Analysis of factors limiting associative N2-Fixation (C2H2 reduction) with two cultivars of Sorghum nutans

Krotzky, A. and Berggolg, R. and Werner, D. (1986) Analysis of factors limiting associative N2-Fixation (C2H2 reduction) with two cultivars of Sorghum nutans. Soil Biology and Biochemistry, 18 (2). pp. 201-207.

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Abstract

A 5–10 times larger nitrogenase activity per plant (max. 8 μmol C2H4 h−1 plant−1) was found in Sorghum nutans cultivar CSV 5 compared to the cultivar IS 5218 (max. 0.9 μmol C2H4 h−1 plant−1). This significant difference was reproduced for all water regimes from 8 to 21% soil moisture. The number of chemoorganotrophic bacteria (“total cell number”) on a medium with six carbon sources was very similar for both cultivars (3−4 × 108 cells g−1 rhizosphere soil). On the other hand, in the “high fixing” variety CSV 5 the number of N2-fixing bacteria was greater than in IS 5218 by a factor of 3, the number of actinomycetes was reduced ten-fold and Arthrobacter strains to one-third or one-quarter. The number of aerobic N2-fixing bacteria growing in an O2 gradient system was increased 100-fold. Cultivar CSV 5 has a reduced photosynthetic area (20–30%), a reduced root weight (up to 50%, depending on the water regime) and a reduced transpiration rate (30–40%) compared to cv. IS 5218. Grain production however is 10–20% greater. At all soil moisture regimes the pH in the rhizosphere of cv. CSV 5 is 0.5–1.5 pH units below the values for cv. IS 5218.

Item Type: Article
Author Affiliation: Fachbereich Biologie, Philipps-Universität Marburg, Karl v. Frischstr., D-355 Marburg, FederalRepublic of Germany
Subjects: Crop Improvement
Divisions: Sorghum
Depositing User: Mr B Krishnamurthy
Date Deposited: 21 Aug 2014 07:52
Last Modified: 21 Aug 2014 07:52
Official URL: http://dx.doi.org/10.1016/0038-0717(86)90028-3
URI: http://eprints.icrisat.ac.in/id/eprint/13387

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