulation of C. arabica seedlings were studied.Result With the increase of shading degree, the total chlorophyll content increased. Compared with S₀ treatment, the net photosynthetic rate, stomatal conductance, light radiation use efficiency and total biomass of C. arabica in S₁ treatment increased by 13.54%, 18.54%, 127.77% and 12.41%, respectively. The total biomass decreased by 11.55% in S₂ treatment. Compared with N₀ treatment, the net photosynthetic rate, stomatal conductance, light radiation use efficiency and total biomass of C. arabica in N₁ treatment increased by 27.25%, 20.77%, 10.80% and 18.47%, respectively, and these traits in N₂ treatment increased by 14.85%, 25.99%, 41.65% and 21.02%, respectively. Compared with S₀N₀, with the increases of shading and nitrogen levels, leaf transpiration rate and light radiation use efficiency increased, leaf water use efficiency firstly increased and then decreased.Conclusion The optimal mode of light and nitrogen management of C. arabica is the combination of light shade and high nitrogen (S₁N₂). This mode is suitable for obtaining high leaf water-radiation use efficiency and biomass.