豆科和非固氮植物氮磷利用效率的比较研究

为深入理解物种养分利用策略,服务于农作物的施肥管理,选择固氮植物大豆及非固氮植物苋菜和稗草为研究对象,同时选择另一试验的苜蓿作为豆科植物的补充材料,利用温室施肥试验研究了固氮和非固氮植物氮(N)、磷(P)元素积累量与生长速率的关系以及NUE的差异。结果表明:豆科植物氮素利用效率在整个生育期显著低于非豆科植物;豆科植物苗期磷素利用效率高于其后几个时期。固氮植物中氮磷积累量每增加一倍对应的总生长速率平均增加0.5~0.7倍(大豆N:0.69,P:0.54;苜蓿N:0.52,P:0.53),显著低于非固氮植物总生长速率2~3倍的增加量(苋菜N:2.75,P:2.23;稗草N:2.87,P:2.10)。4种植物氮磷NUE的差异,体现了固氮与非固氮植物在其生活史中不同的养分利用和分配方式,及不同的环境养分适应策略,但差异背后的生理机制仍需进一步的研究。此外,若要提高化肥利用效率,应在豆科植物生长初期少施氮肥,增施磷肥。

The comparison of nitrogen- and phosphorus- use efficiency between legume and non-nitrogen-fixing plant

Research on nutrient use efficiency (NUE) in plants with different nutrient use strategy,can assist the improvement of crop and fertilizer management.Two nitrogen-fixing species (Glycine max Merr.and Medicago sativa Linn.) and two non-nitrogen-fixing species (Echinochloa crusgali Beauv.and Amaranthus mangostanus Linn.) were taken as study materials to investigate nitrogen (N) and phosphorus (P) use efficiency (NNUE and PNUE) based on greenhouse fertilization tests.The results showed that:PNUEs of legume were higher at seedling stage than other stages;NNUEs of the two legumes were significantly lower than non-nitrogen-fixing plants across all stages.For every double increment of plant N and P accumulation,the total growth rate increased by 0.5-0.7 times (G.max,N:0.69,P:0.54;M.sativa,N:0.52,P:0.53) for legumes,which was significantly lower than that in non-nitrogen-fixing species (A.mangostanus,N:2.75,P:2.23;E.crusgali,N:2.87,P:2.10).The variances in NNUE and PNUE existed among these four plants reflect their differences in nutrient use strategies of these two categories of plant functional types (nitrogen-fixer vs.non-nitrogen-fixer) during their life cycles,although the underlying physiological mechanism is remain unclear.In conclusion,application of low N:P fertilizer ratio to legumes at early stages can make the most of cultivars nodulation and nitrogen fixation,and leading to higher fertilizer use efficiency.