Response of Bromus valdivianus (Pasture Brome) Growth and Physiology to Defoliation Frequency Based on Leaf Stage Development

作者：Iván Ordóñez, Ignacio F. López, Peter Kemp, D. J. Donaghy, Yongmei Zhang, Pauline Herrmann · 发表于：Agronomy · 年份：2021 · DOI：10.3390/agronomy11102058 · 被引用次数：13 · 研究领域：Plant Water Relations and Carbon Dynamics、Pasture and Agricultural Systems、Agroforestry and silvopastoral systems

The increase in drought events due to climate change have enhanced the relevance of species with greater tolerance or avoidance traits to water restriction periods, such as Bromus valdivianus Phil. (B. valdivianus). In southern Chile, B. valdivianus and Lolium perenne L. (L. perenne) coexist; however, the pasture defoliation criterion is based on the physiological growth and development of L. perenne. It is hypothesised that B. valdivianus needs a lower defoliation frequency than L. perenne to enhance its regrowth and energy reserves. Defoliation frequencies tested were based on B. valdivianus leaf stage 2 (LS-2), leaf stage 3 (LS-3), leaf stage 4 (LS-4) and leaf stage 5 (LS-5). The leaf stage development of Lolium perenne was monitored and contrasted with that of B. valdivianus. The study was conducted in a glasshouse and used a randomised complete block design. For Bromus valdivianus, the lamina length, photosynthetic rate, stomatal conductance, tiller number per plant, leaf area, leaf weights, root growth rate, water-soluble carbohydrates (WSCs) and starch were evaluated. Bromus valdivianus maintained six live leaves with three leaves growing simultaneously. When an individual tiller started developing its seventh leaf, senescence began for the second leaf (the first relevant leaf for photosynthesis). Plant herbage mass, the root growth rate and tiller growth were maximised at LS-4 onwards. The highest leaf elongation rate, evaluated through the slope of the lamina elongat...