COMPARISON OF THE EFFECT OF NAP AND POL CYTOPLASMS ON THE PERFORMANCEOF 3 SUMMER OILSEED RAPE CULTIVAR-DERIVED ISOLINE PAIRS

The pol cytoplasm is a male sterile cytoplasm with potential for use i n hybrid summer rape (Brassica napus L.) seed production while the nap cytoplasm is the one most commonly encountered in summer rape cultiva rs. The objective of this study was to compare the performance of thre e cultivar-derived summer rape isoline pairs in the nap and pol cytopl asms to determine the relative effect on performance of these two cyto plasms. One nap line yielded significantly more than its corresponding pol line, three nap lines had significantly higher oil content than t heir corresponding pol lines, two nap lines had significantly higher p rotein content than their corresponding pol lines, and two nap lines p roduced significantly more seed energy than their corresponding pol li nes. There are pleiotropic negative effects (biological costs) associa ted with the pol cytoplasm. These negative effects are affected by nuc lear genotype and appear to be related to the depth of male sterility expressed in the derived pol A-line.