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Tanta University (1995)

Interaction between salt stress, free living nitrogen Fixing bacteria and certain crop plant

El-Silk, Sobhy El-Sawy M. 

Titre : Interaction between salt stress, free living nitrogen Fixing bacteria and certain crop plant

Auteur : El-Silk, Sobhy El-Sawy M. 

Etablissement de soutenance : Tanta University

Grade : Master of Science (MSc) in Botany 1995

Résumé
In this study, twenty different isolates belonging to nitrogen- fixing bacteria were isolated from cultivated and desert Egyptian soils, and fiom marine and fiesh water. from these isolates nineteen were identified as Azotobacter spp. and one was identified as Azospirillum sp. Among these isolates, strain No. 14 was found to adapt growth in nitrogen fiee meQurn supplemented with NaCl concentration up to 0.68 M. This strain was subjected to morphologcal, physiological and biochemical studies. The obtained characteristics were compared with those cited in keys of identification in addtion to Bergey’s Manual (1984). Accordingly, it was identified as Azotobacter beijerinkii and was chosen for subsequent studies. The selected organism was grown in nitrogen-free medium supplemented with 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6M of each of NaCl, Na2S04, K2SO4 and 0.1, 0.2M mixed salts in static and shake cultures at 300C for four weeks. Mer one week intervals, the growth (biomass dry weight), total nitrogen, plant growth regulators, protein profile and accumulation of salts were determined in each culture, and the following results were obtained. 1- The growth and nitrogen fixation decreased by increasing the concentration of each of NaC1, Na2S04, K2SO4 or mixed salts, and by increasing culture age, although there was no correlation between N-fixation and culture age compared to salt non amended culture.

Présentation étendue (EULC)

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