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ARS Home » Southeast Area » Stoneville, Mississippi » Crop Genetics Research » Research » Publications at this Location » Publication #332709
Title: Effect of charcoal rot on selected putative drought resistant soybean genotypes and yield

Author
item Mengistu, Alemu
item Smith, James - Rusty
item Arelli, Prakash
item Bellaloui, Nacer
item CHEN, PENGYIN - University Of Arkansas
item SHANNON, GROVER - University Of Missouri
item Boykin, Deborah
item Ray, Jeffery - Jeff

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2017
Publication Date: 12/7/2017
Citation: Mengistu, A., Smith, J.R., Arelli, P.R., Bellaloui, N., Chen, P., Shannon, G., Boykin, D.L., Ray, J.D. 2017. Effect of charcoal rot on selected putative drought resistant soybean genotypes and yield. Crop Protection Journal. 105:90-101.

Interpretive Summary: Charcoal rot is a disease of soybean that causes significant yield losses in production in the US as well in many other countries around the world. The effect of charcoal rot on drought tolerant genotypes is not well understood mainly because of the confounding effect of drought with that effect of disease severity from charcoal rot. Therefore field experiments using irrigated and non-irrigated treatments were used and compared severities of nine putative drought tolerant genotypes in MG IV and MG V with those of moderate resistance and susceptible controls. Disease was assessed at seven different growth stages and expressed in colony-forming units of the fungus and the area under the disease curve. Disease severity levels under irrigation resulted in less than half of the disease severity levels found in the non-irrigated regime indicating that the non-irrigated treatment significantly increased the severity of charcoal rot. Among nine putative drought tolerant genotypes, four were identified as having moderate resistance under non-irrigation indicating that not all drought tolerant genotypes were resistant to charcoal rot. Our results indicated that non-irrigation may be an appropriate environment for concurrent screening and identification of genotypes with resistance to both charcoal rot and drought stress. The four moderately resistant drought tolerant genotypes that expressed moderate resistant may be valuable sources of resistance for charcoal rot that can be leveraged in breeding programs.

Technical Abstract: Charcoal rot (CR), caused by the fungus Macrophomina phaseolina (Tassi) Goid. is a pervasive disease of economic significance on soybeans ([(Glycine max (L.) Merr.) that is exacerbated when plants are under stress, especially under heat and drought condition. Thus, the objective of this research was to determine the severity of CR on nine putative drought tolerant (DT) genotypes in MG IV and MG V under irrigated and non-irrigated treatments and compare severities with those of moderate resistance (MRC) and susceptible (SCR) controls. Disease was assessed at the V1, V5, R2, R4, R5, R6 and R7 growth stages based on colony forming units (CFU) of M. phaseolina recovered from the lower stem and root tissues, and the area under the disease progress curve (AUDPC). The population density of M. phaseolina increased slowly from the V1 to R6 growth stages and rapidly increased from the R6 to R7 for all genotypes under both irrigated and non-irrigated treatments. Disease severity levels under irrigation (AUDPC=1197) resulted in less than half of the disease severity levels found in the non-irrigated regime (AUDPC=3054) indicating that the non-irrigated treatment significantly (P=0.05) enhanced the severity of CR. Among the nine putative DT genotypes, four were identified as MRC under both irrigation and non-irrigation indicating that not all drought tolerant genotypes were resistant to CR under the non-irrigated environment. Our results indicated that non-irrigation may be an appropriate environment for concurrent screening and identification of genotypes with resistance to both biotic (CR) and abiotic (drought) stresses. The four moderately resistant DT lines and all of the MRC lines may be valuable sources of resistance for CR that can be leveraged in breeding programs.