Experiments were conducted with a Blue M "Vapor-Temp" controlled environment apparatus to show the effect of temperature, light intensity, relative humidity and age upon the rate of CO₂ exchange for twelve barley varieties. All varieties showed an increase in CO₂ uptake with an increase in temperature to a certain optimum, varying with variety. When the temperature was raised above this point, the rate of CO₂ uptake decreased. In all varieties tested the rate of CO₂ uptake increased as light intensity was increased up to 2400 ft. candles. Three out of four varieties tested showed significant changes in rate of CO₂ uptake with changes in relative humidity. All varieties tested showed an initial decrease in rate of CO₂ uptake per unit leaf area as the plants aged from 15 to 30 days. Above this age there was little change in rate of CO₂ exchange. Experiments were also conducted in photoperiod chambers to determine the developmental response of different barley varieties to different photoperiods. It was found that the varieties differed in overall response to photoperiod. Within a variety there was a difference in rate of development between plants subjected to different photoperiods. The optimal photoperiod for head differentiation and for head appearance was 21 or 24 hours for all varieties. / Land and Food Systems, Faculty of / Graduate

A review was made of environmental technology as applied to the engineering and construction of artificial environments for plant physiology research. The results of this study were utilized in the development of an artificial environment which incorporated the nutrient mist technique of growing plants. The quality of the environment in plant growth chambers is partly dependent on the type of control instruments used. Solid state electronic control devices offer many advantages, particularly with respect to accuracy, responsiveness, reliability and remote control. A travelling sensor was developed to detect the environmental conditions within artificial environments by remote control. This sensor greatly increased the rapidity and convenience of measurement with minimum disturbance of the environment. The conditions of light intensity, temperature, wind speed and humidity within a commercial growth chamber, the Percival Model PGC-78, were analysed. The results indicated that the chamber's performance was quite nonuniform for all the variables tested. The manufacturer's specifications for the chamber were considered to be limited in extent and to some degree misleading. The design of the artificial environment system constructed for this project is described. With this system, temperature control of ±½°C was achieved within the plant growth area. In addition, the uniformity of light intensity and air flow in the constructed chambers was superior to the PGC-78. / Land and Food Systems, Faculty of / Graduate

No description available.

No description available.

No description available.

No description available.

Note:

No description available.

No description available.

No description available.