Impact of varying agrometeorological indices on peel color and composition of Kinnow fruit (Citrus nobilis Lour x Citrus deliciosa Tenora) grown at different ecological zones

Kinnow orchards were selected in different ecological zones in districts Sargodha, Toba Tek Singh (TTS) and Vehari of the Punjab province, Pakistan. Three biological replicates in block form were applied by using analysis of variance techniques to assess varying agrometeorological indices impact on fruit color-development and peel composition.Fruit samples were randomly collected on each month's end starting from August up to February. Chromameter was used for measuring coloring parameters and its values a*, b*, C* and L* were increased from August till February with a rapid elevation started at color-break stage, while hue angle (h*) rotated from 120° to 60° of portraying green to yellow shade. An increasing level of chlorophyll contents were noted in August till color-break at the end of October and then diminished afterwards. Whereas, carotenoids increased rapidly upon yellow tinting peel of Kinnow fruits till fully attained deep orange color at the end of February. Ascorbic acid content and total phenolic content (TPC) showed a decreasing trend whereas anthocyanins and antioxidant activity were increased from August to February, with unchanged flavonoids and flavonols level. Fruit firmness was gradually reduced till color-break with rapid reduction noted subsequently. Maturity index represented internal ripening directly increased with color-development.Color development has directly influenced on maturity index and both were increased rapidly after color-break to afterwards. More color development with rapid reduction in chlorophyll, ascorbic acid and TPC level were seen in warm districts namely TTS and Vehari after color-break stage due to accumulating more agrometeorological indices. © 2020 Society of Chemical Industry.