Dual-purpose barley and oat in a Mediterranean environment.

摘要

In Mediterranean environments, forage production for livestock is both difficult and costly due to erratic rainfall. As an alternative, barley, oat and triticale can be used as dual-purpose autumn-sown cereals, thus serving as winter grazing and grain for feed. The present study was aimed at estimating the influence of different management systems (dual-purpose with one and two grazings, soft-dough harvest for silage, full maturity grain only) on grain yield, forage and whole plant production, and on quality-related traits of barley (Hordeum vulgare L.) and oat (Avena sativa L.). The trials were conducted over 2 years (1998/1999 and 1999/2000) in a Southern Italy Mediterranean environment using a flock of sheep for grazing and mechanically clipping the plots, thus simulating the dual-purpose, to obtain forage samples for analyses. Effect of the years was not significant, whereas both crops underwent significant reductions of grain yield, harvest index, thousand kernel weight and seeds/m2 in the dual-purpose plots but not in the grain only plots. The most drastic yield reduction was recorded in oat after two grazings by comparison to the ungrazed treatment (2.4 t/ha versus 3.9 t/ha). Grain protein content was not affected by dual-purpose in oat, and it was independent of the number of grazings in barley. Barley had a higher production of total biomass and milk feed units than oat in the dual-purpose management systems, except for the soft-dough and grain only treatments. In addition, barley reacted positively to both the dual-purpose systems (one and two grazings). More specifically, whole plant biomass increased from 9.6 t/ha when grown for grain only to 13.6 t/ha in the single grazing system, and milk feed units similarly increased, from 7680 to 9216 MFU/ha. Green forage quality was comparable between the two cereals, even though barley whole plants showed lower fibre content, especially after two grazings. The soft-dough stage of both crops had better forage quality parameters, nevertheless, the lower biomass yields and total milk feed units (in the case of barley) rendered this system non-profitable for the environment studied. Barley demonstrated a clear superiority for the dual-purpose systems in Mediterranean Italy and should thus be preferred to oat, except when using oat to interrupt barley monocropping..