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随着我国氮肥施用量的持续增加,氮营养斑越来越多地出现在农业土壤中,并对植物根系生长产生较大影响。但现有研究多把营养斑当作养分浓度均一的斑块,与真实营养斑有很大差异。本研究通过特制容器研究了土壤氮营养斑内不同氮素浓度对玉米根系生长的影响以及根际环境的变化。结果表明,氮营养斑内的氮素浓度影响根系生长趋向性,虽然对植物根系总生物量影响不大,但显著影响植物地上总生物量。氮营养斑内适当的氮素浓度(肥土质量比<1∶4000)会诱导根系生长,提高根系硝酸还原酶活性,增加根系对硝态氮的吸收,促进植物生长;过高氮素浓度虽能刺激根系活力,但却降低根系硝态氮浓度、硝酸还原酶活性,减少根系对氮素的吸收,抑制植物生长。尿素营养斑内,高施肥量时根际pH和硝态氮含量明显较高,可能是对根系生长影响的主要原因。
With the continuous increase of nitrogen fertilizer application in our country, nitrogen nutrition spot appears more and more in agricultural soil, and has a greater impact on plant root growth. However, in the existing research, nutritional patches are mostly used as patches with uniform nutrient concentration, which is quite different from the true nutritional patches. In this study, through special containers, the effects of different nitrogen concentrations in soil nitrogen patch on the growth of maize root system and rhizosphere environment were studied. The results showed that the nitrogen concentration in the nitrogen patch affected the trend of root growth. Although it had little effect on plant total root biomass, it significantly affected total aboveground biomass of plant. Nitrogen nutrition spots within the appropriate concentration of nitrogen (soil mass ratio of <1: 4000) will induce root growth, improve root nitrate reductase activity, increase nitrate uptake of roots and promote plant growth; excessive nitrogen concentration Can stimulate root activity, but reduce the nitrate concentration of nitrate, nitrate reductase activity, reduce root absorption of nitrogen, inhibit plant growth. The results showed that rhizosphere pH and nitrate nitrogen content were significantly higher in urea nutrition spots and higher fertilizer rates, which may be the main reason for the effect on root growth.