R-nj aleurone color selection and grain-filling responses in opaque-2 maize

Summary Field experiments were conducted to determine which grain-filling characteristics were affected by the o2 gene and whether mass selection for degree of aleurone anthocyanin pigmentation controlled by R-nj could improve the grain-fill deficiencies associated with the o2 (opaque) phenotype of a mazie (Zea mays L.) synthetic (NDSE). Divergent mass selection was used to develop high color (HC), low color (LC), and randomly sampled (RC) check substrains. Lag phase duration (LPD), effective filling period (EFPD), and rate of dry matter accumulation (RDMA) for both opaque and normal dent phenotypes of third cycle HC, LC, and RC substrains were evaluated at three N fertility levels for each of two years at Fargo. Normal (O2) pollen produced heavier kernels than o2 pollen at all N rates in 1982. Over years, O2 pollinations averaged 11% longer EFPDs than o2 pollinations, but LPDs were usually longer for o2 pollinations. HC strains averaged 5.6% higher RDMA than RC strains across pollen types while LC strains had higher RDMA than RC strains only for O2 pollinations. These results indicate that selection for LC improved several traits which were deficient in opaque-2 maize and that use of the R-nj gene may be useful in improving opaque-2 maize.Journal article No. 1756 of the North Dakota Agric. Exp. Stn., Fargo