Increasing level of abiotic and biotic stress on Kinnow fruit quality at different ecological zones in climate change scenario

The quality of Kinnow fruit was assessed in different ecological zones by selecting three main districts: Sargodha, Toba Tek Singh (TTS) and Vehari; all of them have varying environmental conditions. Abiotic and biotic stress on fruit quality was assessed. More growing degree days, photothermal index, photo and helio thermal units were computed in Vehari, while hydrothermal units and energy use efficiency were recorded in higher values at TTS. Fruit diameter was measured from April to December and recorded with increased width in TTS and Vehari during May and June. In May, more fruit drop was noted in TTS and Vehari compared to Sargodha due to heat stress. Pests such as citrus thrips, mites and fruit fly infected fruits were recorded in higher percentage at Vehari and TTS, while citrus red scale infestation was seen more in Sargodha. In Sargodha, a higher incidence of citrus scab and melanose was noted on Kinnow fruits, while more stem-end rot infected fruits were recorded at TTS and Vehari. In abiotic stress, more wind scares were noted at Sargodha, followed by TTS, whereas stem injury and styler-end deformity were found to be non-significant. Fruit physical parameters such as width, fresh weight and peel thickness were noted more in TTS and Vehari, while more surface smoothness and firmness were observed in Sargodha. Biochemical properties such as pH, total soluble solids, titratable acidity, sugars, ascorbic acid, total dissolved salts and electrical conductivity showed higher levels in Sargodha than TTS and Vehari. More antioxidant and total anthocyanins were found in Sargodha, while higher levels of total phenolic contents were estimated at TTS and total flavonoids in Vehari. Kinnow fruit of Sargodha received more sensory scores in organoleptic evaluation. Higher percentage of A-grade fruits was harvested from Sargodha and B-grade fruits from TTS and Vehari. More numbers of fruits and weight were obtained from TTS, followed by Sargodha. Extreme events such as heat stress and smog were seen more in Vehari and TTS and subsequently their fruit quality was found to be inferior.