Nitrogen nutrition in nodulated field plants of the shrub tea legume Aspalathus linearis assessed using 15N natural abundance
- Cite this article as:
- Muofhe, M. & Dakora, F. Plant and Soil (1999) 209: 181. doi:10.1023/A:1004514303787
- 195 Downloads
Provision of N, P, and Ca to field plants of A. linearis markedly (P<0.05) increased growth and N nutrition in a very acidic nutrient-poor soil. Application of P and Ca promoted a significant increase in %N derived from fixation and amounts of N fixed compared to those receiving no nutrients. N2 fixation measured under field conditions ranged from 3.8 g N plant-1 in unfertilized control to 7.1 g N plant-1 in fertilized plants. Overall, about 85% increase in N2 fixation was observed with P supply. The high N2-fixing activity in P-treated plants was confirmed by their lower (more negative) ∂15N values. Age of plants also influenced growth and symbiotic activity as the ∂15N values, %N derived from fixation, and N fixed were lower in 1- and 2-year-old plants compared to 3-year-old. The contribution of symbiotic fixation in unfertilized A. linearis to the N economy of the ecosystem ranged from 105 kg N ha-1 in 1-year-old plants to 128 kg N ha-1 in 3-year-old plants, clearly indicating the remarkable adaptation of this symbiosis to the very nutrient-poor, low pH conditions of Cedarberg soils.