Escolha de genitores e estratégias de seleção para caracteres de aparência de tubérculo, rendimento e qualidade de fritura, em batata

Abstract

In potato breeding programs, the choice of parents and selection of strategies must be carefully defined, and incorporated as a practice in programs trying to increase the efficiency and efficacy. The research consisted of five studies. The first study aimed to verify the combining ability of potato parents in early generations of selection. Twelve segregating potato families derived from crosses between two groups of parents in a partial diallel (3x4) were evaluated. The families were evaluated to tuber appearance and yield traits. Data were analyzed for variance and partial diallel analysis. It was found that there is predominance of additive effects of genes for skin color, tuber shape uniformity, tuber pointing, tuber curvature, general tuber appearance, tuber size uniformity, tuber number, tuber yield, and average tuber weight. The second study aimed to estimate the expected response to selection for yield, appearance and fry quality traits. Three hybrid potato populations were studied and evaluated to yield, appearance and fry quality. Data were statistically analyzed according to the REML/BLUP model. The expected response to selection for frying quality suggests that to obtain superior populations, at least one parent of good fry quality should be used. The third study aimed to estimate genetic parameters for yield and tuber appearance traits in early generations of selection. Twelve segregating potato families were evaluated to yield and appearance traits. The experimental design was randomized blocks. It was concluded that selection can be applied with mild to moderate intensity in seedling generating for skin texture, general tuber appearance, tuber number, tuber yield, and average tuber yield. The fourth study aimed to examine correlations between and within generations for tuber appearance and tuber yield in early generations of selection and their implications in the selection. Twelve segregating potato families were evaluated in seedling and first field generation to appearance and yield traits. Correlation analysis between and within generations were performed. The results showed that negative selection can be applied in the seedling generation for tuber IX pointing, tuber number, and average tuber weight. The results also suggest that selection for tuber yield can be applied at mild intensity for average tuber weight and tuber size. The fifth study aimed to compare the efficiency of different index selection methods for selection of superior potato clones. Three hybrid potato populations were studied. Six selection index were compared. The families were evaluated to yield and appearance traits. It was concluded that the multiplicative index and the index based on the sum of ranks are more efficient.