Effect of Irrigation and Soil Water Stress on Densities of Macrophomina phaseolina in Soil and Roots of Two Soybean Cultivars

Abstract

The effects of irrigation and soil water stress on Macrophomina phaseolina microsclerotial (MS) densities in the soil and roots of soybean were studied in 1988, 1989, and 1990. Soybean cvs. Davis and Lloyd received irrigation until flowering (TAR2), after flowering (IAR2), full season (FSI), or not at all (NI). Soil water matric potentials at 15- and 30-cm depths were recorded throughout the growing season and used to schedule irrigation. Soil MS densities were determined at the beginning of each season. Root MS densities were determined periodically throughout the growing season. Microsclerotia were present in the roots of irrigated as well as nonirrigated soybean within 6 weeks after planting. By vegetative growth stage V13, these densities reached relatively stable levels in the NI and FSI treatments (2.23 to 2.35 and 1.35 to 1.63 log [microsclerotia per gram of dry root], respectively) through reproductive growth stage R6. After R6, irrigation was discontinued and root densities of microsclerotia increased in all treatments. Initiation (IAR2) or termination (TAR2) of irrigation at R2 resulted in significant changes in root MS densities, with densities reaching levels intermediate between those of FSI and NI treatments. Year to year differences in root colonization reflected differences in soil moisture due to rainfall. The rate of root colonization in response to soil moisture stress decreased with plant age. Root colonization was significantly greater in Davis than Lloyd at R5 and R8. This was reflected in a trend toward higher soil densities of M. phaseolina at planting in plots planted with Davis than in plots planted with Lloyd. Although no charcoal rot symptoms in the plant were observed in this study, these results indicated that water management can limit, but not prevent, colonization of soybean by M. phaseolina, that cultivars differ in colonization, and that these differences may affect soil densities of the fungus.

Influence of soil texture and moisture on the interaction of Meloidogynejavanica and Macrophominaphaseolina on green beans

“…on several crops (Al-Hazmi, 1988;Jaraba et al, 2014;Shahab, 2014). Similar effects were also reported on the fungus M. phaseolina (Srivastava & Dhawan, 1980;Pande et al, 1989;Husain & Ghaffar, 1995;Diourte et al, 1995;Lodha, 1996;Kending et al, 2000;Jimenez, 2011;Arias et al, 2013). However, effects of soil texture and moisture on the interaction between these two pathogens on green beans are very few or lacking.…”

Temporal analysis of charcoal root rot in forest nurseries under different pathogen inoculum densities and soil moisture content

“…Among the most important factors for the development of the disease are high temperatures and low moisture content in the soil (Wyllie, 1989). Macrophina phaseolina infects plants within a wide temperature range (20 to 35ºC) and is influenced by water stress conditions (Ali & Ghaffar, 1991;Diourte et al, 1995;Kending et al, 2000). Conditions of low moisture content in the soil leading to drought stress have been recognized as the most important predisposing factor for CRR (Reuveni et al, 1982), increasing the susceptibility of the host and decreasing the activity of antagonistic microorganisms to M. phaseolina (Palti, 1981).…”

Seasonal effects of irrigation on land–atmosphere latent heat, sensible heat, and carbon fluxes in semiarid basin

“…Zeng et al: Seasonal effects of irrigation on land-atmosphere latent heat be returned to the atmosphere (Kendig et al, 2000;. This results in a direct augmentation of the latent heat flux (LH) from land to atmosphere (Haddeland et al, 2006).…”