Journal of Agronomy and Field Innovations

Background: Global warming is increasingly endangering the survival of Brassica rapa L., a vegetable with nutritious leaves through disturbances in photosynthesis, cellular membrane integrity, and cellular redox balance.
Aim: It has been aimed in the present study to assess the biochemical response of B. rapa seedlings on exposure to short-term heat stress.
Methodology: The seedlings were subjected to a temperature of 42±2°C in a completely randomized design for 6 hours each day for 5 days along with controls at 25±2°C. Chlorophyll, carotenoids, proline, soluble sugars, proteins, malondialdehyde (MDA), hydrogen peroxide, electrolyte leakage, relative water content, and activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) were estimated and results were analyzed using one-way ANOVA (P<0.05).
Results: There was a decline in chlorophyll a, chlorophyll b, carotenoids, and the moisture content stemming from heat stress as MDA, H2O2, and ion leakage underwent a surge. Proline and the quantity of sugar present increased as well while SOD, CAT, POD, and APX activity significantly increased relative to the control plants indicating an efficient antioxidant capability and osmotic adjustment mechanism.
Conclusion: In the face of heat stress, B. rapa initiates a concerted biochemical defense strategy via osmotic agent accumulation and inducing antioxidant enzymes, however with just a partial success. These biophysical properties can serve as valuable criteria for developing heat-tolerant varieties amid climatic changes.