藜麦幼苗对水氮耦合变化的可塑性响应

Plastic Responses of Quinoa Seedling to Change of Water and Nitrogen Coupling

采用盆栽试验方法，研究了不同水氮条件对藜麦幼苗生长指标、根系生长指标及其生理指标的影响。结果表明：藜麦各测试指标与氮肥用量、灌水控制水平关系极为密切。在同一灌溉水平下，藜麦叶面积、生物量、根系总体积等幼苗及根系生长指标均随氮肥用量的增加呈先增加后下降趋势，而根系过氧化物酶（POD）活性、丙二醛（MDA）含量等生理指标均随氮肥用量的增加呈先下降后增加的趋势；施氮量相同时，叶面积、生物量、根系总体积等形态指标均随灌水量的增加而增大，而POD活性、MDA含量等生理指标均随灌水量的增加而减小，且各处理间差异均达到显著水平；水氮交互作用对各指标均有影响，对叶面积、生物量、根系总体积、POD活性的影响均达到显著水平。在试验设置的水氮范围内，藜麦均表现出不同程度的表型可塑性；在中度或重度干旱胁迫下，施肥均能缓解干旱对藜麦的胁迫。综合考虑，土壤含水量为田间持水量的75％～85％、施氮量为1～2g／kg的组合最优。

A pot culture experiment was conducted in greenhouse to investigate the effects of soil water and nitro- gen （N） on the growth, root system and physiological indexes of quinoa seedling. The results were as follows. All the tested indices of quinoa had close relation with soil water and nitrogen. Under the same irrigation level, the seedling and root growth index of quinoa （ leaf area,biomass,total root volume） increased with the increasing nitrogen rate, but they decreased when nitrogen rate exceeded adosage. However, root physiological indices （POD activity, MDA content） showed an increasing trend after the first decline ; At the same amount of nitrogen fertilizer, the morphologi- cal indices（ leaf area, biomass, total root volume） increased and physiological indexes （POD activity and MDA con- tent） decreased with the increasing irrigation supply; Water and nitrogen interaction affected all the indices, espe- cially on the leaf area, biomass, total root volume and POD activity with a significant level. During the experimental setting range for water and nitrogen, quinoa exhibited varying degrees of phenotypic plasticity ; Under moderate or se- vere drought stress, applying a certain amount of nitrogen fertilizer was able to alleviate the effect of drought stress onquinoa. Taken together, the combination that soil water was controlled 75% -85% field capacity and nitrogen rate was kept 1 -2g/kg was the best. The results could provide the theoretical basis for high productivity and rea- sonable irrigation and fertilization in quinoa cultivation in the loess plateau region.