The Impacts of Interplant Variation on Aboveground Biomass, Grain Yield, and Harvest Index in Maize

Stability of maize (Zea mays L.) hybrids has been major research topics. So far, more emphasis has been placed on the per area grain yield variation, rather than on the plant-to-plant variability within the crop stand, i.e. intra-crop variation. The acquired intra-crop variation of different hybrids was recorded across five environments via the coefficient of variation (CV) of plant-to-plant variability for seven agronomic traits. Hybrids were less variable for plant height (PH) with CVs ranging up to 23%, and most variable for grain yield (GY) with a CV ceiling of 96%. A general negative association of plant-to-plant variability with GY pinpointed hybrids prone to intra-crop variation to be less efficient to capture the available inputs. An adverse affection of intra-crop variation on aboveground biomass (AB) was relatively moderate, while on harvest index (HI) occasional (albeit consistent in one environment). A test established to search whether variance and CV were systematically dependent on mean reflecting a meaningless CV ~ mean negative relationship, was occasionally positive only for AB but not for GY and HI, strengthening thus the value of CV for plant-to-plant variability as a measure of stability. There was also a tendency relationship of AB, GY or HI with interplant variation to follow the exponential than the linear declining pattern, i.e. the Taylor power law (TPL) model. The adverse effect of the interplant variation was more pronounced on GY compared to AB and HI. Consequently, crop stand uniformity seems imperative for optimal use of resources. The findings brought into the forefront the single-plant performance as a crucial breeding goal to moderate the intra-specific competition and acquired interplant variation.