不同密度对棉花根系生长与分布的影响

Effects of Planting Densities on the Growth and Distribution of Root in Cotton(Gossypium hirsutum L.)

利用根钻挖掘法研究了大田条件下6个种植密度对棉花根系生长分布的影响。结果表明:1.5万～8.7万株.hm-2密度水平根干物质质量密度、根长密度在吐絮之前持续增加,而10.5万株.hm-2处理在盛铃期后出现下降。在盛蕾期至初花期,棉花根干物质质量密度、根长密度均随种植密度的增加而增大;在盛花期至吐絮初期,根干物质质量密度以3.3万株.hm-2处理最高,3.3万～10.5万株.hm-2处理根长密度显著高于1.5万株.hm-2。根系垂直分布结果表明,0～30 cm土层内的根干物质质量和根长分别占所测土体中根量的67.80%～97.44%和54.01%～93.33%。低密度处理(1.5万株.hm-2、3.3万株.hm-2)的浅层(0～20 cm)根干物质质量密度和根长密度在盛蕾期均低于其它处理,深层(30～60 cm)根干物质质量密度和根长密度在初花期至盛铃期低于其它处理。吐絮初期,各密度处理根长密度在深层土壤有显著差异。

In this study, the properties of root growth and distribution in cotton regulated by planting densities have been investigated based on the soil core sampling method. At the density of 1.5×10^4-8.7×10^4 plants .hm2, the root dry weight density and the root length density were both gradually increased before the beginning of boll opening stage, then decreased along with the growth progression. However, the above root traits reached the highest at the peak boiling stage at the density of 10.5×10^4 plants, hm-2, being much earlier than the low planting densities. From the budding peak stage to the early-flowering stage, the root dry weight densities and the root length densities in cotton all showed a pattern to be elevated along with the increase of planting densities. During the growth phase from the full-blooming stage to the beginning of boll opening stage, the root dry weight density was the highest at 3.3×10^4 plants-hm-2 among the tested planting densities. The root length densities at 3.3×10^4 to 10.5 ×10^4 plants, hm-2 was significantly higher than that at 1.5×10^4 plants, hm-2. Root vertical distribution analysis revealed that the root dry weight and root length in top soil layer （0-30 cm） accounted for 67.80%-97.44% of the total root weight, and 54.01%-93.33% of total root length （0-60 cm soil layer）, respectively. At lower planting densities （1.5×10^4 plants, hm-2 and 3.3×10^4 plants.hm-2）, the root dry weight densities and root length densities in top soil layer （0-20 cm） were lower than other high planting densities at the budding peak stage. Similarly, the low planting densities mentioned previously had lower above root traits than the high planting densities in deep soil layer （30-60 cm） at growth phase from the early-flowering stage to the peak bolling stage. It did not display a significant variation on root length densities among the tested planting densities in deep soil layer at the beginning of boll opening stage.