基于植物功能-结构模型的玉米-大豆条带间作光截获行间差异研究

Estimating the Differences of Light Capture Between Rows Based on Functional-Structural Plant Model in Simultaneous Maize-Soybean Strip Intercropping

间作种植形成了异质冠层空间结构,但因此导致的作物生长、表型和光截获的行间差异目前还少有定量化。为解析条带间作生产力的行间差异,本研究基于田间观测数据构建植物功能-结构模型(Functional-Structural Plant Model,FSPM),量化间作系统中光截获的行间差异。于2017—2018年开展了玉米和大豆单作、2行玉米和2行大豆的2:2 MS间作以及3行玉米和6行大豆的3:6 MS间作田间试验。基于植物生长平台GroIMP开发了玉米-大豆间作的FSPM,模型较好地模拟了叶面积指数(Leaf Area Index,LAI)、株高和光截获系数动态三个指标,均方根误差(Root Mean Square Error,RMSE)分别为0.24~0.70 m^(2)/m^(2)、0.06~0.17 m和0.06~0.10。田间试验结果表明,间作种植显著增加了玉米节间直径。受玉米遮阴影响,大豆节间变长、变细,且随大豆条带变窄差异越明显。模型模拟的2:2 MS间作玉米光截获比单作玉米高35.6%,3:6 MS边行玉米和内行玉米的光截获分别比单作玉米高27.8%和20.3%。2:2 MS与3:6 MS边行大豆的光截获比单作大豆分别少36.0%和28.8%;3:6 MS大豆内Ⅰ行和内Ⅱ行比单作大豆的光截获分别少4.1%和1.8%。基于三维FSPM,未来可进行不同生长环境下间作种植模式等的布局优化,以达到最佳系统光截获优势。

Intercropping creates a heterogeneous canopy and triggers plastic responses in plant growth and structural development.In order to quantify the effect of planting pattern,strip width and row position on the structural development and light capture of maize and soybean in simultaneous intercropping,both experimental and modelling approaches were used.Field experiments were conducted in 2017-2018 with two sole crops(maize and soybean)and two intercrops:Two rows of maize alternating with two rows of soybeans(2:2 MS)and three rows of maize alternating with six rows of soybean(3:6 MS).The morphological traits of maize and soybean e.g.,leaf length and width,internode length and diameter,leaf and petiole declination angle in different rows and different planting patterns,and photosynthetically active radiation(PAR)above and below the canopy of 2:2 MS were measured throughout the growing season.A functional-structural plant model of maize-soybean intercropping was developed in the GroIMP platform.The model was parameterized based on the morphological data set of 2017,and was validated with the leaf area index(LAI),plant height and PAR data set of 2018.The model simulated the morphological development of individual organs based on growing degree days(thermal time)and calculated the light capture at leaf level.The model well reproduced the observed dynamics of leaf area index and plant height(RMSE:0.24-0.70 m^(2)/m^(2)for LAI and 0.06-0.17 m for plant height),and the fraction of light capture in the 2:2 MS intercropping(RMSE:0.06-0.10).Maize internode diameter in intercrops increased,but the internode length did not change.Soybean internodes in intercrops became longer and thinner compared to sole soybean probably caused by the shading imposed by maize,and the 2:2 MS had longer internodes than the 3:6MS,indicating the effects of strip width.Simulated light capture of maize in 2:2 MS intercropping was 35.6%higher than sole maize.For maize in 3:6 MS intercropping,the light capture of the border rows and inner row were 27.8%and 20.3%higher than sole maize,respectively.Compared to sole soybean,the simulated light capture of soybean in border rows was 36.0%lower in 2:2 MS intercropping,and was 28.8%lower in 3:6 MS intercropping.For 3:6 MS intercropping,light capture of soybean in inner rowsⅠand inner rowsⅡwere 4.1%and 1.8%lower than sole soybean,respectively.In the future,the model could be further developed and used to explore and optimize the planting patterns of maize soybean intercropping under different environmental conditions using light capture as an indicator.