AMMONIUM AND NITRATE APPLICATION ON Physalis peruviana L. PLANTS

Golden berry (Physalis peruviana L.) is an indeterminate habit plant, during its vegetative growth nitrogen is the nutrient most demanded and usually absorbs it as nitrate. A combination of NH4+ y NO3-, where NH4+ is lower than or equal to 50 % of total nitrogen increases plant growth, only under certain circumstances and this beneficial effect varies across cuhivars, but the response to ammonium in golden berry is not known. Therefore, the objective of this study was to evaluate the morphologic response, fruit yield and quality of Physalis peruviana L. plants in two year-old plants, (re-sprout) and in new plants derived from seed, to the joint application of NH4+ and NO3-. Experiments were carried out in a greenhouse with a completely randomized design and treatments of the first experiment were the result of combining the ratio NH4+/NO3- (0:100, 25:75 and 50:50), and sprout vigor (low, medium and high). In a second experiment new plants derived from seeds were used and with the same ratios NH4+/NO3- used in the first experiment. Results were analyzed using ANOVA and treatment means were compared with the Tukey's test (p <= 0.05). In re-sprouting plants, the highest values of final height and stem diameter were obtained in plants with high vigor and with the application of 25 % of NH4+ (p <= 0.05), whereas the highest yield was obtained in plants with high and medium vigor, and with 50 and 25 % of NH4+ (p <= 0.05). Neither NH4+/NO3- ratio in the nutrient solution nor the vigor of the re-sprouts affected the concentration of soluble solids or shelf life of the fruits. In plants from seeds there was also not effect of the NH4+/NO3- ratio on plant height, but with 50 % of NH4+ the diameter of stem increased. The higher yields were obtained in plants treated with the ratio 50/50, and the concentration of soluble solids in fruits did not show a clear effect on the ratio NH4+/NO3-, although at 119 d after transplanting the greatest value in fruits of plants treated only with nitrate (0/100) (p <= 0.05) was reached. Thus, the combined application of ammonium and nitrate increases yield but reduces soluble solids in fruit and shelf life and vigor of re-sprouts is neither determinant nor consistent on yield.