Foliar Applications of Potassium to Control Green Bean Pests and Improve Yield and Quality Under Greenhouse Conditions

Saaid, A., K.F. Abdelgawad, M.M. Ahmed, R.F. Ali and S.S. Ahmed. 2024. Foliar Applications of Potassium to Control Green Bean Pests and Improve Yield and Quality Under Greenhouse Conditions. Arab Journal of Plant Protection, 42(4): 497-510. https://doi.org/10.22268/AJPP-001279 Green bean is attacked by a variety of insect pests such as whiteflies, aphids, leaf miners, and two spotted red mite, which can reduce plant growth and yield up to 100%. Potassium plays an important role in plant growth and resistance to biotic stress. The aim of this study was to compare the effect of different sources of potassium foliar application on infestation of green bean pests and their effect on productivity and quality of green beans. Two field experiments were conducted during 2018/2019 and 2019/2020 growing seasons to assess the response of aphids, whiteflies, leaf miner, and two spotted red mite as well as plant growth, and yield of green bean to three potassium sources (silicate 30%, citrate 35% and sulfate 50%) application under greenhouse conditions. The plants were sprayed 15 days after sowing with 6 ml/L, 8 ml/L and 1.5 g/L of potassium silicate, citrate and sulfate, respectively. The foliar application was repeated three times. The number of the examined pests (insects and mites) was calculated in the tested and control treatments. The results obtained showed that, in both seasons, the lowest population of whiteflies was recorded in response to potassium silicate treatment (15.4 and 16.7 insects/plant), followed by potassium citrate (19.3 and 19.4 insects/plant) compared to the potassium sulfate treatment (control) (21.8 and 20.5 insects/plant), respectively. The lowest aphid population in the first season was reached following silicate treatment (1.46 insects/plant) compared to citrate and control treatments (2.38 and 2.85 insects/plant), respectively, with no significant difference between them. During the second season, the lowest aphid population (1.08 insect/ plant) was reached after silicate treatment, followed by citrate treatment (2.38 insects/plant), and control treatment (5.38 insects/plant). Silicate treatment significantly reduced the population of two spotted mites compared to the other treatments, in both seasons. Silicate treatment produced the lowest leaf miner population in both seasons, compared to other treatments. All the growth parameters (plant height, number of leaves, relative chlorophyll content, plant fresh and dry weight, and dry matter) were improved by potassium silicate treatment compared to potassium citrate and sulfate treatments. The increase in total yield under foliar application ranged from 15.2 to 40.8 % compared to control treatment. The highest plant phenol, tannins, total carbohydrate, and peroxidase concentration were produced following potassium silicate treatment. It was concluded that potassium silicate can enhance plant growth and resistance to insect pests. Keywords: Foliar spray, green bean, potassium fertilizers, pests.