CLIMATE, YIELD AND WHEAT GRAIN PROTEIN CONTENT IN THE SEMIARID REGION OF ARGENTINA

Abstract

In order to establish nitrogen fertilization levels that promote yield increases and protein
content compatible with the wheat quality standard, 18 experiments were carried out in
the semi-arid area of the southwest of the Buenos Aires province between 2016 and 2019.
At tillering five nitrogen (N) levels were applied: Control (mineral N in the 0-0.6 m soil
layer, Ns), 100, 120, 140 and 160 kg N ha-1 determined as Ns + N of the fertilizer applied
as broadcast urea up to the proposed level. At anthesis foliar fertilizer (20 kg N ha-1) was
applied in half of each plot. N levels of 100 and 120N were enough to increase yields, but
they only achieved protein standard with high soil fertility or with yield less than 2000 kg
ha-1. In soils of medium fertility, levels of 140N were required to obtain yields greater than 3,500 kg ha-1 and comply with the standard. When some environmental effect depressed
grain production, the standard was achieved without fertilization or with lower N levels.
On average over N levels at tillering, fertilization at anthesis showed increases in protein
content of 0.8 points but did not affect yield. At equal contribution of N, the division of
the dose between tillering and anthesis did not affect grain protein content. This makes it
possible to decide the last fertilization based on the state of the crop, the expected yield
and shorter-term environmental forecasts.