Genetic analysis of sweet pepper tolerance to low phosphorus availability in the soil
Valter Rodrigues Oliveira; Vicente Wagner Dias Casali; Cosme Damião Cruz; Carlos Alberto Scapim and Nádja de Moura Pires
The objective of this study was to evaluate the mode of inheritance for sweet pepper (Capsicum annuum L.) tolerance to low P availability in soil, defined here as the ability of plants to produce relatively more biomass (total dry weight) under low P conditions. A complete diallel cross was used involving six previously selected genotypes, three tolerant and three intolerant to low P availability in soil. At 75 days after sowing, total dry weight, shoot and root dry weight, ratio root:shoot dry weight, and total P content in the plant were evaluated. There were no significant reciprocal differences in any of the assessed traits. The results showed that genes controlling tolerance to low P were predominantly but not exclusively dominant. Out of the three tolerant parents, two concentrated dominant genes, and the other, recessive genes for tolerance to low P. The analysis of the genetic components of variation showed that both the additive and the dominant gene effects were involved in the control of all the characteristics, with a greater contribution from the dominance to the genetic variability among parents and F1 hybrids. The estimates of the broadsense heritabilities were high, while the narrow-sense were in general comparatively low. Their magnitudes, however, were at a level that allowed successful selection.