Evaluating wheat yield potential determination in the Argentine Pampas

The Argentinean Pampas are considered among the most productive areas of the world. However, few research has been done to explore its potential and constraining factors for wheat production. The objective of this paper was to evaluate variability of wheat yield and yield components potential in the Pampas. For this purpose, a modelling approach was used using 30 years climatic series of various locations distributed along the Pampas. Two biologically founded assumptions related to wheat yield determination were used: (1) potential grain number (GN) is associated with a photothermal quotient (PTQ); and (2) potential grain weight (GW) depends on mean temperature during the grain filling period (TGF). Mean wheat yield potential in the Pampas varied between 5000 kg ha−1 in northern locations to 7300 kg ha−1 in southern ones. GN showed greater variability than GW both, among locations (spatial scale) and years (temporal scale). Anthesis date appeared as a strong yield potential determinant factor; A 10-day delay in anthesis date produce substantial changes in GN and GW, depending on location latitude. This was related to the specific combination of crop phenological development and radiation and temperature changes in the region. A temporal decrease in PTQ during the period 1971–2002 was observed. This decrease was more associated with a radiation decrease than with a temperature increase during this period. TGF did not show any trend during the same period. The importance of estimating wheat yield potential yield and yield-gap reduction is discussed.