JWSS - Journal of Water and Soil Science

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In order to study the genetic variation among local varieties of onion in Iran, an experiment was conducted in the Research Center, Faculty of Agriculture, Tabriz University. Sixteen populations were evaluated for agronomic characteristics and also total seed proteins via SDS-PAGE. Cluster analysis and principal component analysis were used to group the onion populations under study.

 Analysis of variance showed significant differences among varieties for leaf color, leaf length, texture tightness, onion yield per plant, and number of edible layers. No significant differences were observed for the number of twin onions, bulb diameter, and onion dry weight. Hamadan (98-148), Arak (98-95, 98-96, 98-97, 98-103), and Zanjan (98-223) populations acquired the highest onion yield per plant. The significant differences between populations for the majority of characteristics proved the existence of genetic variation in the Iranian onion germplasm. The results from cluster analysis for agronomic characteristics were the same as those from the cluster analysis for the onion yield per plant. The 16 populations were divided into 4 groups. Cluster analysis for the electrophoresis banding pattern resulted in two groups, which was not similar to the dendrogram of agronomic traits. Using principal component analysis, the first principal components determined 97.57% of the total variation. Onion yield per plant was the most important trait in the first principal component and onion dry weight was the second trait in the rank.

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The commercial potato is an autotetraploid species. Certain allotetraploid species such as S. acaule despite theire identical ploidy level are not crossable with commercial potato due to their different endosperm balance numbers. The aim of this experiment was to investigate the possibility of germplasm transferring from allotetraploid species to cultivated potato by the use of diploid species and 2n gametes. For this purpose, one clone of S. phureja was crossed with S.acaule. The resulting F₁ seeds were planted the next year. For evaluation of male fertility and unreduced gametes, the pollen samples of F₁ hybrids stained with acetocarmin glycerol were assessed. For chromosome counting the tips of stolons were fixed and after staining with aceto – iron- hematoxilin were squashed. For future crossing some hybrids were grafted on tomato stocks. Cytologycal observation revealed that hybrids were triplod. Male fertility of hybrids as expected for odd ploidy was low, but approximately all of them had a few large stainable pollen (putative 2n). crossing of the hybrids as male parent with S. tuberosum was not  successful, but reciprocal cross was successful and 72 seeds were obtained from 380 pollination . considering EBN, it is exected that the resulting seeds originate from fertilization of unreduced gametes of triploid and n gamates of S. tuberosum to be pentaploid or near pentaploid. The applications of these hybrid in potato breeding via ploidy manipulation have been discussed.