Application of nano-selenium to tea plants under various nitrogen circumstances improves tea quality and drought resistance

• Drought stress decreased tea quality, N translocation and uptake rates, but increased water use efficiency. • Nano-selenium foliar application alleviated drought stress, enhanced N translocation and uptake rates. • Nano-selenium foliar application increased the leaf Se content, the levels of soluble sugars, amino acids and tea polyphenols. Tea plant ( Camellia sinensis (L.) O. Kuntze) is an important economic crop and frequently exposed to drought stress. However, there is still limited understanding of how drought stress affects nitrogen uptake and amino acid accumulation in tea plants, which are key indicators of both growth and nutritional quality. In this study, we explored the growth and physiological traits, and tea quality of three tea cultivars (‘Longjing 43’, ‘Fuding Dabaicha’, ‘Zhenong 117’) under nano-Se application, drought stress and their interactions. In addition, 15 NH 4 NO 3 and NH 4 15 NO 3 were used to identify the different forms of nitrogen uptake and translocation rates. We found that drought stress decreased growth and biomass, net photosynthetic rate ( A ), photosynthetic nitrogen use efficiency (PNUE), tea quality (amino acids and tea polyphenols), N translocation and uptake rates, but increased water use efficiency (WUE) and oxidative stress. The nano-Se application alleviated drought stress, which increased leaf biomass and total biomass, A , WUE and PNUE in the three tea cultivars, especially under drought stress. In addition, ‘Longjing 43’ had the highest stem biomass and total biomass, A and WUE under combined nano-Se application and drought stress. Furthermore, nano-Se application significantly increased the leaf Se and leaf N contents, the levels of soluble sugars, amino acids and tea polyphenols, and ‘Longjing 43’ had the highest leaf Se and amino acid contents under nano-Se application. We concluded that under nano-Se application, ‘Longjing 43’ improves more as a higher stem biomass and total biomass, A and WUE, leaf Se and amino acid contents, and higher N translocation and uptake rates when suffered drought stress. This is helpful for tea management under future climate change with increasing drought.