Plant Biology and Biodiversity Management

Permanent URI for this collection

http://etd.aau.edu.et/handle/123456789/118

Browse

Browsing Plant Biology and Biodiversity Management by Subject "Acclimatization"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Effectiveness of Meristem Culture and Chemotherapy on the Production of Virus Free Sweet Potato (Ipomoea Batatas (L.) Lam.
    (Addis Ababa University, 2009-07) Jemal, Neja; Feyissa, Tileye (PhD)
    Sweet potato, (Ipomoea batatas), is vegetatively propagated crop. Due to the following cycles of propagation, viruses are accumulated, which seriously affects the sweet potato yield and quality. The objective of this work was to produce virus free sweet potato planting materials through meristem culture and chemotherapy. Stem cuttings of four cultivars were collected from Awasa Agricultural Research Center and planted in a greenhouse at Science faculty AAU. These samples were tested for the presence of sweet potato viruses using NCM-ELISA. From the infected plants, meristems were taken and cultured to make them free from viruses. In addition, shoots from all varieties were taken and treated with ribavirin under different concentrations for one month. NCM-ELISA test was carried out to confirm the success of virus elimination. The in vitro propagated plants from meristem culture were found to be virus free. Samples treated with 10 mg/l ribavirin, gave positive results for SPFMV. On the other hand, 20 mg/l and 30 mg/l, treated samples gave negative results for the tested viruses. In this study, micropropagation system in four sweet potato varieties using meristem culture was established. MS medium with 3% sucrose, 0.7% agar and different concentrations and combinations of plant growth regulators adjusted at a pH of 5.8 was used throughout all experiments. Twelve treatments for initiation of shoots from meristems were done. Significant differences in response to initiation existed among the varieties (p ≤ 0.05). Among all combinations tested, 1 mg/l BAP, 2 mg/l GA3 and 0.01 mg/l NAA gave maximum shoot initiation percentage (90% for Beletech, 70% for Koka-12 and 56.7% for Ogensegen). Shoot initiation for TIS-8250 was not possible in all of the combinations but callusing was highly evident. Shoot multiplication was dramatically improved by subculturing of the initiated shoots onto different concentrations of BAP enriched medium. The highest significant mean numbers of shoots per shooted explant (8.0 for Beletech and 6.7 for Koka-12) were obtained in 2 mg/l and 1.5 mg/l BAP containing medium respectively. Subsequently, well formed shoots were rooted on growth regulator free and IBA enriched medium. The maximum rooting percentage (100%) and the highest mean number of roots per shoot (4.2 and 3.7) were obtained from growth regulator free and 0.1 mg/l IBA containing medium for Beletech and Koka-12 respectively. Rooted plantlets were acclimatized and 91.4% of acclimatized shoots of Beletech and 73.0% of shoots of Koka-12 were survived and successfully established in the greenhouse. Key words/Phrases:-Culture initiation, Multiplication, Acclimatization, Chemotherapy, Virus testing, Sweet potato
  • No Thumbnail Available
    Item
    Micropropagation of Prunus africana (Hook. f.) Kalkman from seedling
    (Addis Ababa University, 2008-07) Abate Shiferaw; Negash Legesse (Professor); Feyissa Tileye (PhD)
    The aim of this work was to develop micropropagation protocol for the threatened, multipurpose Afromontane tree, Prunus africana (Hook. f.) Kalkman, starting from aseptically grown seedlings. Application of 12% CaOCl2 on propagula for 15 minutes, following washing with the common laboratory detergent OMO and rinsing in 70% ethanol for 2 minutes resulted in seedlings that grew healthily and were free from microbial contaminants. Twenty to twenty five-day-old seedlings were used as explants. Among the tested concentrations of growth regulators, 2 mg/l BAP and 0.1 mg/l IBA in full strength MS medium yielded well initiated shoots. Activated charcoal (1g/l) was used for the initiation step, but not required in the subsequent transfers to multiplication media, as browning due to phenolic exudates was not a serious threat. Throughout all experiments, an initial pH value of 5.5 was maintained. Maximum shoot multiplication (4.6 shoots per explant) was obtained in response to 1 mg/l BAP without IBA. The sufficiently long (3-5 cm) and healthy microshoots that were transferred to half strength IBA free MS medium with 0.1% activated charcoal gave maximum rooting percentage (60) medium within 20 days. This was significantly higher from other compositions at P < 0.05. The plantlets each with average 11 roots were transferred to pots, with compost, red soil and sand in a 1: 2: 1 ratio. The pots were placed in a glasshouse for hardening, were covered with polythene plastic for one week, partially uncovered for the other one week, and then completely uncovered. All plantlets survived well. Key words/ phrases:- Acclimatization, Culture initiation, Micropropagation, Propagules, Prunus africana