Basil morphological and physiological performance under trinexapac-ethyl foliar sprays and prolonged irrigation intervals

Global warming and lack of irrigation water put immense pressure on the production of highly economic and water stress sensitive plants such as Ocimum basilicum which is commonly known as "basil''. The study aims to determine the morphological and physiological effects of trinexapac-ethyl (TE) foliar biweekly sprays with 0.1, 0.2, and 0.3 L ha(-1) and/or four irrigation intervals of 1, 2, 3 and 4 days on Ocimum basilicum bush green and purple ruffle cultivars grown in PVC containers under greenhouse conditions. After 8 weeks of irrigation intervals, basil cultivars exhibited significant reduction in leaf number and area, plant dry weight, root dry weight, plant height, photosynthetic rate, stomatal conductance, and transpiration rate, but increased essential oil content in leaves in both cultivars. The application of TE reduced leaf number, leaf area, plant dry weight and plant height but increased root dry weight, photosynthetic rate, stomatal conductance, transpiration rate and essential oil content in leaves in both cultivars compared to untreated plants at different irrigation intervals. The 4 days irrigation intervals and TE spray with 0.3 L ha(-1) increased leaves essential oils quality and quantity compared to 1 day irrigation intervals in untreated plants, but at the same time reduced economic parameters such as plant dry weight. The results of this study suggest the possibility of growing basil cultivars under prolonged irrigation intervals using TE foliar sprays; however, the economic revenue needs to be evaluated. Reduction of plant biomass, increased root weight, and protective effects of TE on photosynthetic efficiency play a major role in drought avoidance mechanism in basil cultivars grown under moderate drought conditions.