干旱区生态环境知识资源中心

Soil water (W), nitrogen (N), and phosphorus (P) availability were manipulated for 2 years in a factorial experiment in a semi-arid grassland in the southeastern Keerqin Sandy Lands, China, to determine what soil resource(s) limits plant growth. We quantified the responses of leaf chemical and anatomical traits for the dominant annual herb Chenopodium acuminatum in this ecosystem to test hypotheses about leaf form and function in relation to soil resource limitation. Nitrogen was the principal limiting factor, and N treatments (alone and in combination with W and P) elicited consistent increases in leaf size and decreases in leaf thickness and water content. Differentiation in the leaf mesophyll between palisade and spongy parenchyma was lacking in N deficient plants and stimulated in all +N treatments. The greater tissue density and cell packing may promote more efficient light capture with improved N nutrition. Mixed additions of W, N, and P were generally more advantageous to leaf expansion and nutrient balance than their isolated additions, therefore water and nutrients synchronous management would be a better approach to promote plant growth at the semi-arid region.