AFRIKAANS: Rumohra adiantiformis (G. Forst.) Ching, die seweweeks- ofknysnavaring se gewildheid as loof in die snyblombedryf neem vinnig toe. Onder natuurlike groeitoestande ontwikkel die seweweeksvaring slegs beperkte hoeveelhede sori op blare, terwyl groot hoeveelhede sori ontwikkel wanneer die varing onder skadunet verbou word. Die teenwoordigheid van oormatige sori lei tot bemarkingsprobleme. Die navorsing is op die perseel van Bergland Tuine kwekery te Krugersdorp uitgevoer om die invloed van etefon, paklobutrasool (PP333), gibberelliensuur (GA3) , sitokiniene en verskillende skaduvlakke op sorivoorkoms en grootte van seweweeksvaringblare te bepaal. Behandeling van PP333 teen 500 mg dm-3 of met etefon teen 144 en 480 mg dm-3 in die blaarknopstadium het die getal sori by volwassenheid van blare betekenisvol verlaag. PP333-behandelings teen 1 000 en 1 500 mg dm-3 in die blaarknopstadium het die sori by volwassenheid van blare hoogs betekenisvol verlaag. Bespuitings met behandelings GA3 teen 57,6 mg dm-3 of sitokiniene teen 0,00062 en 0,0155 mg dm-3 op die blaarknopstadium het tot 'n betekenisvolle verhoging van sori op volwasse blare gelei. PP333 of etefon beinvloed nie die blaargrootte van volwasse blare wat in die jongblaar-, oopgevoudeblaar- en blaarknopstadium behandel is nie. Blare van al drie blaarstadia wat met sitokiniene of GA3 behandel is, was by volwassenheid nie-betekenisvol groter. Die 70% skadunet met bykomstige swartplastiekstroke in 'n noordsuidrigting onderaan gespan het die getal sori op blare verlaag en die blaaroppervlakte betekenisvol vergroot. Faktore soos seisoenale variasie, oesfrekwensie, plantdigtheid, grondvogstatus, waterkwaliteit, peste en plae was nie by hierdie ondersoek ingesluit nie en behoort ondersoek te word. ENGLISH: Rumohra adiantiformis (0. Forst.) Ching, the seven-weeks or knysna fern is a relatively new floral greenery of increasing importance. In its natural habitat the seven-weeks fern produces small numbers of sori on leaves, while commercially cultivated ferns under shade produce large numbers. The presence of excessive numbers of sori have a detrimental influence on the market value of the product. A trial was conducted on the premises of Bergland Tuine nursery in Krugersdorp to determine the effect of ethephon, paclobutrazol (PP333), gibberellic acid (GA3), cytokinins and different shade levels on the presence of sori and size of seven-weeks fern leaves. Leaves treated in the leafbud stage with PP333 at 500 mg dm-3 or ethephon at 144 and 480 mg dm-3 significantly reduced the number of sori on the leaves at maturity. Highly significant reduction of sori on mature leaves were found when PP333 was applied at I 000 and 1 500 mg dm-3 on the leaves in the leafbud stage. Sori numbers on mature leaves significantly increased after treatment of bud stage leaves with GA3 at 57,6 mg dm-3 or cytokinins at 0,00062 and 0,0155 mg dm-3. The leaf size of mature leaves was not influenced when PP333 or ethephon was applied on the leaves at the young leaf, unfolded leaf and leafbud stage. Leaves in all three leaf stages treated with cytokinins or GA3 showed a non-significant increase in leaf size at maturity. The 70% shade net with additional black plastic strips suspended underneath the net in a north-south direction, reduced the number of sori on the leaves and increased the leaf area significantly. Factors such as seasonal variation, harvest frequency, plant density, ground moisture levels, water quality, diseases and pests were not included in this investigation but should be researched. / Dissertation (MSc(Agric))--University of Pretoria, 2011. / Plant Production and Soil Science / unrestricted