Genetic Analysis Of The Important Agronomic Characters In Mini-watermelon

Watermelon is an important part of the horticulture in the world and is an important economic fruit.Its important agronomic characters are the major targets of the breeding experts.Objective: In order to obtain the genetic regularity of the important agronomic characters in mini-watermelon and make the foundation of the breeding of better varieties of mini-watermelon.Methods: In this study,we used the mini-watermelon with anti-cracking, red flesh and small seeds and the mini-watermelon of fruit-cracking, yellow flesh and big seeds as parents to get six generation groups, namely, P1, P2, F1, F2 and back-cross populations BC1P1 and BC1P2.Through measuring its fruit-cracking related traits,flesh color and seed traits drew frequency distribution of the characters, studied the genetic law of the target traits, and got the correlation, regression equation and the path coefficient of every various target characters.Results :1、Studying on fruit-cracking traits showed that fruit split rate, rind hardness and skin elasticity in F2 population appeared transgressive segregation, showed continuous variation, are QTLs controlled by multiple genes.Which fruit split rate in F2 population shows a bi-modal distribution and does not accord with normal distribution, not completely accords with the quantitative traits of classic genetic.The rind hardness and skin elasticity are uni-modal distribution and accord with normal distribution law.2、Flesh color is co-dominance in F1 generation, and yellow to red for incomplete dominant inheritance.Flesh color occurred segregation in F2 population.Flesh color belongs to the quality traits and follows the law of Mendel rule with according to the types of color grouping analysis.According to the different color depth degree classification, flesh color belong to quantitative traits.But the inheritance of flesh color is very complex and need to further research.3、Study on seed traits have indicated that the length and width of seed,thousand-seed weight and seeds per fruit appeared transgressive segregation, show continuous variation, are QTLs controlled by multiple genes in F2 population.The length and width of seed and thousand-seed weight are uni-modal skewed normal distribution and tend to female parent F2 generation segregation population. Seeds per fruit is normally distributed in the F2 generation segregation population.4、The results of correlation analysis show that the rind hardness and skin elasticity, seed width and seed length,seed length and thousand-seeds weight, thousand seed weight and seed width all reached extremely significant positive correlation, seed width and seeds per fruit, thousand-seeds weight and seeds per fruit, fruit flesh color and skin elasticity, fruit slit rate and fruit color all 4 characters are significant negative correlation relationship.5、The results of path analysis show that only between fruit flesh color and fruit split rate exists significant differences.The optimal equation of fruit split rate is obtained:Y = 67.869 7.248X7(R = 0.259, F = 5.319 *). Path analysis showed that the flesh color for the fruit cut crack should be the direct path coefficient of 0.259, determination coefficient is 0.067, the remaining size coefficient of 0.9659.Fruit flesh color have little influence on fruit-cracking, there should be other characters have great influence on fruit cracking.