PLUG-MIX PLANTING OF PREGERMINATED SEED IN ONTARIO

Poor emergence, crusting, lack of uniformity, difficulty in achieving target populations and weed control have been major problem areas in direct seeded tomato trials.
Renewed interest in direct seeding has resulted from the combination of two recent developments, plug-mix planting and pregermination.
The most responsive crops include those, which like tomatoes are not adversely affected by clump seeding.
The technique can consistently produce uniform, rapid emergence, earlier maturity compared with dry seed, and yields equivalent to a transplanted crop.
The following discussion reviews the direct seeded tomato program in light of these developments.

Increasing the efficiency of production by direct seeding higher populations of commonly transplanted crops has received considerable attention in past years.
Although processing tomatoes have been generally grown from transplants at 14 800 to 17 300 plants per hectare most cultivars require a higher plant population to yield sufficient marketable fruit for profitable once-over machine harvest.
Direct field seeding provides the flexibility required to obtain populations for machine harvest at minimal cost in comparison to transplants.
In addition, the direct seeded crop is generally more uniform, with a reduced incidence of disease resulting in longer foliage cover and better quality fruit late in the season.

However, field seeding of tomatoes has encountered many problems and has been relatively unsuccessful for a number of reasons.
Fluctuating environmental conditions in the seed zone, especially temperature and moisture, result in variable germination and emergence.
Soil crusting has resulted in non-uniformity and difficulty in acheiving target populations.
Also, tomato seedlings are poor competitors and weed control remains a critical factor in determining the success or failure of the direct seeded operation.

Each of these problem areas has been alleviated to some extent by the combination of two recent developments; plug-mix planting and pregermination.
The former concept, originally developed at the University of Florida, basically allows seed to be sown in an ideal artificial environment.
A typical "mix" may be composed of shredded peat moss, vermiculite, perlite, dolomitic and calcitic lime, soluble starter fertilizer, a fungicide, and water.
Seed is randomly distributed throughout the mix which is then precision planted at rates of 25 to 50 cc of mix per "plug". The carrier thus also serves as the environment and when planted to the proper depth acts as an efficient anti-crustant.
Depending on seed size, percent germination and the population desired approximately 225 gm of seed are required in 0.6m³ of mix

Symposium on the Timing of Field vegetable Production

G.B. Ure, A. Loughton

https://doi.org/10.17660/ActaHortic.1978.72.13