PROTOCOL

CULTIVATION OF M. truncatula

(Cook lab-University of California, Davis; drcook@ucdavis.edu)

The following is a summary of our current practices; however, we have not spent time trying to optimize conditions. As a consequence there may be room for improvement and we would appreciate any suggestions.

Growth room:
Light: 300 u mol/m²/sec, 14 h light, 10 h dark
Temperature: day 22°C (72^oF), night 18°C (65°F)

Green house:
In Texas, we find that M. truncatula grows well when ambient temperatures are below about 25°C ( 75°F). During the summer months, when ambient greenhouse temperatures approach, or often exceed, 32°C (90°F), plant growth is poor and seed yields low.

Soil:
Brand: Peter's Professional Potting Soil, manufactured by Scotts-Sierra Horticultural Products Co., phone (513)-644-9503.

Seedlings from caissons are initially grown in 3" diameter/2.5" depth pots until they are well established (> 5 leaves), after which they are transplanted to 8" diameter/8" depth pots. [We have learned that the use of small pots (i.e. 6X6 in) for growth of large individuals results in a high mortality rate]. For seed amplification we frequently use flats, with up to 50 individuals in a single flat. For fertilizers, we use slow release formulations such as Osmocote (14-14-14, N-P-K) and a micro-nutrient mix, incorporated into the soil at transplanting or top dressed at later stages. High phosphate fertilizers will accelerate flowering. Plants are grown in the growth room during plant establishment (in 3" pots for typically 2 weeks), and for the first 2 weeks after transplantation into large pots before moving to the green house. Under this regimen, first flowers usually appear at 7-8 weeks after transfer from caisson. Initiation of flowering is delayed when plants are left in the growth room.

Diseases/pest:
The major disease we have experience is root rot. This can be avoided by judicious watering. Typically we allow for soil to become dry between watering. We find that it is better to risk wilting (usually reversible) than over-watering.

The two pests we have experienced are fungal gnats and white flies. Fungal gnats are controlled by Gnatrol (a commercial formulation of Bacillus thurengiensis) applied as soil drench at time of potting. For control of white flies, we spray with Safer-soap (a detergent formulation) which acts as a contact insecticide. A few hours after safer-soap spraying, the soap is washed away using water delivered with a fine mist nozzle.