الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 164 |  |  |
| | | from | 164 | | |
Abstract
This investigation was achieved through out two successive years 2011 and 2012 in the Tissue Culture Laboratory, Horticulture Department, Faculty of Agriculture; Ain shams University, Shoubra El-Khiema, Egypt A protocol for in vitro zygotic embryo rescue and microprogation of avocado (Persea americana Mill) cvs Hass & Fuerte was developed. Different factors such as embryo culture date, medium type (MS& B5), sucrose concentrations were studied. The effect of medium type, cytokinin concentration, number of subcultures and auxin concentration on regeneration of avocado cultures were investigated. The results showed that the best germination percentage (100 %) achieved with embryos cultured after 180 and 210 days from full bloom of avocado cvs. MS medium gave the highest significant value of embryo length with both avocado cvs as compared with B5 medium.
In vitro regeneration of stem node explants obtained from germinated embryos, showed that MS medium recorded the highest significant number of proliferated shoots/explant and shoot length of avocado cv. Hass. the highest value of shoot length was noticed with MS medium. The highest significant number of proliferated shoots/explant was observed with BA at 2 mg/l (1.56) of avocado cv. Hass. The second subculture gave the highest significant number of proliferated shoots/explant (1.7) of avocado cv. Fuerte excised from germinated embryos. MS medium surpassed B5 medium in term of number of proliferated shoots in cv. Hass only. The best rooting percentages was recorded with IBA at 2.0 mg/l (48 and 52%) for shoots of avocado cvs. Hass & Fuerte, respectively, obtained from germinated embryos.
In vitro propagation using stem node explants excised from 3 year-old trees, revealed that the highest survival percentage (40.0 and 36.67) were recorded with B5 and MS media, respectively. MS medium with sucrose at 40 g/L recorded the highest bud development percentage (60.0) of avocado cv. Hass. The highest average shoot length was noticed with MS and B5 media (2.6 and 2.4), respectively of avocado cv. Hass. The highest survival percentage (40.0) was recorded with MS medium of avocado cv. Fuerte. The highest significant survival percentage was recorded with MS medium supplemented with sucrose at 30& 40g/L followed by B5 medium with sucrose at 30&40g/L and WPM with sucrose at 40 g/l.
The highest number of proliferated shoots/explant was recoded with BA at 7.0mg/L plus IBA at 0.2 mg/L in the 3rd and 4th subcultures of avocado cv. Hass. BA at 10mg/L and Kin at 20mg/L recorded the highest number of proliferated shoots/explants (2.8& 2.6), respectively of avocado cv. Fuerte. The highest significant rooting percentage (32& 36%) and the highest number of roots/shoot (2.67& 3.27) were recorded with IBA at 5.0 mg/L of avocado cv. Hass and Fuerte, respectively.
The highest significant survival % during acclimatization (46.67 & 53.3%) was achieved on mixture of sand, peat and vermiculite at a ratio of 1:2:1 for plantlets of avocado cvs Hass& Fuerte, respectively.