Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 11, 2009
Publication Date: N/A
Interpretive Summary: No summary required
Technical Abstract: In recent years the importance of maximising the economic and environmental sustainability of food and fibre production with limited resources has been realised. This has necessitated increases in water use efficiencies in agriculture. Plant based water stress detection tools that correlate the soil and atmospheric loads contributing to plant stress may hold potential for improved efficiencies in irrigation scheduling. One method is the monitoring of plant stress is through leaf canopy temperatures as water stressed plants exhibit higher leaf temperatures due to reduced evaporative cooling. Field based infra-red canopy temperatures were monitored with the SmartCrop irrigation scheduling system in a cotton crop grown in Narrabri, Australia, during the 2007/2008 season. The crop was irrigated under a range of irrigation treatments (25%, 100%, and 125% ETo) as a fixed deficit, using a surface drip irrigation system. Corresponding leaf water potential, soil moisture and weather conditions were monitored to determine the basis of fluctutations in canopy temperatures and the necessity of irrigation. Results show a significant relationship between canopy temperatures and leaf water potentials (P<0.001 and R2=0.76). In the 100% and 125% ETo irrigation treatments other environmental factors were shown to be affecting the regression as soil moisture was no longer driving the changes canopy temperature and leaf water potential. When vapour pressure deficit, radiation and soil water were included in the regression analysis 85% of the variation in the data was accounted for. This research aims to accurately describe the factors that contribute to canopy temperatures. This will provide a better understanding of the physiological environmental processes that affect canopy temperatures and in turn water stress. Thus, enabling the judgement as to weather a measured canopy temperature represents water stress, for use in irrigation scheduling.