Plant and Soil 247:199-209, 2002
Kluwer Academic Publishers, Netherlands
- Total dry matter production and fruit dry weight were only slightly affected by increasing nutrient concentration if nitrate was supplied as the sole nutrient source. Compared to nitrate, ammonium nitrogen caused a decrease in total dry weight, but led to an increase in both total dry weight and fruit fry weight at low concentration if supplied in addition to nitrate nitrogen.
- Dry matter partitioning in plants was affected by the strength of the nutrient solution, but even more by ammonium nitrogen
- Nitrate nitrogen supported an increase in dry matter accumulation in the reproductive organs.
- Nutrient Solutions containing moderate to high concentrations of nutrients are frequently supplied to improve the taste of fruits of hydroponically grown tomato plants. However, this practice may lead to stress eventually resulting in hampered growth and reduced yield.
- In order to optimize yield and fruit quality, it appears to be necessary to adapt concentration and composition of nutrients according to the overall stress imposed on plants.
- Salinity may reduce water use efficiency (Khan et al., 1994 as cited by Claussen, 2002)
- Total dry matter production of fruit dry weight were reduced considerably by ammonium nutrition even at low nitrogen concentration (5mM NH4+-N, standard nutrient solution) if not supplied in combination with nitrate nitrogen. At high ammonium concentration, total dry weight and fruit dry weight were 14% and 6% of the obtained from nitrate-treated plants which were only slightly affected by an increasing concentration of nutrients. Mixtures of both nitrogen forms did not cause any decrease in total dry weight and fruit yield increased more than 20% if ammonium did not exceed 50% of the total nitrogen supplied.
- The efficiency of water use by tomato plants was not much affected by the concentration of nutrients in the nutrient solution as long as nitrate was the only nitrogen source supplied.
- A close relation between WUE and total dry matter production could be observed with all treatments investigated. This is because Carbon gain per unit water lost is always higher for the treatment that gives the highest dry weight gain over the growth period.