行距及密度影响玉米密植潜力的干物质累积和产量构成机制

Characteristics of dry matter accumulation and yield formation of dense planting maize in different row spacings

  • 摘要: 空间布局是决定玉米密植潜力的重要因子,但有关行距配置对不同密度玉米产量及其构成因素的调控研究比较薄弱,使得生产实践中缺乏通过行距配置优化挖掘玉米密植潜力的理论依据。2017—2018年,在带宽相同条件下,研究了7:3(L1:宽行56 cm:窄行24 cm)、6:4(L2:宽行48 cm:窄行32 cm)、5:5(L3:行距配置均为40 cm)3种行距配置对5种密度(D1:82 500株·hm-2、D2:90 000株·hm-2、D3:97 500株·hm-2、D4:105 000株·hm-2、D5:112 500株·hm-2)玉米产量及其构成因素的影响。行距配置、密度及二者的互作效应显著影响玉米籽粒产量,L1行距配置较L3增产5.2%~10.5%,增幅显著;D2、D3密度处理分别较D1密度处理增产6.1%~12.0%、6.5%~15.0%(P < 0.05),L1D3、L2D3产量较L3D1提高了8.3%~34.2%、4.8%~27.5%(P < 0.05),L1D3的增产效果最好,说明宽窄行种植增强了玉米植株的耐密性,提高了玉米群体的密植潜力。宽窄行结合密植有利于提高玉米的生物产量,其中L1行距配置较L3提高3.0%~6.6%(P < 0.05),D3密度较D1密度高3.4%~8.0%(P < 0.05),L1D3较L3D1处理提高5.2%~15.0%(P < 0.05)。宽窄行种植提高玉米密植潜力的原因是:1)提高了玉米生长后期(大喇叭口期至灌浆期)的干物质累积速率,该时期玉米的干物质累积速率L1行距配置较L3提高32.9%~42.0%,D3密度较D1密度高9.2%~23.9%,L1D3处理较L3D1处理高29.1%~34.3%,增幅均显著;2)提高了光合产物向穗部的转移,2017年度玉米收获指数D3密度较D1密度高6.4%,L1D3处理较L3D1处理高16.2%,2018年无显著差异;3)提高了玉米的成穗数和穗粒数,D3密度的成穗数较D1密度高16.0%~20.2%,L1D3较L3D1成穗数高16.9%~25.9%,L1行距配置较L2、L3穗粒数分别高3.0%~4.4%、3.9%~7.0%,提高幅度均显著。56 cm:24 cm宽窄行结合密度97 500株·hm-2是绿洲灌区获得高产,密植潜力充分发挥的理想种植模式。

     

    Abstract: Spatial layout is crucial to determine the dense planting potential of maize. However, the influence of row spacing allocation on maize yield and its components with different planting densities is unclear. This uncertainty leads to a lack of a theoretical basis of the utilization of the dense planting potential of maize by optimizing the allocation of row spacing. From 2017 to 2018, with the same bandwidth, this study investigated how three row spacing allocation treatments-ratios of wide to narrow rows spacing of 7:3 (L1:56 cm:24 cm), 6:4 (L2:48 cm:32 cm), and 5:5 (L3:40 cm:40 cm)-affected maize yield and its components under five planting densities (D1:82 500 plants·hm-2; D2:90 000 plants·hm-2; D3:97 500 plants·hm-2; D4:105 000 plants·hm-2; and D5:112 500 plants·hm-2). Row spacing allocation, density, and their interactions significantly affected grain yield. Compared to L3 row spacing allocation, L1 increased significantly grain yield by 5.2%-10.5%. Compared to D1 density, D2 and D3 increased grain yield by 6.1%-12.0% and 6.5%-15.0%, respectively (P < 0.05). Compared with L3D1 treatment, L1D3 and L2D3 increased grain yield by 8.3%-34.2% and 4.8%-27.5%, respectively (P < 0.05). Compared with L2D3, the regulatory effect of L1D3 was more prominent. The findings indicated that wide-narrow rows spacing allocation could enhance the tolerance of maize plants in higher planting density and increase the dense planting potential of maize. Wide-narrow rows spacing allocation combined with dense planting were beneficial to increase biomass. L1 row spacing allocation significantly increased biomass by 3.0%-6.6% (P < 0.05) compared to L3 treatment. Compared to D1 density, D3 significantly increased biomass by 3.4%-8.0% (P < 0.05). Compared with L3D1 treatment, L1D3 significantly increased biomass by 5.2%-15.0% (P < 0.05). There were three possible reasons for wide-narrow rows spacing allocation increased dense planting potential of maize. Firstly, dry matter accumulation rate of maize was significantly increased from the large bell mouth stage to the filling stage, as evidenced by the 32.9%-42.0% increase of dry matter accumulation rate with L1 row spacing allocation compared to L3 row spacing allocation, the 9.2%-23.9% increase of dry matter accumulation rate with D3 density compared to D1 density, and by the 29.1%-34.3% increase of dry matter accumulation rate with the treatment of L1D3 compared to L3D1. Secondly, there was an increased transformation of photosynthetic product to ear. Compared with the traditional density D1, D3 density increased harvest index by 6.4% in 2017, compared with L3D1, L1D3 increased harvest index by 16.2% in 2017, and there was no significant difference in 2018. Thirdly, a significantly effective ear and kernel number was observed, with a 16.0%-20.2% increase of ear number with D3 density compared to D1 density, 16.9%-25.9% increase of ear number with L1D3 compared to L3D1, 3.0%-4.4%; and 3.9%-7.0% increase of kernel number with L1 row spacing allocation compared to L2 and L3 row spacing allocation, respectively. The wide-narrow rows spacing allocaton of 56 cm:24 cm combined with planting density of 97 500 plants·hm-2 is an ideal planting mode for high yield and high dense planting potential in the Oasis Irrigation District.

     

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