Selection to passion fruit (Passiflora edulis) from cladosporiosis (Cladosporium herbarum) resistance / Seleção de maracujazeiro (Passiflora edulis) para resistência à cladosporiose (Cladosporium herbarum)




At the present time, Brazil is one of the greatest producers of yellow passion fruit. Although, the Brazilian productivity is still considered low, due to many phytotecnical problems, such as: nutritional factors, low quality stock plants, inadequate system of conduction and phytossanitary problems. There are few works on genetic improvement aiming the resistance to phytopatogens in passion fruit trees. The main illnesses caused by fungi in the aerial parts of the plants are: Antracnosis, Cladosporiosis and Septoriosis, among others. Cladosporiosis and Antracnosis are the main fruits illness of the passion fruit trees. Cladosporiosis can occur in all aerial parts of the plant, including leaves, little branches, flowers and fruits. It is a typical young tissue illness. It causes clorosis in the leaves and can lead to the defoliation of the plant. Depending on the severity, it can cause the loss of the growing plant. It is also considered an important illness in the after- harvest season. The aim of this work is to evaluate and to select progenies of half-sibs of passion fruit trees that are resistant to Cladosporiosis. The experiment was held in the campus of UFV, in green house in the fruitculture experimental area. There, ten progenies of half-sibs from previously selected progenies were studied, regarding to its productivity and fruit quality. The studied progenies were: 03, 12, 17, 18, 19, 22, 30, 31, 40 e 64. The experiment was conduced by the distribution of blocks at random, having four repetitions and five plants per plot. The blocks were chosen due to the plants size in the occasion of inoculation. The inoculum was prepared in a spore suspension of the fungi C. herbarum in distilled water (1x106 spores/mL), isolated from leaves of its parents population, and applied through spraying, reaching all the aerial parts, including the abaxial and adaxial faces of the leaves. The inoculated plants remained in the green house under controlled irrigation, until the evaluation. It took ten days so it got to the latent period, and twelve to the inoculation. Beginning the defoliation, the leaves were detached, scanned and quantified to the percentage of the damaged area. The software QUANT was used to get the quantification. The program GENES was used to analyze the variation between plants and to obtain the estimated gain for selection among and within families and combined in the studied progenies. The selection between progenies was made using 20% of selection and it was efficient, highlighting two out of the ten studied progenies as superior, regarding to resistance to Cladosporiosis. The selection within the progenies was realized by using 25% of selection and eight plants were highlighted, being two in each block, one from each gotten progenie in the selection among families, being from progenie 03 the plants 4, 1, 2, 1 and from progenie 19 the plants 3, 4, 2, 3 from blocks 1, 2, 3, 4 respectively. The combined selection showed off as the most efficient because, besides indicating the selected progenies in the other methods, it indicated a third favorable progenie to the recombination for the obtaining of resistant individuals. The combined selection pointed out eight plants as promising: considering the three progenies, it indicated a number of superior plants in each progenie, being two in the progenie 03, two in the progenie 17, and four in the progenie 19. The combined selection was the alternative which presented bigger expected gains. The results suggest that there is the possibility of realizing the selection in an effective way for the evaluated characteristic, getting to resistant individuals.


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