Propagation of some hard rooting economic wood trees through tissue culture tecgnique

The presented experimental work was carried out aiming to propagate teak trees (Tectona grandis Linn) and black sapote (Diospyros digyna Jacq) through tissue culture technique. Tectona grandis L. (teak) is one of the most valuable timber species of the world as it has a centuries-old reputation as the king of timber. Teak tree is a deciduous big tree reaches 80-150 ft. (24-45 m) high. Teak is a forest tree of high commercial and ecological value because of its rapid growth and wood quality. The timper of this important tree is much used in ship-building because of its durability, great strength, water resistant and the ease with which it can be worked. Teak has dimensional stability so it is not twisted or crack open. For its wood beauty and durability, it used in good furniture industrial and decoration. The tree had a volatile oil, so it used in incense. Wood produced varnish after distilling and substitute to linen oil. In addition, leaves produce dye red or yellow to dye silk and cotton. The results of teak showed that winter was the most suitable season to collect explants for their highest survival and lowest mortality percentages. Moreover, winter was also better than other seasons for collecting explants scoring the highest percentages of success and sprouting. On the contrary, June and July were not suitable at all to collect explants due to a very high mortality percentage that reached 100% as a result of phenols exudation. The recommended sterilization agent for teak was sodium dodicyl sulphates (S.D.S.) + mercuric chloride (HgCl2) (MC) for 3 minutes in winter, which was better than MC alone. The only sprouted type of explant was shoot tip, while stem node explant did not sprout at all. Subculturing teak explants into fresh agar water medium for 3 days improved survival percentage, as that successful treatment avoided injurious effect of exudates, which are usually phenolic compounds. It is preferred also to dip shoot tip explants in knobs medium solution immediately after trimming before sterilization, as this gave significantly higher survival percentage and also maintained viability of explants compared to dip into either distilled water or salt solution. The most suitable medium for growth was MS medium at full strength, giving the highest results in all parameters as: survival percentage, shoot height, leaf number and leaf area, compared to other media. Applying BA at 4mg/L . +0.1mg/L Kin after the fifth subculture gave the highest number of proliferated shoots and the longest shoots: The more repeating the number of subcultures, the more increasing the number of shoots, shoot length and leaf number were obtained as the fifth subculture was the best one.The highest shoot number was recorded by using 4mg/L BA +0.lmg/L Kin for explants taken in autumn followed by those in winter. Stem node explant (resulting from the first subculture) was much more responding to any slight concentration of multiplication growth regulators than shoot tip. The best treatment was obtained with BA at 4mg/L+0.lmg/L Kin giving the highest average parameters of each shoot tip and stem node.Moreover, the best ability of rooting formation at all treatments(96.30%) resulted from full strength medium supplemented with 4mg/L IBA.Finally, peat moss+ sand treatment scored the highest survival percentage reaching 100%, and also recorded the highest shoot height, leaf number, leaf area and shoot diameter. In addition, the medium of peat moss with sand at 2:1 (v:v) was the best mixture for most growth parameters (tip viability, shoot length and leaf area). Black sapote is an important economic woody tree used in different purposes like ornamental tree for its beautiful foliage, leathern shining leaves, resistance to insects and finally for edible pretty fruits. The wood is durable and strong, so it used for furniture, masterpieces,frames and statues. However, the results of black sapote lead to some recommendations that, mercuric chloride (MC) alone treatment at 0.1% for 5 min can be recommended as a good surface sterilization for shoot tip and stem node explants, as it recorded moderate mortality percentage and the lowest contamination one. In addition, it can be concluded that, black sapote explants can be collected all over the year round, but the best time to collect them was in the dormancy season, winter and autumn for the lowest mortality percentage and the highest survival and sproutIng percentage In both shoot tip and stem node explants. Moreover, the best medium encouraging vegetative growth (survival and sprouting percentages) was WP medium compared to MS medium for both shoot tip and stem node explants, while, the effect of WP medium concentration was generally not significant in developing growth in both shoot tip and stem node with few exceptions. Negative outcomes were encountered in most of these multiplication trials, particularly, in case of Diospyros digyna, while, the most effective trials were noticed with TDZ and with Zeatin treatments which resulted in minute black callus when kept in darkness. However, this needs more trials in this field.