An experiment was carried out with young guava trees during the period from 1970 to 1972 with differential supplies of phosphorus as foliar spray to determine the nutrient content, seasonal variation of nutrients and to find out the most productive range.
Increasing the phosphorus supply tended to gradually increase the leaf P content. There was no effect on N and K contents of the leaves. Seasonal changes in the concentrations of N, P, K and dry matter have been studied over an annual growth cycle. The peak concentrations of each constituent in the tissues were found before the growth commenced and after the growth ceased, while minimal concentration was found at the end of the season, i. e., after full maturation of fruit. There were two periods in a year, viz., January-February and July-August when N, P and K concentrations in the leaves were stable. There was a significant increase in yield with application of superphosphate. More yield was recorded under the 4 per cent spray treatment in both the seasons and years. Significant positive correlation coefficients were found between yield and leaf P content. Quadratic regression equations were fitted to the relation between yield and rate of phosphorus application. The most productive range for P values was 0.45 to 0.65 per cent on the dry weight basis.