Sample preparation for Transpiration Efficiency using Carbon Isotope Discrimination – DC30-32

Within the manual Protocols for experimental plot sampling, handling and processing of cereals in field experiments by G.J. Rebetzke (Greg.Rebetzke@csiro.au), A. van Herwaarden, B. Biddulph, C. Moeller, R. Richards, A. Rattey and K. Chenu.

There may be the need entry measures of transpiration efficiency (aka leaf-level water-use efficiency). A robust surrogate for transpiration efficiency is carbon isotope discrimination measured using a mass spectrometer.

Method

1. Obtain dried leaf samples from plants sampled at DC30 (c. 5 liguled leaves for spring wheats) using the procedure in preceding section.
2. Mill samples to a consistently fine sample using a 1 mm screen.
3. Ensure mill is cleaned between samples and milling mechanism does not get too warm during the milling process (warm parts are harder to clean between samples).
4. Place milled samples into labelled 30mL screw top vial for storage and transportation (preferably in glass to avoid any static electricity).
5. Send labelled vials along with trial details to an accredited laboratory for processing using a mass spectrometer (Fig. 14). Charge per sample varies but is commonly US$20-40/sample.

a)

b)

Figure 14. (a) The approximate height for cutting leaf blades for drying and grinding for carbon isotope discrimination analysis; (b) A mass spectrometer used in ¹²C/¹³C discrimination analysis

Other resources

Appendix 1. Text description of phenological scale, Zadoks decimal code (DC).
Appendix 2. Picture description of phenological scale, Zadoks decimal code (DC).
Zadoks JC, Chang TT, Konzak CF (1974) A decimal code for the growth stages of cereals. Weed Research 14(6),415-421. doi: 10.1111/j.1365-3180.1974.tb01084.x

Notes and troubleshooting tips

Literature

Download complete manual: Protocols for cereal field experiments_Nov2012.pdf

Health, safety & hazardous waste disposal considerations