الفهرس 
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Abstract
Three pot experiments were carried out at the Floriculture Experimental Farm, Faculty of Agriculture, Assiut University, Assiut, Egypt during the two successive seasons of 2007 and 2008. The aim of this investigation was to study the influence of certain growth regulators (GA3 and cycocel) and chemical fertilizers (kristalone and urea) on growth of Cupressus macrocarpa, Hartw c.v. Goldcrest seedlings. To get plants those have the following commercial characteristics:
1- Rapid growth: to decrease its producing period.
2- Golden green colour: to give a contrast with turf grass as a botanical landscape.
3- Merge in branches with the simplicity of the conical shape to be wider from the lower part and narrow in the top.
A- First Experiment:
This experiment was carried out using:
1- Kristalone: NPK fertilizer (19-19-19+1 MgO) as commercial compound known commercially as a fertilizer for the potting and indoor plants with a suitable price to support the plant with phosphorus, potassium and nitrogen with trace of magnesium.
2- Gibberellic acid (GA3): Gibberellins, in general, as naturally occurring class of plant growth stimulants, have long been used to control plant growth and development, from the germination stage to fruiting and maturity Leopold and Kriedemann (1975).
Homogenous cypress seedlings were arranged in a block randomized design in split-plot with three replicates. The main plots represented. The kristalone levels (control, 5 and 10 gm). Each main plot divided into four sub-plot represented gibberellic acid concentrations (0, 50,100 and 200 ppm). Each replicate consisted of 12 treatments (3 kristalone rates x 4 gibberellic acid concentrations) with 4 plants (pots) per treatment.
The plants were kept under shading conditions until the end of the experiment. For both experiments, the following data were collected:
a. Vegetative growth parameters: Plant height, number of branches per plant, stem diameter, foliage fresh and dry weights per plant.
b. Chemical analysis: Nitrogen, phosphorus, potassium, calcium, magnesium, protein and total carbohydrate percentage in leaves.
The obtained data were statistically analyzed and summarized as follows:
1- Concerning kristalone effect: feeding lemon cypress with kristalone resulted in the highest values of vegetative measurements compared to the control, the highest rate (10g/plant) resulted in the highest increments in growth parameters. The highest concentrations of N, P, K, and Mg and the lowest Ca were obtained from plants received kristalone. The highest level (10g/plant) resulted in the highest increments in the nutrient contents in leaves, calcium pronouncedly decreased below the control (untreated plants) as a result of kristalone application. Meanwhile increasing the concentration of kristalone led to a significant increase in percentage of total carbohydrate, with the best results attained by applying kristalone at 5 g/plant. Applying the highest dose (10g/plant) showed insignificantly lower results. On the other hand, protein content behaved parallel to the results obtained for nitrogen content in branches.
2- With regard to Gibberellin (GA3) application: It was noticed that increasing the concentration of GA3 led to a clear increments in plant height, branches number and foliage fresh and dry weights, with the maximum values attained by applying GA3 at 200 ppm. Applying the highest concentration (300 ppm) showed insignificantly lower values. Meanwhile, the highest concentration of GA3 (300 ppm) exhibited the thickest cypress plants. In addition, the highest concentrations of N, P, K and Mg and the lowest Ca were obtained from plants received GA3, either at medium or high level. Regarding the percentage of total carbohydrate in their leaves, untreated plants (control) contained the highest values; whilst plants treated with the highest concentration of GA3 (300ppm) recorded the lowest figures. On the other hand, protein content is similar to the results obtained of nitrogen content.
3- Concerning to the interaction effects between GA3 and kristalone: fertilizer on growth measurements, data showed that applying a combination of 200 ppm GA3 and 10 g/plant kristalone gave the best results of different growth measurements. Meanwhile, the combined effect of GA3 (200 ppm) plus kristalone (10g) proved to be the most effective treatment on producing better nutritional status. Besides the interaction effect on percentage of total carbohydrate in their leaves, it appeared that 5 g/plant kristalone without GA3 gave the high contents.
B- Second Experiment:
This experiment was carried out using:
1- Urea: a white crystalline solid containing 46% nitrogen, is a plant metabolite derived either from root uptake or from catabolism of arginine by arginase. As a nitrogen fertilizer, urea is intensively used in agriculture either directly, or in the form of ammonium or nitrate after urea degradation by soil microbes. Urea can serve as sole nitrogen source for plant growth.
2- Gibberellic acid (GA3).
Homogenous cypress seedlings were arranged in a block randomized design in split-plot with three replicates. The main plot represented the urea levels (control, 2.5 and 5 g/plant). Each main plot divided into four sub-plots represented gibberellic acid concentrations (0, 125,250 and 500 ppm). Each replicate consisted of 12 treatments (3urea rates x 4Gibberellic acid concentrations) with 4 plants (pots) per treatment.
Plants were kept in the same shading condition of the first experiment. The obtained data were statistically analyzed and summarized as follows:
1- Concerning urea effect: Under the conditions of the present study, feeding lemon cypress with urea at 5g/plant resulted in the highest values of vegetative measurements compared with the tested treatments.
Meanwhile the highest concentrations of N, P, K and Mg and the lowest Ca were obtained from plants received urea either medium or high level. Besides fertilizing the cypress plants with urea increased total carbohydrates in leaves comparing to the control, either at 2.5 or 5 g/pot. Meanwhile, the higher level of urea (5g/pot) was more effective in this respect. On the other hand, protein content is similar related to the results obtained from nitrogen content.
2- For concentration of GA3, increasing the concentration of GA3 led to a significant increase in plant height, branch number and foliage fresh and dry weights, with the favorable results attained by applying GA3 at 250 ppm. Applying the highest concentration (500 ppm) showed lower values. Meanwhile, the highest concentration of GA3 (500 ppm) exhibited the thickest cypress plants.
Over the above mentioned the highest concentrations of N, P, K and Mg and the lowest Ca were obtained from plants received GA3, either medium or high level.
On the contrary total carbohydrates were decreased with increasing the concentration of GA3 during both seasons. On the other hand, protein content paralleled to nitrogen content.
3- With regard to the interaction effects between GA3 and urea fertilizer on growth measurements, data showed that applying a combination of 250 ppm GA3 and 5 g urea /plant gave the best results of different growth measurements producing better nutritional status. Meanwhile the highest total carbohydrate contents were determined in plants treated with the combination of Urea at 5g/pot and GA3 at 0 (control).
C- Third Experiment:
This experiment was carried out using certain combinations between CCC, GA3 and kristalone
• (Cycocel or CCC): (2-chloroethyl)-trimethylammonium chloride is well known as a growth retardant whose effects appear to be virtually the opposite of those of gibberellic acid
Homogenous cypress seedlings were arranged in a block randomized design in split-split-plot with three replicates. The main plots represented the kristalone levels (control, 5 and 10 gm). Each main plot divided into two sub-plots represented gibberellic acid concentrations (0 and 100 ppm). Each sub-plot was divided into three sub-sub-plot represented concentration of CCC. Each replicate consisted of 18 treatments (3 kristalone rates x 2 GA3 concentrations x 3 cycocel levels) with 4 plants (pots) per treatment.
The plants were kept in the same shading condition of the first and experiments. As well as the collected data the obtained data were statistically analyzed and summarized as follows:
1- Concerning kristalone effect: feeding lemon cypress with kristalone at 10gm/plant resulted in the highest values of vegetative parameters compared the tested treatments including the control, except number of branches which reached its highest values when plants were treated with kristalone at 5gm/plant. In addition the highest concentrations of N, P, K and Mg and the lowest Ca were obtained from plants received kristalone at either at medium or high level. Moreover either concentrations of kristalone (5 or 10 g/pot) increased total carbohydrates comparing to the control. The medium level of kristalone (5gm/pot) was most effective in this respect.
2- With regard to CCC application: CCC treatment at 500 ppm combined with GA3 at 100 ppm concentration improved plant height, stem diameter, branches number and foliage fresh and dry weights. Apart from that, the highest concentrations of N, P, K and Mg and the lowest Ca were obtained from plants received GA3 and CCC at either at medium or high level. Meanwhile, the plants were sprayed with the medium level of CCC contained the highest total carbohydrates percentage comparing to either the control or the higher CCC concentration.
3- With regard to the interaction effects between cycocel, GA3 and kristalone fertilizer on growth measurements, data showed that applying a combination of 500 ppm cycocel, 100 ppm GA3 and 10 gm/plant kristalone gave the highest results of plant height and fresh and dry weights. Applying the combination of cycocel at 500 ppm, GA3 at 100 ppm and kristalone at 5 gm/plant enhanced number of branches/plant. However, the combination of both of cycocel at 500 ppm and kristalone at 10 gm/plant produced thicker stems.
Besides the combined treatment of GA3 (200 ppm) plus kristalone (5gm) proved to be the most effective on producing better nutritional status. The interaction effects between cycocel, GA3 and kristalone fertilizer on nutrient contents were found to be in harmony with the vegetative growth measurements where data showed that applying a combination of kristalone at 500 ppm CCC, 100 ppm GA3 and 10 gm/plant kristalone gave the higher values, in most cases. Applying either kristalone at 5gm/pot or CCC at 500 ppm without GA3 had more effect than the combined treatments with GA3 at 100 ppm. Besides, using both kristalone at 5gm/pot and CCC at 500 ppm resulted in better carbohydrates content than the other combinations between both kristalone and CCC. The highest total carbohydrates contents were noticed on plants treated with the combination of kristalone at 5gm/pot, GA3 at 0 (control) and CCC at 500 ppm. On the other hand, protein content is typically related to the results obtained from nitrogen content in branches.