Harvesting date and storage period have conslderaole influence on sunflower
seed quality as measured by seed germination, germination rate, plumule and radicale
length, seedlings dry weight, dehydrogenase activity, tooo-seec fresh weight and
electrical conductivity and field emergence. Two field experiments were conducted at
Tag EI·Eiz Experiment Station, Agriculture Research Center during 2002 and 2003
summer seasons. The aim of this study was to investigate the effect of six harvestIng
dates i.e. 14,21,28,35,42 and 49 days after flowering (OAF) and six storage periods
e.g. 0. 3, 6,9, 12 and 15 months after harvest on sunflower (HeJianthus annuus L. c.v.
Mia\{) seed viability, seedlings vigour and field emergence. The results indicated that:
harvesting early (from 14 to 28 DAF), at the first storage period led to a reduction in
seed germination, germination rate, plumule and radicale length, seedlings dry weight,
dehydrogenase activity, 1000-seed fresh weight, field emergence and an increase in
electrical conductivity. Harvesting from 28 to 42 OAF and stor~Qe sunflower seed crop
for 6 and 9 months resulted in maximum seed viabilhY and seedling vigour,
dehydrogenase activity and 1000·seed fresh weight. field emergence and minimum
electrical conductivity. On the other hand, harvesting lately (after 42 days) caused the
decrease in seed viability and seedling vigour. Also results revealed that, sunflower
seed viability and seedlings vigour decreased directly after harvest and increased
gradually with the increase in storage period up to 9 months after that seed viability
and seedlings vigour were decreased. Meanwhile, electrical conductivity was
increased. Results clear that significantly positive correlation between harvesting
dates; storage periods and field emergence with the most studied traits except
electrical conductivity of seeds while it was Significantly and negatively correlated. In
conclusion, sunflower seeds (c.v. Miak) can be harvested after 28 to 42 days after
flowering and stored for 9 months with having seed viability above the standard (70%)
and high seedling vigour.