Submitted to: Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2004
Publication Date: 1/20/2005
Citation: Melakeberhan, H., Dey, J., Baligar, V.C., Carter Jr, T.E. 2005. Genetic diversity among four erythroxylum taxa assessed by aflp. Nematology, 6:585-592. Interpretive Summary: In the southeastern USA, soil acidity is a major abiotic stress that limits soybean production. Due to their wide range of soil pH tolerance, plant-parasitic nematodes are the major stress factors that affect soybean production in acid soils. Plant-parasitic nematodes are adapted to a wide range of soil conditions and thus present many challenges for crop production at low pHs. In order to manage nematodes effectively in acid soil conditions, it is important to determine the impact of soil pH on nematode population dynamics and pathogenisity. Research was undertaken in greenhouse conditions to evaluate the effect of soil pH on pathogenesis of two types of nematodes on acid soil tolerant soybean genotypes. Both of the nematodes infected soybeans at all of the soil pHs, however, the density of nematodes decreased with decreasing soil pH. Shoot growth of both soybean genotypes was reduced due to nematode infection. Based on the obtained results it was concluded that nematode infection should be considered in breeding programs to develop low soil pH tolerant soybean cultivars. Finding of this research could assist soybean farmers to calibrate their soil liming rates to reduce the extent of nematode pathogenicity to soybean.
Technical Abstract: The effect of soil pH 4.3, 4.6, and 5.9 on the pathogenicity of Heterodera glycines and Meloidogyne incognita on acid-soil-adapted soybean genotypes (Davis and PI 416937) was investigated in three greenhouse experiments over 28 days after inoculation with 0 or 1,000 (exp.1 and 2) and 0 or 5,000 (exp. 3) second-stage juveniles. Although both nematodes infected both genotypes at all of the soil pHs, the numbers decreased with decreasing soil pH. Both genotypes seem to be better hosts for M. incognita than H. glycines, and more so Davis than PI416937. Both nematodes decreased shoot weight at high inoculum, indicating that H. glycines may be more pathogenic than M. incognita. Nematode development after infection of root was not affected by soil pH or by genotypes. Overall, the results suggest that adaptation of these nematodes should be considered in breeding programs to develop low pH tolerant soybean cultivars.