玉米-花生混作系统中的氮铁营养效应

采用盆栽试验的方法研究了不同施氮水平和种间相互作用对花生铁营养、根瘤固氮能力以及系统氮营养的影响。结果表明,在本试验种植密度下,施氮水平和种植方式对下针期单株花生生物量无显著影响。在不同施氮水平下,玉米-花生混作不仅均显著改善了花生铁营养,而且玉米对氮素的大量吸收显著降低了混作花生根际土壤硝态氮的质量分数,从而使得花生根瘤数增加,根瘤固氮酶活性增强。混作花生铁营养受混作玉米氮营养及作物发育状况的影响较大,并且下针期花生固氮酶活性受施氮抑制及花生铁营养改善的促进。这说明,根际土壤硝态氮的质量分数的降低和花生铁营养的改善是石灰性土壤上花生固氮能力增强的关键因素,而花生生物固氮作用的增强是该混作系统体现氮营养优势的主要原因。

Effects of maize-peanut mixed cropping on N and Fe nutrition

The pot experiment was conducted to investigate the effects of different N levels and interspecific interaction on biological nitrogen fixation of nodule,Fe nutrition of peanut and N nutrition in maize-peanut mixed cropping system.The results showed that both N levels and planting modes had no obvious effect on dry weight of peanut plant.The visible nodule number and nodule nitro-genase activities per plant peanut were increased significantly in maize/peanut mixed cropping system,which was not only due to the decreasing of NO3--N content in the rhizosphere of mixed peanut as a result of competition by maize for soil N,but also due to the obvious Fe nutrition improvement of mixed cropping peanut under different nitrogen levels.Moreover,Fe nutrition of mixed crop-ping peanut was related to maize N nutrition and growth stages of crops.Peanut nodule nitrogenase activities in needling stage were enhanced with the improvement of Fe nutrition,but inhibited with N application.Therefore,it was important for the increasing of biological nitrogen fixation of peanut to decrease N content in rhizosphere and to improve Fe nutrition of peanut on calcareous soil,which was the importance way for the N nutrition advantage in maize-peanut mixed cropping system.