Photosynthesis is the basis of life on earth that converts light energy into chemical energy and is the primary component of crop yield. Significant increase in crop yield by enhancing photosynthesis can answer to global food security. With the increase in population size and limited land availability, efforts have been made to grow crops in tough terrains like high altitude areas. As one ascends a mountain, environmental conditions such as heavy UV influx, arid landscape and long winter season can result in various physiological, biochemical and molecular alterations in plants which may affect photosynthesis. In the present review, we focused on critical biological process in plants i.e. photosynthesis with regard to high altitude areas. We also reviewed the role of abiotic factors which play a key role in regulating photosynthesis at altitudinal gradient. Ladakh, often refereed as cold desert due to its high altitude and cold arid climate, is a region where a limited patch of land is available for agriculture due to tough terrain. Over centuries, farmers in Ladakh have evolved self-sustained farming systems notwithstanding scarce resources, amidst a climatically challenging environment. In Leh-Ladakh region, only five months (May to September) are available for farming while the rest of the year is extreme cold and not conducive for crop cultivation snow covered (October to March).As a result, almost no agricultural practices take place during winter season and people are dependent on stored food crops. Army troops are supplied with vegetables and fruits from Chandigarh by Air route which is quite expensive. Earlier, to enhance the yield per hectare of agricultural crops with increasing demand was possible through breeding programs and farming practice but now crops yields are reaching a plateau. One fundamental component of plant productivity that has not been used to select for increased yield is photosynthesis.
Defence Institute of High Altitude Research (DIHAR) is one of the laboratories of Defence Research and Development Organization (DRDO) New Delhi located at Leh, at an altitude of 3500 amsl. It was established in 1962 and is a pioneer organization which mainly focuses on cold arid agro-animal technology. With the help of updated R&D technologies and novel inputs in cold arid agro animal technologies, our mission is to enhance the availability of fresh food for troops in Ladakh. In order to enhance the productivity at high altitude, laboratory and field research is targeted to increase yield potential in agricultural crops. Recent studies have shown that increase in crop yield can be achieved with enhanced photosynthesis. With this objective in mind, Defence Institute of high Altitude Research (DIHAR) situated in Leh–Ladakh aims to enhance the productivity at high altitude, and is targeted to increase yield potential in agricultural crops. Over the century, grain yield has almost doubled yet there is no significant change in the rate of photosynthesis per unit leaf area. In the present study, we reviewed different physiological factors which change as altitude increases and their effect on photosynthesis and subsequently on crop productivity.
