Effect of ascorbic acid on vegetative and reproductive growth of kinnow mandarin

Kinnow (C. nobilis x C. deliciosa) is the most important cultivar of mandarin. This "easy peeler" citrus has assumed special economic importance and export demand due to its high juice content, special flavor, delicious taste and nutritional values. The most important element present in citrus is vitamin C or ascorbic acid. Exogenous application of ascorbic acid plays an important role to increase vitamin C and to produce good quality fruit. The present study was planned to find the effect of exogenous application of ascorbic acid on the vegetative and reproductive growth of Kinnow mandarin. Different concentrations of ascorbic acid (0, 60, 90 and 120 ppm) were applied before flowering (February), after fruit setting (April) and during fruit development stages (August). The observations were recorded on vegetative parameters (tree height, tree spread, trunk girth, number of leaves per flush), reproductive parameters (number of fruits set per tree, June fruit drop), and fruit quality (fruit size and weight, peel weight and thickness, pulp/peel ratio, rag weight, juice percentage and pH, TSS, TA, TSS:TA, ascorbic acid, sugars, total antioxidants, total phenolic contents and leaf mineral contents). Lab experiments were conducted in pomology lab. Institute of Horticultural Sciences, University of Agriculture, Faisalabad during 2013-2014. Randomized Complete Block Design (RCBD) used with four treatments and three replications including control and analyzed by standard statistical techniques using MSTAT-C software and the means were analyzed by using Tuckey's HSD test (p less than or equal to 0.05). Ascorbic acid significantly affected all the physical parameters: fruit size, fruit weight, juice percentage and rag weight, peel weight, peel thickness decreased significantly. Significant results were also obtained for biochemical parameters including TSS, TA, TSS: TA, vitamin C, total sugars, pH of juice. Foliar application of ascorbic acid also significantly affected phytochemical parameters of Kinnow mandarin including its total antioxidant and total phenolic contents. In addition it also affected significantly plant vegetative parameters i.e. plant height, tree spread, although non-significant result was obtained regarding stem girth increase. Reproductive parameters including number of fruit set, fruit drop percentage, total number of fruits per plant or yield also significantly increased. Number of flower set was not affected significantly. Application of ascorbic acid at 90 ppm and 120 ppm performed better as compare to 60 ppm and control on all parameters studied of Kinnow mandarin. After the completion of experiment and obtaining all the results it is suggested that ascorbic acid could be apply as foliar spray to get the good yield and improved quality of Kinnow mandarin.