1975 Volume 44 Issue 3 Pages 308-312
The present study was carried out with sand culture to investigate the influence of nitrogen, phosphorus, potassium, calcium and magnesium levels in culture solution on the nitrate-nitrogen content in tomato fruits, by using Fireball variety.
When tomato plant was grown on culture solution containing either low levels of NO3-N or potassium or high level of calcium, NO3-N content in the fruit was markedly low as compared to the control. In cases of the former two, NO3-N content was always low during the immature through full-ripe stages. On the other hand, the content in the fruit grown on a high level of calcium was as high as that of the control at the immature stage, but decreased during the ripening period. The content of NO3-N in the leaf was also reduced by these conditions.
When tomato plant was grown on either low levels of NO3-N or potassium, or high level of calcium, it was found that the amount of NO3-N absorbed by a plant was low. The contents of total-nitrogen, potassium and organic acids were low and the contents of calcium and reducing sugar were high in the ripe fruit.
When the tomato plant free from NO3-N was supplied with potassium or calcium nitrates as nitrogen sources in culture solution, NO3-N content in the fruit supplied with the potassium salt became much higher after 1 and 5 days of supply than in the fruit supplied with the calcium salt. NO3-N contents in the leaf and calyx supplied with potassium nitrate were also higher than with calcium nitrate, but the differences of indexes of the contents in these between potassium and calcium nitrates were not too remarkable as in the fruit between potassium and calcium nitrates.
