Symbiotic nitrogen fixation and nitrate reduction in two peanut cultivars with different growth habit and branching pattern

DELFINI,R.; BELGOFF,C.; FERNÁNDEZ,E.; FABRA, ADRIANA; CASTRO, S.

PLANT GROWTH REGULATION

SPRINGER

Año: 2010 vol. 61 p. 153 - 159

0167-6903

We have investigated the response of two peanut cultivars (TEGUA and UTRE) with different growth habits and branching pattern structures to different nitrogen (N) sources, namely, N-fertilizer or N2 madeavailable by symbiotic fixation, and analysed the pattern of nitrate reductase (NR) activity in these cultivars. Nitrate and amino acid contents were also examined under these growth conditions. In terms of nitrogen source, cv. TEGUA showed a better response to inoculation with Bradyrhizobium sp. SEMIA 6144 at 40 days after planting, while cv.UTRE responded better to N-fertilizer (5 mM KNO3). Both cultivars showed different patterns of NR activity in the analyzed plant organs (leaves, roots, and nodules), which were dependent on the N source. When nitrogen became available to the plant through symbiotic N2 fixation, thepatterns of NR activity distribution were different in the two cultivars, with cv. TEGUA showing a higher NR activity in the nodules than in the leaves and roots, and cv. UTRE showing no difference in terms of NR activity among organs. The nitrate and amino acid contents showeda similar trend between the two cultivars, with the highest nitrate content in the leaves of fertilized plants and the highest amino acid content in the nodules. The high nitrate content of the leaves of cv. UTRE indicated the better response of this cultivar to N-fertilizer