Rooting of buchu cuttings (Genus : Agathosma)

[摘要] ENGLISH ABSTRACT:Buchu (Agathosma betulina and A. crenulata) are grown commercially as an aromaticcrop and are endemic to the Western Cape of South Africa. Poor rooting of cuttings havelimited the development of superior clones. Under standard mist bed conditions terminal,sub-terminal or basal stem cuttings were taken from March to August. When not treated withan auxin, rooting percentages of between 20 and 25 were obtained. Rooting percentagesincreased to between 40 and 45 after treatment with 500-1000 ppm indolebutyric acid (lBA).Substituting lBA with naphthaleneacetic acid (NAA) did not improve rooting. There was atendency for cuttings with fewer than four leaf pairs to give lower rooting percentages.Plants of Agathosma betulina x A. crenulata, grown in Paarl, and A. betulina, grown inPiketberg, were used as source plants for making cuttings. Paarl plants were shaded with 80percent shade and Piketberg plants with 60 or 80 percent shade respectively from February toOctober 2002. Plants in full sun served as a control. Plants were pruned back initially inFebruary and then two months before samples were taken in March, June, August andOctober at both locations. New shoots were used as cuttings. Terminal cuttings for rootingand for carbohydrate analyses were collected on four different dates (March, June, Augustand October). Cuttings were treated with 500 ppm indolebuteric acid (lBA) and placed inmisting beds with bottom heating (18-25°C) for a period of three months.Shading reduced rooting of cuttings from the Paarl plants. However, it did notsignificantly increase rooting of cuttings taken from Piketberg plants. Rooting percentagewas the highest in August (43%) for cuttings from sun grown plants in Paarl. No consistentrelationship between, respectively, dry mass or carbohydrate content of cuttings and rootingcould be established.Terminal current years' growth, taken from Agathosma crenulata x A. betulina (hybrid)softwood cuttings, collected in January 2002, were extracted with methanol and fractioned bythin layer chromatography (Silica gel) in isopropanol: acetic acid: water (4: 1:1 v/v). Thechromatographs were divided in ten fractions and were bio-assayed for a rooting co-factor with the mung bean rooting test. Extracts from buchu cuttings showed significant activity atthe Rf values of co-factor 3. Co-factors 1,2 and 4 do not seem to be present in significantquantities. However, co-factors with Rf values different from previous reported values werepresent in significant quantities. No inhibition was found in buchu. In fact, all Rf valuesstimulated rooting.

[发布机构] Stellenbosch University