The development of cuttings of the Washington navel orange to the stage of fruit set. II. Drifts in nutrient composition

Abstract

Changes in nutrient content with time, especially of nitrogen and phosphorus content, are presented and are considered in relation to the results for dry weight reported previously. It was found that drifts in nitrogen and phosphorus with time were complementary to the pattern for dry weight noted earlier. The distribution of these nutrients to the developing plant followed a like rhythmic pattern of alternate distribution to shoot and root. There appeared to be no build up of nutrient to trigger off developing of new shoots, and at all times nutrient distribution was preferentially to younger developing parts. Low phosphorus supply caused a lowering of both relative and absolute contents of phosphorus and nitrogen in all plant parts. The pattern of development was not greatly altered in character by low phosphorus but was delayed. All vegetative parts responded similarly in control and low phosphorus plants, and the younger parts did not appear to dominate the older in development. In this regard, the pattern of growth seemed to differ from that of many annuals. The proportion of tissue potassium was lowered and that of calcium raised by ammonium as the source of nitrogen. A concomitant effect on phosphorus and nitrogen metabolism was noted.