A comparative study of plant responsiveness to the duration of episodes of mineral nutrient enrichment

Abstract

summary: Growth, dry matter partitioning and nitrogen capture were compared in two grasses of contrasted ecology, subjected to treatments involving pulses of nutrient enrichment of various durations supplied every 6 d over a period of 6 weeks. The potentially fast‐growing Arrhenatherum elatius ssp. bulbosum (Willd.) Schubler and Martens was superior in rates of nitrogen capture and dry matter production when exposed to long (≥ 10 h) nutrient pulses whereas the slow‐growing species Festuca ovina L. enjoyed an advantage in treatments providing nutrient pulses of between 0.1 and 10 h duration. These results are consistent with differences in mechanisms of resource foraging predicted by the C‐S‐R model of plant strategies and related models. It is concluded that the lower rates of turnover of tissues and the capacity of roots to remain viable under chronic nutrient stress are important components of the ability of Festuca ovina to exploit brief pulses of mineral nutrient enrichment. The range in duration of the pulses advantageous to F. ovina corresponds to that which might be expected to arise from the death and recovery of microbial populations in infertile soils.