Effect of shading and high temperature amplitude on yield and phenolic contents of greenhouse capsicum (Capsicum annuum L.)

Abstract

Low temperature is one of the most important abiotic factor that restrict the optimal production of warm-season vegetables in the cold mountain regions. Studies were conducted to establish the possibility of growing capsicum, a temperature sensitive crop, in a naturally ventilated passive solar greenhouse with high temperature amplitude (25.2±2.5ºC). Despite the temperature fluctuation from 6.8±2.9°C at night to 38.6±4.1°C day temperature, flowering and fruiting were seen. The salable yield inside the greenhouse was 4.5 to 4.8-fold higher that of open field. Red shade net combine with the greenhouse technology significantly increased the intercellular CO2 concentration but affected the photosynthetic rate. Shading delayed flowering and 51-59% reduction in salable fruit yield. Total phenolic contents (TPC) and total flavonoid contents (TFC) of capsicum grown under open field and greenhouse were similar. However, shading reduced the TPC and TFC by 35.2% and 14.6%, respectively inside the greenhouse.