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dc.contributor.advisorPretorius, J. C.
dc.contributor.advisorGrobbelaar, J. U.
dc.contributor.advisorAllemann, J.
dc.contributor.authorBuitendag, Roelof Adriaan
dc.date.accessioned2018-01-18T09:30:10Z
dc.date.available2018-01-18T09:30:10Z
dc.date.issued2012-01
dc.identifier.urihttp://hdl.handle.net/11660/7622
dc.description.abstractEnglish: Regardless of past research, great uncertainty still exists amongst the research community, fertilizer agents and farmers alike with regard to the benefits of foliar inorganic fertilizer application for crop production. This supplied a rationale for investigating foliar nutrition as an agricultural practice, with the main aim of increasing maize kernel yield, under standard farm management practices. Fertilizer salts used in this study included potassium nitrate (KNO3), mono potassium phosphate (MKP) and mono ammonium phosphate (MAP). Three objectives were set in order to obtain information about i) the optimal application growth stage (2004/05 season), ii) the optimum concentration rate (2005/06 season) and iii) the contribution of either the P or K moiety (or both) contained in foliar applied salts towards growth, physiological and yield responses measured in maize (2006/07 season). During the 2004/05 season a 4% solution of MKP and a 3% solution of KNO3 were applied at growth stages V3 and V8. MKP applied at V8 was the best treatment as it increased plant height significantly (11%) as well as plant fresh and dry mass markedly, compared to the control, when measured at the end of the vegetative growth period at V19. The higher yield (+23%) obtained with MKP applied at V8 during season one, compared to treatment at V3, corresponded with an increase in grain filling of the second ear (+16%), total ear mass (+20%), kernel mass (+20%) and number of kernels (+16%) as well as higher total sugar and starch that accumulated in kernels. During the 2005/06 season, vegetative growth and yield parameters showed no significant differences between the single and double rates for both salts applied at V8. However, MKP applied at both the single and double rates contributed to marked yield increases of 12% and 14% respectively. Although neither KNO3 nor MKP significantly influenced chlorophyll content or photosynthesis efficacy (chlorophyll a fluorescence), higher sugar levels were detected in kernels at the milk and soft dough stages as well as starch at harvest of plants treated with both salts and at two different concentrations. This strongly indicated that improvement of sucrose translocation from the leaves to kernels was rather causative of higher carbohydrate content measured in harvestable parts than sugar production per se. During the 2006/07 season MAP had either no significant effect or suppressed both growth and yield eliminating its purpose to verify P or K involvement. Further, the third season was significantly drier compared to the first two seasons further complicating the use of third season data to distinguish between P and K in terms of its involvement in causing the vegetative and yield responses measured in maize. Overall, it was only MKP applied at 4% and at V8 that tended to increase kernel yield over the first two seasons.en_ZA
dc.description.abstractAfrikaans: Ten spyte van vorige navorsing bestaan daar nog groot onsekerheid tussen navorsers, bemestingsagente en boere ten opsigte van die potensiële voordele, al dan nie, wat blaartoegediende bemestingstowwe vir gewasproduksie inhou. Dit het ‘n rasionaal verskaf vir onderhawige ondersoek na blaarbemesting as ‘n landboupraktyk met die hoofdoel om die opbrengs van mielies onder standaard plaasbestuurspraktyke te verhoog. Bemestingsoute wat in die studie gebruik is het kaliumnitraat (KNO3), mono kaliumfosfaat (MKP) en mono ammonium fosfaat (MAP) tegnies ingesluit. Drie doelwitte is geformuleer ten einde inligting te bekom betreffende i) die optimum toedieningstyd (2004/05 seisoen), ii) die optimum konsentrasie (2005/06 seisoen) en iii) die moontlike bydra van P of K of albei om ‘n groei-, fisiologiese- en/of opbrengsrespons by mielies te ontlok (2006/07 seisoen). Tydens die 2004/05 seisoen is ‘n 4% MKP en ‘n 3% KNO3 oplossing apart toegedien op groeistadia V3 en V8. MKP, op V8 toegedien, was die beste behandeling in die sin dat dit planthoogte betekenisvol (11%) sowel as plant vars- en droë massa merkbaar verhoog het teen die einde van die groeiseisoen op stadium V19, in vergelyking met die onbehandelde kontrole. Verder het die hoër opbrengs (+23%) wat met die MKP behandeling op V8 tydens die eerste seisoen bekom is ooreengestem met ‘n verhoging in graanvulling van die tweede kop (+16%), totale kopmassa (+20%), pitmassa (+20%) en aantal pitte per kop (+16%) asook hoër suiker- en stysel akkumulasie in graan in vergelyking met behandeling op die V3 groeistadium. In die 2005/06 seisoen is geen verskille ten opsigte van vegetatiewe groei en opbrengs tussen die enkel en dubbel konsentrasie bespuitings van beide soute wat op V8 toegedien is waargeneem nie. Maar, MKP teen beide konsentrasies toegedien het bygedra tot merkbare opbrengsverhogings van 12% en 14% respektiewelik. Alhoewel nie KNO3 of MKP die chlorofilinhoud of fotosintese kapasiteit (chlorofil a fluoressensie) van blare betekenisvol beïnvloed het nie, het beide soute teen beide konsentrasie bygedra tot hoër suikervlakke in pitte tydens die melk- en sagtedeeg ontwikkelingstadia asook styselvlakke tydens oes. Laasgenoemde het sterk daarop gedui dat verhoogde sukrose translokasie vanaf blare na pitte eerder verantwoordelik was vir hoër koolhidraatvlakke in oesbare gedeeltes as suikerproduksie. Tydens die 2006/07 seisoen het MAP geen betekenisvolle effek op groei en oesopbrengs gehad nie, of beide komponente verlaag, wat die doelwit wat met die MAP toediening gestel was, naamlik om tusssen P en K betrokkenheid te onderskei, genullifiseer het. Die derde seisoen was verder aansienlik droeër as die eerste twee seisoene wat die gebruik van derde seisoen data, om die moontlike rolle van P of K om die gemete response in mielies te verklaar, verder bemoeilik het. Oorhoofs was dit slegs die MKP behandeling teen 4% en op V8 wat geneig het om oesopbrengs te verhoog oor die eerste twee seisoene.af
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectCorn -- Fertilizersen_ZA
dc.subjectCorn -- Nutritionen_ZA
dc.subjectFoliar feedingen_ZA
dc.subjectPhosphatic fertilizersen_ZA
dc.subjectPotassium fertilizersen_ZA
dc.subjectCorn -- Effect of potassium onen_ZA
dc.subjectThesis (Ph.D. (Soil, Crop and Climate Sciences (Agronomy))--University of the Free State, 2012en_ZA
dc.titleThe growth, yield and physiological response of rain fed maize to foliar applied fertilizeren_ZA
dc.typeThesisen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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