A field experiment was conducted on sweet pepper plants (Capsicum annuum L.) Sensei F1 hybrid during winter seasons of 2022/2023 and 2023/2024 under plastic greenhouse at the Research Farm of Vegetables Faculty of Agriculture, Benha University, Qalubia Governorate, Egypt, to investigate the effect of soil applicants, i.e., humic acid at 10 g.kg-1 soil or bentonite at 50 g.kg-1 soil and or humic acid + bentonite at 10 + 50 g.kg-1 soil and without soil application (control) under 3 levels of drought, i.e., 60, 80, 100% of field capacity on vegetative growth, yield and fruit quality of sweet pepper plants grown under drip irrigation system in clay soil conditions. The used plastic greenhouse is 27 * 60 m. The experimental site is at latitude 30o36" N and longitude 31o22"E. Three replicates were used in the split-plot design of the
experiment. According to the obtained results, the soil application of humic acid + bentonite at 10 + 50 g.kg-1 soil under 100% field capacity showed the lowest values of proline content and the highest values of all measured growth parameters, photosynthetic pigments, macronutrient contents such as NPK, and total carbohydrates. Moreover, the highest fruit weight, number of fruits. plant-1, fruit yield.plant-1, total fruit yield.m-2 and water use efficiency were also obtained by applying humic acid + bentonite under 100% field capacity, followed by 80% field capacity. Meanwhile, control treatment came last in this respect. On the other hand, plants irrigated with 60% field capacity without soil
application (control) showed the least values in all studied characteristics, except for proline content. It was also shown that soil application can reduce irrigation requirements by 20%, producing high yields with high physical and chemical quality.