【摘要】 在麦棉两熟双高产条件下,以单作棉和单作麦为对照,利用根钻与DT SCAN扫描仪相结合的方法研究麦棉复合根系群体生长的时空动态分布。结果表明,套作棉和单作棉的根长和根长密度、根表面积以及根系平均直径均随生育进程呈单峰曲线,套作棉40cm以下各土层根系根长和根长密度、根表面积的衰退速率在盛花期后明显低于单作棉,根系平均直径差异较小。套作棉浅层根系干重在盛花期前低于单作棉,深层根系干重在盛花期后显著高于单作棉,在根系总量上超过单作棉。在距棉株水平距离25cm以内,纵向0～20cm土层中根系的根长和根长密度、根总表面积最大,随土层加深而递减。单作棉各土层根长和根长密度以距棉株由近及远地增加,浅层根系在距棉株水平距离12.5cm处较高。套作棉浅层根系以距棉株3.75cm处根系的根长和根长密度最大,随距棉株水平距离的增加而降低;随土层加深,各土层根长最大密度位点逐渐远离棉株。根表面积的空间分布与根长和根长密度相同。根系平均直径在距棉株水平距离3.75cm处随土层加深而降低,而在水平距离12.5cm和21.25cm处,在纵向0～40cm各土层中随土层加深而增大,在40cm以下各土层随土层加深而降低。随土层深度增加,若以棉花主茎垂直向下比喻为弓弦,则单作棉根干重的空间变化呈弓背形分布,而套作棉各土层根干重最大值出现的位点逐渐远离棉株。更多还原

【Abstract】 Cotton-wheat double cropping system is a main planting system in cotton cropping zones in China, but less research has been done in soil nutrient competition while more in light competition of up ground part of composite population in the symbiotic period of wheat-cotton. Under the condition of high yielding cotton-wheat double cropping system, contrasting to the monoculture cotton(C) and the monoculture wheat, the temporal and spatial dynamic distribution of cotton-wheat composite root system(C-W) was studied with drill and DT-SCAN Scanner. The results showed that the root length, root length density, root surface area and root average diameter of cotton in C and C-W had a single-peak curve of changes (during) the whole growth stage. In soil layer below 40 cm, the decline speed of root surface area, root length and root length density of cotton in C-W was obviously lower than in C after blooming stage, and difference of root average diameter was little. The root dry weight of C-W was lower than C before blooming stage in upper layer of soil, but obviously higher than that in deeper layer after blooming stage and the total amount of roots was mere in C-W than in C. Within the distance of 25 cm from cotton plant, the biggest root length, root length density and root surface area were in 0-20 cm soil layer, and descended with the deepening of soil layers. The upper layer root length and root length density were decreased in C and increased in C-W with increasing the distance from cotton plant; and the maximum of them were at the location of 12.5 cm from cotton plant in C but 3.75 cm in C-W. The localities with max value of root length density in every layer were farther from cotton plant with deepening the soil layers. Root surface area spatial-distribution was the same as root length density. At the location of 3.75 cm from cotton plant, root average diameter was decreased with deepening soil layers, while at the locations of 12.5 cm and 21.25 cm from cotton plant, root average diameter increased in 0-40 cm soil layer and decreased in soil layers below 40 cm with the deepening of soil layer. The localities with maximum root dry weight in every layer of C distributed like a bow with vertical taproot as bowstring, and those of cotton in C-W were farther from cotton plant.更多还原