Sucrose was identified by high performance liquid chromatography (HPLC) as the only phloem-mobile carbohydrate in the Boojum tree. This result has implications for carbohydrate metabolism in the desert adapted Boojum and ocotillo, as discussed below.

The alkaline nature of most Arizona soils contributes to widespread iron deficiency in exotic ornamental plants, such as pyracantha. An experiment was conducted in 1987 to evaluate the effectiveness of two soil-applied iron fertilizers (FeEDDHA chelate and a jarosite-type iron silicate, Ironite\) and three rates of foliar- applied FeEDDHA in controlling iron chlorosis symptoms in established pyracantha vines. Soil-applied FeEDDHA was the most effective in reducing iron chlorosis symptoms, followed by the foliar chelate treatments. The iron silicate material had no significant effect on iron chloroses symptoms compared to the untreated control. Both soil and foliar applications of FeEDDHA chelate made in the fall can effectively control iron chlorosis symptoms in established pyracantha.

No description available.

An environmentally-based systems approach to sustainability analyses of organic fruit production systems in New Zealand. This research introduces an approach for the assessment of the sustainability of farming systems. It is based on the premises that sustainability has an environmental bottom line and that there is very limited substitutability between natural capital and other forms of capital. Sustainability assessment is undertaken through analyses of energy and material flows of the system and their impacts on the environment. The proposed sustainability assessment approach is based on two high level criteria for sustainability: efficient use of energy and non-degradation of the environment from energy and material use. Sustainability assessment of organic orchard systems in New Zealand was undertaken to demonstrate this approach. Five indicators which address the two criteria for the sustainability of the orchard systems are the energy ratio, the CO2 ratio, changes in the soil carbon level, nutrient balances, and the leaching of nitrogen. Organic kiwifruit and organic apple systems are modelled based on their key energy and material flows and their interactions with the natural environment. The energy and material flows are converted into appropriate energy and matter equivalents based on coefficients taken from the published literature. Sustainability indicators are estimated over one growing season using two computer modelling tools, Overseer® and Stella®, in a life cycle approach. Sustainability assessment of the organic orchard systems suggests that the approach is useful for evaluating energy use and key environmental impacts that occur in soil, water and atmosphere. The results indicate that the model organic orchard systems are sustainable in terms of energy use and are a net sink of CO2-equivalent emissions. The implication of this result is that organic orchard systems potentially could trade carbon credits under the Kyoto Protocol. The findings also suggest that the sustainability assessment approach is capable of identifying the trade-offs within the sustainability indicators associated with particular management practices. Further research to improve and validate the proposed approach is essential, before it can be practically used for decision making at the orchard level and for policy making at the national level.

Thesis (MscAgric (Horticulture))--University of Stellenbosch, 2007. / More and more markets develop around the world for South African grapes and it becomes a challenge to store grapes for longer and reach the market with superior quality. The most destructive decay fungus, Botrytis cinerea can cause huge economic losses and successful postharvest control in the table grape industry relies on SO2. This gas not only controls the fungus but also causes losses due to phytotoxicity. SO2 also creates allergic reactions amongst certain people. In modern times the focus is on food safety and governments consequently impose certain regulations and restrictions to restrict the use of chemicals and ensure “cleaner” produce. The objective of this study was to find a steriliser to reduce B. cinerea inoculum on the berry surface prior to storage,to be used in conjunction with the current method of control – the SO2 generator pad.

Thesis (MscAgric (Horticulture))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: For many apple (Malus domestica Borkh.) and pear (Pyrus communis L.) cultivars, attractive colour is essential to their profitability on export markets. This study focuses on problems related to poor green colour of ‘Granny Smith’ apples and insufficient red colour of bi-coloured pear cultivars. ‘Granny Smith’ apples often suffer from poor green colour. Green colour of fruit from various orchards was already found to differ midway through fruit development, with these differences being carried through to harvest. In a trial where nitrogen (N) fertilisers were applied using different forms at different times, there was no improvement in green colour. In another trial, artificial shading was applied to fruit only during their early development. Fruit that were shaded during this time were less green at harvest than unshaded fruit. Additional N applications may only improve colour where a deficiency exists. However, green colour may be improved by increasing light distribution early during fruit development. Bi-coloured pears attain their maximum red colour midway through their development, and this desired red colour is mostly lost prior to harvest. Red colour can also increase transiently with the passing of cold fronts. Anthocyanins, responsible for this red colour, may have a photoprotective function which would explain this pigmentation pattern, as photosystems are particularly sensitive to light damage at low temperatures. As ‘Rosemarie’ fruit bent over from a vertical to hanging position during development, peel photoinhibition was reduced as anthocyanins were synthesised. ‘Forelle’ peel was found to be very sensitive to high light levels at low temperatures. Substantial anthocyanin development took place in ‘Cripps’ Pink’ apples when weather conditions were cold, but clear following a cold front. A photoprotective role seems to explain daily changes in anthocyanins in response to temperature, but not the seasonal progression of colour development. For many apple (Malus domestica Borkh.) and pear (Pyrus communis L.) cultivars, attractive colour is essential to their profitability on export markets. This study focuses on problems related to poor green colour of ‘Granny Smith’ apples and insufficient red colour of bi-coloured pear cultivars. ‘Granny Smith’ apples often suffer from poor green colour. Green colour of fruit from various orchards was already found to differ midway through fruit development, with these differences being carried through to harvest. In a trial where nitrogen (N) fertilisers were applied using different forms at different times, there was no improvement in green colour. In another trial, artificial shading was applied to fruit only during their early development. Fruit that were shaded during this time were less green at harvest than unshaded fruit. Additional N applications may only improve colour where a deficiency exists. However, green colour may be improved by increasing light distribution early during fruit development. Bi-coloured pears attain their maximum red colour midway through their development, and this desired red colour is mostly lost prior to harvest. Red colour can also increase transiently with the passing of cold fronts. Anthocyanins, responsible for this red colour, may have a photoprotective function which would explain this pigmentation pattern, as photosystems are particularly sensitive to light damage at low temperatures. As ‘Rosemarie’ fruit bent over from a vertical to hanging position during development, peel photoinhibition was reduced as anthocyanins were synthesised. ‘Forelle’ peel was found to be very sensitive to high light levels at low temperatures. Substantial anthocyanin development took place in ‘Cripps’ Pink’ apples when weather conditions were cold, but clear following a cold front. A photoprotective role seems to explain daily changes in anthocyanins in response to temperature, but not the seasonal progression of colour development. Dwarfing rootstocks are known to improve red colour of bi-coloured pears due to improved light distribution. ‘Forelle’ fruit from six rootstocks of varying vigour were harvested from exposed positions only, so as to establish the effect of rootstock on red colour development independent of the effect of rootstock on canopy light distribution. Fruit from trees on quince (Cydonia oblonga Mill.) rootstocks were found to have redder fruit than those from vigorous BP pear rootstocks. This may be due to higher chlorophyll and carotenoid concentrations present in the peel of fruit from BP rootstocks, whose leaf and peel N were also high. The use of quince rootstocks is recommended where red colour development of bi-coloured pears is a problem. An early season bi-coloured cultivar with good red colour is required. Breeding trials to find such a cultivar are resource intensive. To streamline the process, a method to preselect immature seedlings for their future fruit colour is required. Fruit colour from bearing seedlings was compared with colour of their immature leaves. Trees with red leaves were likely to produce fruit that were too red for the breeders’ requirements. Trees with green or blushed leaves were capable of producing blushed fruit. It would be feasible to cull red-leaved seedlings with minimal risk of losing potential bi-coloured cultivars. / AFRIKAANSE OPSOMMING: Verskeie appel (Malus domestica Borkh.) en peer (Pyrus communis L.) kultivars se winsgewendheid word bepaal deur hul aantreklike kleur. In hierdie studie word die swak groen kleur van ‘Granny Smith’ appels asook rooi kleurontwikkeling van blospere ondersoek. Die groen kleur van ‘Granny Smith’ appels is dikwels onvoldoende. Verskille in groen kleur tussen boorde was reeds gedurende vroeë vrugontwikkeling aanwesig, en hierdie verskille het voortgeduur tot met oes. Groen kleur kon nie deur verskillende bronne en tye van stikstofbemesting verbeter word nie. Stikstofbemesting verbeter groen kleur moontlik net in boorde met ‘n stikstoftekort. Vrugte wat gedurende hul vroeë ontwikkeling oorskadu is, se groen kleur was swakker by oes in vergelyking met vrugte wat nie oorskadu is nie. Groen kleur kan moontlik verbeter word deur ligverspreiding tydens vroeë vrugontwikkeling deur middel van snoei aksies te verhoog. Blospeerkultivars bereik hul maksimum rooi kleur halfpad deur hul ontwikkeling, maar is geneig om hul rooi kleur grootliks voor oes te verloor. Rooi kleur mag egter kortstondig toeneem in reaksie op die lae temperature gepaardgaande met koue fronte. Antosianiene, wat verantwoordelik is vir die rooi kleur, het moontlik ‘n beskermende funksie teen hoë ligvlakke, en hierdie funksie mag moontlik die bogenoemde patroon van rooikleurontwikkeling verklaar. Die natuurlike buiging van ‘Rosemarie’ pere van hul aanvanklike regop oriëntasie tot hul karakteristieke hangende posisie, is gekenmerk deur ‘n afname in fotoinhibisie van die skil en ‘n gelyklopende sintese van antosianien. ‘Forelle’ skil was uiters sensitief vir hoë ligvlakke in kombinasie met lae temperature (16 ºC). ‘Cripps’ Pink’ appels het ‘n vinnig toename in rooi kleur getoon met die koue, maar helder, weerstoestande wat gevolg het op ‘n kouefront. Dit is welbekend dat dwergende onderstamme die rooi kleur van blospere verbeter deur ligverspreiding in die boom te verhoog. Ten einde die effek van onderstam op rooi kleurontwikkeling onafhanklik van die effek van onderstam op ligverspreiding te ondersoek, is ‘Forelle’ pere wat blootgestel was aan vol son geoes van bome geënt op ses onderstamme met verskillende groeikrag. Kweperonderstamme (Cydonia oblonga Mill.) het rooi kleur verbeter in vergelyking met die groeikragtige BP peeronderstamme. ‘n Moontlike rede vir die verbetering is die laer chlorofiel- en karotenoïedkonsentrasies in die skil van vrugte op kweperonderstamme. Bome op peeronderstamme het ook hoër blaaren skil stikstofvlakke gehad. Kweperonderstamme word aanbeveel in gevalle waar rooi kleurontwikkeling van blospere ‘n probleem mag wees. Die RSA vrugtebedryf benodig ‘n vroeë blospeerkultivar met goeie rooi kleurontwikkeling. Die teling van so ‘n kultivar is hulpbronintensief en baie duur. Ten einde die teelproses meer effektief te maak, word ‘n metode benodig om saailinge al voor uitplanting in die boord te selekteer na gelang van hul toekomstige vrugkleur. Die vrugkleur van oesryp pere van draende saailinge is vergelyk met die kleur van hul onvolwasse blare. Bome met rooi blare is geneig om vrugte te dra wat té rooi is om te kwalifiseer as blospere. Die meerderheid blospere is afkomstig van bome met blos of groen onvolwasse blare. Dit is prakties haalbaar om rooiblaarsaailinge uit te dun, met net ‘n klein, aanvaarbare risiko om ‘n moontlike blospeerkultivar in die proses te verloor. / medg2010-1 / Imported from http://etd.sun.ac.za April 2010.

Thesis (MScAgric)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Fruit quality is the most important factor that determines prices for the fruit in the international markets. Although different consumers perceive quality differently there are quality variables that are always associated with poor quality by all consumers. In table grapes (Vitis vinifera L.) these variables may include overall appearance, stem condition, SO2 damage, decay, berry browning and shatter. The presence of these quality defects negatively affects prices and most often results in quality claims. Cooling is the most widely used method to reduce the postharvest loss of fruit quality. In South Africa, most deciduous fruits including table grapes are forced air cooled to a statutory pulp temperature of –0.5°C prior to shipping in an effort to preserve quality, thus ensuring good market prices for the fruits. Despite these efforts, there are still quality claims from the markets and this reduces the returns to the growers. The objectives of this research were to: (i) see if cooling time can be reduced by cooling to higher pulp temperatures of 1.5°C and 3°C without causing quality losses, thus improving the throughput of the cold rooms; (ii) see if the problem of berry browning can be alleviated by cooling grapes to higher pulp temperature, and (iii) see whether pallet positioning in the cooling tunnels and reefer container affect quality. The trends showed better quality when ‘Victoria’ and ‘Regal Seedless’ were forced air cooled (FAC) to pulp temperatures of 1.5 °C and 3 °C as opposed to –0.5 °C. There were no economic losses associated with pre-cooling grapes to pulp temperatures of 1.5 °C and 3 °C. There were no significant differences in berry browning related to pre-cooling treatments. However, cooling time was reduced significantly. In most of the cooling tunnels and reefer containers used in this trial, grape quality results showed no significant differences between the positions in the stack and in reefer containers. However, in cases where there were significant differences, the middle and the rear positions showed better grape quality in terms of stem condition (dry and brown stems) than the front position (near fan) in both the pre-cooling stack and reefer containers. The trends showed that the front is cooler than the back of the pre-cooling stack. The pulp temperature differences between the front and rear positions in the reefer container were as high as 1.23 °C. The trends also showed that the bottom layers of the pallets were cooler than the top layers in the reefer container. FAC to 3°C resulted in a constant reduction in percentage electrolyte leakage after 4 weeks of storage at –0.5°C, while FAC to 1.5°C, -0.5°C and static room cooling (control) in some cases showed an initially low electrolyte leakage followed by an increase in leakage after 4 weeks of storage. FAC grapes to higher pulp temperatures of 3°C and 1.5°C could reduce the cooling time, thereby improving the throughput of cold rooms. There was no clear evidence to suggest that browning was due to pre-cooling practices. Both preharvest and postharvest conditions need to be further investigated to better understand the problems of browning in white table grapes. / AFRIKAANSE OPSOMMING: Vrugkwaliteit is ʼn kritiese faktor in die bepaling van pryse op die internasionale markte. Alhoewel daar variasie voorkom tussen verbruikers in wat vrugkwaliteit is, bly sekere aspekte altyd onveranderd. Ononderhandelbare kwaliteit aspekte in tafeldruiwe (Vitis vinifera L.) sluit die algemene voorkoms, toestand van die trosstingels, SO2 skade, bederf, korrel verbruining en los-korrels in. Indien enige van die kwaliteit-defekte voorkom het dit ʼn negatiewe impak op die prys en lei gewoonlik tot gehalte eise. Verkoeling word algemeen gebruik om die verlies van na-oes kwaliteit te verminder. Die meeste sagtevrugte geproduseer in Suid Afrika (insluitend tafeldruiwe) ondergaan geforseerde verkoeling tot ʼn statutêre pulptemperatuur van -0.5°C, voor verskeping. Ondanks hierdie maatreëls om hoë pryse te verseker, is daar steeds kwaliteiteise in die mark wat lei tot ‘n laer inkomste vir produsente. Die navorsing het dus ten doel gehad om : (i) te bepaal of die tyd van verkoeling verminder kan word, indien na hoër pulptemperature van 1.5°C en 3°C verkoel kan word, sonder ‘n verlies in kwaliteit en sodoende die deurvloeitempo van die koelkamers verhoog; (ii) om te bepaal of die voorkoms van korrelverbruining verlaag kan word indien tot hoër pulp-temperature verkoel word, en (iii) laastens om te bepaal of posisie van die palet in die verkoelingstonnel en verskepingshouer ʼn invloed het op vrugkwaliteit. Tendense toon dat ‘Victoria’ en ‘Regal Seedless’ kwaliteit beter was indien verkoel tot pulptemperature van 1.5°C en 3°C in vergelyking met -0.5°C. Daar was geen ekonomiese verliese waargeneem indien die hoër verkoelingstemperature gebruik is nie. Alhoewel daar geen betekenisvolle verskille in korrelverbruining voorgekom het tussen temperatuur behandelings nie is die verkoelingsperiode verkort. In die meeste van die verskepingshouers, asook in posisies tydens geforseerde verkoeling is daar geen betekenisvolle verskille waargeneem nie. In die gevalle waar daar egter wel betekenisvolle verskille voorgekom het, het die middel en agter posisies beter vrugkwaliteit gehad as die voorste posisie tydens verkoeling asook houerverskeping. Die palette aan die voorkant (naby die waaier) het as ʼn algemene tendens laer temperature as in die agterkant van die verkoelingstonnel. Verskille in pulptemperature tussen palette in die voor en agterkant van verskepingshouers was so hoog as 1.23°C. Die temperatuurdata het uitgewys dat die onderste laag kartonne neig om by ‘n laer temperatuur te wees as die boonste lae kartonne tydens houerverskeping. Geforseerde verkoeling teen 3°C het gelei tot ‘n afname in persentasie elektrolietlekkasie na 4 weke van verkoeling teen -0.5°C. Terselfdertyd het geforseerde verkoeling tot 1.5°C en -0.5°C asook statiese verkoeling (kontrole) in sekere gevalle gelei tot ‘n laer aanvanklike uitlek van elektrolietlekkasie, gevolg deur ʼn verhoging na 4 weke opberging. Geforseerde verkoeling van tafeldruiwe tot pulptemperature van 1.5°C en 3°C verkort die verkoelingstyd en verhoog dus die deurvloeitempo in die verkoelingskamers. Daar was gedurende die studie geen duidelike bewyse gevind dat korrelverbruining voorkom as gevolg van verkoelingspraktyke nie. Beide voor en na-oes praktyke sal verder ondersoek moet word om die invloed daarvan te bepaal op die verbruining van wit tafeldruiwe.

Thesis (MscAgric (Horticulture))--University of Stellenbosch, 2007. / Production of quality fruit is the main aim in horticultural crops. Numerous research reports stress the important role of calcium (Ca) in maintaining firmness and preventing the development of physiological disorders in fruit. This study focused on the effect of water and nutrient management strategies, rootstocks and foliar Ca applications on fruit Ca content. Final Ca content/concentration in apple fruit at harvest did not differ significantly between treatments water with micro jets (hand nutrition), water and nutrients with fertigation, or water and nutrients with pulsating drip when applied to ‘Brookfield Gala’ trees in third leaf, on two rootstocks (M793 and M7). In the second trial, three Ca levels were applied to ‘Brookfield Gala’ trees through a pulsating drip system during three phenological periods to evaluate the effect on Ca uptake of the fruit. During the second season, application of high Ca levels for the period full bloom to harvest gave a higher fruit Ca concentration than with applications of standard or low Ca.

Thesis (MscAgric (Horticulture))--University of Stellenbosch, 2005. / The occurrence of both pre- and postharvest leaf blackening in certain Protea species and cultivars is a problem that severely limits their marketability, vase life and transport options. This research focuses on : (I) The distribution of carbohydrates in inflorescence bearing stems of certain Protea cultivars from harvest, following pulsing with a 10 g.L-1 glucose solution until four weeks postharvest. Stems were held under a variety of postharvest conditions, and (II) The suppression of Protea postharvest leaf blackening with specific focus on the cultivar ‘Sylvia’ (P. eximia x P. susannae).

Thesis (MScAgric (Horticulture))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Creasing, also known as albedo breakdown, is a preharvest disorder that affects the albedo of citrus fruit causing creases on the surface of the fruit. It is a recurrent problem in Navel and Valencia oranges and can cause individual orchard losses which often exceed 50%. Although the contributing factors are known, the physiological basis of creasing development is unresolved and the current control measures do not prevent creasing satisfactory. Hence, better control measures and further understanding of the physiology of creasing development is required. The objective of this two-year study was to determine if the position of fruit in a tree, light and carbohydrate manipulation techniques, and albedo mineral nutrients influence creasing development. Furthermore, the most effective application timing of gibberellic acid (GA3) with the least negative effect on fruit rind colour development and the effectiveness of cytokinins, other products and different root biostimulants to reduce creasing incidence were evaluated. The position of fruit in the tree and light influenced the development of creasing and the distribution of mineral nutrients in the albedo. Creasing incidence was higher on the south side than on the north side of the tree and fruit from the inside sub-sectors had a greater creasing incidence compared to fruit from the outside sub-sectors. The shady part of outside fruit was more creased compared to the sunny part of the fruit and covering fruit with brown paper bags increased creasing severity. The light manipulation techniques used on the leaves and fruit increased the nitrogen (N), phosphorus (P), potassium (K) and manganese (Mn) concentrations in the albedo and differences in the albedo mineral nutrients amongst the sub-sectors evaluated were observed, but creasing severity or creasing incidence was not significantly correlated with the albedo mineral concentrations at harvest. Albedo mineral concentrations earlier in the season may play a role in creasing development, as creasing severity was significantly correlated with copper (Cu), K, and Mn concentrations in the albedo during stage II of fruit development. Creasing incidence and albedo mineral concentrations were not affected by any of the carbohydrate manipulation techniques used in this study. The incidence and severity of creasing was significantly reduced, with a minor negative effect on fruit rind colour development, by the application of GA3, from mid November to mid January. Localised fruit application of CPPU [N-(2-chloro-4-pyridyl)-N-phenylurea], MaxCel (6- Benzyladenine) and CPPU in combination with calcium after physiological fruit drop reduced the incidence and severity of creasing, although creasing incidence was not significantly different from the control. The application of Messenger®, AVG (aminoethoxyvinylglycine) and different root biostimulants did not reduce creasing incidence. The results showed that cytokinins could reduce creasing incidence and justify further studies on application and uptake efficiency. The use of different root biostimulants are not recommended, but it is suggested that treatment effects may be more pronounced over a longer period. / AFRIKAANSE OPSOMMING: Kraakskil is ‘n vooroes abnormalitiet wat die albedo van sitrusvrugte affekteer, deur krake op die oppervlak van vrugte te veroorsaak. Dit is ‘n algemene probleem in Navel en Valencia lemoene en kan boordverliese van tot 50% of soms hoër veroorsaak. Alhoewel die bydraende faktore bekend is, is die fisiologiese basis van kraakskil ontwikkeling onopgelos en die beskikbare beheermaatreëls is nie bevredigend nie. Dus, beter beheermaatreëls en ‘n beter begrip van die fisiologie van kraakskil ontwikkeling is nodig. Die doel van die twee-jaar studie was om te bepaal of die posisie van vrugte in ‘n boom, lig en koolhidraat manipulasie tegnieke en minerale elemente in die albedo, kraakskil ontwikkeling beïnvloed. Die mees effektiewe toedieningstyd van gibberelliensuur (GA3) sonder ‘n negatiewe effek op vrugkleur is bepaal en die effektiwiteit van sitokiniene, ander produkte en verskillende wortel biostimulante om kraakskil voorkoms te verminder, is geëvalueer. Die posisie van vrugte in ‘n boom en lig het kraakskil ontwikkeling en die verspreiding van minerale element in die albedo beïnvloed. Kraakskil voorkoms was hoër aan die suidekant van die boom as aan die noordekant en vrugte in die binnekant van die boom het ‘n groter kraakskil voorkoms as vrugte in die buitekant van die boom gehad. Die skadukant van buitevrugte het meer kraakskil gehad as die sonkant en die toemaak van vrugte met ‘n bruin papiersak het die graad van kraaksil verhoog. Die lig manipulasie tegnieke wat op die blare en vrugte gebruik is, het die stikstof (N), fosfaat (P), kalium (K) en mangaan (Mn) konsentasies in die albedo verhoog en verskille in die albedo minerale elemente tussen sub-sektore is waargeneem, maar betekenisvolle korrelasies is nie tussen die graad en voorkoms van kraakskil en die albedo minerale element konsentrasies by oestyd waargeneem nie. Albedo minerale element konsentrasies vroeër in die seisoen mag ‘n rol speel by kraakskil ontwikkeling, omdat die graad van kraakskil betekenisvol gekorreleer was met albedo koper (Cu), K, en Mn konsentrasies tydens fase II van vrugontwikkeling. Kraakskil voorkoms en albedo minerale element konsentrasies is nie deur enige van die koolhidraat manipulasie tegnieke geaffekteer nie. Die voorkoms en graad van kraakskil is betekenisvol verlaag, met ‘n geringe negatiewe effek op vrugkleur, deur die toediening van GA3 vanaf mid November tot mid Januarie. Gelokaliseerde vrugtoedienings van CPPU [N-(2-chloro-4-piridiel)-N-phenielureum], MaxCel (6- Bensieladenien) en CPPU saam met kalsium na fisiologiese vrugval het die voorkoms en graad van kraakskil verlaag, alhoewel kraakskil voorkoms nie betekenisvol van die kontrole verskil het nie. Die toediening van Messenger®, AVG (amino etoksievinielglisien) en veskillende wortel biostimulante het nie kraakskil voorkoms verlaag nie. Die resultate het getoon dat sitokiniene kraakskil voorkoms kan verlaag en verdere studies op die toediening en opname effektiwiteit word aanbeveel. Die gebruik van verskillende wortel biostimulante word nie aanbeveel nie, maar die effek behoort meer sigbaar te wees na ‘n langer periode van behandeling.