STUDIES ON TECHNIQUES FOR ENHANCING THE SEED QUALITY IN ONION (Allium cepa L.)
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Date
2008
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Abstract
A study was carried out for analysing the efficacy of priming, fungicidal seed treatment
and polymer coating on the storability of onion seeds under different storage
environments and packaging materials for a period of one year. The seeds of onion
cultivar Agrifound Dark Red were used as the experimental material and the seeds were
obtained from three locations viz. Indore, Rajkot and Lasargaon. The initial seed quality
parameters were investigated and depending upon the germination percentage and
incidence of mycoflora, the seed lot from Rajkot was selected for further studies.
Further, the seeds were subjected to specific gravity separation and divided into five
different grades. The specific gravity separation improved the seed quality parameters
significantly over the original seed lot. The grades having germination percentage above
Indian Minimum Seed Certification Standards (70 %) were mixed and used for further
experiments. Also, the seeds were primed with different chemicals and the best treatment
was selected. Priming treatments were found to enhance the speed of germination and
other seed quality parameters to a significant extent. Subsequently, polymer coating was
done using the polymer polykote procured from M/s Chemtura, wherein the seeds were
subjected to seed treatments with and without polymer coating of carboxin, thiram, neem
oil and bio-agents viz. Trichoderma harzianum and Kalisena and stored for a period of
one year under ambient conditions as well as low temperature-low humidity (LTLH)
conditions in two different packaging materials viz. cloth bags and aluminum foil
packets. The primed seeds were also kept under storage with and without polymer
coating and proper controls were maintained in each case. The seed germination and
vigour indices were estimated at an interval of three months and it was observed that
there was a gradual decline in both the parameters due to seed deterioration over the
storage period. However, the extent of deterioration was lesser in case of polymer coated
seeds owing to its specific property of regulating the moisture content. The polymer
coated seeds were also associated with lower moisture content and lesser incidence of
seed borne fungi as compared to the uncoated ones. The efficacy of seed treatments was
evaluated through seedling emergence at the end of the storage period and it was found
that the fungicidal seed treatments proved to be superior in the maintenance of the seed
quality. The bioagents, especially Trichoderma harzianum, were also found effective.
The HPLC analysis of the seed material revealed extensive dust off in case of uncoated
treatments which was significantly reduced by the polymer coating. Hence, the polymer
coating was found as a suitable carrier of seed treatment materials and also facilitated
lower seed deterioration during the storage. The primed seeds were found to exhibit
better longevity under the LTLH conditions as compared to the ambient conditions,
irrespective of the storage containers.
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t-8057