Resumo

ROVEDA, Gabriel  e  POLO, Cristina. Mechanisms of maize adaptation associated with Glomus spp. in soils with low phosphorus availability. Agron. colomb. [online]. 2007, vol.25, n.2, pp.349-356. ISSN 0120-9965.

Phosphorus deficiency is a major limitation to agricultural productivity in tropical regions. This research was addressed to study the mechanisms of maize adaptation in relation to Glomus spp. The research was conducted under controlled conditions in the laboratories of Corpoica, Colombia. The experimental design consisted in completely randomized blocks with six treatments and six replicates: three treatments with different levels of available phosphorus in soil (1, 40 y 100 mg·kg^-1) and the other three with the same P levels plus Glomus spp. The experimental results confirmed a reduction in leaf area and dry matter related to low P levels in soil at 20 days after seedling emergence. As an adaptation mechanism for P deficiency, the seedlings transferred the carbohydrates to the roots at the expense of leaves, thus, modifying the balance of dry matter. This mechanism was evident 10 days after the stress application. Plants associated with Glomus spp. had the highest growth rates, mineral nutrition (N, K. P, Ca, Mg, and S), and sugar concentration in tissue, due to the importance of P in the synthesis of carbohydrates. Plants associated with mycorrhizal fungus increased the protein levels in tissue when amended with 1 and 40 mg·kg^-1 of P in soil. The results suggest that Glomus spp. contributed to the synthesis of stress proteins because of soil phosphorus deficiency. The stress allows the differential expression of genetic information in the synthesis of new proteins called mycorrhizines, which are probably involved in the adaptation mechanisms of plants to stress.

Palavras-chave : tropical soils; phosphorous deficiency; mycorrhizal fungus; protein synthesis.

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