Abstract

In rice, the maturity duration is an important stage that determines grain yield. This study examines the relationship between phytohormones and rice development, providing a foundation for plant growth regulators (PGRs) application to shorten maturity time and improve rice yield. High-performance liquid chromatography with diode-array detection analysis revealed that indole-3-acetic acid (IAA) and gibberellic acid (GA3) levels decline from tillering to panicle initiation, gibberellin A4 appears during tillering, and zeatin emerges during stem elongation and panicle initiation. PGRs treatment was done at the phases of tillering, panicle initiation (pre-booting), or booting stages. The experiment followed a Randomized Block Design. Compared to the control, the flowering was reduced by 2.19 days, and the 1000-grain weight increased by 1.37 g when 50 mg/L IAA was applied at the tillering stage. Treatment with 50 mg/L GA3 at the booting stage improved grain filling and rice production by reducing flowering time by 5.88 days and maturing time by 9.06 days. In addition, it significantly increased panicle length, flag leaf size, and 1,000-grain weight. Treatments with GA3 at panicle initiation have shown significant effects, promoting earlier flowering and maturity during pre-booting. These results suggest the applicability of PGRs in the future of agriculture.

Key words: flowering time, grain weight, Oryza sativa, phytohormone, plant growth regulator, reproductive stages.