Ahmad Aljuoma⁽¹⁾ and Jamila Dirbas^*(1)

(1). Cotton Research Administration–Syria

(*Corrsponding author: Jamila Dirbas..Email: jamila.dirbas@gmail.com)

Received: 04/03/2019                               Accepted: 07/04/2019

Abstract

The experiment was conducted at Hama Agricultural Research Center during 2016, 2017 and 2018 seasons to study the heterosis according to the best parent and inbreeding depression in F₁ and F₂ of the resulted hybrids from top cross program among ten parents of upland cotton. Analysis of variance indicated high significant differences among the genotypes for all characters except sympodial brunch number in F₂. Estimation of heterosis showed significant positive values in some F₁ hybrids that reached 20.18% sympodial brunch number, (44. 74%, 44.30%, 47.06%, 65.00%) opened bolls number and (39.07%, 44.18%) seed cotton yield which may refers to variance of parents in genetic factors that control these traits. Heterosis in F₂ excelled F₁ which indicated to the transgressive segregation. Heterosis accompanied with positive inbreeding depression values indicating to dominance effect. Also, negative values of inbreeding depression were noticed in some hybrids because of F₂ excellence to F₁. To confirm the superiority in these hybrids, it is recommended to be tested in large-scale trials.

Keyword: Cotton, Heterosis, Inbreeding depression, F₁, F₂.

Full paper in Arabic: PDF