Seleção de inoculantes á base de turfa contendo bactérias diazotróficas em duas variedades de arroz

Abstract

The study consisted of a comparison of two-peat materials (Brazil and Canada) containing different C-total content. The peats were inoculated with strains of Herbaspirillum seropedicae ZAE 94, Burkholderia sp. M130, and Azospirillum brasilense Sp109, and monitored during a period of six months in relation to variation on humidity and survival of bacteria in the inoculant. The quantification of viable cells in the inoculant was measured by the Most Probable Number (MPN) method. The rice seeds were pelleted with the respective inoculants, grown in pots containing soil and maintained outside a greenhouse. The dry mass accumulation, N percent, N-total and yield were determined during the plant cycle. The humidity content varied with storage period. The survival measurement showed that only Burkholderia sp. M130 maintained the number of viable cells around 108 g-1 of peat, while there was a reduction in population of other strains. An increase of yield and total N of 13 and 19.4%, respectively in comparison to treatment fertilized with 40 kg N ha-1 was observed for variety IAC4440, inoculated with strain ZAE94. There was no difference in yield of the IR42 inoculated with either ZAE94 or M130, as compared to N control treatment. No significant difference in development of both rice varieties was observed for both peat used. The results suggest that peat can be used as a carrier for production of an inoculant based on diazotrophic bacteria, since it allowed maintenance of a bacterial population up to 108 cells g-1 peat during the storage period of up to 100 days. The results obtained encourage the practice of inoculation of non-leguminous plants.