Abstract
ABSTRACT Crop water monitoring is an important aspect for precise control of irrigation. A reliable and movable technique is needed to properly assess water uptake of crops in the field. Water uptake by field grown maize ( Zea mays L.), in water-limited conditions was verified with the heat pulse system. The temperature difference between two radially inserted thermocouples, one 9 mm above and the other 4 mm below a heater piercing the maize stem, was measured every 0.3 sec following emission of a heat pulse in conditions of varied atmospheric demand. Comparisons of heat pulse system outputs and a high precision transpiration model estimates were done on hourly and daily basis, when low sap velocities were expected to occur. Hourly and daily basis of the heat pulse outputs and model estimates were in agreement. Sensitiveness of the technique was observed even for very low sap velocities.
Highlights
There is a need for a rapid, simple, movable and reliable method for measuring water uptake of herbaceous plants in order to properly monitor the water usage and establish plantwater relationships of agricultural crops with the main purpose of precise irrigation management.The assessment of rate of water uptake from measurements of the rate of sap flow through the stem, for some herbaceous plants and trees have been made by the heat pulse system
The aim of this study is to investigate the water uptake of field grown maize by applying the heat pulse technique, under condition of water stress
Precision of measurement of maize water uptake under low sap velocities depends on the elimination of ambient temperature influence on the sap flow
Summary
The assessment of rate of water uptake from measurements of the rate of sap flow through the stem, for some herbaceous plants and trees have been made by the heat pulse system. For decreasing soil water content, Kramer & Boyer (1995) showed that a more pronounced lag of absorption behind transpiration can be present. This could cause discrepancy between the heat pulse velocity and rate of transpiration all over the day. Further investigation of the technique under conditions of decreased soil water content is needed
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