青枣荫蔽栽培下微润灌溉对小粒咖啡生长和水光利用的影响

为探索小粒咖啡幼树的水光耦合模式,通过小区试验研究青枣荫蔽栽培条件下微润灌溉压力水头对小粒咖啡根区土壤水分分布、生长和光合特性的影响.设置3个压力水头:低水头(H_1.0:1.0 m)、中水头(H_1.5:1.5 m)和高水头(H_2.0:2.0 m);3个青枣荫蔽栽培程度:无荫蔽(S₀:100%自然光照)、轻度荫蔽(S₁:65%~75%自然光照)、重度荫蔽(S₂:45%~55%自然光照).研究结果表明:微润灌溉压力水头和荫蔽栽培水平对小粒咖啡根区土壤湿润体内水分含量均值影响显著,湿润体剖面面积随着压力水头的增大而增大,而随着荫蔽程度的增大略有减小;压力水头增大,微润灌湿润体内含水率均值与均匀度显著增大,荫蔽程度增大,湿润体及体内含水率均值与均匀度略有减小;与S₀相比,S₁的小粒咖啡株高、茎粗、冠幅和叶片数分别增大20.31%,12.44%,24.45%和52.00%;与H_1.0相比,增加微润灌压力水头使小粒咖啡叶片日均净光合速率、蒸腾速率、光能利用效率和瞬时水分利用效率分别增大22.10%~60.75%,28.02%~70.49%,35.51%~81.65%和26.42%~39.61%,而叶片胞间CO₂浓度减少14.16%~31.32%;与S₀相比,增大荫蔽栽培程度,日均净光合速率和蒸腾速率分别增大12.20%~26.10%和5.37%~26.28%,胞间CO₂浓度减小5.88%~11.97%;S₁下表观光能利用效率和瞬时水分利用效率分别增大15.02%和15.53%,而S₂下分别减小5.88%和11.97%;H_2.0S₁处理的小粒咖啡幼树生长、净光合速率、瞬时水分利用效率和表观光能利用效率显著提高,为适宜的灌溉和青枣荫蔽栽培耦合模式.

Effects of moistube irrigation on growth and moisture-radiation use of coffea arabica under jujube shading cultivation

In order to find out the moisture-radiation coupling mode for young coffee tree, effects of water head of moistube irrigation on soil moisture distribution in the root zone, growth and photosynthetic characteristics of coffea arabica were studied under jujube shading cultivation by pot experiment. A design of experiment was completed by involving two factors and three levels, i.e. three water heads such as low(H_1.0:1.0 m), moderate(H_1.5:1.5 m)and high water head(H_2.0:2.0 m), three jujube shade degrees, namely no shading(S₀:100% natural light), moderate shading(S₁:65%-75% natural light), and severe shading(S₂:45%-55% natural light). The results show that the water head and shading degree have a significant effect on the mean soil moisture in the root zone of coffea arabica. The wetted zone size increases with increasing water head, and decreases slightly with increasing shading degree. The mean and uniformity of soil moisture in the wetted zone increases significantly with water head, but decreases slightly with shading degree. Compared with S₀, height, stem diameter, crown width and number of leaves in S₁ are increased by 20.31, 12.44, 24.45 and 52%, respectively. Compared with H_1.0, the average net photosynthetic rate(Pn), transpiration rate(Tr), apparent light use efficiency(ALUE)and instantaneous water use efficiency(IWUE)of leaves are increased by 22.10%-60.75%, 28.02%-70.49%, 35.51%-81.65% and 26.42%-39.61% in H_1.5 and H_2.0, respectively, while the intercellular carbon dioxide concentration(CO₂)is decreased by 14.16%-31.32%. Compared with S₀, an increasing shading degree results in 12.20%-26.10% and 5.37%-26.28% increments in Pn and Tr, but 5.88%-11.97% reduction in intercellular CO₂. In S₁, ALUE and IWUE are increased by 15.02% and 15.53% in S₂, however, decrease by 5.88% and 11.97%. In H_2.0S₁, the tree growth, Pn, IWUE and ALUE of leaves have been enhanced significantly. This treatment should be is a suitable cultivation mode to coffea Arabica young tree under coupled moistube irrigation and jujube shading conditions.