الفهرس 
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Abstract
Two field experiments were carried out at the Experimental Farm, Faculty of Agriculture, Menoufia University, Shebin El-Kom, Egypt to study the effect of some plant stimulant substances on vegetative growth characters (plant height, number of stems and leaves/ m2, stems, leaves and total dry weight/ m2,leaf area/m2, specific leaf area and specific leaf weight and leaf/stem ratio), photosynthetic pigments (total chlorophyll), plant chemical compositions (N, P and K%) and nutritive values (CP and DP%), forage yield (fresh and dry forage yields/fed) and seed yield 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 (Trifolium alexandrinum, L.) varieties during 2015/2016 and 2016/2017 seasons.
Each experiment included twenty five treatments which were the combination of five varieties and five plant stimulant substances. The tested treatments are as follows:
A- Varieties
1- Serw 1
2- Sakha 4
3- Helaly
4- Giza 6
5- Gemmeiza 1
B- Growth stimulant substances
1- Control (tap water)
2- Ascorbic acid (AA) at a rate of 1 g/L
3- Citric acid (CA) at a rate of 1 g/L
4- Humic acid (HA) at a rate of 2 g/L
5- Salicylic acid (SA) at a rate of 0.5 g/L
The treatments were arranged at random in a split plot design with three replications. The main plots were allocated for Egyptian clover varieties, while the plant stimulant substances were assigned at random in the sub-plots.
The obtained results could be summarized as follows:
1- Growth characters:
1- Helaly variety mostly significantly surpassed the other varieties in growth characters (plant height, number of leaves/ m2, stems, leaves and total dry weight/m2 and leaf area/ m2).However, Gemmeiza 1variety had substantial increases in number of stems/ m2. On the other hand, specific leaf area, specific leaf weight and leaf/stem ratio were not significantly differed in the five tested varieties at the four cuts and their averages in both seasons.
2- Foliar application of HA gave the highest values of growth characters (plant height, number of leaves/ m2, stems, leaves and total dry weight / m2 and leaf area/ m2) at the four cuts and their averages in both seasons. However, there are no significant differences among the tested stimulant substances for specific leaf area, specific leaf weight and leaf/stem ratio.
3- The interaction between the varieties and stimulant substances indicate that Helaly variety sprayed with foliar application of HA was the most effective interaction treatment for increasing the plant height, number of leaves/ m2 and stem dry weight and total dry weight /m2 in the two seasons as well as leaves dry weight in the first season. However, the highest values of leaves dry weight in the second season were recorded by Gemmeiza 1variety when it was sprayed with HA. Moreover, spraying Gemmeiza 1variety with SA recorded the highest value of number of stems /m2 in both seasons. On the other hand, the interactions