VARIATION IN TEMPERATE CEREALS IN RAIN-FED ENVIRONMENTS .1. GRAIN-YIELD, BIOMASS AND AGRONOMIC CHARACTERISTICS

The relative performance of barley, bread wheat, durum wheat, triticale and oats was compared in rainfed environments to identify any outstanding features of these species that contribute to high grain yield. Fourteen high-yielding cultivars with a range of flowering times were evaluated in five rainfed environments. There was a terminal drought in all environments but water deficit was not a significant factor before flowering. Barley, which flowered earliest, had a 25% higher grain yield than the other species when averaged over all cultivars. However, the highest-yielding barley had a 39% higher yield than the best wheat when averaged over all environments. There was little variation in the mean grain yield between the durum and bread wheats, oats and triticale but there was substantial variation within each species. After correcting for the husk enclosing the barley grain, the grain yield of barley was 17% higher than that of the other species whereas the highest-yielding barley yielded 28% more than the best wheat. With the exception of oats this higher yield was achieved by a higher above-ground dry mass (AGDM) rather than a higher harvest index. The AGDM of barley averaged over all environments was 22%, 16%, 13% and 2% higher than those of durum wheat, oats, bread wheat and triticale respectively. Barley also had a more extensive and heavier root system than did bread wheat and triticale. Root mass of barley was estimated to be 35% greater, with most of the difference occurring in the top 15 cm, but differences occurred down to 90 cm. No differences were found in rooting depth.