During the two seasons of 2018 and 2019, a field experiment was carried out at The Experimental Farm of Rice Research Department, Sakha, Kafrelsheikh, Field Crops Research Institute, and Agricultural Research Center, Egypt. In order to determine the appropriate stage of potassium silicate application to improve some of morphological, chemical characters related to the lodging resistance and increase the grain yield of Sakha 104 rice cultivar. Four replications of a randomised complete block design were used.. The eight treatments of foliar applications of potassium silicate at the rate of 1.0% were used as follows; (T₁) control (without potassium silicate application); (T₂)at vegetative stage; (T₃)at reproductive stage; (T₄) at maturity stage; (T₅) at vegetative stage+ reproductive stage; (T₆) at vegetative stage+ maturity stage; (T₇) at reproductive stage+ maturity stage; (T₈) at vegetative stage+ reproductive stage+ maturity stage. The results showed that  the most studied characters of Sakha 104 rice cultivar were generally increased by the application of (T₅) treatment followed by T₈ treatment, while (T₁) treatment resulted the maximum degree of lodging. According to the previous results and under the same conditions of experiment, it could be summarized that adding potassium silicate as foliar application at the same concentration 1.0% twice at vegetative and reproductive stages (T₅ treatment) was the best treatment for improving morphological, chemical characters related to lodging resistance and obtaining the highest grain yield of Sakha 104 rice cultivar.