Author
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MARCHETTI, MARCO |
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Submitted to: Rice Production
Publication Type: Experiment Station Publication Acceptance Date: 6/1/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: During flowering, panicles are especially vulnerable to high temperatures. Vulnerability is increased greatly by modes to high winds, resulting in rapid drying of glumes and death of pollen. Evidence that this has occurred is the presence of bleached out panicles and partially bleached panicles (usually the upper part) indicating the panicles were only partially exerted from the boot when exposed to damaging heat and wind. Individual panicles resemble those struck early by borers, but in the field heat damage will involve many more panicles per unit area than would likely occur from stem-borer activity. In the case of both panicle blight (PB) and the above, usually panicles will become discolored from colonization by secondary invaders. If one were to inspect a field two weeks before harvest, it may appear that fungi were the primary cause of panicle damage. In fact, heat stress (or any stress) reduces the plants' resistance to pathogens which are of no importance under good growing conditions. This would explain why fungicide applications to stressed plants have resulted in significant yield increase in heat-stressed fields on occasion. It is important to consider that one may not be observing the primary cause of a problem several weeks after flowering. Although symptoms of heat stress may be more obvious in some varieties compared to others, all souther U.S. cultures suffer significant losses in yield and quality under the environmental conditions which favor PB and other forms of heat-related stress. |
