Azospirillum inoculation in maize seedlings under drought

COHEN A; TRAVAGLIA C; PONTIN M; BOTTINI R

ATIBAIA-SP. Brasil

Congreso; X CONGRESO BRASILEIRO DE FISIOLOGIA VEGETAL; 2003

Sociedade Brasileira de Fisiología Vegetal

AZOSPIRILLUM INOCULATION IN MAIZE SEEDLINGS UNDER DROUGHT Cohen, A. [1]; Travaglia, C. 1; Pontin, M. 1 and Bottini, R.1-2 [1] Lab. Fisiología Vegetal, Fac. Cs. Exac., Fco.-Qcas. y Naturales, Universidad Nac. Río Cuarto, 5800 Río Cuarto, Argentina. Tel.: ++54-358-4676103, Fax: ++54-358-4676230,  e-mail: acohen@exa.unrc.edu.ar, 2 Cát. de Química Orgánica y Biológica. Fac. de Cs. Agrarias, Universidad Nac. de Cuyo, 5505 Chacras de Coria, Argentina. Water deficit is the most important stress limiting productivity of crops. During drought, increased synthesis of ABA in the affected plant reduces water losses. ABA is ubiquitous in higher plants, algae, fungi and endophytic bacteria. The association Azospirillum-plant improves growth and yield, likely enhancing the root system and by consequence the plant uptake of water and minerals. According to previous work and references in literature A. lipoferum increases in in vitro culture medium with low Yw imposed by PEG, and Azospirillum sp. alleviates the effects of water deficit in cereal seedlings under salt and osmotic stresses. Therefore stomata control in the infected plant through ABA production by the bacterium may also be possible. In this work, the ability of A. lipoferum to alleviate temporary drought in maize seedlings was tested. A greenhouse experiment was conducted with seedlings of the Dekalb 696 maize cultivar, inoculated with A. lipoferum USA 5b in PBS medium, or PBS alone. The seedlings were located in plastic pots filled with sand: soil (1:1, v/v) watered with distilled water, and once a week with sterile Hoagland (1/2 strength) solution. Plants were either well watered or drought-stressed (where irrigation was withhold for 10 to 15 days after sowing) and either without or with inoculation with A. lipoferum. The treatments were replicated twelve times in a randomized block design. Inoculated seedlings grew longer and with enhanced foliar area as compared with the non-inoculated, although the differences were not significant. Significant differences were observed in growth of the root system, expressed as fresh and dry weight, in seedlings inoculated with A. lipoferum related to non-inoculated.