Pretorius, J. C.Ceronio, G. M.Molahlehi, Lebone2017-03-222017-03-222000http://hdl.handle.net/11660/5958English: The abscission of the reproductive organs (flower buds, flowers and pods) of the common bean, Phaseolus vulgaris L., has proved to be a very serious problem affecting bean yields. The yield reductions are mainly significant under conditions of environmental stress, which aggravate production of the abscission causing hormones such as ethylene. The study therefore evaluated the effect of certain nutrients, other chemicals and ethylene (growth regulator) applied as foliar sprays to determine their effect in as far as abscission of the reproductive organs in beans is concerned. Glasshouse trials were carried out during the 1998/99 and 1999/00 seasons to investigate the possible preventative role of some micro and macro-nutrients, abscission inhibitors (e.g. Silver) and growth regulators (e.g. ethylene) all applied as foliar sprays. In another trial, three cultivars were compared where no treatments were applied. Data were collected and the following parameters were measured; number of flowers and pods that abscised, pods formed and abscised, pods that matured and could be harvested, dry pod mass at harvest, seed number per pod, dry seed mass per pod and total yield per hectare. Data were analyzed using a SAS software system and interpreted accordingly. The results of this study indicated that flower and pod formation might not be considered as the major factor affecting bean yields. The reason being that flowering percentage was not very different between the treated and the untreated plants. The abscission of flower buds, flowers and pods, however, was relatively high in general, indicating that this is possibly a primary factor affecting poor yields in beans. Ethrel, an ethylene releasing compound, applied as a foliar spray, aggravated the problem of flower and pod abscission. An ethylene antagonist (silver salt) had a slight alleviating effect on organ abscission but did not improve the final yield significantly. Molybdenum and potassium salts improved flower formation to a certain extent but had no real alleviating effect on organ abscission. This was also revealed in the lack of yield improvement. Foliar application of a copper salt as well as treatment with ComCat®, a natural product with biocatalytic properties, did not influence flower and pod abscission significantly, but increased the final yields to some extend. The latter indicates that other factors besides organ abscission could have had an effect on determining the final yield outcome. In the light of these findings, it is suggested that further studies be undertaken to test a wider range of chemicals for their potential to circumvent flower and pod abscission and improve bean yields. The latter could also include treatment at other growth stages, including post flowering. Other attempts could include an investigation into the effect of other known ethylene antagonists such as AVG (L-a.-(2-arninoethoxyvinyl)-glycinehydrochloride), an inhibitor of ethylene synthesis and NBD (2,S-norbornadiene), an inhibitor of ethylene action, on organ abscission and yield outcome in beans. As the results also showed that other factors besides organ abscission could have played a role in yield improvement, it might be worthwhile to investigate the effect of promising chemicals on physiological processes.Afrikaans: Die afspening van reproduktiewe organe (blomknoppe, blomme en peule) van die boontjie, Phaseo/us vulgaris L., was nog altyd as 'n ernstige probleem beskou vanweë die uiters nadelige effek op oesopbrengs. Oesopbrengs verlaging is die ergste onder stremmingstoestande, waarskynlik vanweë verhoogde sintese van hormone soos etileen. Tydens hierdie studie is die effek van verskillende bemestingstowwe, ander chemikalieë en etileen (groei reguleerder), aangewend as blaar bespuitings, geëvalueer in terme van hulle potensiaalom die afspening van reproduktiewe organe in die boontjie te voorkom Glashuisproewe is aanvanklik uitgevoer gedurende die 1998/99 en 1999/2000 seisoene om die moontlike absissie voorkomende rolle van sekere mikro- en makro-elemente, 'n groei reguleerder (etileen) en 'n etileen antagonis (silwer soute), aangewend as blaarbespuitings in 'n enkel konsentrasie, te ondersoek. Vooraf is drie boontjie cultivars, sonder enige behandeling, ook met mekaar vergelyk ten opsigte van groeipatrone. Die cultivar Kranskop, is in alle verdere proewe gebruik. Versamelde data in alle proewe het die volgende ingesluit: aantal blomme en peule gevorm en afgespeen, aantal peule wat wasdom bereik het en geoes kon word, droë peulmassa, aantal sade per peul, droë saadmassa en totale oesopbrengs per hektaar. Data is deur middel van 'n SAS sagteware program statisties geanaliseer. Resultate het daarop gedui dat blom- en peulvorming, of die gebrek daaraan, nie blyk om die primêre rede vir swak oesopbrenste by boontjies te wees nie aangesien die aantal blomme en peule wat gevorm is nie betekenisvol verskil het tussen behandelde en kontrole plante nie. Die afspening van blomknoppe, blomme en peule was egter oor die algemeen hoog wat daarop dui dat dit eerder as 'n primêre rede vir swak oesopbrengste by boontjies gereken kan word. Ethrel, 'n etileen vrystellende produk wat kommersieël in die handel beskikbaar is en as blaarbespuiting aangewend, het die probleem van blom en peul afspening vererger. 'n Etileen antagonis (silwer sout) het 'n geringe voorkomende effek op afspening gehad maar nie oesopbrengste noemenswaardig verbeter nie. Molibdeen en kaliumsoute het tot verhoogde blomvorming aanleiding gegee maar nie afspening of oesopbrengs noemenswaardig beïnvloed nie. Blaarbespuiting met 'n kopersout asook behandeling met ConrCat'", 'n natuurlike produk met biokatalitiese eienskappe, het nie blom en peul afspening noemenswaardig beïnvloed nie maar tog tot aansienlike oesopbrengsverhoging aanleiding gegee. In die lig van hierdie bevindinge word voorgestel dat verdere studies onderneem word om 'n wyer reeks van chemikalieë vir hulle potensiaal om blom- en peulafspening te voorkom, te toets. Laasgenoemde kan ook op ander groeistadia getoets word. Verder kan dit lonend wees om ander etileen antagoniste, te wete AVG (L-a-(2- aminoetoksieviniel)-glisien-hidrochloried), 'n inhibeerder van etileensintese, en NBD (2,S-norbomadiene), 'n inhibeerder van etileen aksie, se effek op afspening te toets. Aangesien die resultate daarop gedui het dat ander faktore, buiten blom- en peulafspening, ook 'n rol by oesopbrengs verhoging kon gespeel het, kan dit lonend wees om die effek van belowende chemikalieë op fisiologiese prosesse te ondersoek.enCommon beanPlant regulators -- Foliar applicationDissertation (M.Sc.Agric. (Agronomy and Horticulture))--University of the Free State, 2000DissertationUniversity of the Free State