Differential response of inbred maize families to the herbicide nicosulfuron / Differential response of inbred maize families to the herbicide nicosulfuron / Resposta diferencial de famÃlias endogÃmicas de milho ao herbicida Nicosulfuron. / Resposta diferencial de famÃlias endogÃmicas de milho ao herbicida Nicosulfuron.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

To obtain recombinant lines in improvement programs, self-fertilization of commercial hybrids is a common practice, since populations derived from such hybrids combine a high mean and great variability. It is important to observe the performance of lines derived from nicosulfuron-sensitive commercial quality hybrids, in respect to herbicide sensitivity, realigning future improvement programs. On this background, the present study tried to quantify the harm done by nicosulfuron to inbred lines derived from hybrid DKB-333B and verify the possibility of selecting productive and nicosulfuron-tolerant lines. One hundred and sixty-nine S0:1 families were evaluated for this purpose during the harvest of 2002/2003, and 36 S0:2 families during the harvest of 2003/2004, all of them derived from the aforementioned hybrid, on an experimental area of the Departamento de Biologia of the UFLA, in Lavras, State of Minas Gerais. The S0:1 families were evaluated in three different experiments set up in a 13x13 triple lattice design, where the plots were represented by a 2m row. A dose of the commercial product was applied in every experiment (0.0 l/ha, 1.5 l/ha, and 3.0 l/ha, respectively). The S0:2 families were evaluated in four experiments in a 6x6 triple lattice design with 2m row plots, where each experiment evaluated the same doses of the previous year and an additional experiment without weed control. The phytotoxic effect of nicosulfuron was assessed in a schematic chart in three evaluation periods. The scores ranged from 1 to 5; 1 represented absence of phytotoxicity and 5 totally destroyed plants, plant height, ear height, and productivity of hulled ears. A difference among the S0:1 families in relation to the phytotoxicity to nicosulfuron was observed. The heritability of the trait was low, however (below 25%), demonstrating the fractiousness of this trait for selection. The evaluation of the damage caused by the herbicide based on grain productivity revealed great variation. Great part of the families was even benefited by the product, probably due the reduced competition with weeds. The tolerance to nicosulfuron was strongly influenced by the crop year, hampering an evaluation of the possibility of selection success.

ASSUNTO(S)

seleÃÃo melhoramento vegetal fitotoxidez inbreeding; selection; hebicide inbreeding selection endogamia fitotoxidez hebicide fitotoxidez fitotoxidez melhoramento vegetal endogamia herbicida herbicida seleÃÃo

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