Corn (Zea mays L.) Management Affects On Plant-to-Plant Variabillity and Grain Yield.

Corn (Zea mays L.) Management Affects on Plant-to-Plant Variability and Grain Yield By: Aric Bos - Department of Plant Agriculture, University of Guelph, ON. N1G 2W1 Advisor: Bill Deen Ð Associate Professor, Department of Plant Agriculture, University of Guelph, ON. N1G 2W1 Certain conditions within a corn field may result in plant spacing non-uniformities, temporal emergence non-uniformities, or post-emergent growth reductions that cause differences in plant growth stage and/or development, increasing the incidence of plant-to-plant variability (PPV). PPV has been associated with yield reductions in corn, particularly if the PPV was caused by temporal variation in emergence. However, others suggest that as long as plants maintain a harvest index of 50%, PPV may not be a concern because of compensatory yield. These confounding results suggest the underlying processes behind these yield reductions are not fully understood. Corn growers can influence growing conditions through management decisions such as rotation, tillage, and nitrogen fertilizer application rates Ð all of which have been associated with corn yields. The objectives of this research are to determine the affect various management systems have on PPV and the correlation between PPV and grain yield. We hypothesize that i.) corn stands will have lower PPV when managed with conventional tillage practices, diverse cropping rotations, and agronomically optimal nitrogen fertilizer rates; and ii.) grain yield is negatively correlated with PPV. Field experiments will be conducted using existing trials at the Elora Research Station (long term rotation, tillage, and nitrogen fertilizer trials) as well as at the University of Guelph, Ridgetown campus (long term rotation/tillage/fertilizer trial). Plant-level measurements will be taken from plants within a randomly assigned 2m section of the plots, which include: emergence, silking and anthesis dates; height and leaf counts at regular intervals; biomass and growth rate estimates at silking; and grain and plant dry weights at harvest. In doing so a measure of PPV, quantified by the coefficient of variation of plant height, leaf number, and dry matter, for each management system can be attained. This research will have practical application in agronomic decision-making at a producer level.