土壤养分异质性对玉米地上部、根系生长及种内竞争的影响

为探究作物之间对土壤养分斑块利用的优先顺序及对作物根系吸收矿质营养的影响，选用玉米品种‘先玉335’为研究材料，设置根箱试验，在养分匀质和异质2种供养模式下设置5个延迟种植时间作为时间梯度对正常种植和延迟种植的玉米的地上部生物量、养分含量、根冠比(T/R)和根系长度等指标进行分析。结果表明，同一根箱内，延迟2~5 d种植的玉米地上部生物量比正常种植的玉米在养分匀质供养环境中低28.4%~74.3%，在养分异质环境中低19.2%~193.0%。延迟种植玉米的根系生物量在养分匀质供养环境中随着种植时间的加长均无显著差异；而正常种植玉米的根系生物量在异质环境中随着延迟种植时间的加长有显著增加。因此，同一根箱内，延迟种植玉米的根冠比显著高于正常种植的玉米，根系总长度和体积与根系生物量的变化趋势类似。在同一根箱内，在匀质供养环境中，正常种植和延迟种植玉米的比根长和根系组织密度在不同种植时间处理间均无显著差异；仅延迟5 d种植玉米的根系组织密度在养分异质环境中显著低于正常种植的玉米。综上，玉米利用养分资源的先后顺序会引起地上部养分产生竞争，尤其是在养分异质环境中，玉米可以通过调整自身来适应养分和竞争环境。

Effects of nutrient heterogeneity on shoot and root growth of Zea mays and intraspecific competition

In order to study the effect of the utilization priority of soil nutrient patches among competing plants and root mineral nutrient uptake of crops, the modern maize(Zea Mays)variety Xianyu 335 was selected as the study material and root-box experiment was conducted. A total of five delayed time were set up under homogeneous and heterogeneous nutrient supply patterns. The aboveground biomass, nutrient content, root-shoot ratio (T/R)and root length of maize under normally planted and delayed planted were determined. The results showed that: In one root-box, the aboveground shoot biomass of the delayed planted maize was significantly 28. 4%-74. 3% lower than that of normally planted maize in nutrient homogeneous environment, while the aboveground shoot biomass of the delayed planted maize was significantly 19. 2%-193. 0% lower than that of normally planted maize from 2-5 d in nutrient heterogeneous environment. The root biomass of the delayed planted maize had no significant changes with the time increasing in both nutrient homogeneous and heterogeneous environments, while the root biomass of normally planted maize exhibited a significantly increased with the delayed planting time increasing. Therefore, in one root-box, the root/shoot ratio of the delayed planted maize was significantly higher than that of the normally planted maize; The root length and volume exhibited similar trends with root biomass. In one root-box, there was no significant difference in the specific root length and root tissue density between normal and delayed corn planting under homogeneous environment; The root tissue density of maize planted only at the delayed 5th day planted maize was significantly lower than that of normal maize planted in the nutrient heterogeneity environment. In conclusion, the order of maize uptaking soil nutrient resources can cause the formation of competitive for aboveground nutrients, especially in nutrient heterogeneous environments, maize adapted to nutrient and competitive environment by adjusting itself.