Pollen control and spatial and temporal adjustment in evaluation of kernel composition of maize inbreds

Maize (Zea mays L) pollen can have an immediate effect on kernel oil, protein, and starch concentration, and evaluation of kernel composition is often done with self pollination. Procedures for adjusting for spatial or temporal variation have not been studied for kernel composition traits in maize. Our objectives were to (i) characterize the effect of pollen control on protein, oil, and starch concentrations in maize inbreds, (ii) determine the impact of open and self pollination on relative ranking of inbreds, and (iii) determine if spatial or temporal adjustments are useful for kernel composition when plants are open pollinated. Thirty inbreds were evaluated for kernel protein, oil, and starch concentrations in open- and self-pollinated treatments at two planting dates in St. Paul, MN in summer 2011. The inbreds differed significantly for oil, protein, and starch concentrations. However, pollination treatment was not significant for oil, protein, or starch concentration. Simple correlations and rank correlations between open- and self-pollinated treatments were high for oil (0.93), protein (0.83 - 0.85), and starch (0.73 - 0.82) concentrations. Neither spatial nor temporal adjustments improved estimates of open- pollinated kernel composition over unadjusted, open-pollinated means. Overall, our results suggested that when relative performance of inbreds is more important than absolute concentrations, maize inbreds can be evaluated for oil, protein, and starch concentrations without the pollen source confounding differences among entries.