There is growing interest in the potential to use high tunnels for the production of warm season vegetable crops such as peppers in Saskatchewan. Given the limited growing area available within the tunnels, growers must utilize production practices that maximize productivity and returns/unit area. The greenhouse industry faces the same challenge and some of the tricks used by greenhouse growers may be of use in high tunnels. For example – greenhouse peppers are typically pruned and trained to grow vertically to increase yields within a limited growing space. In the standard “V” training system, the pepper plant is pruned to form a 2-stemmed plant, with the two shoots that form the V being held apart and supported vertically by twine wrapped around the stems. While this approach has been proven to increase yields over the 6-9 month lifespan of a typical crop of greenhouse peppers, it may not be as effective or necessary when the harvest season is more limited – as in high tunnel production of peppers in SK. Jovicich, Cantliffe and Stoffella have recently compared the standard “V” training system versus a “Spanish” system in unheated low tech greenhouses in Florida. In the “Spanish” system, the plants are staked upright but are not pruned – resulting in bushy plants with 2-4 main stems. Over a 3 month harvest period, they found no yield difference between the two training systems. However, the “Spanish” system produced more “bonus” large-sized fruit and had significantly less grade out due to blossom end rot than the “V” system. Most importantly, the labor involved in training the plants using the “V” system was 75% greater than the labor required in the “Spanish” system. They conclude that the effort involved in the “V” training system could not be justified in situations where the lifespan of the pepper crop is relatively short. Instead, putting lots of plants into the production area was the key to maximizing yields when the growing/harvesting season was limited. When they compared spacings of 50, 25 or 20 cm between plants (with 1.3 m between rows) they found that the closest spacing resulted in the highest yields and also had the fewest problems with fruit quality. University of Saskatchewan trials have come to similar conclusions for peppers and melons growing in high tunnels. However, wider spacings were required for optimum yields of mature fruit in a high tunnel tomato crop.
Source : HortTechnology (2004) p. 507-513.