玉米/大豆和玉米/甘薯模式下玉米磷素吸收特征及种间相互作用

采用根系分隔盆栽试验和田间小区试验相结合的方法，通过研究玉米/大豆和玉米/甘薯套作模式下不同分隔方式及不同供磷水平，即0、35、70、105、140 kg P₂O₅ hm^-2对玉米磷素吸收利用的影响，阐明两种套作模式下种间相互作用及玉米磷素吸收特性。结果表明，2种套作体系中无论施磷与否，玉米均表现出套作优势(Acs>0，NCRcs>1)，且玉米在玉米/大豆套作模式中的竞争能力强于玉米/甘薯模式，大豆和甘薯处于套作劣势，两种模式均促进了玉米磷素积累和产量的提高，施磷70 kg hm^-2时，与根系分隔相比，不分隔时玉米磷素积累和产量在玉米/大豆、玉米/甘薯中分别提高了17.05%、5.62%和16.84%、7.17%，磷素当季利用率平均提高了7.81%。种植模式和施磷水平互作效应显著，两种模式均以105 kg hm^-2处理玉米茎、叶和穗磷素积累和产量较高，且玉米/大豆套作大于玉米/甘薯套作，说明玉米/大豆模式更有利于玉米磷素的积累及产量的提高。

Phosphorus Uptake and Utilization of Maize and Interspecies Interactions in Maize/Soybean and Maize/Sweet Potato Relay Intercropping Systems

A field experiment with different phosphorus (P) application amount including 0, 35, 70, 105, 140 kg P₂O₅ ha^-1 and a root barrier pot experiment with no barrier and plastic barrier were conducted to study the effects of P nutrition on P accumulation and use efficiency of maize in maize/soybean and maize/sweet potato relay intercropping systems along with their inter-specific promotion and mechanism. A pot experiment with and without barrier was conducted to find the inter-specific interactions, when root was separated by plastic barrier, there were not any inter-specific interactions but only P fertilizer effects, when root was not separated, there existed inter-specific interactions and P fertilizer effects at the same time. Results showed that, whether applicating P fertilizer or not, P accumulation of soybean and sweet potato was restrained in no-barrier treatment, but alleviating P application increasing (Acs>0, NCRcs>1). Inter-specific interactions promoted P accumulation by 17.05% and 5.62%, and yield by 16.84% and 7.17% respectively, when P application amount was 70 kg ha^-1; the promoting effects were more obvious with P application. Inter-specific interactions promoted P use efficiency by 7.81%, and P utilization efficiency was higher in maize/soybean than in maize/sweet potato. P accumulation of stems, leaves and grains and maize yield increased with increasing P fertilizer when P application was less than 105 kg P₂O₅ ha^-1, it was opposite while P application was more than 105 kg P₂O₅ ha^-1. P accumulation and yield were significantly higher in maize/soybean intercropping system than in maize/sweet potato intercropping. Intercropping systems-phosphorus application interaction was extremely significant. The results were similar in both field experiment and pot experiment. Therefore increasing the application of P fertilizer and using intercropping are both helpful to improve P accumulation and yield. Compared with maize/sweet potato, maize/soybean is better for promoting P use efficiency.