Study of accelerated aging time effect on seed different size and shapes vigor of hybrid corn (Zea mays), cv. single cross 704

This experiment was conducted in order to evaluate accelerated agingtimeeffect and various size and shapes of hybrid corn, cv. single cross 704 seeds on some germination and seedling vigor traits in 2014 in Seed and Plant Certification and Registration Institute(SPCRI) at Karaj. Experiment was done as a factorial experiment based on  completely randomized design by four replications. In order to seeds size and shape grading, three round sieves by 5.5, 6.25 and7 mm holes diameter size were used for round and flat shapes and medium size separation respectively. Seeds under taken accelerated ageing conditions at 41 centigrade degree temperature and 100 relative humidity at 4 ageing times, 72, 96,120 and 144 hours. Then standard germination test was conducted and normal seedlings percent and mean germination time and seedling weight and length vigor indices were measured. Results indicated that aging time and seed size and shapes effects on determined germination and vigor indices were significant. Aging time for 144 hours caused significant decrease in normal seedlings percent compared to other ageing times and 120 and 144 hours aged seeds had highest mean germination time and then 96 and 72 hours aged seeds arranged respectively. Only 144 hours aging time caused significant seedling length vigor index decrease in comparison to other aging and highest and lowest seedling weight vigor index investigated at 72 and 144 hours aging times respectively. Also, highest normal seedlings percent and mean germination time related to flat shape and medium size seeds and highest and lowest seedling length and weight vigor indices amounts belonged to flat and round shape seeds respectively comparison indicated that normal seedling percentage, seedling length and weight vigor indices in three seed sizes had significant different and the highest and lowest rates were in flat and round respectively.