Document Type : Original Article
Authors
1
Dept. of Genetics, Faculty of Agric. Mansoura University, Egypt.
2
Vegetables Breeding Department, Horticulture Res. Inst. (HRI), ARC, Giza, Egypt.
3
Biology Dept., Fac., of Arts and Science- Rafha, Northern Border Univ., Saudi Arabia,91431 Vegetable Breeding, Horticulture Inst., ARC, Giza, Egypt. 12619
Abstract
This study was conducted at Kaha Research Farm of Vegetables Breeding Department, Horticultural Research Institute, (HRI), Agric. Res. Center (ARC), Giza, Egypt, during the period from 2008 to 2010. The study aimed to estimate heterosis versus the mid-parents and the better parent, general (GCA) and specific (SCA) combining ability variances, nature of gene action, heritability in both broad and narrow senses in some summer squash for economic earliness traits. These traits included number of first female flowering node (No.1stF.F.N); date of first male flower (D.1stM.F.); data of first female flower (D.1stF.F.); first picking date (1stP.D.) and early yield per plant (E.Y./P.kg.). Seven imported squash varieties, namely Eskandarani (P1); Zucca Patisson custard white (P2); All Green Bush (P3); Courgette Orelia (P4); Sakiz (P5); Copi (P6) and Gapla (P7) were used as parental varieties in the present investigation. Diallel crosses (with reciprocals) were made between these parents to obtain 42 F1,1r hybrids according to the complete diallel crosses mating design. All genotypes were evaluated in randomized complete-blocks designs with three replications. The results indicated that the parental varieties Courgette Orelia (P4) and Gapla (P7) seemed to be the best combiners for earliness traits such as number of first female flowering node (No.1stF.F.N); date of first male flower (D.1stM.F.); data of first female flower (D.1stF.F.) and first picking date (1stP.D.). The parents Zucca Patisson custard white (P2) and Copi (P6) were the best combiners for early yield per plant (E.Y./P.kg.). In general, the performances of most F1,1r hybrids were variable and the results cleared that no hybrid was the best all for earliness traits. The results showed the importance of general (GCA) and specific (SCA) combining abilities. GCA was larger than their corresponding estimates of SCA for most earliness traits. Reciprocal effects (r) were significant for most earliness traits. In the same time, the estimates of heritability in broad sense were larger in magnitudes than their corresponding estimates of narrow sense.
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