トマトの生育ならびに開花•結実に関する研究 (第3報)

The present studies were carried out to ascertain the influence of nitrogen, phosphorus and potassium nutrition on the growth and the flower formation of “Fukujyu No. 2”tomato seedlings. The experiments were conducted by means of sand culture with the following culture solution as the standards.<br>Salts Concentration<br>NH₄NO₃ 228.6mg/l N: 120ppm<br>Ca(NO₃)₂•4H₂O 337.3mg/l P: 60ppm<br>Ca(H₂PO₄)₂ 226.3mg/l K: 60ppm<br>K₂SO₄ 207.3mg/l<br>MgSO₄•7H₂O 245.9mg/l<br>FeCl₃•6H₂O trace<br>MnCl₂•4H₂O trace<br>H₃BO₃ trace<br>ZnSO₄•7H₂O trace<br>1. Effect of nitrogen level on the vegetative and reproductive responses.<br>Tomato seedlings were grown under the three levels of nitrogen (5, 20 and 120ppm) for 50_??_60 days from cotyledon expansion.<br>The higher the concentration of nitrogen in the solution, the more vigorous the plants growth and the earlier the flower buds differentiation, resulting in the decrease in the number of leaves to the first inflorescence, and in the increased number of flower and the acceleration of their development.<br>2. Effect of nitrogen level asscociated with light intensity on the vegetative and reproductive responses. <br>Light and nutrients were controlled in all the combinations of three different nitrogen levels (20, 80 and 160ppm) with two light intensities (100 and 50 per cent of natural day light).<br>The higher the level of nitrogen, the more vigorous the plant growth, the earlier and the more in number of flower bud differentiation and development under the higher light intensity. Under the lower light intensity, on the other hand, the higher level of nitrogen (160ppm) restricted the plant growth and retarded the flower bud differentiation, resulting in the less number of flowers.<br>3. Effect of the level of phosphorus on the vegetative and reproductive responses.<br>Seedlings were grown under the different phosphorus supply (0.1, 0.5, 2, 10, 60 and -180ppm).<br>The higher the phosphorus level, the more vigorous the growth, and earlier and much more flower buds differentiated with the decrease in the number of leaves to the first inflorescence, and their development was accelerated.<br>4. Effect of potassium level on the vegetative and reproductive responses.<br>Seedlings were grown under the various levels of potassium (0.5, 10, 60 and 180ppm).<br>The higher the level of potassium toward 60ppm, the plant grew up more vigorously and earlier much more flower buds differentiate. The potassium level higher than 60ppm restricted, on the other hand, the plant growth and retarded the flower bud differentiation, resulting in the less number of flowers.<br>5. The optimum concentrations of each elements on the growth and the flower formation of tomato plants were 120_??_160ppm for N, 60_??_180ppm for P and 60 ppm for K.<br>6. Relations between the flower formation and chemical constituents in tomato seedlings.<br>The chemical constituents in the top of seedlings at 50 or 70 days stage grown at the various levels of nitrogen, phosphorus and potassium varied significantly and they showed high correlation with the total number of flowers up to the third inflorescence. The seedlings grown under the higher levels of nitrogen and phosphorus showed high levels of carbohydrates, especially total sugars, and nitrogen compounds, especially protein, and formed many flowers. Carbohydrates, especially sugars, and nitrogen, especially protein, seem essential for the balanced growth and reproductivity of tomato plant.