Pre-harvest Foliar Application of Oxalic Acid Improves Strawberry Plant Growth and Fruit Quality

Abstract

Delicate fruit of strawberry is susceptible to high temperature stress and fungal infection. An extensive spray program is usually adapted to secure yield and fruit quality which sometimes pose a serious threat to consumer health. However, development of eco-friendly, economical and safer strategies has always been in focus of R&D sector. In this study, field-grown strawberry plants cv. Chandler were sprayed with 1, 2 or 3 mM oxalic acid at flowering stage. Interestingly, foliar application of oxalic acid in low doses (1 mM and 2 mM) had more growth-promoting effect on strawberries whereas foliar application of 3 mM oxalic acid either negatively affected or remained ineffective. Low-dose applications of oxalic acid resulted in enhanced nitrogen (1.5-fold), phosphorus (2.5-fold) and potassium (1.75-fold) levels in leaf petioles. Increase in primary macronutrients was also correlated well with enhancement in plant growth indicators including dry biomass (1.5-fold), leaf area (1.7-fold), specific leaf area (2.8-fold) and leaf area ratio (2.6-fold), root weight ratio (1.9-fold), root-to-shoot ratio (1.4-fold). Only, leaf chlorophyll and fresh fruit weight were negatively impacted by oxalic acid. In addition to increase in number of fruits per plant, oxalic acid also improved sensory properties of strawberry fruits mainly due to increase in sugar: acid ratio (1.6-fold), ascorbic acid contents (1.2-fold) and non-reducing sugars (2-fold). Overall, foliar application of 1 mM oxalic acid favoured vegetative growth and enhanced yield and fruit quality of strawberry cv. Chandler.