PREDICTING PRE-HARVEST SPROUTING SUSCEPTIBILITY IN BARLEY: LOOKING FOR “SENSITIVITY WINDOWS” TO TEMPERATURE THROUGHOUT GRAIN FILLING IN VARIOUS COMMERCIAL CULTIVARS

GUALANO N. Y BENECH-ARNOLD R.

Mendoza, Argentina

Simposio; 11th International Symposium on Pre-Harvest Sprouting in Cereals; 2007

Under particular environmental conditions, the lack of dormancy typical of the modern cultivars of malting barley (Hordeum vulgare L.) is enhanced, leading, in case of rainy weather before harvest, to pre-germination and/or sprouting (PHS) of grains in the mother plant. Both adversities, respectively, reduce the storability and viability of the seeds, which are requirements for malting use. A quantitative relationship between the air temperature during a narrow window of the grain filling period and the PHS susceptibility of the crop was established for one barley cultivar. We sought the existence of similar sensitivity windows and test their PHS susceptibility predictive value for a wide range of barley cultivars commonly sown in Argentina (Quilmes Ayelén, Q. Painé, Q. Palomar, B1215 and Scarlett). Several sowing dates were used to explore a wide range of thermal conditions during grain filling. Grain filling period was divided into 50ºCday intervals and mean temperature was calculated for each one. Grain dormancy was monitored using a germination index (GI). For all cultivars (except B1215) significant regressions (p < 0.05) were obtained between the temperature during the last stages of seed development (275-350ºCday after anthesis) and the GI half-way between physiological and harvest maturity. Preliminary validation of the predictive models constructed with these regressions showed that the PHS susceptibility of a barley crop was sub estimated. However, the linear relationship between temperature in the “sensitivity window” and GI after physiological maturity was confirmed. This suggests the action of environmental factor/s other than temperature on the dormancy release pattern.