Effects of stem training on the physiology, growth, and yield responses of indeterminate tomato (Solanum lycopersicum) plants grown in protected cultivation

The lower yield of tomatoes grown in tunnels, due to the limited space, remains a challenge. Stem training has long been identified as one of the most important horticultural practices used to improve the yield and fruit quality of tomatoes grown in commercial tunnels; however, there is little information available on the dome-shaped tunnels that are used, particularly by smallholder farmers. The common stem-training methods used in tunnels include the Single-Stem (SS), the Double-Stem (DS) and the Two-Plants-per-Pot (TPP) methods. Their effect on the plants’ growth, development and physiology varies significantly, and hence, it affects crop productivity. The experiment was conducted in an 8 m × 30 m dome-shaped tunnel and the treatment included the single-stem, double-stem and two-plants-per-pot methods. A higher photosynthetic rate was observed in the SS treatment, followed by the DS treatment. Similar trends were found in the growth, yield and fruit quality parameters of the SS and DS treatments. However, the DS and TPP treatments exhibited, on average, a higher number of fruits, as well as a higher colour index, TSS, TA and Brima per harvest, than the SS treatment. The study indicated that the double-stem and two-plants-per-pot training methods are the best for farmers who seek to optimize their yields and maximize their profits for this cultivar.