Use of hydroponic culture to assess the mineral nutrition of zucchini squash

This is a case study of the Systematic Variations method proposed by Homes and Van Schoor (1993) for optimizing mineral nutrition of hydroponically grown zucchini squash (Cucurbita pepo L). Treatments were eight formulations with different ratios of NO3-, SO42-, PO43-, Cl-, K+, Ca2+, Mg-2+,Mg- and Na+ x two total nutrient levels (0.5 and 1 eq plant(-1)). An unfertilized treatment was also tested. Each nutrient ratio treatment was defined by a high proportion of one nutrient and a low proportion of the others in front of the same anion:cation ratio and total concentration. Treatment yields were used to calibrate the response function relating yields to nutrient proportions and total nutrient levels in the medium and then to estimate the optimal proportions and the best concentration for high zucchini production.