Changes in nitrogen concentrations of corn leaves near silking time

Abstract

Abstract Precision in tissue testing to characterize the nitrogen (N) status of corn (Zea mays L.) is more important than ever before because of current concerns about the effects of N fertilizers on environmental quality. This study was conducted to assess the importance of errors associated with differences in physiological age of plants when plots receiving various rates of N fertilizer are sampled at a single time during the period of silk emergence. Ear leaf samples were collected at four times between early and late silking from five experiments at different locations in Iowa during 1987. Nitrogen deficiencies delayed silking by less than 2 days. After adjustments for delays in the onset of silking, the rates of silk emergence were similar for all N rates. Rapid rates of silk emergence indicated that it is practically impossible to sample leaves at a specific silking percentage such as 50 or 75%. Leaf N concentrations were not significantly influenced by time of sampling during the period of silk em...