Influence of plant growth regulators on growth, yield, and quality of tomato grown under high temperature in the tropics in the summer

Abstract

ABSTRACT Yield of tomato (Solanum lycopersicum L.) is affected by high day and night temperature and high humidity which can occur together. Plant growth regulators may minimize adverse environmental effects to increase tomato yield. A field experiment was conducted in 2015 and 2016 to evaluate effects of foliar-applied plant growth regulators gibberellic acid (GA3) and 4-chloro phenoxy acetic acid (4-CPA) on growth, yield, and quality of tomato subjected to high day and night temperature (around 30°C) and high humidity, avg. 83%. Concentrations of GA3 were 0, 25, 50, 100 or 125 mg GA3∙L−1, and concentrations of 4-CPA were 0 or 20 mg 4-CPA∙L−1. Gibberellic acid was applied alone during pre-anthesis at 30 days after transplanting; 4-CPA was applied at anthesis and a second dose 7 days later. Application of 50 mg GA3∙L−1and 20 mg 4-CPA∙L−1 produced the heaviest individual fruit (76.2 g) and greatest yield (46.1 t∙ha−1) with higher total soluble solids (4.48 °Brix) and vitamin C (31.6 mg/100 g). Combined application of 50 mg GA3∙L−1 and 20 mg 4-CPA.L−1 was economical and could be applied under high temperature and humidity to increase quantity and quality of tomato fruit.