Effects of sulfur supply on sulfur content and conformation within peanut leaves

Greenhouse experiment was conducted to study content and conformation of sulfate(S),glutathione,and insol- uble S fraction within different aged peanut leaves.The content of glutathione decreased with the leaf aging increase, whereas an opposite trend was observed for SO_4~(2-)content.The concentration of insoluble S was similar for all leaves. With the sufficient S supply,SO_4~(2-),glutathione,and insoluble fraction accounted for 4.4%,4.6% and 91% of total S in the young leave,respectively.In the middle and old leaves,60% to 80% of total S accumulated as SO_4~(-2),and glu- tathione accounted for less than 1%.The concentrations of all S-containing compounds,particularly SO_4~(-2),decreased in the young and middle leaves without S supply.Glutathione was not a major S source for peanut during S deficiency.Low N supply aggravated the symptoms S deficiency.The different aged leaves had no-unique responses to S deficiency. Young leaves are more sensitive to S deficient than middle and old leaves.