Influence of exogenous applications of plant growth regulators on fruit quality of young 'Kinnow' mandarin (Citrus nobilis × C. deliciosa) trees.

Young 'Kinnow' mandarin (Citrus nobilis Lour × C. deliciosa Tenora) trees often produce inferior quality fruit with less juice and more rind and rag contents. The influence of plant growth regulators (PGRs) on fruit quality of mature citrus trees is well documented. However, little is known about the role of PGRs on the fruit quality of young 'Kinnow' mandarin trees. Therefore in the present investigation PGRs viz benzyladenine (BA) and kinetin (20 mg L) were applied at flowering (FL) stage and, BA, kinetin (10, 20 & 30 mg L) and gibberellic acid (GA3) 10 mg L were applied at fruit setting (FS) stage to 'Kinnow' mandarin trees and their effect on fruit quality was evaluated immediately after harvest (D1) and after seven days of shelf (D7) at ambient conditions (20±2oC; 60-65% RH). The PGRs alone had significant influence on juice mass (%), rag mass (%), ascorbic acid (AA mg 100 mL) and reducing sugars (%) whereas, rind mass (%), TSS, titratable acidity (TA), TSS:TA and total sugars (%) were not affected by PGRs applications. Irrespective of shelf duration the fruit harvested from young trees treated with 10 mg L GA3, 30 mg L BA and kinetin at FS showed significantly higher juice contents (50.53%, 49.8% & 51.64%) and lower rag contents (26.5, 26.6 & 25.83%), respectively in comparison with control. Maximum reducing sugars (1.62%) was observed with 20 mg L kinetin at flowering and maximum AA contents (58.45 mg 100 mL) of juice were observed with control. Interaction of PGRs and shelf duration had significant effect on reducing sugars (%), non reducing sugars (%) and AA (mg 100 mL) contents. All fruit quality parameters except non reducing sugars (%) were significantly affected by shelf duration. Our results validated that fruit quality parameters except AA contents of young 'Kinnow' mandarin trees could be improved by the exogenous application of kinetin. © 2012 Friends Science Publishers