Meta-analysis of nitrogen fertilization effects on wheat grain protein in Argentina

by Open Science Repository Agriculture
(July 2013)

Abstract

The effect of nitrogen (N) fertilization on yield and grain protein concentration (PC) in wheat was analyzed using a meta-analysis approach. N recovery (NR) was also calculated. We pooled 59 independent field trials containing 171 treatment means conducted on 20 different locations in the Argentinean Pampas from 1995 to 2008. Data was collected from scientific journals, technical reports and published and unpublished studies from the authors. Variables included in the database for each trail were: year, location, ecological zone, variety quality group, timing and rate of N fertilization. For grain yield and PC, treatment means were classified into four groups: early high, early low, late high and late low. For NR analysis, trials were classified into soil-applied N fertilizer, applied up to tillering stage, and foliar-applied N, applied during stem elongation or later. Early soil N fertilization increased yield by 1489 kg ha^-1 and PC by 0.64% when more than 100 kg N ha^-1 were applied and by 599 kg ha^-1 with lower N rates, but had no effect on PC. Late foliar-applied N fertilization increased PC by 1.31% points when the N rate was equal or greater than 20 kg ha^-1 , but had no effect on yield. Lower N rates increased PC by 0.50% points and slightly increased yield by 270 kg ha^-1. Late foliar N fertilization showed a trend for greater NR, averaging 19.01%, than early soil-applied fertilization which averaged 12.71%. Even though a frequent recommendation in Argentina is early N application for increasing PC, here we demonstrate that foliar N fertilization after heading is more likely to increase PC than early soil-applied N.

Keywords: wheat, N fertilization, grain protein concentration.

Full text

Meta-analysis of nitrogen fertilization effects on wheat grain protein in Argentina