INHERITANCE OF BORON STATUS IN SUNFLOWER

The breeding of sunflower cultivars adapted to soils low in available B may have particular relevance since this crop has a high B requirement, and B deficiency is widespread in certain sunflower-producing areas. A field study was carried out on a Doveton clay loam (thermic Typic Rhodustult) in which 6 sunflower inbreds and their 15 hybrids (excluding reciprocals) were tested for differences in B status as measured by the B concentration in the topmost mature leaf at flowering. The 21 entries were grown with and without B fertilization. Significant differences were recorded among parents, among offspring and between parents and offspring with respect to B concentrations in the leaf, number of plants with B deficiency symptoms and seed yields. Highly significant general combining ability (GCA) effects were recorded, whereas the specific combining ability effects generally were nonsignificant. Highly significant positive correlations were recorded between the means and the GCA effects of the inbreds in the characters measured. The susceptibility of a hybrid to B deficiency could be predicted from the performance of its parents since those inbreds with a high B status readily passed this character to their offspring.