Relationships between shoot to root ratio, growth and leaf soluble protein concentration of Pisum sativum, Phaseolus vulgaris and Triticum aestivum under different nutrient deficiencies

Relations between shoot to root dry weight ratio (S : R), total plant dry weight (DW), shoot and plant N concentration and leaf soluble protein concentration were examined for pea (Pisum sativum L.), common bean (Phaseolus vulgaris L.) and wheat (Triticum aestivum L.) under different nutrient deficiencies. A regression model incorporating leaf soluble protein concentration and plant DW could explain greater than 80% of the variation in S : R within and between treatments for pea supplied different concentrations of NO3– or NH4+ in solid substrate; pea and bean supplied different concentrations of N, P, K and Mg in liquid culture; and wheat supplied different concentrations of N, P, K, Mg, Ca and S in liquid culture. Addition of shoot or plant N concentration to the model explained little more of the variation in S : R. It is concluded that results are consistent with the proposal that macronutrient effects on S : R are primarily mediated through their effects on protein synthesis and growth.