Mixed cropping of barley (Hordeum vulgare) and wheat (Triticum aestivum) landraces in the central highlands of Eritrea

Abstract

A common cropping system in the central highlands of Eritrea is mixed cropping of barley (Hordeum vulgare) and wheat (Triticum aestivum); it is called hanfetz (Tigrigna word). Mixtures may give higher yield, better yield stability, better food quality and more animal feed. Factors affecting the productivity of mixtures include genotype combination, crop density and component crop ratio.Grain yields differed significantly among genotype combinations in certain years. A combination of Ardu 12/60 + Kenya + Mana gave high mean grain yield (2009 kg ha-1) and a relative yield advantage (RYT= 1.57) of 57% increase in grain yield over the sole crops. Harvest index, biomass, stand cover and thousand grain weight were well correlated with yield. Wheat plants were first suppressed by barley but later on grew taller than barley. The potential yield increase for mixtures over barley sole cropping may be associated with the relative height and higher light use (efficiency). Some genotype combinations also showed reasonable yield and resistance to stress with a drought susceptibility index Crop ratios of 100/50 (2275 kg ha-1) and 100/25 (2241 kg ha-1) were the best in grain yield when averaged over the three basic crop densities (100% = 100, 200 and 300 plants m-2) and years. Barley showed greater competitive ability than wheat. For barley the intra-specific competition was more important than the inter-specific competition. In such studies, yield advantage can be either due to the density effect or complementary use of resources. The drawback of the additive design is that yield advantage may be partly due to increased density. However, niche differentiation showed that mixtures shared resources efficiently and the yield advantage was the result of complementary use of resources. In the study under drought stress, an additive ratio (higher density) did not result in higher total yield compared to that in replacement series. The niche differentiation in both years under drought stress also showed that the yield advantage was due to complementary use of resources among the crop species.Stability analysis of barley and wheat mixtures on yield data from a large set of experiments showed that mixed cropping was significantly more stable than barley and wheat sole cropping. Some of the genotype combinations such as Ardu 12/60 + Kenya + Mana and Ardu 12/60 + Mana were more stable than others.The most promising genotype combinations and crop ratios obtained from this study have to be verified on farm and demonstrated to farmers before the technology is released for use.</p