大麦/豌豆间作系统种间竞争力及产量对地下作用和密度互作的响应

种间关系是间作高产和资源高效利用的重要生物学基础,揭示种间关系对间作产量的影响,对优化间作技术具有重要理论指导意义。本研究通过盆栽试验,设计根系完全分隔(地上互作)与不分隔(地上地下互作)2种种间作用关系,及2个大麦种植密度(15株·盆~(-1)、25株·盆~(-1)),探讨了根系相互作用与密植对大麦间作豌豆种间竞争互补关系及产量的影响,以期为建立基于优化种间关系提高间作产量的管理技术提供理论依据。结果表明:1)与单作相比,间作可提高群体干物质积累量3.6%~11.3%,其中地下作用的贡献率为53.9%~63.5%;增加大麦种植密度,使根系不分隔间作处理的群体干物质量提高12.5%~14.4%,根系完全分隔间作处理提高3.3%~6.7%。同样,与单作相比,间作群体籽粒产量提高8.6%~38.8%,地下作用的贡献率为2.4%~16.2%;增加大麦种植密度,不分隔与分隔间作处理的籽粒产量分别提高7.0%~10.9%与1.2%~2.6%,说明地下根系相互作用是间作密植的重要基础。2)间作可提高大麦、豌豆的收获指数,大麦提高8.7%~21.0%、豌豆提高3.3%~31.7%;间作大麦收获指数随着大麦种植密度的增加而增大,而间作豌豆收获指数随着大麦种植密度的增加而降低,根系完全分隔处理降低作用更明显。3)根系不分隔地下作用可提高间作群体土地当量比(LER),增加大麦种植密度降低了LER,说明地下根系相互作用是产生间作优势的主要原因。4)地下作用明显增大了大麦相对于豌豆全生育期的平均竞争力,增长率达40.1%~89.1%;增加大麦种植密度,平均竞争力提高11.0%~49.9%。5)间作群体籽粒产量与大麦相对于豌豆全生育期的平均竞争力呈二次相关关系,当该竞争力在0.35、0.13时利于间作大麦、豌豆获得高产。本研究表明,通过增加大麦种植密度(如本研究的25株×盆~(-1))来适度提高大麦的竞争优势,特别是大麦灌浆期的竞争优势有利于间作群体整体产量的提高。

Competitiveness and yield response to belowground interaction and density in barley-pea intercropping system

Interspecific relationship is an important biological basis for high-yield and efficient utilization of resources in intercropping systems. It can reveal the effects of interspecific relationships on the yield of intercropping systems, providing the theoretical and guiding basis for optimizing intercropping agriculture. To this end, a pot experiment was set up to investigate the effects of root interaction and planting density on grain yield, interspecific competition and complementarity of barley-pea intercropping system. In the experiment, two kinds of species interactions were set, only aboveground interaction (whole root partition of two intercropped crops) and aboveground and belowground interaction (without root partition between two intercropped crops), in combination with two planting densities of barley (15 plants?pot-1 and 20 plants?pot-1). The study was designed to provide the theoretical basis for raising yield management technique under intercropping based on interspecific relationship optimization. The study showed that: 1) compared with the corresponding monoculture system, average dry matter accumulation of intercropping systems increased by 3.6%-11.3%. The contribution rate of belowground interaction was 53.9%-63.5%. For the intercropping system with belowground and aboveground interactions, increased planting density of barley enhanced dry matter accumulation of the system by 12.5%-14.4%. But, for the intercropping system only with aboveground interaction, it increased by 3.3%-6.7%. Similarly, barley-pea intercropping total grain yield was 8.6%-33.8% higher than the average grain yield of the corresponding monocultures. The contribution rate of the existing belowground interaction was 2.4%-16.2%. With increasing planting density of barley, the intercropping system existing both belowground and aboveground interactions increased total grain yield by 7.0%-10.9%; while the intercropping system existing only aboveground interaction only increased by 1.2%-2.6%. This suggested that belowground interaction was critical for close planting in intercropping systems. 2) Compared with corresponding monoculture treatments, intercropping increased harvest indexes (i.e., HI) of barley and pea by 8.7%-21.0% and 3.3%-31.7%, respectively. The harvest index of intercropped barley increased with increasing planting density of barley while that of intercropped pea decreased. The trend of the decline was more obvious under whole root partition. 3) Belowground interaction without root partition increased land equivalent ratio (LER), but high planting density of barley decreased LER in barley-pea intercropping system. This suggested that belowground root interaction was the main force behind the advantages of intercropping. 4) The belowground interaction significantly increased the competitiveness (by up to 40.1%-89.1%) of barley to pea during the period of co-growth. The average competitiveness increased by 11.0%-49.9% with increasing barley planting density. 5) A quadratic relationship existed between total grain yield of barley-pea intercropping system and the average competitiveness of barley to pea during the whole period of co-growth. High grain yields of both crops were obtained when competitiveness was 0.13-0.33. Our results showed that appropriately improving the competitiveness of barley and pea intercropping system (especially at barley grain-filling stage) by increasing the planting density of barley (25 plant?pot-1) increased total grain yield of the intercropping system.