NITROGEN ACCUMULATION AND GROWTH OF FRUITING TOMATO PLANTS IN HYDROPONICS

The principles of managing both water and nutrients for horticultural crops has proven its efficacy since yields achieved under glasshouses are highest among those produced in other agrosystems.
The "ecological-price" of such practice, however, is rather high to pay since large amounts of fertilisers are leached from this agrosystem to the groundwater.
These leachates eventually contribute to nitrate pollution which is nowadays a matter of serious concern.
This increasingly important constrain imposes to better adjust nitrogen supply to plant demand for yield production, but up to date we have no sound model relating nitrogen uptake to dry matter accumulation in an horticultural crop.
Thus, knowledge into this area of research is lacking.

An experimental work was undertaken along these lines.
Tomato plants were grown at 3.8 or 4.8 mS cm^-1 in NFT systems, under low and high water vapour deficit regimes.
The aim was to compare plant growth and nutrient uptake under different regimes of transpiration.
The culture was monitored for 3 months starting on 7 month old plants in their 15^th week of production.
Growth and nitrogen uptake by the crops was not modified by the treatments.
Nitrogen accumulated in the aerial biomass in proportion to the dry matter.
The %N in the foliage was relatively constant and richer than that of vascular organs and fruits.
A model is proposed to link %N to dry matter accumulation in the crops.

International Symposium on Water Quality & Quantity-Greenhouse

C. Bellert, J. Le Bot, M. Dorais, J. Lopez, A. Gosselin

Lycopersicon esculentum Mill., model, salinity, water vapour pressure deficit

https://doi.org/10.17660/ActaHortic.1998.458.37