Different soil structure and water conditions affect the growing response of Lolium perenne L. and Bromus valdivianus Phil. growing alone or in mixture

摘要

Abstract: Restricting plant available water in the soil can negatively affect pasture growth. Lolium perenne L. (Lp) and Bromus valdivianus Phil. (Bv) are important components of the permanent pastures in southern Chile. The aim of this study was to investigate the growth response of Lp and Bv when subjected to soil water restriction, contrasting soil structure conditions and growing as a single species pasture or in a mixture. The treatments were two soil physical conditions (undisturbed (US) and disturbed soil (DS)), two soil water restriction levels (optimum PAW and very-dry PAW), and three pastures (Bv, Lp and Bv+Lp). The US provided more water to plants regardless of the soil water restriction, and Bv and Lp presented more development (highest accumulated herbage mass) in US than in DS, under a similar soil water restriction. The soil structure and soil water restriction did not modify the tiller number of Bv, although Lp showed different tiller numbers under each condition, soil structure and soil water restriction. The conservation of the soil structure (undisturbed soil) has an important role in pasture productivity by providing a continuous pore system, which certainly improved the water accessibility for the growing species.