Models of growth and development of wheat in relation to plant nitrogen

Abstract

Wheat plants were grown in culture solutions differing in nitrogen concentration and transferred between the solutions at the time of floral initiation. Rates of growth and development were expressed in relation to the nitrogen concentrations of the whole plants. Growth rate increased and developmental rate decreased with increased plant nitrogen concentration, the extent depending on the developmental stage when the nitrogen was supplied, the duration of supply, and the concentration of nitrogen in the solution. Simple dynamic models fitted to the data accounted for 97% of the variation in observed biomass and 93% of the variation in rate of development. The models are based on a concept of relative nitrogen concentration, an expression of the actual nitrogen concentration of the plant in relation to the maximum and minimum possible nitrogen concentrations at a particular developmental stage. The models suggest possibilities for calculating the growth response to nitrogen fertilizer applied at any time during the development of a crop.