Root rot of wheat: Inoculation and screening techniques, yield loss assessment, and germplasm evaluation
1998
Mergoum, M. | Quick, J.S. | Hill, J. | Nsarellah, N. | Nachit, M.M. | Pfeiffer, W.H.
The effects of root rot inoculation on the agro-physiological traits of wheat were evaluated in laboratory/greenhouse and field experiments in Colorado and Morocco during 1986-1990. Under laboratory/greenhouse conditions, inoculated adult plants had significantly lower leaf relative water content, reduced plant height, fewer tillers, and higher cell ion leakage compared with non-inoculated plants. Wheat genotypes differed significantly for most traits studied . Genotypes CO840186 and Sandy were the most susceptible and tolerant to root rot, respectively. At Colorado, in early planting trials, root rot severity, measured by average root rot score (ARRS) and white heads (WH), was significantly higher compared with normal planting. Genotypes significantly differed for grain yield, test weight, and reaction to root rot. Seeding rates and inoculation with Fusarium acuminate and Cochliobolus sativus did not significantly affect disease development; CO840186 was most affected. Seed treatment with imazalil and Trichoderma harzianum did not inhibit disease development. WH due to root rot was, in general, a more accurate measure of root rot severity than ARRS to differentiate between genotypes under Colorado field conditions. Under Moroccan conditions, N level had no significant effect on disease epidemics. From February to April, 1989/90, high root rot incidence (WH percentage) after seed inoculation with a spore suspension coincided with severe drought. Inoculation significantly reduced grain yield and kernel weight, and increased WH percentage of both durum and bread wheat cultivars. Durums were generally more affected by inoculation than bread wheats for all studied traits.
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