Effect of Weather on Physiological Aspect and Quality of Kinnow Mandarin under Sub-Tropics Foothill Himalayas

Abstract

Weather conditions, particularly temperature, exert a profound influence on the physiological performance and fruit quality of Kinnow mandarin. Variations in maximum and minimum temperatures significantly affect key physiological processes such as chlorophyll retention, leaf water balance, and metabolic activity, which in turn determine the accumulation of sugars, acids, and antioxidants in the fruit. However, the stage-specific impacts of these climatic factors across different phenological phases remain insufficiently understood. A two-year field experiment (2014–2015) was conducted on eight-year-old, drip-irrigated Kinnow mandarin trees under subtropical Himalayan foothill conditions. Meteorological parameters including maximum temperature (Tmax), and minimum temperature temperature (Tmin), relative humidity (RH), rainfall, and evaporation were correlated with physiological traits such as chlorophyll content, relative leaf water content, and leaf water concentration, as well as fruit quality parameters including total, reducing, and non-reducing sugars, acidity, ascorbic acid, total phenols, and flavonoids. Results revealed that Tmax, Tmin, and evaporation during the First fruit set to maximum fruit set stage (K3), and evaporation during the flowering to first fruit set (K2), positively influenced leaf water content in Kinnow mandarin. Furthermore, fruit quality parameters such as total sugars, reducing sugars, non-reducing sugars, and ascorbic acid were positively affected by Tmax and Tmin at the First fruit set to maximum fruit set stage (K3), and by Tmax and RH at the maximum fruit set to fruit harvest stage (K4) stage. In contrast, acidity, total phenols, and total flavonoids were positively influenced by rainfall and Tmin at the First fruit set to maximum fruit set stage (K3), and by rainfall at the maximum fruit set to fruit harvest stage (K4) stage. These findings indicate that specific climatic factors at particular developmental stages play a decisive role in regulating physiological performance and fruit quality, emphasizing the importance of stage-specific, weather-based orchard management to produce high-quality Kinnow mandarin fruits.