Triticale cultivar mixtures: Productivity, resource use and resource use efficiency in a Mediterranean environment

Cultural systems based on mixtures of varieties may be more successful in resource use and resource use efficiency than those based on single varieties. Two triticale cultivars of different phenology (Bienvenu, intermediate; and Oceania, spring) grown in pure stands were compared with mixtures of the two (25:75; 50:50 and 75:25). Field experiments were carried out in Sardinia (Italy) in five experiments created by combining seasons, sowing date and sites. At the terminal spikelet of Bienvenu, the best mixtures produced 38, 89 and 82 % more biomass than Bienvenu in pure stand, depending on the experiment, due to a higher crop growth rate associated with a higher RUE (r = 0.60*). In the case of dual purpose utilization, this means that the winter herbage production of triticale at the terminal spikelet stage of an intermediate or winter cultivar is improved when mixed with a spring cultivar, at least in the Mediterranean environment explored here. Complementarity and differences between mixtures and pure stands in biomass production by anthesis were the exception rather than the rule. By the anthesis of Oceania, mixtures only produced more biomass than the Oceania pure stand on three occasions (11.8 and 11.9 t ha−1 vs. 9.3 t ha−1 and 10.7 t ha−1 vs. 8.7 t ha−1). In these cases, the superiority of the mixtures was due to a higher intercepted PAR (also reflected in greater transpiration), attributable to the pattern of LAI development. Differences in grain yield were only expressed when a cold stress during anthesis compromised the grain set of the spring cultivar. Here, mixtures played a fundamental role in increasing the stability in grain yield, suggesting that differences in the developmental rate between mixture components reduced the mixture sensitivity to specific abiotic stresses.