Search

This study was carried out to determine the critical period in oats, which is relevant for locating that period under the best climatic conditions. Trials were conducted in the Argentinian Pampas during 2015–2016, using four oat genotypes with different growing cycle. The experimental design was a split-split-plot, with three replications; being genotypes the main plot and the subplots six shading treatments [unshaded control and five shaded treatments during 25 days, from different growth stages [GS31 (first-visible-node), GS32, GS33, GS40 (boot), and GS60 (flowering)]. GY and its components [(number of panicles (NP), grains number per panicles (GNP), grains number per square meter (GN), and thousand kernel weight (TKW)] were determined at harvest. GY was sensitive to radiation limitations, showing falls of 20 to 70%, varying according to shading and genotypes. The shading mainly affected GY between GS32 and a few days after flowering in the short-intermediate cycle genotypes, and from GS33 in those with the longest cycles. Regression analysis showed that GN was the most affected yield component, being GNP more sensitive to stress and closely related to GN than NP. TKW showed less magnitude reductions (4.6 to 17.4%), being the shading at GS40, the one that caused the greatest decreases. [ABSTRACT FROM AUTHOR]

Abstract: 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 5000kgha−1 in northern locations to 7300kgha−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. [Copyright &y& Elsevier]