Arbuscular-mycorrhizal inoculation of five tropical fodder crops and inoculum production in marginal soil amended with organic matter

Five fodder crops, Zea mays, Medicago sativa, Trifolium alexandrinum, Avena sativa, and Sorghum vulgare were inoculated with a consortia of indigenous arbuscular mycorrhizal (AM) fungi in non-sterile PO43--deficient sandy loam soil amended with organic matter under field conditions. Shoot and root dry weights and total uptake of P and N of all the test plants were significantly increased by AM inoculation. Mycorrhizal inoculation increased yield in terms of shoot dry weight by 257% in T. alexandrinum followed by 50% in A. sativa, 28% in Z mays, 20% in M. sativa and 6% in S. vulgare. Variation in dependence on mycorrhiza was observed among the fodder crops. T. alexandrinum showed a maximum dependence of 72% in contrast to 5.7% dependency in S. vulgare. Plant species showed differences in percentage AM colonization, with a high root infection recorded in Z mays (76%). Spore production and infectious propagules (IP) were as high as 78 spores/IP g(-1) and 103 spores/IP g(-1) in S. vulgare. This study clearly indicates the potential of using indigenous AM inoculations in fodder crops grown in marginal soils along with in situ large-scale production of AM inocula.