Midstorage seed treatment in rice (Oryza sativa L.)

Abstract

The present investigation entitled "Midstorage seed treatment in rice (Oryza sativa L.)" was carried out at the Department of Seed Science and Technology, College of Agriculture, Vellanikkara, Kerala during 2023-2025. The study aimed to assess the effect of mid-storage seed treatments on seed quality parameters, biochemical parameters, seed health, and seed infestation of rice varieties Jyothi, Uma, and Manuratna stored under ambient conditions. This study consisted of experiments on three rice varieties subjected to seven mid-storage treatments. Five-month-old seeds of varieties Jyothi, Uma, and Manuratna were treated with: T₁ - Control, T₂ - Hydration-dehydration treatment, T₃ - Neem oil @ 2 ml kg⁻¹ seed, T₄ - Neem cake @ 5 g kg⁻¹ seed, T₅ - Hydration-dehydration + Neem oil @ 2 ml kg⁻¹ seed, T₆ - Hydration-dehydration + Neem cake @ 5 g kg⁻¹ seed, and T₇ - Neem oil + Neem cake. The treatments were evaluated using a Completely Randomized Design (CRD) with three replications. Seeds were stored under ambient conditions, and observations were recorded on seed quality parameters, seedling parameters, biochemical parameters, seed health, and seed infestation at monthly intervals up to seven months after storage (MAS). The results revealed that the performance of treated seeds including viability and vigour were significantly better compared to the control across all three varieties. A significant effect was observed in seeds treated with hydration-dehydration + neem oil (T₅), hydration-dehydration (T₂), and neem oil + neem cake (T₇) across all varieties. In variety Jyothi at the end of storage (7 MAS), T₅ - Hydration-dehydration + Neem oil treatment recorded better germination per cent (81%), seed vigour index I (1414), seed vigour index II (1546), less electrical conductivity (0.708 dSm⁻¹), less moisture content (11.47%), dehydrogenase activity (0.646 OD value), α-amylase activity (2.12 mg maltose min⁻¹), seedling dry weight (0.173 g), and field emergence per cent (73%). T₂ - Hydration-dehydration treatment recorded better performance in shoot length (7.99 cm), root length (9.32 cm), and protease activity (1.85 OD value). In variety Uma at the end of storage (7 MAS), T₅ - Hydration-dehydration + Neem oil recorded better germination per cent (82%), seed vigour index I (1873), seed

vigour index II (1767), shoot length (9.79 cm), root length (13.11 cm), seedling dry weight (0.204 g), less electrical conductivity (0.729 dSm⁻¹), dehydrogenase activity (0.549 OD value), α-amylase activity (2.10 mg maltose min⁻¹), protease activity (1.49 OD value), and field emergence per cent (72.00%). T₂ - Hydration-dehydration treatment showed comparable performance in most parameters. In variety Manuratna at the end of storage (7 MAS), T₅ - Hydration-dehydration + Neem oil recorded better germination per cent (82%), seed vigour index I (1848), seed vigour index II (1787), shoot length (9.58 cm), root length (12.96 cm), seedling dry weight (0.204 g), less electrical conductivity (0.628 dSm⁻¹), dehydrogenase activity (0.511 OD value), α-amylase activity (1.78 mg maltose min⁻¹), protease activity (1.61 OD value), speed of germination (26.18), and field emergence per cent (85.00%). T₂ - Hydration-dehydration showed similar effectiveness in maintaining seed quality parameters. Seed health assessment at the end of storage revealed that T₇ - Neem oil + Neem cake recorded the lowest seed microflora infection per cent in blotter paper method without sterilization (Jyothi - 56.77%, Uma - 56.77%, Manuratna - 47.87%) and in agar plate method without sterilization (Jyothi - 56.77%, Uma - 55.26%, Manuratna - 47.87%). Seed infestation studies showed that T₇ - Neem oil + Neem cake recorded the lowest number of adult insects (Jyothi - 10.25, Uma - 6.50, Manuratna - 6.50 per 100 g seed), lowest number of infested seeds (Jyothi - 125.00, Uma - 120.00, Manuratna - 118.00 per 100 g seed), and lowest percentage of infestation (Jyothi - 9.90%, Uma - 10.06%, Manuratna - 10.86%) across all three varieties at the end of storage. T₄ - Neem cake also showed effective control of seed infestation. Among all the treatments, T₅ (Hydration-dehydration + Neem oil @ 2 ml kg⁻¹ seed) and T₂ (Hydration-dehydration) demonstrated superior performance in maintaining seed quality parameters, while T₇ (Neem oil + Neem cake) and T₄ (Neem cake) were most effective in controlling seed health and infestation. The combination treatment of hydration-dehydration with neem oil (T₅) emerged as the most effective mid-storage seed invigoration technique for enhancing seed viability and longevity in rice under ambient storage conditions, extending seed storability and maintaining higher germination, vigour, and biochemical activity throughout the storage period.