CONCENTRATION OF K+, Ca2+ AND NH4+ ON YIELD, FRUIT QUALITY AND VEGETATIVE SPROUTING OF FOUR CULTIVARS OF STRAWBERRY

Abstract

Background. The yield and the quality of the fruits in strawberry, it’s depending of the genotype, the environmental conditions and the nutritional state of the crop. The composition of the nutrient solution is decisive in the vegetative development, yield and quality of fruits in strawberry. Objective. To evaluate the effect of nutrient solutions with different concentrations of K+, Ca+2 and presence or not of NH4+ in the vegetative growth, production and quality of fruit from four strawberry cultivars: Festival, Monterey, Zamorana and CP-LE-07. Methodology. A hydroponic system was used in plastic containers with red basaltic volcanic rock. Steneir’s nutrient solution (1961) was supplied by changing the concentrations (in meq L-1) of potassium 1.75 and 5.25, calcium 2.25, 4.5 and 6.75, and ammonium 1.5. In the vegetative-flowering stage, the number of leaves, stolons and small plants was quantified in the flowering fruiting stage, the production of fruit per plant was determined. Fruit quality was evaluated by fresh weight, diameter and length of fruits, firmeness, color, total soluble solids, titrable acidity, pH ant the º Brix /Titrable acidity ratio. Results. In the variables of vegetative sprouting, there were highly significant differences in the two study factors: nutrient solution and cultivars. There was an interactive effect between both study factors. Production per plant showed no differences in the nutrient solution factor. In the post-harvest quality of the fruit there were highly significant differences for º Brix, firmness and the relationship º Brix/Titrable acidity in the nutrient solution factor. Implications. The composition of the nutrient solution should be adjusted according to cultivar to promote vegetative and generative growth and fruit quality. Conclusions. The addition of NH4+ only increased the vegetative growth in the Monterey cultivar and the different concentrations of K+ and Ca+2 in the nutrient solution had not effect on the vegetative-flowering stage. The concentration of 5.25 meq L-1 of K+ in the nutrient solution increased the weight, length and firmness of the fruit. The increase from 2.25 to 6.75 meq L-1 of Ca+2 negatively affected the post-harvest quality of the fruit. In most of the variables studied, strawberry cultivars had an interactive response with nutrient solutions.