Combining Ability Of Wheat Genotypes Regarding Pre-Harvest Sprouting.

Pre-harvesting sprouting in wheat (Triticum aestivum L.) is defined as the germination of grains in the ear before harvesting, being a worldwide problem that reduces the quality and economic value of the wheat grain. The objective of this work was to estimate the general and specific combining ability of eight wheat genotypes, in order to indicate the best combinations in crosses and aiming to increase the tolerance to pre-harvesting sprouting in wheat. Crosses were performed in the year 2010, using the following genotypes as parents: BRS 220, MARFIM, SUPERA, VALENTE, BRS 194, FRONTANA, ITAIPÚ and QUARTZO.  In the winter of 2011, the experiment was conducted in the experimental field of the Plant Genomics and Breeding Center, Federal University of Pelotas, located in Capao do Leao County, RS, Brazil. The ears were harvested at physiological maturity (ears that lost their colour while node culms were still green). Laboratory analyses were performed in the fixed generations (F₁ and parents), using the random block design with three replications. Each replication consisted of five ears. The percentage of germinated grains (%GG) were counted and analysed with the aid of the software GENES. The combinations MARFIM x FRONTANA, MARFIM x ITAIPU, MARFIM x QUARTZO presented reduced values for %GG in the F₁ generation. The combinations BRS 220 x SUPERA, BRS 220 x VALENTE and VALENTE x ITAIPU presented reduced mean values for %GG, suggesting a reduced contribution of favorable alleles from the parental VALENTE, and a reduced complementary action with alleles from the other genotypes, was translating in a reduced tolerance to pre-harvesting sprouting. The character %GG in the genotypes FRONTANA and QUARTZO enable hybrid F₁ populations with high performance per se. Also, predictable performances were found for the genotypes QUARTZO and FRONTANA with high and negative GCA values for %GG indicating a contribution of addiitive gene effects for the increase in dormancy, decrease in effects caused by the germination and higher flour quality. For SCA, the genotypes BRS 220, MARFIM, BRS 194 and ITAIPU presented negative values for the character %GG, indicating the presence of heterosis when this genotypes are crossed. The pre-harvesting sprouting is controlled by genes with additive (GCA) and non-additive (SCA) effects. The genotypes QUARTZO and FRONTANA present the best potential to be used in crossing blocks aiming to improve for pre-harvesting sprouting.