580 CROP SCIENCE, VOL. 47, MARCH–APRIL 2007 ABSTRACT Breeders face many complex choices in the design of effi cient crossing and selection strategies aimed at combining desired alleles into a single target genotype. Both population genetic theory and a breeding simulation tool were used to study the effects of different strategies on population size and number of marker assays required to recov...

Effects of inbreeding and heterosis and the difference between them were estimated by comparing linecross (L), topcross (T), inbred (I) and control line (C) Hereford females for reproductive and preweaning growth traits of their progeny. Inbred females (average inbreeding coefficient = 26.5%) originated from four single-sire inbred lines. Control females (average inbreeding coefficient = 6.9%) ...

Two-tester analysis of topcross crossings soybean varieties, which differ in valuable economic traits and ecological geographical origin, was used the research. According to indicators combining ability, value varieties determined by elements crop structure. In hybrid populations, degree frequency positive transgressions have been determined, is a selection material for creation new hybridizati...

Abstract Single-cross pearl millet hybrids are widely grown in India, but this cultivar type has not been adopted Africa. Hybrids from India have proven to be highly susceptible downy mildew disease Africa, the continent where originated. We investigated an alternative strategy of growing topcross both parents African origin and only partially inbred. root characteristics – length, diameter, ar...

Breeds of larger mature size tend to grow more rapidly and be older when attaining a given level of fatness. Hereford, Limousin, and Piedmontese are of approximately equal mature size and yet may vary in body composition at a given degree of maturity. However, direct comparisons among these three breeds were not found. Therefore, the objective of this research was to compare Hereford, Limousin,...

Topcrosses are routinely used in maize-hybrid programs. This study aimed to evaluate heterosis components and combining ability predict hybrid means between synthetics from two groups of S1 maize lines using the intergroup topcrosses model that includes S2 lines. Two groups, each with 30 lines, were crossed an topcross system, a mixture one group as tester for contrasting group. Simultaneously,...