IFEVA   02662
INSTITUTO DE INVESTIGACIONES FISIOLOGICAS Y ECOLOGICAS VINCULADAS A LA AGRICULTURA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Grain yield generation in wheat and barley under contrasting soil nitrogen levels.
Autor/es:
ABELEDO GL; ALZUETA I; MIRALLES DJ
Reunión:
Congreso; 6th. International Crop Science Conference, Bento Goncalvez,; 2012
Resumen:
Comparative studies between wheat and barley aimed at understanding the ecophysiological basis related to yield generation in response to different nitrogen (N) conditions are scarce. The main objective of the work was to analyze biomass generation and its partitioning to the grains in wheat and barley cultivars under contrasting soil N levels at sowing (from 40 to 200 kg N ha-1). Changes in biomass production (measured in terms of radiation interception and radiation use efficiency), grain yield (GY) and its numerical components were evaluated. GY ranged from ca. 195 to 750 g m-2 and, independently of the N condition, barley cultivars showed higher or similar GY than wheat cultivars. GY variations were explained by changes in grain number per unit area (R2 = 0.78, P < 0.001); however, wheat and barley differed in the way to generate grain yield. While in barley spikes m-2 was the numerical component that better explained variations in grains m-2, changes in grain number m-2 in wheat were associated with variations in spikes m-2 as well as in grains spike-1. Barley cultivars showed higher harvest index (P < 0.01) than wheat (mean of 0.49 and 0.37, respectively). Differences between species in partitioning were associated with variations in the chaff dry weight at maturity as wheat showed a higher proportion of chaff in the spike at maturity than barley (means of 27 and 17%, respectively). Barley also showed higher efficiency than wheat in establishing grains per gram of chaff. The same trend maintained after correcting the data by the proportion of hull in the barley grains. Thus, variations in grain yield between species (or cultivars) were modulated through changes in harvest index (due to mainly variations in the chaff proportion) and the efficiency of establishing grain per unit of biomass of spike at maturity. Despite the lack of differences in total above-ground biomass between species, wheat and barley differed in variables associated with biomass generation. Total photosynthetically active radiation (PAR) absorbed was higher in barley than in wheat, but the efficiency with which absorbed PAR was converted into biomass was superior in wheat than in barley. In both species, N variations modified GY through changes in total biomass generated at maturity without modifications in harvest index. Analysis of the differences between species in yield generation is a tool for improving their performance under farm conditions (by breeding or management).