Seed Vigor and Field Performance of Winter Oilseed Rape (Brassica napus L) Cultivars

The effect of seed vigor on field performance of two oilseed rape cultivars ( Licord and Okapi) was investigated in 2008 at the Research Farm of the University Tabriz Iran The experiment was arranged as factorial based on RCB design with three replications A sub sample of seeds of each cultivar was kept as control The other two sub-samples of each cultivar with about 15% moisture content were artificially deteriorated at 40 C for 9 and 12 days ( Licord) and 7 and 10 days ( Okapi) Consequently three seed lots for each cultivar with different levels of vigor were provided The results showed that the mean emergence time increased with decreasing seed vigor However the highest percentage of seedling emergence was obtained for the high quality seed lot and decreased with decreasing seed lot vigor Decreasing seed vigor led to significant reduction in ground cover of both cultivars mainly due to poor stand establishment Ground cover of Licord was higher than that of Okapi Plants from high vigor seed lots of both cultivars had higher leaf chlorophyll content Index at early stages of growth compared with those from low quality seed lots Grains per plant 1000 grain weight and grain yield per plant for plants from deterrorated seed lots were higher than those from high vigor seed lot However these advantages in individual plant performance were not sufficient to compensate for low stand establishment Consequently gram yield per unit area significantly improved with increasing seed vigor of oilseed rape cultivars even within the range of acceptable germination