| Popis: |
At this stage of the populational breeding use in Latin America it is important to carry out basic studies to allow an in-depth knowledge of how the method is working in rice. This chapter describes the effect of one recurrent selection cycle and three recombinations (one before selection and two after it) in the upland rice population PCT-4, developed for acid soil conditions. The study was carried out in two environments or treatments with different levels of lime. To determine the responses to selection the variables measured were: reaction to soil acidity (AC); number of days to 50% flowering (FL); grain yield (RDTO); ten panicles weight (PPA); number of filled (GL) and empty grains (GV); plant height (HT); number of tiller per square meter TAM); and 1000 grain weight (P1000). FL and GV were statistically smaller when less lime was applied; RDTO, GL and PPA were smaller in the higher level of lime. Under one cycle of recurrent selection RDTO, PPA, GV, GL, HT, TAM and P1000 did not present changes in behavior. The recombination effects were variable, for RDTO and GV two recombinations produced positive effects but for FL it was contrary. Three recombinations caused negative effects in FL and RDTO and positive in HT. In general, there was not a clear trend towards positive or negative effects. Thus we can conclude that for PCT-4, it is not recommended to apply more than one recombination between recurrent selection cycles. |
