VARIABILIDAD DEL RENDIMIENTO POR PLANTA DE MAÍZ ANTE LA FERTILIZACIÓN NITROGENADA

CAVIGLIA, OP; MELCHIORI, RJM.; GVOZDENOVICH, JJ; FACCENDINI, N

Rosario, Argentina

Congreso; VII Congreso Nacional de Maíz; 2005

Nitrogen (N) can affect yield per plant (RTOpl) variability and yield per unit area in maize. The mechanism involved in this response could be related to yield improvement of dominated plants, i.e. those in 33th percentile of biomass distribution. The objective of this work was to evaluate the effect of N on: yield per plant variability, the relationships between dominated and dominant plants, and its association to yield per unit area. In 5 experiments, carried out in Paraná, Argentina (31º50´ S), yield and shoot biomass per plant were evaluated on 20 consecutive individuals per plot. Treatments were laid out in a complete block design and included two N rates (0 and 140-210 kg N ha-1). Yield per unit area (RTOA) was estimated using RTOpl and interplant spacing in the rows. Coefficient of variation (CV) of RTOpl was also calculated. Plants located in 33 and 67th percentile of biomass distribution were considered dominated and dominant, respectively. RTOA increased by effect of N in 4 of 5 experiments from 4785-9422 to 9125-12000 kg ha-1. RTOA was strongly (p<0.0001) related to RTOpl, however CV was not affected by N. RTOpl of dominated plants was increased by N effect in a higher proportion than in dominant ones, but not enough to reduce CV. Nonetheless, relative difference between dominated and dominant plants, i.e. difference as a percentage of dominated plants, was directly associated to CV. The slope of that function was more higher in well-fertilized treatments than in controls. Pooling all data, RTOpl and RTOA were negative associated  to CV. A multiple, linear, model that included CV and RTOpl accounted (p<0.0001) for 90% of RTOA variation.