This experiment was conducted as a factorial experiment based on a completely randomized design with three replications at two locations: Agricultural and natural resource center of Ardebil province (Moghan) and seed and plant certification and registration institute of Karaj in 2013. The treatments included: planting date in three levels (10-May, 25-May and 9-Jun), seed moisture content at harvest time in four levels (30%, 25, 20 and 15) and seed size in three levels (flat, round and medium). The measured traits were a standard germination test, mean time of germination, seedling weight and length vigor index, germination percent in radical emergence test and germination percent in cold test. The results illustrated that delayed planting caused reduction of seed quality and this reduction was more obvious in delayed harvest (15%), also the reduction rate in round seeds was more than flattered and medium seeds. The minimum percentage of germination and vigor were seen in round seeds of third planting date and moisture harvest by 15%. So it is recommended for corn seed production to sow the seeds before the last week of May and when seed moisture content reached 30 percent, cob harvesting should be started and the harvest not is delayed.
The need to identifying seeds with low vigor and poor emergence led to introduce of various seed vigor tests. The purpose of this experiment was to assess the ability of controlled deterioration test for evaluation of seed vigor and prediction of oilseed rape seed lots emergence in the field. Samples of 19 seed lots were obtained from nineteen farmers of Razavi and Northern Khorasan Provinces, which have been cultivated during 2009-2010 growth season, set to physiological germination test before and after controlled deterioration (CD). The estimating of seedling emergence percentage of each seed lot in the field calculated 30 days after sowing. The correlation between laboratory results before and after CD of seeds and field emergence showed that correlation of final germination, normal seedlings and mean germination time before CD with emergence in the field respectively with 0.072, 0.24 and 0.042 correlation coefficient, were not significant, but laboratory results after CD had significant correlation with emergence of seed lots in the field. As, final germination, normal seedlings and mean germination time respectively with 0.57, 0.51 and 0.49 correlation coefficient predict emergence percentage of seed lots in the field. The high correlation between laboratory results after controlled deteriorated test with the seedling emergence in the field indicated that the CD test is able to assess the field emergence of oilseed rape seed lots before sowing.
This study was conducted to evaluate the effects of accelerated aging and natural storage on seed germination and seedling heterotrophic growth of chickpea in Gorgan University of Agricultural Sciences and Natural Resources in 2014. The experiment was carried out, adopting a completely randomized design with four replications. Treatments were 8 aging levels (i.e., 2 years, and 4 years natural storage; 1, 2, 3, 4, 5 days of accelerated aging and a control). The results showed that the effect of aging treatment on all the traits was significant. Reduction of germination percentage, germination rate, root and shoot length seed vigor index and seedling dry weight of 4 and 5 accelerated aging days was higher than 2 and 4 natural storage years. The electrical conductivity of seed lots increased by an increase in accelerated aging to 4 and 5 days, which was higher than 2 and 4 natural storage years. This is due to incapability of a membrane to keep its permeability, which is the result of the higher sensitivity of seeds to accelerated aging. Reduction of the rate and efficiency of reserves used and also dynamic reserves in natural storage was lower than 4 and 5 accelerated aging days. However, maximum rate and efficiency of reserves used and also dynamic reserves were obtained at 2 accelerated aging days. This could be due to increase in repair reaction rates under these conditions and activation of hydrolytic enzymes in seeds. Finally, the results of the present study revealed that damages to chickpea seed at 4 and 5 accelerated aging days are more than 2 and 4 natural storage years, which leads to the reduction of germination percentage and rate.
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