N and P colimitation of N-2-fixing and N-supplied fynbos legumes from the Cape Floristic Region

作者：Maistry Pravin M; Cramer Michael D; Chimphango Samson B M^*

来源：Plant and Soil, 2013, 373(1-2): 217-228.

DOI：10.1007/s11104-013-1793-y

• limitation
• NXP interaction
• Synergistic colimitation
• Shoot N:P

Legume species in the fynbos vegetation of the Cape Floristic Region, that fix N-2 in soils with low P, may have evolved for enhanced acquisition and efficient use of P. It was hypothesized that N-2-fixing and combined-N supplied (N-supplied) A. linearis, P. calyptrata and C. genistoides are adapted to low P and would be relatively unresponsive to increased P of 100 mu M. %26lt;br%26gt;18 legume species were evaluated for their nodulation response to low P availability. The N X P interaction was then examined in A. linearis, P. calyptrata and C. genistoides reliant on either N-2-fixation or 300 mu M N (NH4NO3), and receiving 0.1, 1.0, 10 and 100 mu M P (NaH2PO4). %26lt;br%26gt;In the species selection experiment, A. linearis, P. calyptrata and C. genistoides, with the greatest nodule fresh weight (FW) and nodule FW to root FW ratio, were the most prolific nodulating species. In the N X P experiment, with low P supply, the biomass of N-2-fixing P. calyptrata and C. genistoides was consistently greater than that of N-supplied plants. In contrast, with high P supply of 100 mu M P, all N-supplied plants accumulated more biomass than the corresponding N-2-fixing plants. High P-use efficiency, poor down-regulation of P uptake and P storage was evident in A. linearis and P. calyptrata. %26lt;br%26gt;The growth response to P and the significant N X P interactions indicate that N-2-fixing and N-supplied plants were not adapted to low P, but rather colimited by both N and P.

• 出版日期2013-12