Exploring Pima and Upland Cross-Combinations to Identify Fusarium Oxysporum f. Sp. Vasinfectum Race 4 Resistant Cottons By Combining Ability of Superior Cultivars

A cotton breeding program strives to identify the best performance cultivars or breeding lines which can be used as parents in crosses. Multi-cross combinations provide the means of performance of each parent and assess the combining ability or productivity of parents through the hybridization process in which the desirable genes or traits are transmitted to their progenies. Knowledge of the genetic combining ability for superior-parental resistant Fusarium oxysporum f. sp. vasinfectum race 4 (FOV4) Upland (Gossypium hirsutum L.) and Pima (G. barbadense) parental-entries is critical for the improvement of FOV4 resistance and to broaden the cotton crop genetic base. In 2014-2015, Pima and Upland cultivars or germplasm lines with known FOV4 resistance were selected and crossed in multi-combinations or in diallel and modified diallel designs to develop progeny and new populations and assess FOV4 resistance.  The parents and F₁ populations were then grown under FOV4 pressure in the field and greenhouse and evaluated. The FOV4 infection response-results of parents and the F₁ populations will be examined to evaluate the combing ability of both selected Upland and Pima cottons.