Recurrent selection in potato for heat tolerance. / SeleÃÃo recorrente em batata visando a tolerÃncia ao calor

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

All potato cultivars most planted in Brazil come from temperate countries. They are not adapted to the tropical conditions and this results in poorer tuber yields. The objective of this research was to study how recurrent selection can contribute to the development of more adapted potato clones to the tropical climate. The base population (SR0) used in this study was made from thirteen clones and two cultivars. The cycle one population (SR1) was formed from the interbreeding of thirteen clones and two cultivars in the fall season of 2001, generating 16 families from which SR1 clones were selected. The cycle two population (SR2) was obtained from biparental crossings between 31 SR1 clones, 15 open pollinated SR1 clones, 5 ESL clones and the cultivar Atlantic in the summer of 2004. 197 families were produced from which SR2 clones were selected. The SR1 clones were selected at the seedling stage under green house conditions in the fall of 2002 and then selected again in the field at the first clonal generation (C1) at the end of 2002. The second clonal generation (C2) was evaluated in the winter of 2004, in an experiment in triple lattice. The C3 and C4 generations were evaluated in randomized complete blocks with three replications during the summer of 2004 and spring of 2005, respectively. The SR2 clones were evaluated at the seedling generation under green house conditions in the fall of 2004. The C1 generation was visually evaluated in the field at the end of 2004 and the C2 generation was evaluated in randomized complete blocks with two replications in the summer of 2005. An experiment was set up to evaluate all clones from the SR0, SR1 and SR2 cycles during the winter season of 2006. After all evaluations the realized genetic gains were estimated between SR0, SR1 and SR2 for all traits. Genetic gains were obtained for all traits between SR0 and SR1: tuber yield 3.1%, percentage of large tubers 5.8%, tuber average weight 9.1%, percentage of second growth tubers reduction of 37.7%, percentage of tuber cracking reduction of 55.4%, tuber specific gravity 0.56% and tuber appearance 28.0%. Genetic gains were also observed between SR1 and SR2 populations, except for percentage of second growth tubers and tuber appearance. The gains were 24.0% for tuber yield, 10.5% for percentage of large tubers, 11.0% for percentage of average tuber weight, 100% for reduction in tuber cracking and 0.55% for tuber specific gravity. Concerning the winter season experiment there were no significant differences between the selection cycles for all traits.

ASSUNTO(S)

potato tolerÃncia ao calor. heat tolerance melhoramento vegetal batata melhoramento genÃtico seleÃÃo recorrente plant breeding recurrent selection

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