Seedling growth of irrigated rice as a function of seed treatment with gibberellic acid

Abstract

This study aimed to evaluate the early growth stages of irrigated rice (Oryza sativa L.) seedlings from cultivars SCS-112, BRS-7 Taim, BR IRGA 410 and IRGA 417, under three different temperatures, i.e. 15, 20 and 25 °C, as a result of seed imbibition in a gibberellic acid (GA₃) solution at concentrations of  zero, 150, 300, 450, 600 and 750 mg L^-1. The lengths of the shoot and the primary root of seedlings were recorded at three, seven and 21 days from sowings on germination paper. Interactions between the main factors were observed for all the response variables. Rice cultivars have differential sensitivity to variation in the concentration of gibberellic acid on seed treatment according to the temperature and the time of evaluation. Cultivar BRS-7 Taim shows a better response three days after sowing to imbibition of seeds in GA₃ solution on shoot and primary root lengths, at temperatures of 15, 20 and 25 °C. The response to GA₃ in shoot growth of rice seedlings increases as the temperature is raised, which also increase the concentrations of greater growth increment due to the regulator. Root growth is little affected by the GA₃ at seven and 21 days after sowing.