Density-dependent plant type plasticity and adaptation strategy in two Avena sativa cultivars

摘要

Integrated studies on plant type plasticity and adaptation strategy in cultivated plants are critical for both crop breeding and field management.A controlled greenhouse experiment was conducted to test a hypothesis that different leaf types of oat have different strategies to adapt density stresses.Two oat genotypes, 'Manotick' with erect leaf architecture, and 'Oa1316-1' with prostrate leaf,were grown in four planting densities in a factorial experimental design with 4 replicates.Density was adjusted by varying the number of seeds planted in each container (cone) and the space between containers, thus creating either aboveground competition only or both roots and aboveground competition situations.Our data showed that yield, leaf area, chlorophyll content, plant height and stem diameter of both genotypes decreased significantly with increasing plant density.Biomass allocation to aboveground organs decreased while the allocation to underground organs increased with increasing plant density.Under high density stress (8 and 16 plants per container) conditions,compared to solid treatment, Manotick allocated 3-10％ more biomass to the root system,produced 50％ more tillers, leading to higher number of non-productive tillers, and resulted in lower harvest index under the alternative arrangement.In contrast, the prostrate type Oa1 316-1 allocated proportionally more biomass to the panicles and stems, and less to the root system.Consequently,there were fewer tillers in Oa1361-1.Our data indicates that yield differences between the two types of oats resulted from diverse life history strategies.With increasing plant density and strengthening plant-to-plant competition, Manotick reduced aboveground biomass allocation, which led to lower yield, while Oa1 316-1 decreased biomass allocation to the roots, but increased biomass allocation to the stems and panicles under increasingly competitive environment.These adjustments in prostrate type genotypes maintained high and strong stems, ensured biomass allocation to reproductive components and achieved high final yield.