Zn-quantum dot biochar regulates antioxidants and nutrient uptake to improve rapeseed growth and yield in drought stress

Drought stress is one of the major abiotic factors that cause a significant decline in the crop's productivity. It can disturb photosynthesis by inducing oxidative stress by producing reactive oxygen species. Recently, the use of quantum has gained the attention of scientists due to its potential positive impacts on plants under stress conditions. That's why a current study was conducted to explore the impact of Zn-quantum dot biochar (QDB) on rapeseed growth under drought stress. There were four levels of QDB, i.e., control (no QDB), 0.2 %, 0.4 %, and 0.8 %, applied on a w/w basis in soil under normal irrigation and drought stress. Results showed that 0.8 %QDB performed significantly better in improving seedling's emergence, plant height, number of branches/plants, number of pods/plants, pod length, seed weight/plant, 1000 seeds weight, and total biomass of rapeseed under normal irrigation and drought stress. At 0.2 %, 0.4 %, and 0.8 % QDB levels, the photosynthetic rate was 9.19 %, 11.78 %, and 13.46 % higher than the control under drought stress. Compared to the control, the transpiration rate increased by 61.40 % with 0.2 % QDB, 123.46 % with 0.4 % QDB, and 199.71 % with 0.8 % QDB. The percentage increase in stomatal conductance ranged from 44 % for 0.2 % QDB to 129 % for 0.8 % QDB under drought stress. In conclusion, 0.8 %QDB can potentially reduce drought stress and improve the leaf water contents and nutrient uptake in rapeseed.