R. Maich

The meiotic index in hexaploid triticale. Direct and indirect ways to improve it

Abstract The starting point in the chain of events concerning fertility is the meiotic division. Thus, to improve the meiotic performance of triticale is a sure biological way of promote its evolution. Sixty F2 derived families were evaluated during 1997 (F2 :.3) and 1998 (F2 : 4), in order to measure the direct and indirect responses to selection for the improved percentage of normal tetrads, or meiotic index, in hexaploid triticale. A significant direct response to selection in respect to the meiotic index was observed, but not indirectly through spikelet fertility. However, we have found that there is the possibility for selection at the end of the reproductive process (i.e. per spikelet fertility) without a negative effect on the percentage of normal tetrads.

Is it possible to obtain cytologically superior recombinants within a cyclically grain yield improved hexaploid triticale population

Abstract The aim of the present investigation was to determine the existence of better genic recombinant lines with respect to the meiotic index in a cyclically improved hexaploid triticale population. From the 12 F2: 3 families selected from the original population (C0) and from the 17 S1 superior progenies belonging to the new C1 population, 2 random samples of five families each one were taken. Additionally, five check varieties were evaluated. Two sowing dates were considered for evaluation, utilizing a completely randomized design with four replications for each. The meiotic index (MI) and grain yield (GY) variables were measured. Among experimental materials, one family showed a MI mean value significantly superior to that of the parental variety used as grain producer (Tatú), even when it was significantly smaller than that of the forage cultivars. The GY of this family also showed a significantly superior mean value with respect to the mentioned grain variety. The appearance of an agronomically and cytologically superior recombinant family was verified after two recombination instances (C1); on the other hand, when only one recombination process did occur, none of the C0 derived family was significantly superior to the parental grain variety in both aspects.