Effects of Phosphorus Application Rate on the Growth of Fruit Vegetable Seedlings

Abstract

The effects of applied phosphorus on the growth of vegetable seedlings were studied to obtain the optimum rate of application of this element in nursery soils.
1. The best performance of cucumber and tomato seedlings was obtained with 3, 000 mg of P₂O₅•liter^-1 of nursery soil (P₂O₅•liter^-1) and 2, 000 mg P₂O₅•liter^-1 for eggplant. The response of the tomato seedling to phosphorus depended on the amount of phosphorus fixed by the nursery soils. And the optimum rate of the phosphorus application for tomato was 1, 000 mg P₂O₅•liter^-1 in Kidokoro and Mikatahara soils, 3, 000 mg P₂O₅•liter^-1 in Tochigi soil, and 500 mg P₂O₅•liter^-1 in Yabitsu soil.
2. A high correlation was obtained between P₂O₅ concentration in water-saturated soil solution and that of water soluble P₂O₅ (w-P₂O₅), but not with Truog-P₂O₅ in the soil : water extracts (1 : 40 and 1 : 200, v/v, respectively).
3. w-P₂O₅ and Truog-P₂O₅ content of the nursery soil did not change appreciably during the growing period.
It is concluded that the availability of applied phosphorus to maximize plant growth in nursery soils can be ascertained by the w-P₂O₅ concentration in the 1 : 40 soil : water extract. We found the optimum value to be 36 mg/100 ml of nursery soil for tomato, cucumber and eggplant.