Growth of the Strawberry Plant in Relation to Nitrogen and Phosphorus Nutrition

Strawberry plants were grown in conditions producing moderate or severe deficiencies of phosphorus and nitrogen, and the effect on leaf growth assessed in terms of weight and area increases, and the number and size of their constituent cells. Deficiency of both phosphorus and nitrogen reduced the rate of leaf production. Decreased leaf areas were due almost entirely to lower cell numbers and, to a lesser extent in severe deficiency, to smaller cells. The rate of cell production was markedly reduced by phosphorus and nitrogen deficiency, but continued until maximum leaf area was attained, increases in mean cell size having ceased earlier. There was no nutritional effect on cell number or cell size before leaf emergence and it is suggested that the rapid divergence of response thereafter may be related to photosynthetic development after emergence.

The effect of phosphorus and nitrogen deficiency on potential fruit yield was confined to the inhibition of branch crown proliferation and the lack of available sites for flower initiation. There was no effect of nutrient level on the number of flowers initiated on each apical meristem. Results suggest that any manipulation of nutrient status aimed at increasing fruit yields should be predominantly concerned with increasing branch crown formation, thus providing additional sites for flower initiation.