Two field experiments were carried out at the Experimental Farm, faculty of Agriculture, Menoufia University, Shebin El-Kom, Egyptduring 2015/2016 and 2016/2017 seasons to investigate the effect of some plant stimulant substances(control,ascorbic acid 1 g/L, citric acid 1 g/L, humic acid 2 g/L and salicylic acid 0.5 g/L)as foliar application on vegetative growth performance(plant height, number of leaves and stems/m2,stems and leaves dry weight/m2,total dry weight/m2 , leaf area/ m2, specific leaf area and specific leaf weight/ m2 and leaf/stem ratio),photosynthetic pigments(total chlorophyll), plant chemical composition(N,P and K%) and nutritive value(P and DP%), forage yield( fresh and dry forage/fed) and seed yields and its components (number of heads/ m2, number of seeds/head, 1000-seed weight, seed weight/head and seed yield/fed) of some Egyptian clover varieties (Serw1, Sakha4, Helaly, Gemmeiza1 and Giza 6).The results obtained could be summarized as follows:
1-The Data indicated thatHelaly variety surpassed the other varieties in most growth characters (plant height, number of leaves/ m2, stems, leaves and total dry weight/m2 and leaf area/ m2), photosynthetic pigment (total chlorophyll),Chemical composition(N %) and nutritive values(crude protein and digestible protein percentage),forage yield(total fresh and dry forage yields/fed)and seed yield and its components(number of seeds/head, seed weight/head and seed yield /fed). However, Gemmeiza 1 variety surpassed the other varieties in number of stems/ m2 and number of heads/ m2.On the other hand, the highest values ofP% and K% were recorded by Sakha4.Serw1variety gave the highest value of 1000-seed weight in both seasons.
2- Foliar application of humic acid was superior to the other rest stimulant substances in most characters studied of growth characters and forage yield. However, Salicylic acid produced generally the highest values of chemical composition and nutritive values and seed yield and its components. On the other hand, unsprayed clover plants gave the lowest values of most characters studied.
3-The interactions between Egyptian clover varieties and stimulant substances were found to be significant for most characters under study.It could be concluded that Helaly variety treated with foliar humic acid being the most effective combined treatment for maximizing fresh forage yield/fed, while the same variety when treated with foliar salicylic acid produced the highest values of seed yield/fed of Egyptian clover under the experiment conditions.
4-Seasonal fresh and dry forage yields were significantly and positively correlated with characters studied except number of stems/m2, number of seeds/head and seed weight/head in the first season and 1000-seed weight in the two seasons. Also seed yield/fed was significantly positively associated with all characters studied except 1000-seed weight in both seasons.