Sulphur Deficiency Symptoms
Sulphur deficiency symptoms vary between crops. In canola, deficiency symptoms may begin as early as the one-leaf stage (Figure 2a), with the newest leaves turning yellowish green with dark vein coloration. Leaves may take on a “cupped” appearance and later, a reddening from the leaf margins (Figures 2b and 2c).
Flowers are usually smaller and paler yellow, and they produce small, underdeveloped purplish-coloured pods (Figure 2d). Under mild S deficiency, there may be good vegetative growth, but flowers and pods will be underdeveloped.
For cereals and forage grasses, the yellowing of newly emerging leaves is a strong indicator of S deficiency (Figure 3). Depending on the degree of deficiency, the leaves may be a shade of light green to entirely yellow.
Yellowing of the new growth occurs because S is immobile in the plant; therefore, newly emerging leaves cannot “scavenge” S from older leaves. This situation is in contrast to nitrogen deficiency symptoms in which the older leaves turn yellow first because nitrogen is translocated or “scavenged” from older leaves to support new growth.