A simple test to detect sulphur deficiency in wheat

Abstract

Wheat grain from sulfur-adequate plants remains straw yellow in colour when soaked in glutaraldehyde, but grain from sulfur-deficient plants turns brown or purplish brown. This observation is the basis of a proposed test to identify low-sulfur grain samples, and thus to identify sites requiring sulfur fertilizer. The colour formed during treatment with 4% glutaraldehyde in pH 6.8 phosphate buffer is ranked zero (no colour change), 1, 2 or 3 (maximum colour intensity). A glutaraldehyde score is then awarded on the basis of the percentage of grains in each of these four colour classes. Scores range from 0 to 300 with sulfur-deficient samples having scores > 100. The glutaraldehyde score was highly correlated with N/S ratio in the grain (v = 0.88***) and negatively correlated with percentage sulfur in the grain (r = -0.60** *). In a program to identify wheat-grain samples which are deficient in sulfur for breadmaking quality or yield, the glutaraldehyde test could be used in preliminary sorting to identify those samples requiring further testing.