Negash, Legesse (PhD)Berhe, Desta2018-06-272023-11-082018-06-272023-11-081997-06http://etd.aau.edu.et/handle/123456789/3966The rooting responses of branch cuttings of Juniperus procera Hochst. ex Endl., obtained from juvenile and mature source plants to foul' plant growth regulators (PGRs), namely, indole-3-acetic acid (IAA), indole-3-butydc acid (lBA), naphthaleneacetic acid (NAA), and 2,4- dichlorophenoxyacetic acid (2,4-D) at vadous concentrations (lrrJ to lrr9 iW) were examined ill sand culture. Assessments 011 survival, callusing and rooting of the cuttings were conducted 16 and 32 weeks after the treatments. Odgin of root primordia was examilled microscopically, amI establishment and perfonnance of stecklil;gs were done 011 sample rooted cuttings. It was found that the developmental stage of the source plants from which the cuttings were derived, and the type, as well as the cOllcentratioll of the PGR, markedly affected the survival of the cuttings. About 77% of the cuttings obtained from Class 111 source plants (mature) died out withill the first 30 days after treatment; while 34% of the cuttings obtained from Class 11 (mature), and 90% of the cuttings obtained from Class I source plants (juvenile) survived until the end of the investigatioll. Callusing and rootillg of the cuttings were greatly affected by the developmental stages of the source plants. Sixteen weeks after treahnent, meall percentage callusillg of cuttillgs obtained from Class I source plants was significantly greater thall that obtailled from Class 11 source plants (p ,:; 0.05). The highest attainable percelltage of callused cuttings obtained from Class I source plants was 56, treated at 10-' 1'vlIAA and lrrs lW NAA. The corresponding percentage for the cuttillgs obtained from Class II source plants was 29, treated at 10-' M IBA. At this time, ollly 2% of the cuttings obtained from Class 1 source plants were rooted. Thirty two weeks after treatment, 24% of the cuttings obtained from Class 1 source plants were rooted. By this time, only a single cutting from Class II source plants rooted. The highest attainable percentages of rooted cuttings obtailled from Class I source plallts was 60 treated at 1 rr7 1'1'1 IAA. The cOlrespondillg percentages were 50, 44 and 25 for NAA (treated at 1rrJ J'rI), IBA (h'eated at lrrs 1'vI) alld 2,4-D (treated at 10-' and lrr7 M), respectively. The control resulted in 29% rooting. The melli/maximum attainable root numbers pel' rooted cuttings in IAA (treated at 10-' iW), IBA (h'eated at 1rr3 M), 2,4-D (treated at lrr9 M) and NAA (treated at lrrs i',I) were 17.0 ± 4.1, 14.5 ± 12.5, 9.7 ± 6.7 and 7.0 ± 3.0, respectively. The mean root number per rooted cuttings ill the conh'ol was 17.0 ± 1.7. The highest attainable mellll root length was 372 ± 51.5 mm, for cuttillgs treated at lrrJ M NAA. The correspollding values for IBA (h'eated at lrr3 M), IAA (treated at 10-' M) and 2,4-D (treated at 10-' M) were 113.7 ± 11.7mm, 90.7 ± 5.6 mm and 67.7 ± B.B 111m, respectively. The /IIean root length of the cuttillgs rooted ill the cOllh'ol was 93.9 ± 7.3 /11m. Regression analysis showed that the cOllflibution of callusing to rootillg is velY small (Rt = 0.2070, P ,:; 0.05). III this species, cells of callus tissue, xylem rays, trach~ids, c011ex alld cambium resulted ill the fonnatioll root primordia. Stecklings with well developed root systems were easily established and grew well, indicatillg the possibility of propagating the species by asexual means.enBiologyThesis