Climatic constraints behind spatial and temporal variability of wheat yields in the Pampa region of Argentina

Abstract

Context

The Argentine wheat belt region is centered on the humid pampas, i.e. the main wheat producing area of  Argentina and is considered at global scale one of the most important in the world for its production of cereals and oilseeds crops. In this whole area wheat is exposed to contrasting climatic conditions.

Objectives

The main objective was to study, at a regional scale, the spatial and temporal variability of wheat yields in Argentina and its relationship with climatic conditions. We seek to answer 3 questions: (a) How does climate affect the spatial distribution of wheat yields in the Pampas region? (b) What are the main agroclimatic variables that modulate the temporal variability of wheat yields in the Pampas region? and (c) Based on what is identified in “b”, is it possible to determine areas of homogeneous behavior?

Methods

A large agrometeorological data base was contrasted with the yield of wheat recorded in the main area of wheat production in Argentina from 1985 to 2021. The CRONOTRIGO (http://cronotrigo.agro.uba.ar/) model was used to establish the phenology of different wheat cultivars for a range of optimal sowing dates and associate phenological stages to the climatic variables.

Results and conclusions

In the studied area average yield ranged from 1200 to 3600 Kg ha⁻¹, with the lowest and the highest yields in the north and southeast region, respectively. The combination of yield variability with agroclimatic variables allowed the identification of two mega-environments, mainly affected by the water deficits and by the VPD during the critical period, maximum temperatures, and heat shock events during grain-filling period at the west, and photothermal quotient during the critical period at the east. Mega-environment located at the east showed a lower climatic influence over yield variability than that located at the west of the wheat belt. This analysis allowed us to identify homogeneous regions in terms of agroclimatic variables affecting yield variability in wheat.

Significance

This information provides insight for understanding the spatio-temporal variation in wheat yield, which will help to reduce yield gaps by adjusting agronomic management according to the main environmental constraint.