Impact of PGRs, polyamines and potassium to improve pomegranate flowering behaviour, fruit set and fruit quality

Abstract

Ever changing climate is affecting the flowering pattern in pomegranate worldwide. It is the need of the hour to find out some chemicals that can not only enhance hermaphrodite flowers and fruit set but also enhance fruit quality. The present investigation aimed to evaluate the effect of plant growth regulators (three), polyamines (two) and other chemicals (five) on photosynthesis, flowering ratio, fruit set and quality of pomegranate fruits. Pomegranate trees were treated at full leaf expansion stage. Potassium dihydrogen phosphate (5000 ppm), spermidine (1.5 ppm) and naphthalene acetic acid (NAA) (20 ppm) were the best treatments to significantly enhance hermaphrodite flowers, as the hermaphrodite to male flower ratio was 0.39, 0.37, and 0.35, respectively, compared to 0.22 in the control treatment. Except spermidine, NAA and paclobutrazol, all treatments increased the fruit setting significantly, with potassium dihydrogen phosphate (5000 ppm) being the most effective treatment with 66% fruit set compared to 43% in control trees. In mature fruits, compared to control, NAA enhanced total phenols, ascorbic acid and total antioxidants (3%, 15%, 7%, respectively) followed by ascorbic acid treatment (250 ppm); potassium dihydrogen phosphate (5000 ppm) and putrescine (44 ppm) enhanced the anthocyanin content and hence aril color significantly (11% and 10% respectively). Though the use of NAA in pomegranate production is commercial practice, two sprays of ascorbic acid can also be included to enhance the nutritional quality of fruits. Foliar application of potassium dihydrogen phosphate twice at flowering stage could be highly useful for quality pomegranate production due to the enhanced number of hermaphrodite flowers, fruit setting and fruit color. Overall, use of these chemicals can be beneficial to pomegranate farmers to get more remuneration from harvest.