EFFECTS OF SOILLESS MEDIUM ON THE GROWTH AND FRUIT YIELD OF TOMATOES SUPPLIED WITH UREA AND/OR NITRATE

Tomato plants were grown in the inorganic (rockwool and sand) and organic media (peatmoss and baggasse) supplied with the nutrient solution containing urea, nitrate and their mixture, and the growth and fruit yields were compared with those grown in NFT. Effects of the medium on the urea-N transformation were also investigated.
When urea was the sole N source, the organic media inhibited the vegetative growth of plants, compared with the inorganic media.
However, the growth inhibition was improved by the combined application of nitrate with urea.
Stem length of plants grown in NFT with urea nutrition showed a intermediate between those grown in organic and inorganic media, and it increased with the supplement of nitrate.
When nitrate was the sole N source, the apparent effects of media on the vegetative growth were not recognized.
Compared with the inorganic media, the organic media inhibited the fruit yield, and the inhibition was the most serious when urea was the sole N source.
The fruit yield of tomatoes grown in NFT increased with the increase of nitrate ratio to urea in the nutrient solution.
With urea or urea+nitrate nutrition, the concentrations of leaf NH₄⁺-N and NO₃^–-N were high in the plants grown in the organic and inorganic media, respectively.
A high concentration of leaf urea-N was detected in the plants grown in NFT. With each N nutrition, the concentration of leaf total-N was lower in the plants grown in the organic media than in the inorganic media.
Transformation of urea to NH₄⁺-N was more active in the organic media than in the inorganic media, but nitrification in the inorganic media was faster than in the organic media.

International Symposium on Growing Media and Hydroponics

H. Ikeda, X. Wen Tan, Y. Ao, M. Oda

growing medium, tomatoes, Lycopersicon esculentum, nitrogen form

https://doi.org/10.17660/ActaHortic.2001.548.16