Monitoring the developmental stages of Calendula officinalis L. nutrients efficacy under hot weather mitigation through nutrients in Haripur, Pakistan

This study examines the effect of different doses of N and P fertilizer on Calendula officinalis L. (marigold) during the hot weather in summer (May–July) in Pakistan. The aim was to determine whether fertilization can help minimize the impacts of climate change. During the summer peak seasons (May, June, and July), the trial was conducted in potted plants with different N and P application levels to monitor the quality and quantity of C. officinalis. The results showed that the interactive effects (N × P) gave higher values for plant height, number of leaves, fresh weight, leaf length, and number of branches. The application of P only gives more flowers. In May and July, maximum values of malondialdehyde (MDA), chlorophyll, and lipid peroxidation were observed in leaves. The change in Li and K was measured in May and June, with slight differences observed in July. The phytochemicals, such as total phenolic contents (84.41 mg GAE/g), total antioxidants (36.3% DPPH), total carotenoids, and total flavonoid contents (16.2 and 0.9 mg/100 g), were found to be highest with the interactive effects of both N and P doses in the 2 years of study. It was concluded that higher doses of both N and P effectively controlled flower loss and improved the quality of florets in hot weather.