How to include mineral nutrition in crop growth models? The example of phosphorus on maize

Abstract

Crop growth models have made considerable progress in recent years and their predictive value is now quite acceptable under non-limiting conditions. However, under nutrient limited conditions, their predictive value is still poor. So far, a so-called “stress factor” is often used to account for the lower biomass production, but the exact steps of the biomass production process which are affected by nutrient deficiency are not well identified.

This communication synthesises recent results about maize growth under phosphorus deficiency and examines their implications for modelling. Although P is known to be involved in the photosynthetic process, it was shown that a reduction of the net photosynthesis per unit leaf area was not likely to be the simple cause of the growth reduction of field-grown maize under moderate P deficiency. By contrast, P deficiency had a drastic negative effect on leaf growth. The reduced total plant biomass production under P deficiency was shown to be the consequence of this reduced leaf area and its subsequent effect on light interception. Several evidences suggested that P effects on root growth and biomass partitioning between shoots and roots were also likely to be an indirect consequence of the P effect on leaf growth.

An overall interpretation was proposed which involves the source-sink relationships for carbohydrates within the plant. Implications of these findings for modelling were discussed.