Thermo-Tolerance in Tomato: Acetyl Salicylic Acid Affects Growth and Yeld Tomato (Solanum Lycopersicum L.) Under the Agro-Climatic Condition of Islamabad, Pakistan

Abstract

Exogenously applied various levels of acetyl salicylic acid (ASA) including ASA0 (Control), ASA1 (0.30mM), ASA2 (0.60mM), ASA3 (0.90mM), ASA4 (1.20mM), ASA5 (1.50mM) were investigated for induction of thermo-tolerance in tomato seedlings, transplanted in different growth conditions i.e. open field (average 32?C) and plastic tunnel (average 45?C/4h daily) in Islamabad, during summer 2016. The experiment was laid out in randomized complete block design (RCBD) with split plot arrangement having twelve treatments, and three replications. Examining different growth conditions, maximum number of days to flowering (18.05), plant height (65.97 cm), stem diameter (1.69 cm), number of leaves plant-1 (35.37), number of flowers plant-1 (88.61), number of fruits plant-1 (39.05), total yield (28.48 tons ha-1), chlorophyll content (58.78 µg.g-1), and leaf relative water content (74.25%) was recorded in the open field. While investigating acetyl salicylic acid levels, ASA4 (1.20 mM) treatment showed significant results and minimized the heat stress with maximum number of leaves recorded (36.28), flowers (105.53), total yield (30.97 tons ha-1), chlorophyll content (62.24 µg.g-1), and leaf relative water content (74%) as compared to heat stress (control). Predominantly, ASA4 (1.20 mM) produced better results with respect to growth and yield in both growth conditions by enhancing heat tolerance in tomato seedlings