Zinc stress in mustard as altered by sulfur deficiency

To see the effect of sulfur (S) deficiency oil zinc (Zn) stress, mustard (Brassica campestris L.) cv. 'T59' was grown in refined sand at two levels of S, deficient (0.02 mM) and normal (2 mM) each at three levels of Zn, low (0.01 mu M), adequate (1 mu M), and excess (100 mu M). In Mustard, the effects of low Zn-such as decrease in biomass, pod, and seed yield;, concentration of chlorophyll a and b and S in leaves and in seeds; decreased activity of carbonic anhydrase; and stimulation in ribonuclease activity-were accentuated further by S deficiency, suggesting a synergistic role for both nutrients. Sulfur deficiency, oil the other hand, further accentuated the effects of excess Zn, such as reduction in biomass, pod and seed yield; accumulation of Zn in leaves; reduced concentration of S ill leaves and seeds; activity of carbonic anhydrase-, and an increase in the stimulated activity of catalase and acidphosphatase in mustard leaves. This finding shows a positive interaction between S and Zn. With low Zn, the stimulated Hill activity-that of catalase and peroxidase-was lowered and the reduced concentration of Zn in leaves and seeds was accelerated further under S deficiency. Apart from this, low Zn affected S deficiency by further lowering the biomass, pod and seed weight; S concentration in leaves and seeds, chlorophyll a, and carbonic anhydrase; and further stimulated that of ribonuclease activity. The above-mentioned findings also reflect a synergy between S and Zn at low levels.