INFLUENCE OF DIFFERENT ROOTSTOCKS ON PHYSICO-CHEMICAL QUALITY ATTRIBUTES OF KINNOW MANDARIN.

Citrus holds the position of top ranked fruit crop of Pakistan in terms of area and production. 'Kinnow' (Citrus reticulata Blanco) is considered as the trademark of Pakistan's citriculture industry and occupies the share of 95% out of total citrus production in Pakistan. But there is an alarming problem of single rootstock culture. Rough lemon (Citrus jambhiri Lush.) has monopolized the citrus industry in Punjab province. Rough lemon is susceptible to phytophthora and waterlogging. There is an absolute need for substitute rootstock for higher yield and improved fruit quality of Kinnow. A rootstock scion interaction research trial was conducted during 2017 to 2019. Kinnow was grafted on eight rootstocks, i.e. Cox mandarin, Fraser hybrid, Troyer citrange, Cleopatra mandarin, Poncirus trifoliata, Benton, C-35 and Carrizo citrange. Experiment was laid out according to Randomized complete block design (RCBD). Each rootstock was considered as single treatment and replicated thrice. Performance of six year old Kinnow trees grafted on different rootstocks was evaluated on the basis of physicochemical quality attributes of fruits. Data was taken for two consecutive years and average was calculated. Results revealed that rootstocks had a significant role in manipulating the morphological and biochemical quality attributes of Kinnow fruits. Kinnow fruits from the trees grafted on Poncirus trifoliata rootstock showed the maximum fruit diameter (84.03 mm), peel weight (28.99 g), rag weight (87.68 g) and individual fruit weight (221.85 g). Poor performance of Troyer citrange regarding morphological quality parameters was observed. Total soluble solid (TSS) (13.76 °Brix), Vitamin C (69.38 mg/100 ml) and Total antioxidants (72.32 % inhibition) in Kinnow juice were maximum on Fraser hybrid. Carbohydrate analysis of Kinnow juice by HPLC method revealed that concentration of sucrose, fructose and glucose was highest in Fraser hybrid rootstock. Poor performance of Troyer citrange and C-35 rootstocks was recorded regarding all biochemical parameters of Kinnow. It is concluded that physicochemical quality of Kinnow is manipulated by different rootstocks. Poncirus trifoliata and Fraser hybrid rootstocks can be used as alternate rootstocks for citrus industry of Pakistan to substitute the traditional rootstocks like rough lemon and sour orange. [ABSTRACT FROM AUTHOR]