Articles
THE NICOLET LETTUCE MODEL: A THEME WITH VARIATIONS
Article number
654_7
Pages
71 – 78
Language
English
Abstract
The NICOLET model has been developed to predict the growth and nitrate content of greenhouse lettuce.
Four single-organ versions have been developed: [1] abundant supply of nitrogen (1998), [2] mild N-stress (1999), [3] severe N-stress (2003), and [4] ontogenetic changes of organic-N and water content (in preparation). The abundant-N model [1] and the mild-stress model [2] have two compartments: structure and vacuole, while the severe-stress model [3] requires a third compartment: excess-carbon, and the ontogenetic model [4] has separate metabolic and support structural sub-compartments.
The main special features of the NICOLET model are [1] the osmotica balance of the vacuole, where nitrate and hydrocarbons play a complementary role in maintaining a constant osmotic potential, [2] the excess-carbon compartment, where dry carbon compounds are stored, and [3] the sub-division of the structure into sub-compartments of different compositions.
Loosely speaking, the first feature controls the nitrate concentration, the second controls the organic-N and water contents, and the third controls the ontogenetic changes.
The NICOLET model has been able to mimic normal seasonal variations of nitrate content, as well as the effects of drastic N-stress treatments.
These results are illustrated by comparing measured data with model-simulations.
Accurate prediction of nitrate concentration is difficult, due to its sensitivity to changes in the environment.
Exact control of nitrate under commercial conditions may require transient corrective measures, such as N-interruption, in conjunction with a good plant-nitrate monitoring system.
Four single-organ versions have been developed: [1] abundant supply of nitrogen (1998), [2] mild N-stress (1999), [3] severe N-stress (2003), and [4] ontogenetic changes of organic-N and water content (in preparation). The abundant-N model [1] and the mild-stress model [2] have two compartments: structure and vacuole, while the severe-stress model [3] requires a third compartment: excess-carbon, and the ontogenetic model [4] has separate metabolic and support structural sub-compartments.
The main special features of the NICOLET model are [1] the osmotica balance of the vacuole, where nitrate and hydrocarbons play a complementary role in maintaining a constant osmotic potential, [2] the excess-carbon compartment, where dry carbon compounds are stored, and [3] the sub-division of the structure into sub-compartments of different compositions.
Loosely speaking, the first feature controls the nitrate concentration, the second controls the organic-N and water contents, and the third controls the ontogenetic changes.
The NICOLET model has been able to mimic normal seasonal variations of nitrate content, as well as the effects of drastic N-stress treatments.
These results are illustrated by comparing measured data with model-simulations.
Accurate prediction of nitrate concentration is difficult, due to its sensitivity to changes in the environment.
Exact control of nitrate under commercial conditions may require transient corrective measures, such as N-interruption, in conjunction with a good plant-nitrate monitoring system.
Publication
Authors
I. Seginer, R. Linker, F. Buwalda, G. van Straten, P. Bleyaert
Keywords
lettuce, Lactuca sativa, growth, nitrate content, nitrogen stress, ontogenetic change
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