Effect of Dopamine on Growth, Some Biochemical Attributes, and the Yield of Crisphead Lettuce under Nitrogen Deficiency

Nitrogen (N) represents the most important nutrient for plant growth and productivity, but extreme and ineffective usage of N fertilizer results in boosted plant production expenditures and environmental contamination. For the world's sustainable food production and environmental profits, there has been increased research interest in reducing the use of N fertilization along with improving plant N deficiency (ND) tolerance. Dopamine (DA), a potential antioxidant, mediates several physio-biochemical processes in plants under normal or stressful conditions. However, their roles in increasing ND tolerance in crisphead lettuce are not well-documented. We investigate the role of DA concentration (0.50 and 100 mu M) on the growth and yield of crisphead lettuce plants under ND. Under normal conditions (100% recommended N fertilizer dose), DA (50 and 100 mu M) application significantly enhanced growth, chlorophyll concentration, N%, antioxidant enzymes activity, as well as yield and its components, decreased nitrate accumulation and oxidative biomarkers compared to untreated plants (0 mu M DA). ND significantly decreased plant growth and yield attributes as well as evoked oxidative impairment and nitrate accumulation as compared to 100% recommended N fertilizer dose in the absence of DA. However, within ND conditions, the application of DA concentrations significantly mitigated ND-induced oxidative burst and improved plant growth, chlorophyll concentration, N%, nitrate concentration, peroxidase, catalase, superoxide dismutase, total soluble solid, vitamin C, dry matter %, and total sugars, over 0 mu M DA treated plants. Current findings highlighted that exogenous application of 100 mu M DA could reinforce the crisphead lettuce plant's resilience to ND by minimizing reactive oxygen species accumulation and promoting enzymatic antioxidants alongside growth, yield, and quality improvement. The beneficial effects of DA in lessening ND's drastic impacts on crisphead lettuce resulted from upregulating antioxidant enzyme activity, impairment of oxidative biomarkers, and maintaining chlorophyll levels. The current findings open pioneering prospects to reduce nitrogen fertilization by DA application without any drastic effect on plant productivity. But further research is needed to fully understand DA effects and their mechanisms in inducing ND tolerance in different plant species, including crisphead lettuce.

Automated summary

Nitrogen is crucial for plant growth and productivity, but excessive and ineffective use of nitrogen fertilizer leads to higher production costs and environmental pollution. To promote sustainable food production and protect the environment, there is growing interest in reducing nitrogen fertilization and improving plant tolerance to nitrogen deficiency. Dopamine, an antioxidant, plays a role in various physiological and biochemical processes in plants. However, its impact on crisphead lettuce's tolerance to nitrogen deficiency has not been well-documented.