The trans-Himalayan Ladakh region remains cut-off for over six months in a year due to heavy snowfall. Availability of locally grown fresh vegetables is restricted to summer months and therefore, there are seasonal differences in dietary intake of food. Passive solar greenhouse has played a significant role not only in production of leafy vegetables in sub-zero temperature during winter months but also helped in extending the growing season in Ladakh. It is now a common practice to raise vegetable nurseries in spring and grow leafy vegetables during winter months in the greenhouse. Each year an average of 733 greenhouses covering 44313.4 m2 area are being established in Leh district. Passive solar greenhouse structures such as Ladakhi greenhouse, trench, polytrench, polyench, polycarbonate, FRP and polynet have been designed and tested in the inhospitable environment of trans–Himalaya. The greenhouse is used mainly during winter, and majority of farmers (91.7 %) do not use the structures in summer. Insect-pest, irrigation in winter and frequent replacement of cladding materials are the major problems being faced by the farmers in the region. There is a need to improvise the greenhouse design to make it economically viable and technologically feasible to grow a variety of crops, especially during winter months.

Greenhouse experiments were conducted in three seasons (2017-18, 2018-19, 2019-20) to study the feasibility to grow cabbage, a temperature sensitive crop, during freezing winter months at high altitude (elevation 3340 m) trans-Himalayan Ladakh region. Three varieties viz. Golden Acre, Videshi and Megaton were studied under an improvised passive solar greenhouse. Head was formed in all the varieties despite the temperature extremes (0.0±1.6 to 39.5±0.9 ºC) inside the greenhouse. The mean marketable head weight ranged from 428.6±72.1 g to 831.2±193.0 g, depending on the variety. The mean head weight of Golden Acre was 831 g, which is 15-fold higher as compared to that of the crop grown under traditional greenhouse in Ladakh. However, the marketable head weight was lower as compared to the yield potential of the varieties. It took 133-163 days for Golden Acre to reach maturity for harvest as compared to the expected 60-65 days. Dramatic declines in intercellular CO2 concentration, photosynthesis rate and water-use efficiency were observed at 2:00 PM, which indicated that the plants were severely affected by high temperatures inside the greenhouse. High temperature inside the greenhouse resulted in bolting, head-splitting and loose head forming, and it ranged from 8-36% of the crop depending on the year and variety. The study suggested that cabbage can be successfully grown under improvised passive solar greenhouse during severe winter months in the trans-Himalayan Ladakh.

No abstract

No 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.