燕麦+箭筈豌豆混播草地混播优势的测度与影响因素分析

从混播牧草地上部分生长效率与种间竞争格局、地下部分根系构型与生物固氮效率角度出发,将不同混播群体结构(行距+同行/异行/异行阻隔)作为燕麦+箭筈豌豆型草地混播优势的影响因素,利用盆栽试验分析和比较混播牧草在不同混播群体结构中地上部、地下部因素对混播优势的相对贡献,以及不同混播群体结构氮素固定、转移和利用效率对混播系统生态功能的贡献,以期明确豆禾混播草地的种间竞争过程及其混播优势产生的机理。结果表明,1)豆禾异行混播+15 cm行距处理(Y₁₅)的混播群体结构具有较佳的产量优势,燕麦的竞争率和侵占力均高于与之混播的箭筈豌豆;2) 豆禾同行混播+15 cm行距处理(T₁₅)和Y₁₅均具有较高的应用生物固氮量、转氮率及豆科牧草对草地氮产量的贡献率;3)牧草产量与牧草叶片初始荧光(F_o)和单位面积捕获光能(TR_o/CS_o)均呈显著的正相关(P<0.05);牧草产量与根系形态特征参数和根系构型均呈极显著正相关(P<0.01);4)地上部和地下部因素对燕麦+箭筈豌豆混播系统混播优势的相对贡献分别为21.64%和78.36%,综合体现为地下部分贡献远大于地上部分。

Effects of different planting configurations on yield of Avena sativa and Vicia sativa mixed plantings with soybean in alpine pastures

This research investigated the aboveground growth efficiency, together with belowground root morphological characteristics and spatial configuration for mixed plantings of the forages Avena sativa(As) and Vicia sativa(Vs), in trays of area 70 cm×45 cm, and 30 cm depth. The aim was to assess the competitive dynamics and the relative contribution of aboveground and belowground traits of the two species to the mixed cropping advantage in different plant spacings, and the nitrogen fixation, and nitrogen transfer and utilization efficiency of the different mixed cropping planting configurations, in order to clarify the inter-specific competition process. Four planting configurations with two monoculture controls were included in the experiment: As+Vs mixed within rows at 15 cm row spacing(T15);As+Vs in alternate rows at 15 cm row spacing(Y15);As+Vs in alternate rows at 15 cm spacing with a root barrier between(YZ15);As+Vs in alternate rows at 30 cm row spacing(Y30);monoculture As(CK1);and monoculture Vs(CK2). The results indicated that: 1) Forage yield was approximately 60% higher(P<0.05) for the T15 and Y15 planting configurations than for YZ15 and Y30, and this yield gain was reflected in higher land equivalent ratios(1.5, 1.4, 1.0 and 1.2 for T15, Y15, YZ15 and Y30, respectively). The aggressivity of As was substantially greater than that of Vs in all planting configurations. 2) The mixed cropping advantage of T15 and Y15 could be attributed partly to improved light utilization aboveground and partly to enhanced N fixation belowground and capture of legume-derived N by the more aggressive As. The relative contribution of aboveground and underground factors to the mixed-cropping advantage was about 22% and 78%, respectively. 3) Forage yield was positively correlated with the initial fluorescence efficiency(F) of the forage leaves and the capture of light energy per unit area(TRo/CSo) values(P<0.05). There was a significant positive correlation between forage yield and root morphological parameters and root configuration(P<0.01). 4) Because oats are strong competitors, they are also the main contributor to the advantages of mixed sowing. Therefore, in an environment of strong competition and high nutrient utilization efficiency, the T15 and Y15 planting configurations exhibited strong mixed planting advantages over CK1 and CK2, and LER ratios near 1.5.