Abstract
Amon g the hybrids of the cultivated form named 'Batavo', originating from Holland, and 6 primitive forms of the yellow lupin was one hybrid combination found (Batavo X primitive No. 5), which in F2 and F3 gives fertile and sterile plants with the ratio 3 : 1. The gene causing sterility was appeased as a result of crossing over at the time of prophase of meiosis in the sporogenic cells of F1 plants. This gene in homozygotic condition in F2 and F3 plants causes the coalescence of chromosomes, disturbances in the process of meiosis and microsporogenesis what leads to forms with non viable microspores. The sterile plants blossom abundantly but they give not pods and seeds.