Lee Tarpley

Instrumentation enabling study of plant physiological response to elevated night temperature

BackgroundGlobal climate warming can affect functioning of crops and plants in the natural environment. In order to study the effects of global warming, a method for applying a controlled heating treatment to plant canopies in the open field or in the greenhouse is needed that can accept either square wave application of elevated temperature or a complex prescribed diurnal or seasonal temperature regime. The current options are limited in their accuracy, precision, reliability, mobility or cost and scalability.ResultsThe described system uses overhead infrared heaters that are relatively inexpensive and are accurate and precise in rapidly controlling the temperature. Remote computer-based data acquisition and control via the internet provides the ability to use complex temperature regimes and real-time monitoring. Due to its easy mobility, the heating system can randomly be allotted in the open field or in the greenhouse within the experimental setup. The apparatus has been successfully applied to study the response of rice to high night temperatures. Air temperatures were maintained within the set points ± 0.5°C. The incorporation of the combination of air-situated thermocouples, autotuned proportional integrative derivative temperature controllers and phase angled fired silicon controlled rectifier power controllers provides very fast proportional heating action (i.e. 9 ms time base), which avoids prolonged or intense heating of the plant material.ConclusionThe described infrared heating system meets the utilitarian requirements of a heating system for plant physiology studies in that the elevated temperature can be accurately, precisely, and reliably controlled with minimal perturbation of other environmental factors.

High night temperature and plant growth regulator effects on spikelet sterility, grain characteristics and yield of rice (Oryza sativa L.) plants

Mohammed, A. R. and Tarpley, L. 2011. High night temperature and plant growth regulator effects on spikelet sterility, grain characteristics and yield of rice ( Oryza sativa L.) plants. Can. J. Plant Sci. 91: 283–291. The presence of seasonally high night temperature (HNT) as a result of global warming, occurring during the critical stages of development, could reduce rice yield and quality. To understand how a combination of HNT and plant growth regulators (PGR; α-tocopherol and glycine betaine) affects yield and yield-related parameters of rice plants, we conducted three pot experiments under two levels of night temperature (NT; 27 and 32oC) with or without PGR treatments. Plants were subjected to a HNT through the use of continuously controlled infrared heaters, starting 20 d after emergence (DAE), from 2000 until 0600. Plants were treated with α-tocopherol and glycine betaine 20 DAE. The NT had no effect on number of productive tillers, main-stem panicle length or number of primary branches per panicl...