MSc

An experiment on the effect of halogens and packing materials on paddy seeds was undertaken at the Department of Seed Science and Technology, College of Horticulture, Kerala Agricultural University (KAU), Vellanikkara, Thrissur with seeds of rice variety Jyothi pertaining to rabi 2013-14, summer 2013-14 and kharif 2014. The experiment aimed to standardize the optimum dose and mode of application of halogens and elucidate the impact of seed treatment with halogen and the packing material on seed quality and longevity. The experiment was conducted as completely randomized design involving two factors (packing material and halogenation dose) with two replications. Treatments comprised of a combination of a packing material either jute bag (P1) or polyethylene bag of 400G (P2) with seed halogenation (T) at different doses. Observations recorded on germination, seedling shoot and root length, seedling dry weight, seedling vigour index I and II, electrical conductivity of seed leachate, seed moisture content and seed infection were statistically analyzed and results interpreted.
Seed quality and longevity during storage were found to be significantly influenced by packing material, dose of halogen and the interaction effects of packing material and dose of halogen throughout the storage period.
Irrespective of halogenation, seeds of all the three seasons stored in polyethylene bags (400G) were significantly superior to that in jute bags with respect to germination and other seed quality parameters like seedling length, seedling dry weight, seedling vigour index I and II, electrical conductivity of seed leachate, seed moisture content and infection by seed microflora at the end of storage. Seeds of rabi and summer 2013-14 stored in polyethylene bags (400G) retained viability above minimum seed certification standards (MSCS) (80%) for eleven and eight months compared to eight and four months in case of jute bags respectively. Hence, results pointed out that there was definite advantage in storing seeds in polyethylene bags
(400G) over storing them in jute bags both with respect to seed qualities and prolonging seed longevity.
Seeds halogenated with calcium oxychloride (CaOCl2) in combination with carrier calcium carbonate (CaCO3) @ 3g each/kg of seed (T5) recorded significantly high germination, seedling shoot length, seedling dry weight and seedling vigour index I and II. It also recorded the least electrical conductivity, moisture content and seed infection at the end of storage irrespective of the packing material and season of seed production. In addition, T5 prolonged seed viability above MSCS for a period of twelve and nine months compared to nine and six months in untreated seeds (T1) in rabi and summer 2013-14 respectively. Results thus proved the superiority of halogenation at T5 (CaOCl2+CaCO3@ 3g each/kg seed) in retaining seed qualities and prolonging seed longevity during storage. T3 (CaOCl2 @ 6 g/kg seed) that exhibited lower seed deterioration next to T5 retained viability above 80 per cent for nine and seven months in rabi and summer 2013-14 respectively, is adjudged the next best halogenation dose.
The interactive effect of packing material and seed halogenation indicated that, seed treated with CaOCl2 through carrier CaCO3 @ 3g each /kg of seed (T5) and stored in polyethylene bags of 400G (P2) i.e., treatment combination P2T5, exhibited significantly higher seed qualities at the end of storage in all three seasons. P2T5 had also retained viability above MSCS for longer period both in rabi and summer 2013-14 (fourteen and ten months respectively) compared to untreated seeds packed in jute bag (P1T1) (eight months and six months respectively). Among the various combinations, P1T5 (CaOCl2+CaCO3 @ 3g each/kg seed and packing in jute bag) was found consistent in all three seasons with respect to maintain seed quality parameters at the end of storage. Seeds in P1T5 had retained viability above MSCS for eleven and eight months in rabi and summer 2013-14 respectively, indicating its advantage over untreated seeds packed in jute bag (P1T1).
Hence, halogenation with calcium oxychloride through carrier calcium carbonate (T5) and packing in jute bags is also a viable option for prolonging seed longevity.
Considering the above, it can be concluded that, to maintain higher seed quality and prolonging viability during storage, it is best advisable to store rice seeds in moisture vapour proof polyethylene bags (400G) at ten per cent moisture after treating with halogen calcium oxychloride along with carrier calcium carbonate @ 3g each/ kg of seed i.e., P2T5 followed by P1T5 (CaOCl2+CaCO3 @ 3g each/kg seed and packing in jute bag).