Relationships between shoot to root ratio, growth and leaf soluble proteinconcentration 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 w eight (DW), shoot and plant N concentration and leaf soluble protein concen tration were examined for pea (Pisum sativum L.), common bean (Phaseolus vu lgaris L.) and wheat (Triticum aestivum L.) under different nutrient defici encies. A regression model incorporating leaf soluble protein concentration and plant DW could explain greater than 80% of the variation in S : R with in 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 concentr ations of N, P, K, Mg, Ca and S in liquid culture. Addition of shoot or pla nt 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 ma cronutrient effects on S : R are primarily mediated through their effects o n protein synthesis and growth.