پژوهشهای زراعی ایران (Mar 2020)
Evaluation the Effects of Priming and Seed size on Biomass yield, Water Use Efficiency and some Ecophysiological Characteristics of Onion (Allium cepa L.)
Abstract
Introduction Seed priming is widely used for enhancing seedling performance by improving the rate and uniformity of germination and decreasing seed sensitivity to external factors. Several types of seed priming are commonly used: Hydro-priming, halo-priming, osmo-priming, thermo-priming, solid matrix-priming and bio-priming. Seed size is another factor that can affect seed germination and seedling establishment. Seed size is an important physical indicator of seed quality that affects vegetative growth and is frequently related to yield, market grade factors and harvest efficiency. The effect of seed size on germination and following seedling emergence has been investigated by many researchers in various crop species/ cultivar. In the present study, impacts of different pre-sowing treatments and seed size on biomass yield, water use efficiency and some ecophysiological characteristics of onion ecotypes in an ecological agroecosystem were investigated. Materials and Methods In order to investigate the effects of different pre-sowing treatments and seed size on biomass yield, water use efficiency and some ecophysiological characteristics of onion ecotypes, a field experiment was conducted in 2012-2013 cropping season at Agricultural and Natural Resources Research Center of East Azarbayjan, Iran. This experiment was a factorial experiment based on a randomized complete block design with three replications. Experiment treatments included priming at four levels: hydropriming, osmopriming (in %2 KNO3), priming with flamin amino acid (in 2%) and control (without priming). Seed samples of the two cultivars were sieved by slotted screens and placed into three groups of seed diameter size, including small, medium, and large and ecotype at two levels, including Red Azarshahr and Zarghan. Following characteristics such as biomass yield, bulb water use efficiency, biomass water use efficiency, water consumption, relative water content, stomatal conductance in bulbing and bulb filling stage, productivity score, harvest index, growth ratio, bulb production energy value, plant received energy value, bulb production energy value were measured. Results and Discussion Results of field experiment showed that seed priming improved the biomass yield and ecophysiological characteristics of onion of both ecotypes. The highest biomass yield (105.98 ton.ha-1), bulb water use efficiency (4.98 kg.m3), biomass water use efficiency (13.30 kg.m3), harvest index (%82) and relative water content (%86) belonged to priming with flamin amino acid, respectively and the lowest were achieved from control plants. Mean comparison indicated that the higher values of biomass yield, bulb water use efficiency, biomass water use efficiency, harvest index and relative water content were obtained from large seed size 100.33 (ton.ha-1), 4.88 and 13.30 kg.m3, 80 and 85 percent, respectively and the lower level were found for small seed size. Based on the results there were significant differences between ecotypes in all studied traits. Moreover, mean comparison showed that the highest amount of biomass yield, bulb water use efficiency, biomass water use efficiency, harvest index and relative water content were obtained from Red Azarshahr ecotype 100.40 (ton.ha-1), 4.80 and 13.15 kg.m3, 81 and 91 percent, respectively and the lowest of it were found to Zarghan. Conclusions According to the results mentioned above, seed priming treatments improved biomass yield and ecophysiological characteristics as compared to the unprimed. Among different treatments, seed priming with folammin amino acid 2% was more effective than the potassium nitrite 2% and hydropriming. Large seed size significantly increased the biological yield and ecophysiological characteristics. Accordingly, the importance of seed priming and seed grading were obvious in this study, so seed priming with flamin amino acid 2% and large seed size should be used for onion planting in order to ensure high biomass yield, and to improve ecophysiological characteristics of onion. Therefore, priming with flamin amino acid 2% and large seed are recommended for onion cultivation under the same environmental conditions with the experiment.
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