Response of wheat (Triticum aestivum L.) and barley (Hordeun vulgare L.) to salinity stress

Bagwasi, Gaesejwe (2015-12)

Thesis (MSc)--Stellenbosch University, 2015.

Thesis

ENGLISH ABSTRACT: Good quality water for agricultural use is rapidly becoming a luxury due to competition for this water among the municipal, industrial and agricultural sectors. This has often forced growers to use poor quality water for irrigation. Salinity is one of the main sources of poor water quality and high electrical conductivities (EC’s) due to salinity may become a problem. The aim of this study was to compare the response of South African spring wheat and South African spring barley at germination, seedling growth, vegetative growth, reproductive growth and maturity stage to salinity stress caused by irrigation with saline water. This study was conducted in the laboratory and under controlled glasshouse conditions at the University of Stellenbosch in the Western Cape Province of South Africa. Treatments in trial 1 (incubation trial) were made up of three wheat cultivars (SST 027, SST 056 and SST 087) and three barley cultivars (Nemesia, Erica and Hessekwa) exposed to five EC levels of NaCl solutions (4, 8, 12, 16 and 20 dS m-1) and a control (0 dS m-1) of distilled water, during the germination phase. In trial 2 (pot trial), wheat cultivar SST 027 and barley cultivar SVG 13 were also subjected to the above solutions, but plants were grown till the tillering stage. In trial 3 (pot trial) cultivars used in trial 2 were subjected to five nutrient solutions with EC levels of 1.6, 3, 6, 9 and 12 dS m-1 and allowed to grow till maturity (harvesting stage). Fully balanced nutrient solution with EC = 1.6 dS m-1 was used as a control and NaCl was added to the solutions to obtain the needed EC. In trial 1, final germination percentage (FGP), salt tolerance (ST) and germination rate (GR) were measured at 7 days after incubation. The study showed that when the EC level was increased, FGP, ST and GR of all wheat and barley cultivars tested were decreased. However, significant reduction was only observed at high EC levels with regard to FGP and ST. Wheat cultivars recorded faster GR compared to barley cultivars and tended to be less sensitive to salinity in the germination stage. Cultivars from the same species did not show significant differences. In trial 2, shoot length (SL), root length (RL), shoot fresh weight (SFW), root fresh weight (RFW), shoot dry weight (SDW) and root dry weight (RDW) were measured at 35 days after planting (DAP). In general, the study showed that salinity had a significant (P0.05) effect on seedling growth of all measured parameters of both wheat and barley. Mean values for most growth parameters were higher for barley cultivar SVG 13 as compared to wheat cultivar SST 027. However, little evidence was found to show that barley is more salt tolerant than wheat at the seedling stage. In trial 3, selected growth parameters were measured at tillering (28 DAP), booting (54 DAP), flowering (71 DAP) and maturity stage (150 DAP). The study showed that salinity had a significant (P0.05) effect on the vegetative growth, reproductive growth and grain yield of both wheat and barley. Although barley generally produced higher dry weights especially at the early growth stages no clear evidence was found that South African spring barley is more salt tolerant than South African spring wheat.

AFRIKAANSE OPSOMMING: Besproeiingswater met ‘n goeie kwaliteit vir landboukundige gebruik word vinning baie skaars weens kompetisie, a.g.v menslike en industriële gebruik. Produsente word dus dikwels gedwing om water met ‘n swak kwaliteit te gebruik vir besproeiing. ‘n Hoë sout inhoud (brakwater) soos gemeet deur ‘n hoë elektriese geleidingsvermoë (EC), mag dus ‘n problem wees. Die doel van hierdie studie was om te bepaal hoe Suid Afrikaanse lente koring en gars gedurende ontkieming asook saailing-, vegetatiewe-, reproduktiewe- en rypwordingstadiums reageer teenoor soutstremming wat veroorsaak is deur besproeiing met brakwater. Die studie is uitgevoer in laboratoriums en onder gekontrolleerde glashuistoestande by die Universiteit van Stellenbosch in die Weskaap Provinsie van Suid Afrika. Behandelings in die eerste proef (inkubasie studie) het bestaan uit drie koring kultivars (SST 027, SST 056 en SST 087) en drie gars kultivars (Nemesia, Erica en Hessekwa) wat tydens ontkieming benat is met vyf NaCl-oplossings met EC waardes van 4, 8, 12, 16 en 20 dS m-1 onderskeidelik, asook ‘n kontrole met gedistilleerde water (0 dS m-1). In die tweede proef is die koring kultivar, SST 027 en die gars kultivar SVG 13 in ‘n potproef ook aan bogenoemde oplossings blootgestel maar toegelaat om tot die stoelstadium te ontwikkel. In die derde proef is genoemde twee kultivars besproei met vyf voedingsoplossings met EC-waardes van 1.6, 3, 6, 9 en 12 dS m-1 en toegelaat om tot oesstadium te ontwikkel. ‘n Volledig gebalanseerde voedingsoplossing met EC = 1.6 dS m-1 is as kontrole gebruik en NaCl is by ander oplossings gevoeg om die verlangde EC te verkry. In die eerste proef waar die finale ontkiemingspersentasie (FOP), sout toleransie (ST) en ontkiemingstempo (OT) na 7 dae gemeet is, is gevind dat FOP, ST en OT van al die koring en gars kultivars wat getoets is, met toenemende EC gedaal het. Statisties betekenisvolle afnames in FOP en ST is egter slegs by hoë EC waardes waargeneem. Koring kultivars het vinniger ontkiem as gars kultivars en was geneig om meer tolerant teenooor sout stremming te wees vergeleke met gars. Verskille tussen kultivars van dieselfde spesie was egter weglaatbaar klein. In die tweede proef waar plante toegelaat is om te groei tot die stoelstadium (35 dae na plant) is al die gemete planteienskappe (stingel- en wortellengte, asook vars en droë massas van stingels en wortels) van beide gars kultivar, SVG 13 en koring kultivar, SST 027, betekenisvol verlaag deur ‘n toename in EC van die besproeiingswater. Hoewel gars ten opsigte van die meeste gemete eienskappe groter gemiddeldes as koring getoon het, is weinig bewys gevind wat daarop dui dat die getoetsde gars kultivar SVG 13 meer souttolerant is as die koring kultivar SST 027. In die derde proef waar dieselfde koring en gars kultivars vanaf plant tot oestyd besproei is met genoemde voedingsoplossings en metings tydens stoelstadium (28 dae na plant), stamverlenging (54 dae na plant), blomstadium (71 dae na plant) en oesrypstadium (150 dae na plant) gedoen is, is alle gemete vegetatiewe-, reproduktiewe- en opbrengskomponente van beide spesies verlaag deur die soutstremming. Hoewel gars ook in hierdie proef veral gedurende vroeë groeistadiums groter droë massas as koring geproduseer het, is geen konkrete bewyse gevind wat daarop dui dat die getoetsde Suid Afrikaanse lente gars kultivar SVG 13 meer sout tolerant is as die koring kultivar SST 027.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/97822
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