[Effects of intercropping on light energy utilization characteristics and productivity of diffe-rent feed crops].

To explore light energy utilization characteristics and yield effect of different legume-gramineae intercropping patterns, we set up five kinds of monocropping patterns including alfalfa, triticale, oats, maize and sorgo as reference in a field experiment. The light energy utilization chara-cteristics and productivity of four kinds of intercropping patterns including alfalfa-triticale, alfalfa-oats, alfalfa-maize and alfalfa-sorgo were examined. The contribution degree of each light energy index to yield formation was analzyed using path analysis method. The results showed that the contribution of each index of light energy to yield from large to small was as follows: leaf area index (LAI)=1.236, net photosynthetic rate (Pn)=0.519, canopy openness (DIFN)=0.302, intercellular CO2 concentration (Ci)=-0.026, stomatal conductance (gs)=-0.116, transpiration rate (Tr)=-0.188, PAR interception rate (FIPAR)=-1.708. Light use efficiency (LUE) as a comprehensive indicator of light energy utilization had the largest value (1.367). Compared with monoculture, the values of LAI, Pn, gs, Tr and FIPAR of four kinds of gramineae grasses increased under intercropping and the values of DIFN and Ci decreased, while alfalfa showed an opposite trend. Compared with monoculture, the LUE of four kinds of gramineae grasses under intercropping was significantly increased. The increase rates of triticale and oats (35.2% and 30.4%) were higher than that of maize and sorgo (28.7% and 26.3%). The decrease rates of alfalfa intercropping with triticale and oats (6.1% and 8.3%) were obviously lower than that of maize and sorgo (21.8% and 24.5%). The values of land equivalent ratio (LER) of four kinds of intercropping patterns was all greater than 1. The LER values of alfalfa-triticale and alfalfa-oat were significantly higher than those of alfalfa-maize and alfalfa-sorgo. It could be seen that LAI had the largest direct contribution to yield, followed by Pn. Among the four intercropping patterns, two patterns, alfalfa-triticale and alfalfa-oats, had greater improvement potential of light energy utilization and yield.为探究豆-禾间作模式中的光能利用特征及产量效应,本研究以苜蓿、小黑麦、燕麦、玉米、甜高粱5种单作模式为参照,对苜蓿-小黑麦、苜蓿-燕麦、苜蓿-玉米和苜蓿-甜高粱4种间作模式开展田间试验,研究其光能利用特征和生产能力,并采用通径分析法探讨光能利用各指标对产量形成的贡献程度.结果表明: 光能利用各指标对产量的贡献由大到小依次是叶面积指数(LAI,1.236)、净光合速率(Pn,0.519)、冠层开度(DIFN,0.302)、胞间CO2浓度(Ci,-0.026)、气孔导度(gs,-0.116)、蒸腾速率(Tr,-0.188)、光合有效辐射(PAR)截获率(FIPAR,-1.708);光能利用率(LUE)作为光能利用各指标的综合体现,其数值最大(1.367).与单作相比,间作提高了4种禾本科牧草的LAI、Pn、gs、Tr和FIPAR,降低了DIFN和Ci,而苜蓿则呈相反的变化趋势.4种禾本科牧草间作下LUE与单作相比均显著提高,其中,小黑麦和燕麦的平均增幅(35.2%和30.4%)高于玉米和甜高粱(28.7%和26.3%),且与小黑麦、燕麦间作的苜蓿其LUE的平均降幅(6.1%和8.3%)明显低于与玉米、甜高粱间作(21.8%和24.5%).4种间作模式的土地当量比(LER)均大于1,其中,苜蓿-小黑麦和苜蓿-燕麦的LER值显著大于苜蓿-玉米和苜蓿-甜高粱.LAI对产量的直接贡献最大,其次是Pn.4种间作模式中,苜蓿-小黑麦和苜蓿-燕麦的光能利用提升潜力和增产潜力更大.