种植模式对机采棉冠层光能利用与产量形成的影响

    Effects of planting pattern on canopy light utilization and yield formation in machine-harvested cotton field

    • 摘要: 冠层内部的光辐射传输特征是优化种植模式,促进农机农艺深度融合,实现标准化种植和机械化作业的重要决定因素。然而,机采棉种植模式对冠层内光辐射传输及产量形成的调控机理尚不清晰。为此该研究开展2 a的田间试验,在相同种植密度条件下,设置3种机采棉种植模式:一膜三行(S1)、一膜四行(S2)和一膜六行(S3),研究了冠层结构、冠层有效辐射和产量形成的演化特征,分析了种植模式、冠层光截获与产量构成因子间的相关性。结果表明,不同种植模式下棉花的冠层结构及其内部的光辐射传输特征具有明显的时空异质性。与S3处理相比,S1处理在生长前期,水平方向上冠层透过率呈"V"形变化,此时,行距的扩大增加了棉田行间的光合有效辐射(Photosynthetically active radiation,PAR)透过率,但对棉行附近的透过率无显著性影响;在生长后期,棉田封行,各处理水平方向上的透过率变化幅度较小,但S1处理下层的透过率显著高于S2和S3处理。平均行距的增加显著提升了棉花下部的结铃数和棉铃质量,最终提高了产量,S1处理2 a籽棉产量为6 507.50和6 161.08 kg/hm2,较S2处理提高10.66%(2017)、10.29%(2018),较S3处理提高23.10%(2017)、15.32%(2018)。平均行距、产量构成与下层光截获率呈极显著正相关关系,与中层、上层和总光截获率呈负相关关系。说明平均行距的增加会降低中、上层的光截获率,提高下层的光截获率,从而增加产量,虽然冠层总光截获率有降低的趋势。综上所述,S1处理可以改善冠层下部光能传输情况,提高冠层下部光能截获量,保证冠层下部生殖器官的发育,提高下部的结铃数和棉铃质量,最终实现产量的提升,是一种利于农机农艺深度融合的新型种植模式,研究结果可为机采棉机艺融合技术的发展提供参考。

       

      Abstract: Abstract: Light radiation transmission inside the canopy is an important determinant to optimize planting patterns for deep integration of agricultural machinery and techniques, thereby realizing standardized planting and mechanized operation. However, it is still unclear about the regulation mechanism of machine-harvested cotton planting mode on canopy light radiation transmission and yield formation. In this study, a two-year field experiment was carried out under the same density in Xinjiang cotton areas of western China, in order to clarify the effects of planting patterns on canopy light utilization and yield in mechanically harvested cotton. Three kinds of machine-harvested cotton were set. An investigation was also made on the evolution characteristics of canopy structure, canopy effective radiation, and yield formation under different configurations. The correlation analysis was carried out between planting pattern, canopy light interception, and yield composition factors. The results demonstrated that there was an obvious spatial and temporal heterogeneity in the canopy structure of cotton under different planting patterns and the characteristics of light radiation transmission inside. The canopy transmittance of S1(Each film planting three rows) changed in the horizontal direction of "V" in the early stage of growth, compared with the treatment of S3. Meanwhile, the expansion of row spacing increased the distribution of PAR(Photosynthetically active radiation) between the rows in the cotton fields, but there was no significant influence on the transmittance near the rows of cotton. In the later stage of growth, the transmittance of the cotton field in each horizontal direction changed slightly, but the transmittance of the lower layer under the treatment of S1 was significantly higher than that of S2(Each film planting four rows) and S3(Each film planting six rows). The average row spacing significantly enhanced the boll number and weight at the lower part of cotton, finally promoting the yield. The two-year seed cotton yields of S1 cotton were 6 507.50 and 6 161.08 kg/hm2, which were 10.66%, 23.10%(2017) and 10.29%, 15.32%(2018)higher than that of S2 and S3 cotton, respectively. There was a significant positive correlation between the average row spacing, the yield composition, and the light interception rate of the lower layer, whereas, a negative correlation was found between the middle layer, the upper layer, and the total light interception rate. This indicated that the average row spacing reduced the optical interception rate in the middle and upper layers, while increased the optical interception rate in the lower layer for higher yield, although the total optical interception rate in the canopy tended to decrease. The "each film planting three rows" machine-harvested cotton planting mode can increase the PAR transmittance in the middle and lower parts of the upper canopy in the vertical direction, where the utilization efficiency of light energy was improved as a whole, compared with the arrow row treatment. The number of bolls increased by 16.7%, the quality of cotton bolls increased by 6.6%, and the final yield increased by 19.21%, compared with the traditional one. The planting mode mainly determined the light transmission in the vertical direction, thereby dominating the PAR transmittance and interception in the canopy. The light transmittance of the middle and lower canopy gradually increased, with the increase of average row spacing. The varying degrees alleviated the excessive concentration of interleaved leaves between the wide and narrow rows, resulting in the canopy closure and the supply of photosynthetic products in the middle and lower canopy. Therefore, the "each film planting three rows" machine-picked cotton planting mode can be expected to concurrently improve the cotton yield and light energy utilization. Consequently, the quality of mechanical picking can greatly promote the deep integration of mechanical harvesting and agricultural machinery

       

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