Plant Science

• Products
• Custom Applications
• Reference Material

Plant Science Products

• AP4 Porometer
• Delta-T Scan System
• HemiView System
• Net Radiometer (Delta T)
• Root Washer type RWB
• SunScan canopy analysis system
• UV Sensors (Delta T)
• WinDIAS Image Analysis System

• Data Logging
• Soil Moisture
• Water
• Weather Stations

AP4 Porometer

The AP4 Porometer measures stomatal aperture in terms of leaf conductance to water vapour. This is a major determinant of water loss from plant leaves and of CO2 uptake in photosynthesis.

• Direct readout of conductance or resistance
• Simple and rapid calibration in the field
• Minimises leaf stress during measurement
• Outstanding value and ease of use

Applications

Loss of water vapour through plant leaf stomata is one of the critical factors linking transpiration with ambient temperature, pressure, humidity and wind speed. The stomata are sensitive to light, relative humidity (RH), carbon dioxide (CO2), water stress, pathogens and pollutants. The AP4 Porometer makes accurate, repeatable and convenient field measurements of stomatal conductance using the cycling diffusion principle. When combined with leaf area and leaf temperature measurement, the instrument enables water loss from a whole plant or crop canopy to be estimated.

The AP4 is therefore an invaluable tool for quantifying the effect of various influences on stomatal behaviour. It also has an important role to play in comparing the performance of different crop varieties in response to environmental variations and stresses.

Practical Experience The theory behind the cycling porometer is well understood (ref. 1), and is backed by Delta- T's considerable manufacturing experience of this type of instrument through four evolutionary stages. Over 1000 Delta-T porometers have been used worldwide since the first was devised by Dr. J. L. Monteith in 1974 (ref. 2).

Easy and convenient use

The innovative design of the AP4 provides users with logical, convenient operation and a comprehensive range of features and functions. In particular, the AP4 offers an automated, rapid cycle that gives temperaturecompensated readings, and straightforward calibration.

New users can quickly make effective use of the AP4, without a deep knowledge of all the options available to the more experienced user. A [HELP] button provides operating assistance, especially useful for field work, while a [SET] button conveniently recalls operating settings stored previously.

In use, the AP4 is carried on a shoulder strap in its own protective carrying case, with the keyboard, control buttons and display at a convenient working level. The sensor head, on a flexible cable, is simply clipped on to the leaf to be measured. Once the instrument has been initialised, a [READ] button on the head allows singlehanded operation. Successive readings can be taken, evaluated and stored just by pressing this one button. Stable readings are audibly indicated by a double beep'.

Step-through procedures from menus displayed on the LCD guide the user through the processes of calibration, taking readings, and the review and output of stored data.

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Delta-T Devices supplies high quality research equipment for agronomy, plant science, soil science, eco-physiology, meteorology and environmental monitoring.

Visit the Delta-T Web Site: www.delta-t.co.uk/