توصيفگر ها :
تنوع ژنتيكي , گوجهفرنگي , ليكوپن , صفات كمي , صفات كيفي , گلخانه , Genetic diversity , Tomato , Lycopene , Quantitative traits , Qualitative traits , Greenhouse
چكيده انگليسي :
Tomato is one of the most consumed vegetables worldwide, valued both for fresh market sales and as a processed food product. evaluation and selection in breeding programs are essential to identify high-performance and quality lines. Phenotypic selection is crucial in assessing genetic diversity through breeding lines and in achieving desired diversity. Numerous studies have investigated the genetic diversity of cultivated and wild tomato species globally. However, the genetic diversity of tomatoes in Iran, especially from the two groups of beef and cherry tomatoes, has not simultaneously been studied to exploit their potential in hybrid production. In this study, 160 tomato genotypes were evaluated in a randomized complete block design with three replications in a greenhouse. Morphological traits such as stem length and diameter, single fruit weight, sepal type, root nematode rate, pericarp thickness, fruit shape, fruit skin color, number of locules, chlorophyll greenness index, and fruit firmness, along with yield-related traits such as the number of ripe fruits per plant, average fruit weight, yield, and fruit lycopene content, were measured under greenhouse conditions. Analysis of Variance revealed significant differences among genotypes for all traits. Using cluster analysis, 160 genotypes were divided into 9 groups, and 132 seedling genotypes into 7 groups. Wild species exhibited greater genetic diversity than cultivated varieties. Variance analysis of plant traits showed that beef genotypes had the highest single fruit weight, yield and fruit firmness, while cherry genotypes had lower pericarp thickness, higher plant height, lycopene content, and greater fruit numbers. Variance analysis of seedling traits revealed that beef genotypes had the highest fresh and dry root, and stem dry weights, whereas cherry genotypes excelled in root volume and seedling length, contributing to better nutrient absorption and faster growth. Biplot analysis identified the first two principal components explaining over 75% of total variation. Traits such as fruit weight, fruit number, and pericarp thickness had the strongest positive correlations with yield. An inverse relationship between fruit number and single fruit weight was observed. Canonical correlation analysis showed that fresh root weight and seedling length had a direct correlation with total plant performance in beef genotypes, whereas in cherry genotypes, the correlation was inverse, with stem diameter having the greatest impact on performance. Analysis of cumulative yield trends showed that beef tomatoes had a steeper performance increase compared to cherry tomatoes. The cumulative yield in cherry genotypes was approximately half that of beef genotypes. Separate clustering of the two groups based on various traits showed a clear distinction between beef and cherry genotypes. Wild genotypes had the lowest lycopene content, likely due to prioritizing survival and stress resistance. The superior genotypes in separate clusters based on performance were identified as those with high fruit weight, greater fruit numbers, and stress resistance. The best genotype from the beef group was genotype 135, and the best genotype from the cherry group was genotype 74. The results of this study confirm significant genetic diversity among tomato genotypes in Iran, which can serve as a valuable resource in hybrid breeding programs for improving yield, fruit quality, and biotic and abiotic stress resistance.
