The application of nanoparticles on the physiological, morphological, enzyme activities, and nutrient uptake of lettuce under different irrigation regimes

Abstract This study aimed to determine the effects of selected plant growth-promoting silver nanoparticles (AgNPs) on certain physiological traits, plant growth, enzyme activity, and plant nutrient content of lettuce grown under different irrigation regimes. In this research, four irrigation regimes were tested as experiments in a randomized complete block design layout: I 100 (full irrigation), I 80 (20% deficit), I 60 (40% deficit), and I 40 (60% deficit). Additionally, four nanoparticle doses (AgNP 0 , 0 ppm; AgNP 20 , 20 ppm; AgNP 40 , 40 ppm; and AgNP 80 , 80 ppm) were applied to the crop. The results demonstrated that the head diameter of lettuce decreased by 28% and 30% under the I 60 and I 40 water stress conditions, respectively. However, AgNPs enhanced the head diameter of lettuce by 10.9% compared to the control (non-application of AgNPs). The application of AgNPs increased the nutrient content of lettuce, including potassium (K), sodium (Na), iron (Fe), copper (Cu), and manganese (Mn), by 38%, 19%, 23%, 367%, and 20%, respectively. Plant height was 98.2% higher in the full irrigation treatment (I 100 ) than in the 40% irrigation treatment (I 40 ). Dry matter content was 10.2% higher in the AgNP 80 treatment compared to the AgNP 0 treatment. In addition, the highest catalase (CAT) enzyme content was obtained in the AgNP 40 treatment. The present research suggests that applying AgNPs represents a sustainable and eco-friendly strategy for improving lettuce’s plant growth and nutrient uptake under water stress conditions. Therefore, AgNPs can be used in drought stress tolerance studies.