Studies on the growth and fruiting in the tomato. II.

Abstract

1. Effect of photoperiod on the vegetative and reproductive responses.Tomato seedlings were grown under 4-, 8-, 12-, 16-, 20- and 24-hour photoperiod, respectively, for 60 days from cotyledon expansion.The longer the photoperiod up to 16-hour-day, the more vigorous the plant growth, the earlier the date of flower bud differentiation, and the more the number of flowers. The photoperiod longer than 16-hour-day, on the other hand, restricted the plant growth and retarded the flower bud differentiation, resulting in the increase in the number of leaves to the first inflorescence and the less number of flowers.It may be concluded that the most favorable photoperiod for the plant growth and flower formation is 16-hour day.2. Effect of combination of photoperiod with temperature on the vegetative and reproductive responses.The seedlings were grown in all the combinations of two photoperiods (8- and 16-hour) with four different thermoperiods (day and night combinations of 17°C with 24°C).The long-day induced the more vigorous growth followed with the earlier flower bud differentitation, development and the increased number of flowers than the short-day at any thermoperiods.Day-temperature of 17°C retarded the plant growth, the flower bud differentiation and its development, and on the other hand, increased the number of flowers than 24°C at both night-temperatures.Night-temperature of 17°C hastened and invigorated the flower bud differentiation, resulting in the decrease of the number of leaves to the first inflorescence with the increased number of flowers than 24°C at both day-temperatures.3. Effect of combination of light intensity and night temperature on the vegetative and reproductive responses.Seedlings were grown in all the combinations of four different light intensities (100, 74, 49 and 24 per cent of natural day light) with two night temperature (17°C and 25°C).The higher the light intensity, the more vigorous the growth, being followed with the earlier flower bud differentiation with the decrease in the number of leaves to the first inflorescence, the increased number of flowers and the acceleration of their development in either of the night-temperatures.4. Relationships between the flower formation and chemical constituents in tomato seedlings.The chemical constituents in the top of seedlings at 50 or 60 days-stage grown under all combinations of photoperiods, light intensity and thermoperiod varied significantly correlating with the total number of flowers up to the third inflorescence. The seedlings grown under the longer photoperiod, higher light intensity and lower night-temperature showed higher level of carbohydrates, especially total sugars, and nitrogen compounds, especially protein, and differentiates many flowers.5. Seedlings of heavy top weight in comparison with the plant height, with high level of sugars and protein, yield much more fruits, grown under the above related any combinations of light and temperature factors.