Air and substrate temperatures in greenhouse and open area of strawberries grown in vertical system and their influence on yield

The experiments were done at Latvia University of Life Sciences and Technologies in 2019 and 2020. Strawberries were planted in growing bags with sphagnum peat and placed on a vertical growing system in three levels – 10, 90, and 155 cm and grown there for two seasons. The two identical growing systems were installed – in plastic greenhouse and open area. The aim of this paper is to evaluate differences in air temperatures among plants and substrate temperatures in both areas in all three levels, sunny and overcast weather, and in morning, noon and afternoon. Both air and substrate temperatures were higher in the greenhouse conditions by 5.4 and 6.2°C, respectively. At the open area, there were lower temperatures in mornings, but no significant differences between levels in both overcast and sunny days. At the greenhouse, significantly lower air and substrate temperatures also were measured in both overcast and sunny mornings and no significant differences between levels in overcast days. However, significant temperature differences were measured between levels in sunny days – the air on the top level had 3.6°C higher temperature than on the bottom level, and substrate had 3.0°C higher temperature on the top level than on the bottom level, in average. Although strawberries had some different response to these conditions, the berry yield was not significantly different in different levels in both open field and greenhouse conditions. Tested cultivars’ yield had different response to growing in greenhouse and open area.