COMPARISON OF THE EFFECT OF nap AND pol CYTOPLASMS ON THE PERFORMANCE OF INTERCULTIVAR SUMMER OILSEED RAPE HYBRIDS

Abstract

The objective of this study was to compare the performance of male fertility restored intercultivar F1 hybrids in the nap and pol cytoplasms to determine the relative effect on performance of these two male sterility inducing cytoplasms. F1 hybrids (all were 2n = 39 because a common 2n = 40 restorer line was used to produce the F1 hybrids) in both cytoplasms exhibited superior relative performance compared to the conventional cultivar Regent for seed yield, total dry matter and total protein yield. F1 hybrids in the pol cytoplasm performed significantly poorer than F1 hybrids in the nap cytoplasm for seed yield, total dry matter, harvest index, percent oil, total oil yield, and total protein yield. These results suggest a biological cost associated with the presence of the pol cytoplasm. The cost of the pol cytoplasm, relative to the nap cytoplasm, was affected by parental cultivar, but was consistent over a variety of environments.Key words: Cytoplasm cost, Brassica napus L., cytoplasmic male sterility, heterosis, hybrid