Dry matter accumulation and pattern of radiation interception in wheat and barley

MIGNONE CM; ABELEDO LG

Mar del Plata, Argentina

Conferencia; 7th International Wheat Conference; 2005

The main objectives of this work were to compare (i) dry matter (DM) accumulation and its partitioning to the reproductive organs, and (ii) to analyze the pattern of radiation interception and radiation use efficiency (RUE) along the crop cycle of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). A field experiment was conducted at the Faculty of Agronomy of the University of Buenos Aires (34º 35´ S, 58º 29´ W). Treatments consisted of a factorial combination of a low-yielding (released to the market ca. 20 years ago) and a high-yielding cultivar (a modern cultivar) of wheat and barley under two levels of nitrogen (N) availability at sowing (70 and 160 kgN ha-1). Dynamics of leaf and tillering appearance, photosynthetically active intercepted radiation (PAR), and DM accumulation were measured along the crop cycle. Grain yield increased from 330 to 475 g m-2 and from 210 to 330 g m-2 for barley and wheat, respectively, as N availability was increased from 70 to 160 kgN ha-1. Although maximum grain yield of wheat was lower than barley, the yield of the high-yielding wheat cultivar was more responsive to the increase in N availability than that of barley. Grain yield was significantly correlated with both total above-ground biomass at maturity (r2= 0.67  p<0.05) and harvest index (r2= 0.91  p<0.05). In addition, ear dry matter at anthesis explained variations in grain yield (r2= 0.69  p<0.05). The ratio between ear DM and stem DM, measured from booting to maturity, was higher in barley than in wheat. Final number of tillers per main stem was higher in barley (2.1) than in wheat (1.0), this which was associated with differences in tiller mortality. Rate of tiller appearance and rate of leaf appearance was similar between wheat and barley. Along the crop cycle, barley showed a higher efficiency in PAR intercepted than wheat. RUE was not different between both crops.