Monitoring rose oscillatory transpiration by integrating a greenhouse climate computer and physiological sensors

The vast potential for climate control computers to fine-tune crop production cannot be tapped until we learn more about dynamic responses of plants to their greenhouse environment. These responses must be investigated by integrating recently developed electronic biosensors into computer systems. Three types of biosensors--sap-flow gauges, electronic-balance lysimeters, and leaf-temperature sensors--were electronically linked into a climate computer using datalogger stations, serial communication cables, and customized programming.; Model SGA10 (Dynamax, Inc., Houston, Texas) heat-balance sap-flow gauges were mounted on the main stem of potted rose plants (Rosa hybrida L.) Gauges overestimated whole-plant transpiration (WPT) but simple linear regressions (average {dollar}rsp2 = 0.921{dollar}) between each sap-flow gauge and associated lysimeter were used to adjust data and reduce errors to {dollar}<{dollar}20%. Waveform analysis predicts that these gauges can detect cyclic patterns in WPT with ranges greater than {dollar}approx{dollar}8 g{dollar}cdot{dollar}h{dollar}sp{lcub}-1{rcub}{dollar} and periods longer than {dollar}approx{dollar}9 min.; Two distinct response patterns in WPT were monitored at night when HID lamps were turned on: (1) step change to a higher but steady rate of WPT after stomates opened; (2) wide oscillations in transpiration (OT) unrelated to any monitored microclimate rhythms. Leaf-air-temperature-difference (T{dollar}sb1{dollar}-T{dollar}sb{lcub}rm a{rcub}{dollar}) oscillated inversely to WPT. Phase, relative amplitude, and period of stomatal conductance and CO{dollar}sb2{dollar}-exchange rate calculated by a portable gas-exchange unit mimicked WPT oscillations.; OT occurred in all rose plants (n = 23) monitored. OT had sine-wave patterns with periods between 40 and 120 min, ranges between 2 and 56 g{dollar}cdot{dollar}h{dollar}sp{lcub}-1{rcub}{dollar}, and increasing, steady, and decreasing amplitudes. Sometimes adjacent plants had stable and oscillatory patterns in WPT. Usually phase, periods, and amplitudes in OT differed in adjacent plants.; OT has not been previously reported for any commercially-important floricultural crop. Rose OT usually developed by the time shoots formed pea-sized buds and persisted through anthesis. 'Moonlight' and 'Fire N Ice' plants exhibited more frequent and stronger patterns of OT than 'Samantha' plants.; As additional biosensors are developed and linked into the computer network to monitor plant physiological and morphological processes, the "speaking plant" approach might be adopted, where plants directly control their own environment.