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Abstract SUMMARY The present investigation was mainly conducted to study the effect of light intensity on culture survival percentage, the effect of some plant growth regulators on the Fragraia x ananassa cv. Festival micropropagation, anatomical structure, some bio. chemical analysis, and growth parameters. For this purpose: 1- Runner tips and runner segments having 1.00-1.25 cm long were set up to utilize as explants to study the role of light in browning of bud-derived tissue cultures which incubated in (dark, 500 lux and 2000 lux) in a growth chamber for a week. 2- Strawberry establishment in vitro culture, the survival of explants from the browning experiment were transferred to MS medium supplemented with different concentrations of NAA and BA. 3- Trifoliate leaves with the petiole (15 mm long) from one-month-old in vitro plants were used as explant cultured on MS medium supplemented with different concentrations of TDZ was used to induce adventitious shoots and separated for anatomical study. The experiments were carried out successively during the years of 2016-2019. The obtained results are summarized in the following: A. The histological observations for adventitious shoots 1. Adventitious shoots initiated from some parenchyma of ground tissue in the midvein zone of the explant. 2. The ontogenesis of adventitious shoots was described by successive stages. a. After four weeks of culture, cell dedifferentiation was recorded in the midvein parenchyma and forming small groups of divided cells called meistemoid centers. b. After six weeks, further development of these masses resulted in the formation of bud primordial with normally organized shoot apical meristems and leaf primordial and arising from the explant as small protrusions c. After two weeks from subculture on MS TDZ free, the adventitious shoots continue to elongate with forming new lateral branches and observed on the adaxial side of the explant. B. Effect of light intensity on culture survival percentage Total darkness (light intensity) treatment resulted in 100% survival rate of strawberry cultures, i.e. zero% death. C. Strawberry establishment in vitro culture 1. Using BA singular led to shooting formation but using BA in combination with NAA led to callus formation 2. No significant difference in the number of shoots per culture between both concentrations was used 3. The highest positive number for total shoots (25 shoots per culture) and the highest number of roots per plantlet (18.3) were observed with the concentration of 0.5 mg l-1 BA by rebate the subculture 4. No significant difference was shown on shoot length, number of leaves/explant, and root length between the different treatments 5. On the positive side, the highest value in both of chl a and chl b (2.07 & 1.16 mg/g fw) and total phenol contents (0.328 ug/g fw) were recorded with 0.5 mgl-1 BA 6. It is clear that no significant difference was observed in carotenoid concentration, total sugars, with both BA concentration D. Shoot regeneration from leaf explant 1. After 6 weeks from culturing, all the TDZ treatments showed buds formation from strawberry leaf explants without callus formation 2. The highest number of shootlets/explant, total shoots, and number of leaves/explant was showed with 1.5 mg l-1 TDZ which recorded 5.0, 51.3, and 12.0, respectively 3. TDZ treatments enhancing significantly chlorophyll a, b, carotenoid and phenolic compounds concentrations which recorded 1.27, 0.70, 0.22 mg/g fw and 0.21 ug/g fw, respectively was found at 1.5 mg l-1 TDZ. E. Somatic embryogenesis None of the treatments used in embryo production succeeded. |