Yield and quality of Italian ryegrass as affected by supplemental irrigation

Abstract

A field trial was conducted in order to evaluate the effect of supplemental irrigation on increasing and stabilizing Italian ryegrass (Lolium multiflorum Lam.) yields, in southern Portugal. The following irrigation treatments were tested: rainfed (control), and irrigation up to 25%, 50% and 100% of soil water holding capacity. Two different varieties were used, one annual (Pollanum) and the other biannual (Lipo). The results showed that for Pollanum, even a small amount of water increased yields significantly even though the greatest values were reached at the highest watering regime. The other variety, Lipo, did not respond so well at the 25% irrigation treatment. Thus, since water is becoming a scarce and expensive resource it seems that the best choice is Pollanum and the lowest irrigation treatment. Although in case of no irrigation water available, Lipo variety seems more advantageous. The number of harvests was three under rainfed conditions, and five for all irrigation treatments. For crude protein and digestible dry matter yields, the trends were similar to dry matter yield.