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Publication Date
1981
Description
After forage crops are cut mechanically, they usually undergo some degree of natural drying before being stored or further processed. During early stages of drying, plant respiration continues. Treatments or management practices that hasten drying and reduce postharvest respiration are desirable, because they minimize quantity and quality losses. Our objective was to determine the effects of brief microwave treatment on subsequent natural drying rate and respiration of alfalfa (Medicago sativa L. ). Duplicate samples of field grown Apollo alfalfa were subjected to focused microwave energy (2,450 MHz) generated at 0.25, 0.50, or 1.0 kilowatt of power for 3, 6, or 12 seconds. Control and microwave-treated samples were dried at 0% relative humidity in a drying chamber. Moisture percentage and respiration rates were measured immediately before and after microwave treatment and 18 hours after treatment. A hypothetical example is given to show that small reductions in initial moisture percentage of forage are associated with relatively large water losses. Conversely, relatively small amounts of water must be removed to dry a sample that is already less than 50% moisture. Increasing power and time of exposure to microwave energy increased the amount of water lost during the treatment and decreased percentage of moisture and respiration rates in samples measured immediately after treatment. The initial treatment removed 6% to 37% of the original leaf-sample water, depending on power and exposure time. Respiration was reduced slightly by weaker treatments but completely inactivated by longer, higher-power treatments. All except the weakest microwave treatment resulted in samples that contained less than one-half as much moisture as the controls after 18 hours at 0 % relative humidity. By 18 hours, posttreatment respiration rates of treated samples were one-half or less than one-half of the respiration rates of control samples, most of the treatments having completely or almost completely inactivated respiration by that time. Stem drying and respiration rates were more labile to microwave treatment than those ofleaves. We conclude that brief, focused microwave treatment removes substantial amounts of moisture from alfalfa leaves and stems, results in lower total drying time, and reduces or stops respiration. The treatments imposed had a range of effects, and the resulting data can serve as a base for future calculations of power requirements and economic thresholds.
Citation
Seif, S A.; Holt, D A.; Lechtenberg, V L.; and Vetter, R J., "Effects of Microwave Treatment on Drying and Respiration in Cut Alfalfa" (1981). IGC Proceedings (1977-2023). 10.
(URL: https://uknowledge.uky.edu/igc/1981/section10/10)
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Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Effects of Microwave Treatment on Drying and Respiration in Cut Alfalfa
After forage crops are cut mechanically, they usually undergo some degree of natural drying before being stored or further processed. During early stages of drying, plant respiration continues. Treatments or management practices that hasten drying and reduce postharvest respiration are desirable, because they minimize quantity and quality losses. Our objective was to determine the effects of brief microwave treatment on subsequent natural drying rate and respiration of alfalfa (Medicago sativa L. ). Duplicate samples of field grown Apollo alfalfa were subjected to focused microwave energy (2,450 MHz) generated at 0.25, 0.50, or 1.0 kilowatt of power for 3, 6, or 12 seconds. Control and microwave-treated samples were dried at 0% relative humidity in a drying chamber. Moisture percentage and respiration rates were measured immediately before and after microwave treatment and 18 hours after treatment. A hypothetical example is given to show that small reductions in initial moisture percentage of forage are associated with relatively large water losses. Conversely, relatively small amounts of water must be removed to dry a sample that is already less than 50% moisture. Increasing power and time of exposure to microwave energy increased the amount of water lost during the treatment and decreased percentage of moisture and respiration rates in samples measured immediately after treatment. The initial treatment removed 6% to 37% of the original leaf-sample water, depending on power and exposure time. Respiration was reduced slightly by weaker treatments but completely inactivated by longer, higher-power treatments. All except the weakest microwave treatment resulted in samples that contained less than one-half as much moisture as the controls after 18 hours at 0 % relative humidity. By 18 hours, posttreatment respiration rates of treated samples were one-half or less than one-half of the respiration rates of control samples, most of the treatments having completely or almost completely inactivated respiration by that time. Stem drying and respiration rates were more labile to microwave treatment than those ofleaves. We conclude that brief, focused microwave treatment removes substantial amounts of moisture from alfalfa leaves and stems, results in lower total drying time, and reduces or stops respiration. The treatments imposed had a range of effects, and the resulting data can serve as a base for future calculations of power requirements and economic thresholds.
