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- Assessment of Soybean Yield Loss Due to Bacterial Pustule
Assessment of Soybean Yield Loss Due to Bacterial Pustule
Thesis Abstract:
Experiments were conducted to assess quantitatively and qualitatively yield losses due to bacterial pustule caused by Xanthomonas phaseoli var. sojensis (Hedges) Starr and Burkholder, of soybean varieties TK-5, CES-434, L-114 and Clark 63.
The inoculation experiment showed that seed weight, seed volume, protein content, fat content, and percent germination were reduced at all stages of injection in all soybean varieties. The highest decreases In these parameters were observed in plants inoculated at the flowering stage. However, no significant differences in these parameters were noted between inoculations at 15 days before flowering, flowering and pod formation stages, regardless of variety. Differences in average percent loss in the parameters between varieties at the same stages of inoculation were neither significant. The number of pods and seeds per plant varied within the variety but were mostly reduced in plants inoculated at the flowering stage.
The experiment on the effect o varying disease intensities showed that increasing inoculums concentration increased yield reduction in all soybean varieties. The linear regressions of seed weight on disease intensity were statistically significant, except for CES-434.
The experiment on the effect of initial pustule intensities on yields of CES-434 and L-114 (supposedly moderately resistant varieties) indicated that the extent of loss in yields depended on the severity of the disease.
Based on the results of the study, it could be concluded that TK-5, CES-434, L-114 and Clark 63 had the same degree of susceptibility to bacterial pustule. Infected plants of all these soybean varieties produced less number of pods, or empty pods or pods with small seeds which dried up prematurely, resulting in losses in seed weight, viability and protein and fat contents.