Influence of Pre-harvest Calcium and Potassium Sprays Combined with Coloured Polythene Bagging on Postharvest Quality and Shelf Life of Rainy Season Guava (Psidium guajava L.) cv. Lucknow-49

<title>Abstract</title> <p>Rainy-season guava (Psidium guajava L.) fruits are characterized by poor quality, rapid softening, high physiological weight loss, and short shelf life under ambient conditions. The present investigation was conducted during 2015–16 and 2016–17 at the Postharvest Technology Laboratory, Acharya Narendra Deva University of Agriculture and Technology, Ayodhya, India, to evaluate the effect of preharvest calcium and potassium nutrition combined with fruit bagging on the postharvest quality and storage behaviour of guava cv. Lucknow-49. The experiment was laid out in a Randomized Block Design with sixteen treatments and three replications. Treatments comprised foliar application of calcium chloride (2%), potassium sulphate (2%), their combinations, and perforated coloured polythene bags applied 30 days before harvest. Fruits were harvested at physiological maturity and stored under ambient conditions. Physicochemical and sensory parameters, including total soluble solids (TSS), titratable acidity, ascorbic acid, total sugars, fruit firmness, physiological loss in weight (PLW), and organoleptic quality, were recorded during storage. The combined application of calcium chloride (2%) and potassium sulphate (2%) with blue polythene bagging (T₁₆) proved most effective. This treatment recorded the highest TSS (15.40 and 13.78%), ascorbic acid (197.11 and 195.28 mg 100 g⁻¹ pulp), and total sugars (17.44 and 16.91%) during the respective years. It also maintained higher fruit firmness, reduced PLW, improved sensory quality, and extended shelf life by 8–10 days compared with untreated fruits. The combined application of CaCl₂ (2%) + K₂SO₄ (2%) with blue polythene bagging significantly improved TSS, ascorbic acid, total sugars, fruit firmness and shelf life while reducing physiological loss in weight under ambient storage conditions.</p>