Bio- priming for enhancing seed quality, longevity and growth in rice (Oryza sativa L.)

Abstract

The study “Bio-priming for enhancing seed quality, longevity and growth in rice (Oryza sativa L.)”, was carried out at the Department of Seed Science and Technology, College of Agriculture, Vellanikkara, in two varieties, Uma and Manuratna with five treatments - Pseudomonas fluorescens (T₁), coconut water (T₂), P. fluorescens + Trichoderma viride + coconut water (T₃), hydropriming (T₄), and control (T₅). Seeds were dried to <10 per cent moisture and stored in gunny bags and polyethylene bags (700 gauge) for periodical evaluation of seed quality. Manuratna variety in gunny bags exhibited progressive deterioration, than poly bags storage, although the extent varied across treatments.After nine months, treatment T₃ (P. fluorescens + T. viride + coconut water) recorded the highest germination (83.50%), vigour index-II (1383), seedling dry weight (0.163 g), dehydrogenase activity (0.706 OD value), and protease activity by the end of gunny bag storage, and recorded longer shoot and root length, α-Amylase activity (2.29 mg maltose/min) under poly bag storage. T₁ (P. fluorescens) reported the highest values in seedling dry weight (0.167 g), least mean germination time by the end (9 months) of gunny bag storage and highest germination (83.50%), longer shoot and root length, increased dehydrogenase activity (0.778 OD) and protease activity were evident under poly bag storage. Uma stored in gunny bags, showed greater susceptibility to deterioration relative to Manuratna. At the ninth month, T₁ reported highest germination (82.50%), vigour index-II (1315), dehydrogenase activity, and protease activity (2.17 OD value) lowest mean germination time (4.36 days) under gunny bag, Whereas higher germination (82.50%) and dehydrogenase activity (0.747 OD value) reported in poly bag storage. Treatment T₃ (P. fluorescens + T. viride + coconut water) registered highest germination (81.00%), protease activity (2.28 OD value) and dehydrogenase activity at the end (9 months) of gunny bag storage, and in poly bag storage T₃ recorded highest germination (83.50%), vigour index II (1342). These results confirm that Uma deteriorates faster than Manuratna but benefits significantly from microbial priming. Insect infestation reported to increase toward the end (9 months) of storage. In Manuratna T₁ (P. fluorescens) recorded the highest undamaged seed weight (96.57 and 97.80 g), least damaged seeds (1.68 and 1.63 g), infestation per cent (5.57 % and 2.82 %) and adult insects (61.00 and 41.00) at the end of gunny and poly bag storage, respectively. Treatment T₃ (P. fluorescens + T. viride + coconut water) reported least adult insect count (18.00) under poly bag storage. Similar trends were observed in Uma, where T₁ consistently reported highest undamaged seeds (97.82 g), least damaged seeds (1.56 g), infestation per cent (6.55 %) in gunny bag storage, Treatment T₃ (P. fluorescens + T. viride + coconut water) registered highest undamaged seeds (99.10 g), lowest damaged seeds (1.05 g), number of adult insects (39.00) under poly bag storage. Seed infection report of Manuratna, at the end (9 months) of gunny and poly bag storage recorded least infection per cent in treatment T₁ (P. fluorescens) (24.00 % and 23.00 %, respectively) under blotter test method. T₃ (P. fluorescens + T. viride + coconut water) registered least infection (47.00 %) in agar plate test under poly bag storage. In Uma, T₁ (P. fluorescens) treatment recorded least infection in agar plate method (43.00% and 60.00%) at the end of gunny and poly bag storage, respectively. Whereas T₁ recorded lowest seed infection in blotter method (27.00%) under gunny bag storage. T2 (Coconut water priming) recorded least infection (24.00 %) in blotter method under poly bag storage. Growth studies in Manuratna, T₃ reported for accelerated flowering (78.75 days), superior root traits, total root length (3104.00 cm), surface area (524.00 cm²), and root volume (2.04 cm³). Plant height was highest in T₂ – coconut water (66.75 cm). In Uma, T₃ recorded highest field emergence (85%), grains per panicle (48.00) and maximum total root length (2840.75 cm), root surface area (523.00 cm²), and root volume (1.93 cm³). Plant height was greatest in T₁ (69.00 cm) and T₄ – hydropriming reported for earliest flowering (82.00 days). Seed treatment with P. fluorescens (10g/kg) recorded best for enhancing seed quality and storability followed by P. fluorescens (10g/kg) + T. viride (4g/kg) + coconut water (85%) treatment. Among different packaging, polyethylene bags retained higher seed quality and vigour over extended storage period. In pot culture studies of primed seeds T₃ consistently recorded superior for growth performance in both cultivars.