荫蔽栽培与亏缺灌溉对干热区小粒咖啡生长和冠层结构的影响

干热区小粒咖啡水、光管理粗放,高效生产受到限制。通过大田试验,采用完全组合设计,设3个灌水水平[充分灌水(FI)、轻度亏缺灌水(DIL)和重度亏缺灌水(DIS)]和4个荫蔽栽培模式[无荫蔽(S0):单作咖啡;轻度荫蔽(SL):4行咖啡间作1行香蕉;中度荫蔽(SM):3行咖啡间作1行香蕉;重度荫蔽(SS):2行咖啡间作1行香蕉],研究香蕉荫蔽栽培下亏缺灌溉对干热区小粒咖啡生长和冠层结构的影响。结果表明:与FI相比,其余灌水处理的株高增量和新梢长度分别减少13.62%～23.94%和8.82%～13.96%,总定点因子增加9.55%～34.97%。与S0相比,其余荫蔽处理的株高增量、茎粗增量、冠幅增量、新梢长度和叶面积指数分别增加18.33%～33.65%、6.43%～15.47%、5.38%～12.60%、8.82%～24.69%和5.18%～22.85%,冠层开度、林隙分数、平均叶倾角、总定点因子和透光率分别减少4.42%～15.50%、4.85%～16.49%、5.50%～15.07%、13.78%～41.44%和10.36%～31.78%。相关分析表明,冠层开度、林隙分数、平均叶倾角、直接定点因子、间接定点因子、总定点因子、冠下直接辐射、冠下间接辐射、透光率和消光系数相互之间均呈显著正相关,且分别与冠层叶面积指数呈显著负相关。聚类分析表明,当类间距离为5时,可将12个处理分为3类, FISS、DILSS和FISM处理为第1类, FISL、DILSL、DILSM、DISSS、FIS0和DISSM处理为第2类, DILS0、DISSL和DISS0处理为第3类。其中第1类的生长状况最佳,可作为干热区小粒咖啡灌水处理和香蕉荫蔽栽培模式的优选组合。该结果可为干热区小粒咖啡水光管理提供理论指导。

Effects of shade cultivation and deficit irrigation on the growth and canopy structure of Coffea arabica L. in dry-hot region

Highly efficient production of Coffea arabica L. is limited due to irrigation and light management challenges in dry-hot regions. To investigate the effects of an irrigation deficit on the growth and canopy structure of C. arabica under the shade of banana plants, a field experiment was performed using different irrigation levels and shade cultivation modes. A complete combination design was adopted, with three levels of irrigation, i.e. full irrigation (FI), light-deficit irrigation (DI_L) and severe deficit irrigation (DI_S), and four modes of shade cultivation, i.e. no shade cultivation (S₀:monoculture C. arabica), light shade cultivation (S_L:intercropping of four lines of C. arabica and one line of banana), moderate shade cultivation (S_M:intercropping of three lines of C. arabica and one line of banana) and severe shade cultivation (S_S:intercropping of two lines of C. arabica and one line of banana). Compared with FI treatment, other treatments of irrigation decreased the height increment and shoot length by 13.62%-23.94% and 8.82%-13.96%, respectively, and increased the total fixed-point factor by 9.55%-34.97%. Compared with S₀ treatment, other shading cultivation treatments increased the height increment, stem diameter increment, crown width increment, shoot length, and leaf area index of the canopy by 18.33%-33.65%, 6.43%-15.47%, 5.38%-12.60%, 8.82%-24.69% and 5.18%-22.85%, respectively; and decreased the opening, gap fraction, mean leaf dip angle, total fixed-point factor and transmittance of the canopy by 4.42%-15.50%, 4.85%-16.49%, 5.50%-15.07%, 13.78%-41.44% and 10.36%-31.78%, respectively. The opening, gap fraction, mean leaf dip angle, direct fixed-point factor, indirect fixed-point factor, total fixed-point factor, direct radiation of the crown, indirect radiation of the crown, transmittance, and extinction coefficient of the C. arabica canopy were significantly positively correlated with each other and were significantly negatively correlated with leaf area index. Cluster analysis indicated that the twelve treatments could be divided into three categories. The first category was FIS_S, DI_LS_S and FIS_M; the second category was FIS_L, DI_LS_L, DI_LS_M, DI_SS_S, FIS₀ and DI_SS_M; and the third category was DI_LS₀, DI_SS_L and DI_SS₀, when the distances between classes was five. It was clear that the best growth condition was the first category, which can be used as a suitable combination of irrigation and banana shade cultivation mode for C. arabica in dry-hot regions. The results of this study provide theoretical guidance for the irrigation and light management of C. arabica in dry-hot regions.