Contribution of the early-established plant hierarchies to maize crop responses to N fertilization

ROSSINI, M.A.; OTEGUI, M.E.; MARTINEZ, E.L.; MADDONNI, G.A.

FIELD CROPS RESEARCH

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2018 vol. 216 p. 141 - 149

0378-4290

Maize crop production depends on nitrogen (N) availability, N uptake by the crop and the efficiency with which absorbed N is used to produce biomass (NUE BIOM) or grain yield (NUE GRAIN). This framework assumes unique efficiency values for the whole stand, with no distinction among plants in spite of the inherent inter-plant variability of plant growth, especially under crowding stress. In this work we assessed the degree of contribution of different early-established groups of plants to crop responses to N fertilization of two maize hybrids (H) with different tolerance to crowding stress (high for AX820 and low for AX877) cultivated at two stand densities (9 and 12 pl m-2). Groups corresponded to the lower, mid and upper terciles (Ts) of the crop, representing dominated, intermediate and dominant plants, respectively. In most cases, lower and mid Ts had a greater participation in crop biomass and grain yield responses to N fertilization. The response of NUE BIOM and NUE GRAIN to N fertilization was higher for the lower and mid Ts than for the upper T. For each N level, crop NUE GRAIN was negatively related to inter-plant variability in plant NUE GRAIN. When no N was added, the reduction in crop NUE GRAIN of both hybrids was mainly caused by the increased inter-plant variability in plant N uptake (i.e. resource capture). Additionally, the crowding-intolerant AX877 under the most stressful condition (12 pl m-2 and no added N) had a reduced crop NUE GRAIN due to the enhanced plant-to-plant variability in grain yield (i.e. resource use). Consequently, the early-established plant-to-plant variability pattern conditioned crop NUE GRAIN; the predominant path was hybrid dependent.