ABSTRACT
Lettuce bacterial leaf spot caused by Xanthomonas campestris pv. vitians is an aggressive disease that is difficult to control. So far there are no reports of the reaction of biofortified lettuce genotypes to different isolates of the bacteria. Thus, the objective was to evaluate the aggressiveness of X. campestris pv. vitians, as well as the reaction of biofortified lettuce genotypes to bacterial spot. Two experiments were performed in two distinct seasons (winter and summer), in greenhouse at the Vegetable Experimental Station of the Federal University of Uberlândia (UFU). The experimental design in both experiments was a randomized block design, in a factor scheme of 5 × 4 (five genotypes and four strains), with four repetitions. Were evaluated the severity and the area under the disease progress curve. In general, the biofortified lettuce 'Uberlândia 10000' was more resistant to most bacterial strains in the summer cultivation, and in the winter period UFU 'Crespa 206'. The commercial cultivar Robusta was the most susceptible to the strains during both seasons. The UFU E125 strain was the most aggressive for most genotypes in both seasons.
Subject(s)
Xanthomonas campestris/genetics , Lettuce/genetics , Genotype , VegetablesABSTRACT
The growth habit directly influences the tomato architecture, impacting on agronomic performance of mini-tomato hybrids. However, little is known about the growth habit of mini-tomatoes hybrids obtained by the crossing of dwarf lines versus normal lines with different growth habits. The objective of this study was to determine the type of growth that occurs when crossing a mini-tomato dwarf line versus normal phenotype lines with indeterminate, determined and semi-determinate growth habit. The methodology consisted of biparental crosses [determined from a cross between a dwarf line with normal lines of different growth habits (determinate, semi-determinate and indeterminate)] and reciprocal backcrosses of the F1 to the parents [normal lines (P1) and dwarf line (P2)], and obtained the F2 generation. Was evaluated phenotypically the growth habit in each generation. The growth habit proportions of F1 (P1xP2), F1 (P2xP1), F2, F1RC1 (P1) and F1RC1 (P2), were classified after checking the expected and observed frequencies using the ² test (F= 0.05). Was concluded that, when the determined and semi-determined growth habits are used as parents to produce hybrids, in F2 population growth habits shows 3:1 type segregation. Futhermore, regardless of the normal parent growth habit, the hybrids (F1) always will show indeterminate growth when they are crossed with the mini-tomato dwarf line of this study.
O hábito de crescimento influencia diretamente o desempenho agronômico de híbridos de minitomate. No entanto, pouco se sabe sobre o hábito de crescimento de híbridos de minitomate obtidos pelo cruzamento de linhagens anãs versus linhagens de fenótipos normais com diferentes hábitos de crescimento. O objetivo deste trabalho foi determinar o tipo de crescimento que ocorre entre o cruzamento de uma linhagem anã de minitomate versus linhagens de fenótipos normais com hábito de crescimento indeterminado, determinado e semi-determinado. A metodologia constou de cruzamentos biparentais recíprocos (determinados pelo cruzamento entre uma linhagem anã e linhagens normais com hábito de crescimento determinado, semi-determinado e indeterminado) e retrocruzamentos da geração F1 com os genitores [linhagens normais (P1) e linhagem anã (P2)] e obtenção de geração F2. O hábito de crescimento foi avaliado fenotipicamente em cada geração. As proporções do hábito de crescimento em F1(P1xP2), F1 (P2xP1), F2, F1RC1 (P1) e F1RC1 (P2), foram realizadas após verificação das frequências observadas e esperadas, utilizando o teste ² (F = 0,05). Foi concluído que, na obtenção de híbridos quando os genitores possuem hábito de crescimento determinado e semideterminado, na população F2 ocorre uma segregação do hábito de crescimento do tipo 3:1. Além disso, independentemente do hábito de crescimento dos parentais, os híbridos sempre irão possuir crescimento indeterminado quando forem obtidos pela linhagem anã de minitomate deste estudo.