Impact of biopriming on seed quality and longevity in Rice (Oryza sativa L.)

Abstract

The study "Impact of bio-priming on seed quality and longevity in rice" (Oryza sativa L.) was conducted at the Department of Seed Science and Technology, College of Agriculture, Vellanikkara to study the effect of different seed priming treatments on seed quality and seed longevity under natural as well as accelerated ageing. Pseudomonas fluorescens, Trichoderma viride, coconut water was used for seed priming rice variety Jyothy. Seeds of rice variety Jyothy were treated with the following treatments: -, Pseudomonas fluorescens @ 10g/kg (T1), Trichoderma viride @ 4g/kg (T2), Coconut water @ 75% (T3), P. fluorescens + T. viride (T4), P. fluorescens + coconut water (T5), T. viride + coconut water (T6), P. fluorescens + T. viride + coconut water (T7), Hydro priming (T8), Control (untreated) (T9). Both treated and untreated seeds were dried to <10 per cent moisture content and packed in Polyethylene bags (700 guage). The treated seeds were allowed to age both naturally and under accelerated ageing conditions. There were significant differences among the treatments on seed quality parameters. Irrespective of the treatment, germination, seedling growth (dry weight, length of root and shoot), vigour index- I (VI-I), vigour index- II (VI-II), speed of germination, SOD enzyme activity, dehydrogenase enzyme activity decreased significantly over the storage period. A significant increase in seed moisture content, electrical conductivity, Mean Germination Time (MGT), Time taken for 50% germination (T50) and seed microflora, was observed with increase in storage period. Seed treatment with P. fluorescens (10g/kg) + T. viride (4g/kg) + coconut water (75%) retained a germination per cent of (83.69%) and higher vigour indices among the treatments after nine months of storage followed by Pseudomonas fluorescens @ 10g/kg (T1) and P. fluorescens + T. viride (T4) while treatment hydropriming (T8) was found to be inferior in all quality parameters. Coconut water treatments were found to be superior in increasing root and shoot length of the seedlings across the storage period which was reflected in the vigour indices. Bio priming with P. fluorescens resulted in early emergence of seedlings. Seed microflora was found to increase significantly towards the end of storage period. This increase was least in P fluorescens @ 10g/kg (T1), Aspergillus spp., Pencillium spp. were observed in the primed seeds. In present study it was found that among bio primed treatments P fluorescens treated seeds performed better than T. viride treated seeds in all quality parameters. Accelerated aged seed samples were gathered and tested at daily intervals for 7 days to evaluate seed quality parameters. In general, dry priming performed better than wet primed seeds. Vigour indices was found to be highest in bio primed seeds (T2, T4 , T7) than othertreatments Seed longevity is found to be higher in bio primed seeds which can be evaluated from speed of germination (T1, T4, T7), electrical conductivity (T2, T4 ), dehydrogenase and SOD enzyme activities. Seed infection (%) increased towards the end of ageing period and recorded least in P. fluorescens treatments (T1, T7, T5) Seed treatments P. fluorescens (10g/kg) + T. viride (4g/kg) + coconut water (75%) was the best treatment followed by P fluorescens @ 10g/kg of seeds in improving seed quality as well as seed longevity. Treatments P fluorescens @ 10g/kg (T1), T. viride @ 4g/kg (T2), P. fluorescens + T. viride (T4), P. fluorescens + T. viride + coconut water (T7) of seed may be used as seed treatments to enhance seed longevity in rice.