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| Publication Type:
| Report |
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| Content Type: | Abstract or Summary only |
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| Author(s): | Kalmowitz, K. E.;
Monaco, T. J.;
Burton, J. D. |
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| Author Affiliation: | Department of Horticultural Science, North Carolina State University, Raleigh |
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| Title: | Physiological changes in annual bluegrass (Poa annua) following inoculation with biocontrol agent, Xanthomonas campestris MSU |
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| Meeting Info.: | Charlotte, NC: January 18-20, 1993 |
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| Source: | Southern Weed Science Society Proceedings. Vol. 46, 1993, p. 387. |
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| Publishing Information: | Champaign, IL: Southern Weed Science Society. |
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| # of Pages: | 1 |
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| Keywords: | TIC Keywords: Poa annua; Xanthomonas campestris; Inoculation; Physiological responses; Biological control
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| Abstract/Contents: | "Controlled-environment experiments were conducted in 1991 in the Southeastern Plant Environment Laboratory (Phytotron) to evaluate physiological changes in plant water status in annual bluegrass plants inoculated with the biological control agent Xanthomonas campestris strain MSU. This bacterial pathogen of annual bluegrass induces a leaf wilt prior to tissue necrosis and plant death. Research objectives were to determine if changes occur in leaf water potentials in inoculated annual bluegrass plants; if these changes occur before visual symptoms; and, if water stress alters biological activity of the pathogen. Annual bluegrass was seeded at 200 seeds per 7.5 cm styrofoam cup and grown for 28 days prior to inoculation. A single high rate of inoculum (10[to the 9th] cfu ml-1) and a control of sterile-distilled water were applied at 1-ml per cup of annual bluegrass plants with an atomized sprayer. Wet grass blades were cut to 3.4 cm above the cup rim directly following inoculation. Treatments included inoculated and noninoculated plants with (50 ml water of [of water] daily) and without (100 ml of water daily) water stress. Water regimes were imposed 1 d prior to inoculation. Plants were grown and evaluated at 26 C in a 12-h photoperiod for 9 D. Leaf water and osmotic potentials were determined on three leaf subsamples per cup of annual bluegrass plants with precalibrated thermocouple psychrometers 1, 3, 5 and 7 DAT. Thermocouple chambers were equilibrated in a water bath at 25 C for 3 h before measuring microvoltage ([Mu]V) output. Osmotic potentials were determined on frozen tissue that was thawed at ambient temperature and equilibrated as above. Pressure potential is the calculated difference between water and osmotic values for each subsample. Cups were weighed every 24 h to determine gravimetric water content and to account indirectly for changes in plant transpiration. Reduction (%) in daily water consumption was calculated as: before water weight/after water weight * 100. Plant fresh weights and control evaluations were taken a 9 DAT. The experiment was repeated twice with 4 replications each and 2 cups per treatment. Experiments were analyzed as a split-plot design over time and regression analyses were performed over leaf water potentials and days to determine treatment effects on plant water status. Means were separated by LSD at P> or =0.05. Changes in leaf water potentials were detected between 3-5 DAT for inoculated plants +/- water stress; whereas differences in daily water use were observed after 5 DAT and coincided with visual symptoms of wilt. Inoculated and water stressed plants maintained higher pressure potential at 5 DAT and may have resulted in the more gradual reduction in water use as compared to inoculated, well-watered plants. Inoculated annual bluegrass (+/- water stress) had the lowest fresh weights at 9 DAT. Water stress does not appear to affect the ability of Xanthomonas campestris strain MSU to control annual bluegrass." |
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| Language: | English |
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| References: | 0 |
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| Note: | This item is an abstract only! |
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| ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Kalmowitz, K. E., T. J. Monaco, and J. D. Burton. 1993. Physiological changes in annual bluegrass (Poa annua) following inoculation with biocontrol agent, Xanthomonas campestris MSU. South. Weed Sci. Soc. Proc. 46:p. 387. |
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