Investigation effects of seed vigor on grain yield, sedling and some seed characteristics in spring wheat (Triticum aestivum L.)

In order to determine the effects of seed vigor on grain yield، yield component and some seed quality characteristic in spring wheat، an experiment was conducted in 2006-2007 cropping season، at Research Farm of East Azarbyjan Agricultural Jihad organization، Iran، Tabriz. Seeds of spring wheat (C. V. Kawier) were divided into four sub–samples three of which were artificially aged 40oC for 20، 25 and 30 days (V2، V3 and V4 respectively). Consequently four seed lots with different vigor levels (V1، V2، V3 and V4) were provided. Traits germination speed، growth rate، percentage viable seeds، germination rate، percentage normal seedlings، seed vigor Index، length plmule، length ridicule، seedling length and seedling dry weight for each seed lot were determined in laboratory. Subsequently، all four seed lots were sown in the field. Using R. C. B. design with four replicates. Rate and percentage emergence، percentage ground cover، number of fertile tillers and plans per unit area، ear length، grains /ear، grains /plant، number of grains per unit area، thousand grain weight، harvest index and grain yield per unit area were recorded for different treatments in the field. The effect of seed on rate and percentage emergence، percentage ground cover، number of fertile tillers and plants per unit area، number of grains and grain yield per unit area was significant. In all these traits، plants form vigorous seed lots (V1 and V2) were superior، compared to those form poor seed lots (V3 and V4). Grain yield per unit area for plants form V3 and V4 seed lots (low – vigor seeds) was 32-48% less than for plants form V1 seed lot (the most vigorous seeds). Because of this considerable effect of seed quality on grain yield of wheat، the necessity of producing high vigor seeds and also separating the effects of genotype from those of seed deterioration in variety traits become more evidence.