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Glyphosate Stress Induction of Banana

Glyphosate Stress Induction of Banana,

As measured by HRM Sap Flow Meter & Leaf Psychrometer.

Dr. Beng Umali, Applications Scientist

CASE STUDY SUMMARY

Application: Sap flow and leaf water potential on banana

Location: South Johnstone, QLD.

Products: SFM1 and PSY1

Measured Parameters: Sap velocity in cm h-1 and Leaf Water Potential in MPa

Outcomes: Sap flow (heat ratio method) in banana measured in upper region of the central cylinder; leaf water potential followed diurnal variation; sap velocity and leaf water potential provided insights into the physiological state of the banana plant after glyphosate injection.

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SFM Banana

Overview

Sap flow measurement is now the most common method of directly measuring transpiration in plants. The technique not only allows for providing accurate measurements of water use in plants but also provides insights into the overall health and physiological state of the plant. An even more powerful tool for measuring the physiological state of the plant is water potential. This principle unifies the different driving elements for water status in plants.

This short investigation, in collaboration with Queensland Department of Agriculture and Fisheries – South Johnstone Centre for Wet Tropics Agriculture, looks at sap velocities and leaf water potential on banana that has been injected with glyphosate to induce stress.

Methods

Heat Ratio Method Sap Flow Meter (SFM1) was installed in the upper region of the central cylinder. The installation guide was positioned in the upper region of the central cylinder; the probes were then inserted easily. The guide was then removed and the probes reinserted in the installation site.

The Leaf Psychrometer was installed in the 3rd leaf of the plant by abrading a small section in edge of the leaf blade to remove the cuticle and expose palisade layer. This is to ensure that the leaf clamp can be positioned to hold the psychrometer head in the installation site. The installation was sealed by filling the edge of the site with vacuum grease.

RESULTS

InnerSapVelocity_1

Fig 1. Sap velocity (cm hr-1) of banana

Banana_PSY1

Fig 2. Leaf water potential (MPa) of banana

  • Sap velocity followed a normal diurnal pattern for 13 days prior injection of glyphosate becoming less pronounced after the injection.
  • Banana leaf exhibited diurnal pattern of water potential reaching a maximum of -3.58MPa on a 48°C day (inside greenhouse)
  • Leaf water potential responded to environmental demands: ex. Day 8 at reaching -0.4MPa on a relatively cool and low radiation day.
  • Night time water potential also gradually decrease resulting from the gradual dehydration stress with glyphosate injection; on day 20, measurement stopped and necrosis was observed at the installation site.