With the maximum and minimum temperatures soaring, the crop yield is likely to witness a loss of 10 to 40 per cent in parts of Himachal Pradesh. Solan has witnessed the highest temperature of 37.5^oC and lowest of 20^oC this season, which was among the highest temperatures recorded in the recent years,  said scientists of Dr YS Parmar University of Horticulture and Forestry, Nauni. The area abounds in the cultivation of tomatoes, off-season vegetables and stone fruits. Tomato is grown over 6,609 hectares in Solan and Sirmaur, which is nearly 65 per cent of the state’s share. Dr Satish Bhardwaj, head of the Department of Environmental Sciences, said all crops had a certain natural threshold limit of climatic components beyond which they did not grow normally. Kharif  crops grown in summer  required about 18-20^oC night and 25 to 30^oC day temperatures during sowing. High temperature affects the phenology of various fruit crops and it has been observed that flowering, pollination and fruit set of tomatoes and peppers can be adversely affected by extreme temperatures. The optimum range for the growth of tomato and pepper is 18-26^oC and if the temperature increases beyond 35^oC, it affects the fruit set, while if the temperature goes beyond 32^oC, pollen sterility occurs and flowers may also drop in pepper. Similarly, an increase in temperature beyond the optimum range causes delayed curd initiation in cauliflower, while if the temperature goes beyond 40^oC, the bulb size onion is reduced. Source - https://www.freshplaza.com