BACKGROUND: Infestation of seeds by pests during storage leads to deterioration in quality. Seed coating is an effective option
to overcome themenace. Unlike synthetic fungicidal seed coats, little is known of those based on botanicals. This study aims at
developing azadirachtin-A-based pesticidal seed coats tomaintain seed quality during storage.
RESULTS: Polymer- and clay-based coats containing azadirachtin-A were prepared and evaluated for quality maintenance of
methyl cellulose, polyethylene glycol, polyvinyl chloride, polyvinyl acetate, polyvinyl pyrrolidone and Agrimer VA 6 polymers
and the clay bentonite were used as carriers. The time for 50% release (t1/2) of azadirachtin-A into water from the seeds coated
with the different coats ranged from 8.02 to 21.36 h. The half-life (T1/2) of azadirachtin-A in the coats on seed ranged from 4.37
to 11.22 months, as compared with 3.45months in azadirachtin-A WP, showing an increase by a factor of nearly 1.3–3.3 over
the latter. The coats apparently acted as a barrier to moisture to reduce azadirachtin-A degradation and prevented proliferation
of storage fungi. Polyethyl methacrylate, polyvinyl acetate and polyvinyl pyrrolidone were significantly superior to the other
polymers. Azadirachtin-A showed a significant positive correlationwith seed germination and vigour, and negative correlation
with moisture content.
CONCLUSION:Effectivepolymericcarriers forseedcoatsbasedonazadirachtin-Aare reported. Thesecheckedseeddeterioration
during storage by acting as a barrier to moisture and reduced the degradation of azadirachtin-A.
c 2008 Society of Chemical Industry