Genetic progress in Argentine bread wheat varieties released between 1918 and 2011: Changes in physiological and numerical yield components?

LO VALVO P; MIRALLES D J; SERRAGO RA

FIELD CROPS RESEARCH

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2017

0378-4290

Argentina from 1918 to 2011 (emphasizing the last 20 years) characterizing different agronomic traits of interestfor breeders. Experiments were carried out with a wide range of bread wheat cultivars and conducted under fieldconditions without nutritional and water restrictions. Yields showed a significant (R2 =0.68) tri-linear trendwhen associated with the cultivar?s year of release. Until the 40s, when the first inflection point occurred, thegenetic progress in terms of yield was 0.8 kg ha−1 yr−1 (0.02% yr−1). Between 1940 and 1999, yield geneticprogress reached its highest value (51 kg ha−1 yr−1; 1.17% yr−1) but changed after 1999 when values becamelower compared to the previous period, showing a value of 14 kg ha−1 yr−1 (0.18% yr−1). Changes in grainyield were mostly explained by increases in harvest index and not by those in above-ground biomass. Plantheight showed a negative bi-linear trend with the year of release, reaching an inflexion point well before theintrogression of semi-dwarfing genes in commercial cultivars. Grain number increased ca. 63% when moderncultivars were compared to older ones, which explains most of the grain yield changes. In contrast to grainnumber, no significant differences between old and modern cultivars were found for grain weight, with averagevalues of ca. 30 mg grain−1 for all environments explored.