Photosynthesis is the process by which photoautotrophic organisms absorb solar radiation and utilise carbon dioxide and water to produce carbohydrates. Stress factors impacting components like photosystems, pigments or electron transport chain can reduce the optimal photosynthetic performance of plants. C3 photosynthesis occurs in over 95% of plant species and thrive well in cool and wet climates, and are staple food crops. As a result, the majority of atmospheric CO₂ is fixed by the C3 pathway and is catalysed by the enzyme Ribulose bisphosphate carboxylase-oxygenase. Plant photosynthetic rate is directly determined by factors like light intensity, atmospheric CO₂ concentration, temperature and other abiotic or biotic stresses.
Light is an important environmental factor affecting photosynthetic rate due to huge fluctuations in spectral qualities and seasonal variations of irradiance. It also depends on factors like leaf orientation that affects the interception of incident light. It is an important natural factor impacting plant productivity, because diurnal irradiance varies over several orders of magnitude. Plants have evolved numerous strategies to account for the effects of sudden exposure to differing levels of light, like adjusting leaf orientation to the solar beam. Hence, the regulation of photosynthesis by the amount of incident light is a significant area of current research.
Knowledge on the impact of varying environmental conditions like light and CO₂ on photosynthesis can have many implications on regulating conditions and plant adaptations. It is predicted that the increase in atmospheric CO₂ will be 500-1000 ppm by the year 2100. Hence, understanding how plants will respond to rapid changes in CO₂ concentration is an essential step in predicting the impact that factors like drought, temperature, salinity, and global warming will have on terrestrial ecosystems. Because of its carbon absorbing ability, photosynthesis decreases the concentration of the greenhouse gas, CO2, and therefore would help alleviate global warming. Furthermore, due to decreasing farmable land, and extreme biotic stresses due to global warming, it is a challenging task to ensure optimal food and nutrient security. Hence, there is a need to increase global crop yields for food and bioenergy, as gains from conventional agricultural practices are less than the world population growth. As an estimate, global food production must increase 50% by 2030 to adequately feed the global population. So, it is also a crucial time to employ the extensive knowledge of photosynthetic processes to improve crop productivity.
This study aims to determine the effect that varying light intensity and CO₂ concentrations will have on the surface area of Eruca sativa leaves. E. sativa is a C3 plant from the Brassicaceae family in the Mediterranean zone with medicinal and nutritional properties. For this purpose, 1800 E. sativa plants were cultivated in varying light and CO2 conditions for four weeks, keeping the nutrients, water supply, and temperature constant. They were grown with a light period from 6am to 7pm using metal halide lamps. Since the glucose synthesised through photosynthesis is utilised for the growth and maintenance of plant cells, the photosynthetic rate can be an indication of the plant growth rate within the same species. Moreover, it is known that leaf surface area is the most important indicator of photosynthetic performance because rapid leaf growth allows more effective absorption of solar energy and better yield. If E. sativa is subjected to high light, then the leaf surface area will be higher than when it is subjected to low light conditions. If E. sativa is grown in an elevated CO₂ condition, then the leaf surface area will be greater than when it is grown in an ambient CO₂ environment.
At elevated CO₂, subjecting Eruca sativa to high light led to greater leaf surface area than when it was subjected to low light. At high light intensity, plants grown in elevated CO₂ concentrations had higher surface area than those grown in ambient CO₂ concentrations. There is a significant statistical difference between the leaf surface area of plants grown under elevated CO₂ and ambient CO₂ under high light as p
