Effect of Pre-treatment and Seed Size on Quantitative and Qualitative Characteristics of Two Onion (Allium cepa L.) Genotypes

Seed priming is a type of pre-sowing seed treatment known to improve seed performance by increasing seed germination rate and uniformity. Another factor which could be helpful for rapid and uniform germination and emergence is seed size. Seed size is a component of seed quality which has an impact on the performance of crop. The main objective of this work was to study the effect of priming and seed size on quantitative and qualitative characteristics of two onion genotypes.
In order to evaluate the effect of priming and seed size on quantitative and qualitative characteristics of onion genotypes a factorial field experiment based on a randomized complete block design with three replications was conducted in 2012 and 2013 cropping season at Agriculture and Natural Resources Research Center of East Azarbayjan, Iran. The experimental treatments included priming (at four levels: hydro priming, osmopriming (in 2% KNO3), priming with folammin amino acid (in 2%) and control (without priming), seed size (at three levels: small, medium and large) and genotype (at two levels: Red Azarshahr and Zargan). Quantitative characteristics included bulb fresh and dry yield, bulb, leave fresh and dry weight and qualitative characteristics included percentages of soluble solids and dry matter, bulb pH, pyruvic acid content, bulb and Leave ash of onion.
Analysis of variance for the measured traits indicated that all characteristics significantly were affected by priming and seed size. Results showed that seed priming and seed size improved quantitative and qualitative characteristics of onions. The highest bulb fresh and dry yield, total soluble solids and dry matter, were obtained from plant that primed with folammin amino acid 58.17, 7.27 (tha-1), 12.54, 13.67 percent, respectively, and the lowest were achieved from control plants. Also, mean comparison indicated that the higher values of bulb fresh and dry yield, total soluble solids and dry matter were obtained from large seed size 58.99, 7.37 (tha-1), 11.14, 12.45 percent, respectively and the lower values were found to belong to small seed size. Genotypes mean comparison showed that the higher values of bulb fresh and dry yield, total soluble solids and dry matter were obtained from Red Azarshahr cultivar 53.46, 6.68 (tha-1), 12.62, 11.81 percent, respectively.
According to the results mentioned above, seed priming treatments improved quantitative and qualitative characteristics as compared to the unprimed. Among the treatments, seed priming with folammin amino acid 2 % was more effective than the potassium nitrite 2 % and hydropriming. Large seed size significantly increased the quantitative and qualitative characteristics. Accordingly, the importance of seed priming and seed grading was obvious in this study, so seed priming with folammin amino acid 2% and large seed size should be used for onion planting in order to improve quantitative and qualitative characteristics of onion. Therefore priming with folammin amino acid 2 % and large seed are recommended for onion planting for the places with the same environmental conditions.