Relationships between yield of winter wheat and bacterial and protozoan fatty acids affected by different green manure amendments

Abstract

ABSTRACT Soil microorganisms play important roles in crop growth and nutrient cycling. This study investigated the influence of the temporal changes in soil fatty acids (FAs) mainly derived from microorganisms by the incorporation of different green manures on the subsequent crop yield of winter wheat. Plants (Sesbania rostrata or Sorghum bicolor) as green manure were cultivated as the preceding crop, followed by the cultivation of winter wheat. Soil FA structure was characterized by the analysis of the relative abundance of FA methyl esters (FAMEs). Principal component (PC) analysis of the abundance of FAME signatures indicated that the composition of soil FAs was clearly altered by different soil management regimes. The amount of soil FAMEs increased with the incorporation of green manure, and this increase was maintained during wheat cultivation. A positive correlation was observed between wheat yield and the ratio of FAMEs derived from Gram-positive and Gram-negative bacteria at stages of tiller emergence and heading. FAMEs from Gram-positive bacteria and protozoa also positively correlated with one of the wheat yield components, 1,000 grain weight. These results may suggest that the amount of bacterial and protozoan FAs at tiller and heading stage following green manure incorporation is useful to predict the winter wheat productivity.