University of Guilan Iranian Journal of Seed Sciences and Research 2476-3780 12 4 2026 03 20 Effect of different concentrations of the growth regulator Pix (mepiquat chloride) on germination percentage and biochemical indices of sesame seeds (Sesamum indicum L.) cultivar Darab 1 under different storage conditions Effect of different concentrations of the growth regulator Pix (mepiquat chloride) on germination percentage and biochemical indices of sesame seeds (Sesamum indicum L.) cultivar Darab 1 under different storage conditions 76 90 9716 10.22124/jms.2026.9716 FA Ramin Zeylabpoor Department of Agronomy and plant Breeding, Yasouj University, Yasouj, Iran Ali Moradi Department of Agronomy and Plant Breeding, Faculty of Agriculture and Natural Resources, Yasouj University, Yasouj, Iran Hojat-Allah Latifmanesh Dept. of Agronomy and Plant Breeding, Yasouj University, Yasouj, Iran Hamidreza Balouchi Dept. of Agronomy and Plant Breeding, Yasouj University, Yasouj, Iran AliReza Yadavi Department of Agronomy and plant Breeding, Yasouj University, Yasouj, Iran Journal Article 2026 04 20 Introduction: Seed deterioration is an irreversible process and one of the major challenges in agriculture, leading to reduced seed quality and vigor. Temperature, seed moisture content, and storage duration are among the most important factors affecting the rate of seed deterioration.<br />Materials and Methods: This study was conducted to investigate the effects of different concentrations of the plant growth retardant Pix (mepiquat chloride) on germination and biochemical characteristics of sesame (<em>Sesamum indicum</em> L.) seeds (cv. Darab 1) under different storage conditions. The experiment was arranged as a four-factor factorial in a completely randomized design with three replications. Treatments included two storage temperatures (15 and 25 °C), two seed moisture contents (9 and 15%), three Pix concentrations (0, 3000, and 4500 mg L^-1), and three storage periods (60, 120, and 180 days).<br />Research Findings: Results showed that increasing storage duration, seed moisture content, and temperature significantly reduced soluble protein content and peroxidase activity, whereas soluble sugars, malondialdehyde, proline content, and electrical conductivity increased. Application of Pix, particularly at 3000 mg L^-1, mitigated these detrimental changes. The highest germination percentage (85.33%) was observed in seeds treated with 3000 mg L^-1 Pix, stored at 15 °C with 9% seed moisture. Under critical storage conditions (25 °C and 15% seed moisture), germination of control seeds and those treated with 4500 mg L^-1 Pix declined to zero after 60 days, whereas seeds treated with 3000 mg L^-1 Pix maintained a germination of 23%.<br />Conclusions: These findings suggest that Pix may exert a protective role under storage stress by alleviating oxidative damage and reducing the severity of seed deterioration, thereby preserving part of the seed germination potential. Introduction: Seed deterioration is an irreversible process and one of the major challenges in agriculture, leading to reduced seed quality and vigor. Temperature, seed moisture content, and storage duration are among the most important factors affecting the rate of seed deterioration.<br />Materials and Methods: This study was conducted to investigate the effects of different concentrations of the plant growth retardant Pix (mepiquat chloride) on germination and biochemical characteristics of sesame (<em>Sesamum indicum</em> L.) seeds (cv. Darab 1) under different storage conditions. The experiment was arranged as a four-factor factorial in a completely randomized design with three replications. Treatments included two storage temperatures (15 and 25 °C), two seed moisture contents (9 and 15%), three Pix concentrations (0, 3000, and 4500 mg L^-1), and three storage periods (60, 120, and 180 days).<br />Research Findings: Results showed that increasing storage duration, seed moisture content, and temperature significantly reduced soluble protein content and peroxidase activity, whereas soluble sugars, malondialdehyde, proline content, and electrical conductivity increased. Application of Pix, particularly at 3000 mg L^-1, mitigated these detrimental changes. The highest germination percentage (85.33%) was observed in seeds treated with 3000 mg L^-1 Pix, stored at 15 °C with 9% seed moisture. Under critical storage conditions (25 °C and 15% seed moisture), germination of control seeds and those treated with 4500 mg L^-1 Pix declined to zero after 60 days, whereas seeds treated with 3000 mg L^-1 Pix maintained a germination of 23%.<br />Conclusions: These findings suggest that Pix may exert a protective role under storage stress by alleviating oxidative damage and reducing the severity of seed deterioration, thereby preserving part of the seed germination potential.