Weakness of apetalous rape varieties with different cytoplasm types and its surmountable path in Brassica napus.

The comparison tests of some Brassica nupus apetalous rape varieties with different cytoplasm types were carried out to find the weakness of poor growth vigor and serious chlorosis of heart leaf under lower temperature in winter and to probe into the corresponding surmountable path.The results showed that the growth vigor and heart leaves of most lines with Brassia campestris cytoplasm and Brassia juncea cytoplasm were poor and serious chlorosis under lower temperature in winter except the varieties with Brassica nupus cytoplasm.The stability of apetalous character of the apetalous lines with different cytoplasm types was lines with Brassia juncea cytoplasmlines with Brassica nupus cytoplasmlines with Brassia campestris cytoplasm and there was significant difference in the stability of apetalous character among different lines with the same cytoplasm type.The number of flowers with petals increased from inflorescence bottom to top in all tested lines,especially the number of flowers with petals of the upper inflorescence obviously increased during later flowering stage.The death buds occurred on the inflorescence bottom,especially on the main inflorescence bottom in the apetalous sterile lines and sterile lines with normal petals,and their death bud rate was similar basically,but there was obvious difference among different years.The closed buds occurred in apetalous sterile lines seriously and its proportion was up to 28.6%～33.4%.The pod and seed setting of the apetalous sterile lines was poor and there was obvious difference in pod and seed setting between apetalous sterile lines and sterile lines with normal petals.