Sowing and planting of Nicotiana attenuata in Jiffy pots (JP)

The Deapartment of Molecular Biology has developed a tried and tested method over three decades of field experiments, to successfully germinate N. attenuata using Jiffy pots.

Generally N. attenuata takes around 21-30 days from the beginning of the sowing process to ready for planting in the field.

1. Seeds: Two copies of seed aliquots are collected and the seeds are soaked in a solution of gibberellic acid (GA3), ethanol and liquid smoke for 1 hour. After 1 hour the seeds are given an additional treatment of smoke solution, where they will soak for approximately 10 hours until sowing. As seeds are directly sown into the Jiffy pots, they must also be soaked in a solution of Utah soil and Borax.

The Jiffy pots are then stored in large 32 liter shoe boxes (see picture below) where they will remain until planted in the field. The boxes used for storing the Jiffy pots while germinating seeds means that temperatures are stabilized and better humidity conditions can be achieved.

Jiffys placed in a 32L shoe box
Jiffy pots covered with transplant soil.

2. Sowing: The Jiffy pots are organized according to their genotypes, and holes are ripped in the top where the seeds are sown at a standardized depth.Sowing plans are determined based on known germination rates and are generally separated by experiment and germination rate. Pipettes are used to precisely place seeds into the middle of the Jiffy pots. The seeds are then covered with transplant soil (teku; Klasmann-Dielmann Steckmedium #300/TS1) which is primarily a base of milled peat and perlite. The transplant soil prevents the seeds from drying out as the transplant soil wicks moisture from the Jiffy pots that have been soaked, has been shown experimentally to speed up the germination process and prevent algal growth.

Concrete and plastic pools at Lytle Ranch Preserve, Utah.

3. Monitoring: The shoe boxes are sealed and placed in concrete or plastic pools, exposed to natural light. Seedlings begin to germinate after around 6 days, with some genotypes taking up to 10-14 days. When the pools are exposed to strong sunshine mesh/shade cloth is placed over the boxes to reduce the chances of the plants from overheating; conversely during spring Styrofoam is placed over the boxes, or boxes are stored inside over night, to prevent freezing.The lids of the boxes are kept on until the plants have germinated and have their 3rd or 4th leaf. From the fifth day, the plants are checked everyday. When 50% of the plants have produced their 'true leaves' the hardening-off process begins where the lids are removed and the plants are kept hydrated to prevent drying out - killing the experiment. The plants are then watered twice a day and EasyLog® thermometers are installed in the boxes to monitor temperature and humidity.

Spraying seedlings with insecticide after planting.
Sieves protecting plants during early stages of planting. (D. Kessler 2016)

4. Planting: Once the irrigation system is operational, the drippers must be placed in the correct location to faciliate planting in correct formations. One day before planting, plants are sprayed with an insecticide. Scientists prepare a planting map and labels for the field plots, and the seedlings are planted accordingly. The seeldings are unwrapped from their Jiffy pot constraints and planted directly into the field plot. Once the seedlings are planted, additional protection may be required, such as placing a sieve over the plant to prevent grasshoppers from feeding on the seedlings. Once planted, seedlings are treated with another dose of insecticide and are then consistently monitored.

5: Maintainence: As the seedlings develop, the field plots are continuously weeded, as N. attenuata's natural habitats are after fires and hence, have little natural competition. The plants are irrigated in the evenings throughout the field season, for periods long enough to see wet circles around each cluster.

Sowing and planting of Nicotiana attenuata to achieve a natural root (NR)

Growing N. attenuata in Jiffy pots prevents the development of natural root morphologies. Direct sowing into the field plot is shown to encourage a natural tap-root structure, unlike the bi-lateral root growth shown to develop when transplanted from Jiffy pots.

Plastic domes placed over seeds directly sown into the field plot. I.T Baldwin 2019

The seed preparation and germination procedures for direct planting are the same as for the Jiffy pots (above), however seeds are directly sown into the field plot using a pipette. To protect the seedlings and to ensure their development, small plastic domes are placed over the seedlings.