In vitro hardening of date palm cv. Medjool vitroplants affects growth in the nursery

In vitro hardening of date palm (Phoenix dactylifera L.) cv. Medjool shoots were 
accomplished as pre-acclimatization using ascorbic acid 0, 50,100,150 or 200 mg/l in the MS   
rooting medium. Positive response occurred with ascorbic acid (150 mg/l) which scored the 
highest significant values of root length (11.66 cm) and root circumference (1.93 mm) after 8 
weeks of incubation. Subsequently this affects saplings cultured  in growing mixture  containing 
compost and perlite (1:1, v/v) which raised saplings survival from 80 to 93.33 % after 12 weeks 
in acclimatization as well as reflected significant values of total chlorophyll (2.93 mg/g D.W.), 
total soluble sugars (29.33 %) and ascorbic peroxidase activity (1102.33  Units/g, F. W.). Results 
revealed that plastic leggy bags [ 20 cm ( w ) X 40 cm ( h ) ] filled with the growing mixture sand  
+  coarse sawdust ( 2:1, v/v ) and  fertigated with Stimifol ( 0.5 g/l ) once a week for 9 months 
under greenhouse conditions in the nursery, recorded the highest  significant values of total 
leaves no. (7.3), pinnate leaves no. (5.5), plant height (57.0 cm), leaf width (5.3 cm) and  stem 
circumference ( 2.7 cm ). This was accompanied by the highest significant values of dry weight 
(15. 79 %), T.H. Carbohydrate (38.99 %), lipids content (4.48 %).  Also this was  accompanied 
by a consequence higher value of total soluble phenol  ( 0.85 g / g protein ) and the highest 
significant values of crude protein (36.15 % )  and PAL activity (220 nkat / g protein ). However, 
using a mixture containing sand + foam recorded the lowest values of all growth characters and 
chemical analysis under study. Results may be considered very helpful to the researchers and 
highly supportive to the nurseries at the commercial level, as it introduces effective and cheapest 
natural raw materials to fulfillment of the huge demand of insufficient big quantities required. In 
addition, it has great beneficial effect to the national environment through implementation of rice 
shell and coarse sawdust as a good practical recycling and environmental bioremediation and 
finally reduces production costs.