الفهرس 
CONTENTSOnly 14 pages are availabe for public view
 |  | from | 100 |  |  |
| | | from | 100 | | |
Abstract
This study was executed during the period from 2014 to 2015 at the tissue culture laboratory of Horticulture Dept., Faculty of Agriculture, AssiutUniversity.Two (Musa spp.) banana cultivars namely Grand Nain (G) and Zeev (Z) grown in vitro were used in this study as explants. The propagated plants were subcultured every 6 weeks for multiplication in 500 ml culture jars contained MS medium (Murashigae and Skoog, 1962).
Tolerance experiment:
In this experiment, each of the two above mentioned cultivars were subcultured on Two media each contained one of the two osmotic agents:
1-Sodium chloride (NaCl) at 0, 30, 60 , 120 and 200 mM/L .
2- Polyethylene glycol (PEG 600) at 0,10,20,30 and 40 g/L .
Measurements:
Data samples were collected after 6 weeks for each experiment, plantlets were washed up from the agar or media residues with sterilized water and the following traits were measured for each experiment:
A)Vegetative Parameters:
The vegetative parameters were; plantlet height (cm), average number of leaves/explant and plantlets fresh and dry weight (g).
B)Physiological Parameters:
1-Total chlorophyllcontent:
Leaves were collected from the mid-section of the plantlets in order to minimize leaf age variability effects. Chlorophyll was measured with SPAD-502 equipment (Minolta Camera Co. Ltd., 1989), expressed as SPAD unit.
2-Potassium and Sodium contents:
Plantlets were collected, oven-dried at 75 Cofor 22 h and 110 Co for 2 h and grounded. Samples of 0.2 g from each plantlet were digested according to Jackson,(1973) and K+ and Na+ contents were determined by flame photometry (Digital Flame Analyzer, Cole Parmer, Illinois, USA) .
The obtained results could be summarized as follow:
I: Effect of salinity stress exposed as (mMNaCl):
I-1: Effect of salinity on vegetative parameters
I-1-1:plantlet height (cm):
The average plantlet height gradually and significantly decreased by increasing NaCl concentration from zero to 200 mM/L. The highest values of plantlet highT were occurred by control treatment (zero Nacl) in both tested cultivars: Grand Nain (8.33 and 10.00 cm) and Zeev (12.00 and 8.70 cm) during the two experimental seasons. All treatments significantly decreased the plantlet height as compared with control of both cultivars .
I-1-2:Average number of leavesplantlet :
The average number of leaves /plantlet of both tested cvS.significantly decreased by increasing NaCl concentration from zero to 200 mM/L during the two seasons. The highest average number of leaves/plant for both tested cultivars was found with control treatment (zero NaCl), while the lowest average number was recorded with 200mg/L NaCl treatment during both seasons, No significant differences were found between Grand Nain and Zeev concerning the number of leaves/plantlet as affected by different NaCl concentrations.
I-1-3: Fresh weight:
With increasing the applied NaCl concentration from zero to 200 mM/L significant decreasing of plantlet fresh weight of the two investigated cultivars was recorded . Untreated Grand Nain and Zeev plantlet with NaCl had the highest values of fresh weight during the first season , while 30 mM/L NaCl gave the highst values in the second season for both studied cultivars.
I-1-4: Dry weight :
All NaCl concentrations (except 30 mM/L with Grand Nain cv.) significantly decreased the average dry weight /plantlet and the lowest values were found by 200 mM/L NaCl in Grand Nain cv and Zeevcv , during the two experimental seasons.
I-1-5: Total chlorophyll content:
All NaCl treatments significantly decreased that total chlorophyll content in both tested cultivars plantlet comparing with control during 2014 and 2015 seasons.The highest values of chlorophyll content were found in the untreated plantlet (zero NaCl) of Grand Nain and Zeevcvs. On the other hand, 200 mM/L of NaCl gave the lowest values of chlorophyll content in Grand Nain and Zeevplantlet during both tested seasons.
I-2: Effect of salinity in nutritional status:-
I-2-1:Effect of salinity (mMNaCl) on potassium (K) content:-
Generally, all NaCl concentrations significantly decreased potassium (K) content in the plantlet of both cultivars compared with control. The highest values of K content were recorded in the untreated (control) plantlet of Grand Nain and Zeevcvs during the two seasons. On the other hand, thelowest percentages of K were recorded by application the highest concentration ofNaCl (200 mM/L) in Grand Nain and Zeevcvs during 2014 and 2015 seasons.
I-2-2-:Effect of salinity (mMNaCl) on Sodium content %:-
All treatments significantly increased the percentages of sodium in the plantletcomparing with control for bothcultivars during 2014 and 2015 seasons. Sodium (Na) % parallels and significantly increased by increasing the applied NaCl concentrations, meaning that the highest values ofNa content were recorded in the plantlets of Grand Nain and Zeevcvs. by using 200 mM/L NaCl during the two seasons. Meanwhile the lowest Na contents were recorded in the untreated plantlet ( zeroNaCl) of Grand Nain and Zeevcvs. in both seasons.
II: Effect of drought stress exposed as PEG :
II-1: Effect of drought on vegetative parameters:
II-1-1:Plantlet height :
The average plantlet height of both cultivars gradually and significantly decreased with increasing the concentrations of PEG treatments during the two tested seasons. Moreover, all PEG treatments significantly decreased the average plantlet height of Grand Nain and Zeev banana cvs. during the two seasons as compared with control plantlet (zero PEG).The highest values of plantlet height for Grand Nain and Zeevcvs were recorded in control treatment(zero PEG) during both investigated seasons, respectivily .
II-1-2:Number of the plantletleaves:
All PEG concentrations significantly reduced the average number of leaves/plantlet compared to the control treatment (zero PEG) . So that, the untreated plantlet produced the highest average number of leavesfor Grand Nain cv and Zeevcvs during both seasons.Moreover the average number of leaves/plantlet gradually decreased by increasing the applied PEG concentrations and reached its minimum values by 40 g PEG for Grand Nain cv and for Zeev cv. both seasons.
II-1-3:Fresh weight:
The average fresh weight of untreated plantlets (control) with PEG had the highest values for Grand Nain and Zeevcvs. comparing with other treatments during both seasons. With increasing the applied PEG concentrations from zero to 40g , gradually reduction in average fresh weight was recorded and reached the minimum values by using 40g of PEG for Grand Nain and Zeev plantlets during the two investigated seasons .
II-1-4:Dry weight (g) :
The obtained data indicated that similar tendency was found concerning fresh and dry weight of both studied cultivars during both experimental seasons.Increasing PEG concentrations up to 40g significantly produced the lowest values of dry weight for Grand Nain and Zeev plantlets during both investigated seasons. The highest average of dry weight was recorted in untreated plantlet (Zero PEG) for both tested cultivars during both seasons.
II-1-5:Total chlorophyll content:
Significantly decrement in the chlorophylls content was occurred in the plantlet of both tested cultivars during 2014 and 2015 by all PEG treatments as compared with control (Zero PEG) .So that the highest values of total chlorophyll content for Grand Nain and Zeevcvs. were recorded in the untreated plantlets. Moreover the plantlets content of total chlorophylls gradually decreased by increasing the applied concentrations of PEG in the both tested cultivars and reached the minimum values by using 40g PEG concentration during both experimental seasons.
II-2:Effect of drought (PEG) on nutritional status:-
II-2-1:Effect of drought (PEG) on potassium(K%) content :-
Potassium content significantly decreased by increasing the concentrations of PEG and reached its minimum percentage by using 40g of PEG in Grand Nain cv and Zeev plantlets during both seasons.The highest contents values of K% were measured in the untreated plantlets (Zero PEG) for Grand Nain and Zeev plantlets as compared with other PEG treatments during both studied seasons.
II-2-2: Effect of drought (PEG) on Sodium % content:-
The percentage of sodium (%) gradually and significantly increased by increasing PEG concentrations in the plantlets of both tested cultivars and reached its maximum values with 40g PEG during both investigated seasons.
Conclusion:
The in vitro plantlet of Grand Nain and Zeev banana cultivars were negative affected by salinity and drought strees under all concentrations of NaCl and proline compared with control. It could be recommented to carry out more of selection experiments to induce tolerance of banana plantlets aganist