Journal of Advances in Biology & Biotechnology

Rice is a key staple crop supporting global food security, particularly in Asia. In coastal rice-growing regions, increasing climate variability, including heavy rainfall and flooding at maturity, has led to greater incidences of lodging and pre-harvest sprouting, resulting in yield and quality losses. Plant growth regulators such as chlormequat chloride and maleic hydrazide are used to modify plant architecture, regulate growth, and improve physiological efficiency. The current study aimed to evaluate the effects of growth regulators, specifically maleic hydrazide and chlormequat chloride, on the growth and physiological characteristics of rice (Oryza sativa L.). The field experiment was conducted on rice at the wetland farm of S.V. Agricultural College, Tirupati, Andhra Pradesh. The experiment was laid out in a randomized block design with three replications and seven treatments. The treatments comprised T₁ -Control; T₂ - Maleic hydrazide @ 5000 ppm; T₃ - Maleic hydrazide @ 10,000 ppm; T₄ - Maleic hydrazide @ 15,000 ppm; T₅ - Chlormequat chloride @ 250 ppm; T₆ - Chlormequat chloride @ 500 ppm and T₇ - Chlormequat chloride @ 750 ppm during rabi, 2020 -21. Among the treatments, chlormequat chloride @ 500 ppm (T₆) recorded superior growth performance with higher number of leaves plant-1 (62.00), maximum culm diameter (6.09 mm) and root length (26.15 cm) along with reduced specific leaf area (208.99 cm2 g-1), higher specific leaf weight (59.04 g m-2) and chlorophyll content (2.24 mg g-1). These findings show that chlormequat chloride mainly improved structural growth and biomass production, while maleic hydrazide enhanced leaf physiological traits. Overall, the study highlights that the proper use of growth regulators can improve growth efficiency and performance in rice.