الفهرس 
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Abstract
Three experiments were conducted to cover research plan as follows:
5.1. First Experiment This experiment was conducted in laboratory, Department of Botany, Faculty of Agriculture, Ain Shams University, Shubra El-Kheima, Kalubia, Egypt, during September of 2008 for 21 days on open pollinated true seeds of potato (Solanum tuberosum L) cv. “Cara” (TPS) to investigate TPS germination and seedling vigor. Seeds were soaked for 24 hour in the following agents:
• Gibberellic acid (GA3) at 1000, 1500 ppm
• Combination of KNO3 + K3PO4 at (0.118 mol/l + 0.09 mol/l) and (0.236 mol/l + 0.18 mol/l) respectively • Humic acid (HA) at 50, 100 and 250 ppm in the form of Egyptian commercial product called “Hammer” (86% potassium humate)
Germination percentage, mean germination rate and vigor index were recorded for 21 days from sowing. The best soaking treatments in this study were selected to examine their influence on seedling vigor in pots experiment. Seedling length and fresh weight were recorded at 30 DAS. The results of first experiment could be summarized as follow:
a. The highest significant increases of germination percentage and VI were obtained by soaking for 24 h at GA3 1000 ppm or HA at 100 ppm respectively; whereas, these treatments achieved the lowest significant values of MGR which means they were faster than others and control treatments.
b. Soaking treatments of GA3 at 1000 ppm or HA at 100 ppm gave the highest significant values of seedling length and seedling fresh weight at 30 DAS comparing with control plants from all previous results and from the commercial point of view which ensure the lower price of HA comparing with GA3; humic acid at 100 ppm treatment was the more favorite soaking treatment for seed germination and seedling vigor.
5.2. Second Experiment
This study was conducted at Kafr El- Zayat Research Station in the Governorate of Gharbia at the seasons of 2009 and 2010 to investigate the influence of foliar applications of potassium at 2% (w/v) KCl, boron at 0.2 % (w/v) H3BO3, CPPU at 20 ppm and humic acid (Hammer) at 250 ppm on growth, chemical constituents, seedling tubers (G0) yield and its components. Three samples were taken at 50, 70 and 90 DAS. Growth parameters; plant height, leaves number, shoot fresh and dry weights were recorded in all samples. Chemical analyses were recorded in the second sample. Seedling tubers yield and its components were recorded at harvest (128 DAS) in both seasons. Amylases activity was recorded after cold storage period (22 weeks at 4 °C). Detection of mosaic viruses (PVX and PVY) were done by DAS-ELISA. The results of second experiment could be summarized as follows:
1. Growth parameters
The highest significant values of plant height, leaves number, shoot fresh and dry weights at 50 days after sowing (DAS) were obtained by K+CPPU+HA treatment comparing with control plants respectively in the first season. Similar trend was observed regarding the second season.
At 70 DAS, The highest values of plant height were achieved by K+B+HA comparing with control plants in both seasons respectively. K+CPPU+HA gave the highest values of leaves number in both seasons respectively. Maximum values of shoot fresh weight were recorded by CPPU+HA and K+B+CPPU comparing with control plants in the first and second season respectively. K+CPPU and K+CPPU+HA gave the highest values of shoot dry weights comparing with control plants in both seasons respectively.
At 90 DAS, CPPU+HA was the best treatment for improving most plant growth parameters in both seasons comparing with other ones. The highest values of plant height were resulted in K+CPPU+HA comparing with control plants. Maximum leaves number/ plant was achieved by CPPU+HA and B+CPPU+HA in the first and second season respectively. K+CPPU+HA and HA or CPPU+HA led to the maximum values of shoot fresh weight in the first and second season respectively. K+CPPU+HA and CPPU+HA gave the highest values of shoot dry weight comparing with control plants in the first and second season respectively.
2. Shoot dry matter accumulation rate (SDMAR)
SDMAR, increased rapidly in the period between 50 and 70 DAS, and then decreased later in the period between 70 and 90 DAS in all treatments in both seasons with the exception of CPPU+HA in the second season. The best results were achieved by K+CPPU and K+CPPU+HA in the first and second season respectively.
3. Seedling tubers yield and its components.
a- The maximum significant number of seedling tubers / m2 was achieved by the combined treatment of K+CPPU+HA and K+B+CPPU comparing with control plants in both seasons respectively. Furthermore, It was noticed that K+B+HA take the same trend in both seasons.
b- The maximum significant increases of seedling tubers weights (g/m2 or ton/fed.) were obtained by the second order of combinations; K+CPPU+HA (110, 86%) or K+B+CPPU (107, 89%) over the control plants in both seasons respectively.
c- No significant differences in the sprouting ratio of seedling tubers were detected between all treatments comparing with control plants in both seasons.
d- Specific gravity and dry matter ratio were affected by some treatments in two seasons. The highest significant increases were obtained by K+CPPU in the first season; whilst, K+B+CPPU treatment achieved the best results in the second one.
4. Chemical composition
a. The highest values of total chlorophylls and total phenolic compounds were obtained by K+CPPU+HA comparing with control plants in both seasons respectively.
b. The maximum significant increases in total carbohydrates and free amino acids were achieved by K+CPPU+HA and K+B+CPPU comparing with control plants which recorded in both seasons respectively.
c. CPPU+HA, K+CPPU+HA and CPPU individually were achieved the highest results in nitrogen concentration.
d. The maximum values of potassium concentration were obtained by K+CPPU and K+HA whereas, B decreased potassium content comparing with control plants.
5. Amylases activity
a. The highest significant increase in the amylases activity of seedling tubers (after 22 weeks of cold storage at 4 °C to terminate the dormancy period) was obtained by K+CPPU+HA comparing with control plants.
b. The differences among treatments in amylases activity did not affect the sprouting ratio of seedling tubers.
5 - Detection of mosaic viruses (PVX and PVY) by DAS- ELISA.
The values of ELISA reader (at 405 nm) did not reached 2.5 times fold of a negative control value in all treated or control plants. These results mean no mosaic viruses infections were detected in the produced seedling tubers.
5.3. Third Experiment
This study was also, carried out at Kafr El- Zayat Research Station during two successive autumn seasons of 2009-2010 and 2010-2011 respectively. Seedling tubers which produced previously in summer seasons of 2009 and 2010 from TPS (different treatments of the second experiment) and traditional seed tubers of “Cara” cultivar were stored from May to October (22 weeks) and then used as planting material to evaluate their productivity without treatments in autumn seasons. The yield at harvest included: yield/plant (g), total yield ton/fed, marketable tubers/plant (g), marketable tubers weight percentage and yield components included: specific gravity and dry matter ratio. Starch content of the produced seed tubers was also, investigated.
The obtained results of this experiment could be summarized as follows:
1- Yield and its components.
a- Seedling tubers of untreated plants (control2) showed significant decrease in the yield reached 22.4 and 18.9 % lower than control1 (traditional seed tubers) in both seasons respectively.
b- The treated plants with K+B+HA and K+CPPU reduced this gab up to 12.5 and 13.4% in both seasons respectively.
c- Seedling tubers of the treated plants with K+B+HA and HA achieved significant decrease in the marketable tubers weight ratio, reached 18.5 and 21.7% lower than control1 comparing with seedling tubers of untreated plants (control 2) which recorded 26.7 and 26.5% in both seasons respectively.
d- Insignificant differences were detected between all seedling tubers treatments in the produced tubers yield.
e- No significant differences in specific gravity and dry matter ratio were detected between the traditional seed tubers and all seedling tubers of all previous treatments (Second Experiment) in both seasons respectively.
2- Determination of starch content
No significant differences in seed tubers’ starch content between the traditional seed tubers and different seedling tubers of pervious various treatments of the second Experiment.
It could be concluded from the present study that it is possible to produce seedling tubers from true potato seeds (TPS). Such technology provides an economic alternative comparing with traditional seed tubers. HA at 100 ppm was the more favorite pre-soaking treatment for TPS germination and seedling vigor. Using bioregulators (CPPU and/or HA) and nutrients elements (K and/or B) as foliar application can enhance the growth parameters, in addition, increase the yield and its attributes of seedling tubers. Foliar application of K+CPPU+HA at 40, 60 and 80 DAS gave the highest values of plant growth parameters of true seed plants (plant height, leaves number, shoot fresh and dry weight). The maximum significant values of seedling tubers yield included number/ m2 and weights (kg/m2 and ton/fed) were obtained by K+CPPU+HA or K+B+CPPU. Enhancing growth parameters was found to be associated with increasing total chlorophylls, carbohydrates, FAA, phenolic compounds, nitrogen and potassium concentration in the leaves of subjected plants, previous effect could be a reason for improving potato seedling tubers yield and yield attributes (specific gravity and dry matter content). All treatments had insignificant effect on sprouting percentage (22 weeks after harvesting). The most promising treatments which satisfy the objective of this study are K+CPPU+HA or K+B+CPPU.
I. Prospective
This study provides an alternative method for potato production in Egypt by using open pollinated TPS of Cara cultivar instead of the traditional seed tubers. The combined treatment of K+CPPU+HA as a foliar application achieved an increase in the rate of seedling tubers production reached 11.48, 11.26 ton/fed. comparing with control plants 5.46, 6.04 ton/fed in both seasons respectively. This rate is very acceptable because the average rate of potato production by the traditional method is 11.3 ton/fed under Egyptian conditions (FAO, 2008). However, benefit studies revealed in Table (22) that the cost percentage of TPS method recorded 40.3 % compared to 55 % of traditional method. So, TPS method reduced the cost percentage of total cost of one fedden to 15 % comparing to traditional method. But the writer hopes to increase the yield of seedling tubers to 35 ton/fed. by using hybrid TPS due to its superiority in the yield production. So, it must be concerned the breeding programs to produce and register new genotypes to be more suitable for our environmental conditions, in addition to focus on physiological side through using nutrient elements (K and B) and /or bioregulators (HA and CPPU) to increase the ability of TPS-plants on seedling tubers production and improving its quality.