Effect of shading and high temperature amplitude in greenhouse on growth,photosynthesis, yield and phenolic contents of tomato (Lycopersicum esculentum Mill.)

Low temperature is the major environmental factor that limits the optimal field production of tomato in the high altitude mountain regions. Studies were conducted to determine the feasibility of growing tomato, a temperature sensitive crop, in a naturally ventilated passive solar greenhouse with high temperature amplitude (24.7 ± 3.0 °C). The study also aimed to determine the application of shade net combined with low-cost greenhouse technology. Despite the temperature fluctuation from 6.6 ± 2.1 °C at night to 39.1 ± 4.7 °C day temperature, flowering and fruiting were observed under the greenhouse conditions. The marketable yield inside the greenhouse was 1.8-times higher compared to open-field. Shading significantly affected the photosynthesis and results in increased sub-stomatal CO₂ concentration. Shading resulted in delayed flowering and 48% reduction in marketable yield. Total phenolic contents (TPC) of tomato grown under open-field and greenhouse conditions were similar. However, greenhouse conditions resulted in a 35% decrease in total flavonoid contents (TFC) of tomato fruit. Shading reduced the TPC and TFC by 29 and 16%, respectively under greenhouse conditions.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12298-021-01032-z.