Selection of Diploid and Tetraploid Banana Hybrids Resistant to Pseudocercospora fijiensis

Abstract

Black Sigatoka, a disease caused by the fungus Pseudocercospora fijiensis, can lead to the complete loss of banana and plantain production in the absence of chemical control. The development of resistant cultivars is the focus of many banana breeding programs and is an alternative to the use of fungicides. In order to define a refined method of selection in genetic breeding programs, this study evaluated 23 improved diploids, seven tetraploids, and two commercial cultivars in the presence of P. fijiensis. Four selection criteria were considered: means of the disease severity index (ID) and area under the disease progress curve (AUDPC) estimated over the total period of the experiment, only in summer, only in winter, and the emission and harvesting of bunches. The selection of genotypes was more effective in the winter, and the evaluation of four leaves no. 3 emitted after six months of growth was efficient at differentiating the resistant and susceptible genotypes. For the improved diploids and tetraploid hybrids, DI varied from 0.0 to 48.8 and from 15.1 to 63.5, respectively, and the AACPD for the improved hybrids and tetraploid hybrids varied from 0.0 to 2439.5 and 1000.2 to 3717.7, respectively. The tetraploid hybrid of the Prata-type CNPMF0906 and the commercial cultivar, which is a hybrid of the BRS Princesa Silk type, showed quantitative resistance and can be used by banana producers. Results suggest that the guidelines adopted for the selection of genotypes resistant to black Sigatoka may include methodologies that reduce the evaluation time. In addition, new sources of resistance to the disease and the influence of its genetic inheritance in future crosses were found.

SCS453 Noninha and SCS454 Carvoeira - new banana cultivars of the Prata subgroup

“…Disease severity in the different genotypes was evaluated every 20 days over five production cycles, on a 0 to 6 score scale proposed by Gauhl et al (1993), where 0 = no symptoms; 1 = lesions on less than 1% of the leaf area or a maximum of 10 lesions; 2 = lesions on 1 to 5% of the leaf area; 3 = lesions on 6 to 15% of the leaf area; 4 = lesions on 16 to 33% of the leaf area; 5 = lesions on 34 to 50% of the leaf area; 6 = lesions on 51 to 100% the leaf area. From these scores, the disease severity index and area under the disease progress curve (AUDPC) were calculated (Gonçalves et al 2021). The experiment was arranged in a randomized block design, with four replications.…”