It is now accepted that climate change is going to have its impact on global food production. The three primary factors undergoing changes with climate change such as, average global temperature, CO2 concentration in the atmosphere and annual precipitation will have their effect on crop production.
While increase in CO2has a positive impact, temperature increase adversely affects crop yield. Rainfall pattern will change with increase in temperature and will have its impact on crop production.
Apart from crop production, the quality of produce from different crops is likely to be affected by climate change. Quality parameters of produce from different crops such as, cereals, pulses, oilseeds, fibre crops, sugar crops, condiments and spices, fruits and vegetables, commercial crops etc., vary widely according to their use.
According to SAleena Ahmed of Montana State University and John Richard Stepp of University of Florida, USA (2016) the quality parameters of consumable crops include, the presence and concentration of phytonutrients and secondary metabolites, bioactivity as well as organoleptic properties such as colour, visual appeal, aroma, taste and texture and shelf life. Further, presence of toxins and association of any microorganism need to be examined to ensure food safety.
Research results are available on quality of a number of crops affected by climate change. In general, increase in CO2content decreases protein and mineral content of produce. Increase in temperature reduces vitamins and alters organoleptic properties of fruits and vegetables.
A recent review and analysis of 343 research publications showed that organically produced crops and food items have statistically higher concentrations of antioxidant secondary metabolites compared to those produced in conventional system.
Effects of climate change on quality of some crops: Rice and wheat: Increased concentration of CO2in the atmosphere is likely to increase yield of rice and wheat but reduce their protei content and some of the minerals. The composition of their starch is also affected. The bread and chapati making quality of wheat is likely to be adversely affected. In rice the cooked rice may be harder to chew due to increase in amylose content of the grains.
Mustard: There is an increase in the seed size and seed weight due to increase in CO2and improvement in yield. There is also some increase in unsaturated fatty acids resulting in the improvement of the quality of the oil
Groundnut: Change in temperature and rainfall may change health related quality (ratio of oleic and linolenic acid) of its oil.
Fruits and vegetables: Generally, increase in CO2 improves Vit-C, sugars, acids and carotenoids in different fruits and vegetables but elevated temperature decreases vitamin C, starch, sugars, antioxidants, anthocyanins, volatile flavour compounds in fruits. A higher temperature with water stress reduces vitamins, antioxidants and minerals in fruits and vegetables.
Potato: Increase inCO2content in the atmosphere is likely to affect post-harvest quality of tubers, with decrease in their sugar content,increased susceptibility to tuber malformation and incidence of scab.
Tomato: Tomatoes exposed to very low ozone concentrations results in increase in its vitamin A content. Elevated CO2 has positive effect on Vitamin C, sugars, acids and Vitamin A content of tomato. Oranges and Tomatoes: Deficit irrigation increases sugars, anthocyanins and even volatiles of the fruits.Elevated CO2 improve the vitamin C, sugars, acids and carotenoids.
Apple: Rainfall, temperature, and humidity influence terpenes and volatiles affecting its flavour. Bilberries (small blue berries): Anthocyanidin concentration in bilberries is influenced by climatic factors, Sensory quality and health-related benefits.
Grapes: Cooler temperatures are positively correlated to phenolic compounds and antioxidant properties, sensory quality and health-related benefits. Increase in CO2level increases tartaric acid (sourness) in grapes.
Coffee: Environmental temperature during development dramatically influences fatty acid content and health-related properties.
Tea: Polyphenolic catechins, which determines the quality of tea drink, is affected by variation of weather condition.
Coriander (Dhania): Weather conditions in 1997 favoured linalool and camphor concentrations in coriander fruits and sensory qualities.
(Dr Mitra is a former Dean, Agriculture and Professor of Soil Science and Agricultural Chemistry, OUAT. Information given is based on reported research results)