Carbon and Sulfur Concentrations are Negatively Correlated in Seeds of Canola

Abstract

ABSTRACT Seeds collected from canola grown under a wide range of soil nitrogen (N) and sulfur (S) fertility conditions were analyzed for their carbon (C) and S concentrations to investigate the relation between the two, and their interactive reactions to seed yield. The treatments involved applications of three S fertilizers [elemental S (SF); gypsum (CS), calcium sulfate (CaSO4); and ammonium sulfate (AS), (NH4)2SO4], representing differing S availability, in a S-deficient soil at three rates, and a control treatment (CT) receiving N only. In another soil high in available S, urea [(NH2)2CO] applications were made at two sites with four rates at each site. All rates were replicated four times. Despite divergences in yield and seed C and S concentrations, a significant negative linear correlation between seed C and S concentrations was found in each of the experiments (P < 0.05∼0.001), where S and N relationships varied. Seed C : S ratios were curve-linearly correlated to the yield and the relationships were described by second order polynomial equations. This C : S ratio explained 52 to 74% of variability in yield. Optimum yields were obtained with C : S ratio around 70∼100. Seed C : S ratios outside of this range were often associated with reduced yields.