Contribution of contrasting plant hierarchies to the response to N fertilizer in maize

CAVIGLIA, O.P.; MELCHIORI, R.J.M.

FIELD CROPS RESEARCH

ELSEVIER SCIENCE BV

Año: 2011 vol. 122 p. 131 - 139

0378-4290

The typical size structuring process that occurs as a consequence of intra-specific competition in maize promotes the appearance of contrasting plant hierarchies (i.e. dominated and dominant individuals). This process may become more intense under low nitrogen (N) availability. The alleviation of plant competition by N addition may reduce plant yield variability through a differential response to N in individuals of contrasting hierarchies. In this work, the response to N of dominated and dominant plants from stands with contrasting N supply (0 to 140-200 kg N ha-1) was examined on 11 experiments carried out in Paraná, Argentina, (31º50’ S; 60 º31’ W) in a broad range of growing conditions that included the variation of the year, genotype, plant population and sowing date. Our objectives were: i) to evaluate the response to N in contrasting plant hierarchies of maize, ii) to quantify the contribution of dominated and dominant plants to the response to N of the overall stand and, iii) to study the effect of N on relationships between plant hierarchies and stand variability. Response to N of yield per plant was associated with biomass per plant in non-fertilized controls, tending to be higher in plants with low biomass. The response to N of yield per unit area (i.e., considering all individuals of the stand) was related to the response to N of dominant and dominated plants (P50-60%), dominant plants had a considerable lower response than dominated plants, whereas at a lower level of response (