Kernel number prediction in maize under nitrogen or water stress

Final kernel number in maize (Zea mayvs L.) is closely associated with the physiological condition of the crop during the critical period bracketing silking. The objective of this study was to determine whether there is a common underlying relationship between kernel number per plant (KNP) and plant growth rate (PGR) during that critical period when plant growth varies because of different abiotic stresses. A relationship between KNP and PGR obtained from a previous study of variation in plant density and incident radiation was used as reference. KNP and PGR were measured in experiments in which incident radiation per plant, nitrogen (N), and water availabilities were the experimental sources of variation. The equation fitted to the data obtained at different radiation levels explained 72% of the variation in the data obtained at different levels of N or water availability. Moreover, different models for each set of data did not provide a significantly better fit than a single model for the two sets of data combined. A common relationship between KNP and PGR was also obtained when N supply and water availability were variable. The relationship between KNP and PGR obtained for treatments in which PGR was varied through plant density and shading also could predict KNP for conditions in which PGR was affected by water and/or N deficiencies. The PGR during the critical period of kernel set is a good predictor of the capacity of the maize plant to set kernels under a wide range of environmental and management practices.