Record ID No. |
1567 |
Author(s) |
Correa, A; Strasser, RJ; MartinsLoucao MA , 2008 |
Affiliation |
Correa A, Univ Lisbon, Fac Ciencias, CEBV, Campo Grande, Edificio C4, Piso 1, P-1749016 Lisbon, PORTUGAL |
Title |
Response of plants to ectomycorrhizae in N-limited conditions: which factors determine its variation? |
Source. Vol.(no):Page |
Mycorrhiza, 18(8): 413-427 |
Categories |
Arbuscular Mycorrhiza |
Subjects |
Biochemistry |
Sub-subjects |
Miscellaneous |
Country |
Portugal, Europe |
Abstracts |
In the present work, the following hypotheses were tested: (1) the negative effects of mycorrhization over host plant productivity in N-limited conditions are due to N retention by the fungal partner and not due to excessive C drainage; (2) If mycorrhization results in decreased N uptake, the host plant decreases its C investment in fungal growth. The effects of mycorrhization over a wide range of combinations between N availability, N concentration in plant tissues, and degree of mycorrhizal colonization were studied in Pinus pinaster L. Mycorrhizal with Pisolithus tinctorius. Several plant productivity parameters, the seedlings' N status, chl a fluorescence (JIP test), and mycorrhizal colonization were measured. N was always limiting. A gradient of mycorrhizal effects over the host plant's growth and vitality was successfully obtained. The mycorrhizal effects on plant growth and N uptake were very strongly and positively correlated, and no evidence was found of a C limitation to growth, confirming hypothesis 1. Indications were found that the plants continued to provide C to the fungus although the N supplied by it was increasingly lower, denying hypothesis 2. A new index, the mycorrhizal N demand-supply balance, was found to efficiently explain, and to have a curvilinear relation with, the variation in response to mycorrhization. The mycorrhizal effect on host plant growth was not related to a negative effect on its photosynthetic performance and, therefore, reflected changes in resource allocation between host plant and mycorrhizal fungus, not in plant vitality. |