VARIATION IN INDUCTION OF HOMOEOLOGOUS PAIRING AMONG CHROMOSOMES OF 6X HORDEUM-PARODII AS A RESULT OF 3 TRITICALE (XTRITICOSECALE WITTMACK) CULTIVARS

Intergeneric hybrids were obtained between Hordeum parodii Covas s.l. (6x) and three cultivars of triticale (.times. Triticosecale) at frequencies of 0.47 to 1.21% of pollinated florets. The triticale cultivars varied in their chromosome constitutions of the rye genome as well as the telomeric heterochromatin content of some of the rye chromosomes. The average chiasmata frequency per cell varied from 0.58 to 13.14 in different hybrid combinations. The differences in the chiasmata frequencies in the different hybrid combinations were attributed to a meiotic pairing control mechanism in H. parodii whose function was affected primarily by the rye chromosome constitutions of the triticale cultivars and to a lesser extent by the heterochromatin content of the rye chromosomes.