Seasonal Allocation and Efficiency Patterns of Biomass and Resources in the Perennial Geophyte Sparaxis grandiflora Subspecies fimbriata (Iridaceae) in Lowland Coastal Fynbos, South Africa

Abstract

The seasonal allocation and efficiency of biomass and resources (starch, soluble carbohydrates, N, P, K, Ca, Mg, Na, Zn, Fe, Mn and Cu) within and between the constituent plant parts of Sparaxis grandiflora subspecies fimbriata , a deciduous, synanthous geophyte, are described. The sequential production of roots, leaves and a new daughter corm, with fruit production phased in during the development of the daughter corm, results in continual transfer of resources when the plant is not dormant. The new daughter corm serves as the major sink for the allocation of dry matter and resources during the vegetative, reproductive and senescent periods. The parent corm is the major source of resources in the early stages of the vegetative period. The amount of resources allocated to the reproductive structures was comparatively low when compared with that allocated to vegetative plant parts. The corms have highly flexible storage capacities for a variety of nutrients, particularly the better conserved nutrients such as nitrogen, phosphorus, potassium, and carbohydrates. The dynamic patterns for the majority of the resources revealed high allocation when metabolic activity was also highest. Efficient recovery or recycling of important resources from senescing organs results in a similar or greater allocation to the daughter corm than the amount that was present in the parent corm of the previous growth season. This is seen as an advantage to these plants that grow in a seasonal environment where soils are of low nutrient status.