Capacidade combinatória e heterose em híbridos de pimentão com resistência múltipla a doenças

Abstract

Sweet pepper ranks third among the most cultivated solanaceous vegetables, and occupies in Brazil an área of ca. 12000 ha with a total yearly production of 350 thousand metric tonnes. In the past few years there has been a significant increase in pepper yields, especially after the more widespread use of hybrid cultivars and of protected cultivation. One major problem of the sweet pepper crops is the incidence of diseases, especially the Phytophthora capsici blight, viral diseases and root knot nematodes. The continuous search for new hybrids with multiple disease resistance is thus a major research priority. The objectives of the present work were therefore: (i) to estimate the combining ability of sweet pepper lines with resistance to one or more pathogens (Pepper yellow mosaic virus, Phytophthora capsici, Meloidogyne incognita); (ii) to estimate heterosis and its components in hybrids between these lines; (iii) to develop multiple-disease resistant hybrids and to identify those that are competitive with current commercial hybrid checks. The experiments were carried out in plastic houses at the experimental farm of HortiAgro Sementes S.A. Ten sweet pepper breeding lines and thirty experimental hybrids were used in the study; 20 of these hybrids were obtained by crossing two groups of parental lines (group I= seed parents 1=PIX-044B-01-01, 2=PIX-044B-13-01, 3=PIX-045B-27-02, 4=PIX-045B-32-03 and 5=PIX-052B-06-01; group II – pollen parents: 1'=Carolina Wonder, 2'=Charleston Belle, 3'=MYR-29-09-05 and 4'=MYR-29-11-08), and 10 were additional experimental hybrids. In addition, six commercial hybrids (Konan-R, Magali-R, Martha-R, Stephany, Mallorca, Magnata Super) and the accession Criollo de Morellos-334 were used as checks. Two sets of experiments were carried out: one (which included the 30 experimental hybrids and the 6 hybrid checks) evaluated agronomic traits, and the second set was comprised of three diferente trials for evaluation the reaction to each of the three pathogens (PepYMV, P. capsici, M. incognita). Estimates of heterosis and their components were obtained for the traits total fruit yield, mean fruit mass, early yield, pericarp thickness, depth of insertion of fruit peduncle, and fruit lengh/diameter ratio. Additive gene effects were important in the expression of all traits under evaluation. Non-additive effects were also of importance in the expression of percent of plants without symptoms of PepYMV or Phytophthora capsici. Lines Carolina Wonder, Charleston Belle, PIM-013 e MYR-29-03-02 were found to have good general combining ability for traits total and early fruit yield. The experimental hybrids 2x1' = F1(PIX-044B-13-01 x Carolina Wonder), 2'x3' = F1(Charleston Belle x MYR-29-09-05), 4x1' = F1(PIX-045B-32-03 x Carolina Wonder) and 5'x3' = F1(PIM-013 x MYR-29-09-05) were considered promising as putative commercial releases, because they present both multiple disease resistance and horticultural traits comparable to the commercial checks.