The agricultural use of bio-stimulants to increase crop yield is increasing as a result of the
ever growing human population. Since bio-stimulants do not have the negative environmental
effects usually associated with fungicides and pesticides, the identification and testing of new
bio-stimulants are a priority. It was previously shown that treatment of wheat cultivar PAN
3377 with a crude Lupinus albus L. seed suspension extract increased the yield compared to
an untreated control.
The agricultural use of bio-stimulants to increase crop yield is increasing as a result of the
ever growing human population. Since bio-stimulants do not have the negative environmental
effects usually associated with fungicides and pesticides, the identification and testing of new
bio-stimulants are a priority. It was previously shown that treatment of wheat cultivar PAN
3377 with a crude Lupinus albus L. seed suspension extract increased the yield compared to
an untreated control.
During the current study, the bio-stimulatory effect of a 60% purified extract called SS was
investigated. The initial aim was to analyse the effect of the purified SS extract on yield of
the wheat cultivar Thatcher+Lr34. No significant increases in yield or any of the associated
parameters were obtained in response to SS treatment. This indicated that, while the crude
and complex SS extract increased yield in wheat, the purified molecule was unable to do it.
To validate the glass house results, proteomic analysis of SS treated wheat cultivar
Thatcher+Lr34 was done. Results indicated that the purified SS extract mainly targets the
photosynthetic machinery of the plant by altering three main pathways. While the levels of
polypeptides active in both the Calvin cycle and electron transport chain were generally
down-regulated following treatment, a few polypeptides involved in the PSII and general
repair mechanisms, were up-regulated. These results were validated by qPCR analysis of
three randomly selected genes from each of the mentioned pathways. When wheat cultivar Tugela was treated with the 60% pure SS extract and exposed to heat
stress, a stabilising effect on chloroplast ultrastructure was observed. Thylakoid membranes
were intact and no induction of the membrane stabilising gene OEE2 was observed.
However, when infected with RWA, the 60% pure SS extract was unable to facilitate
chloroplast membrane stabilisation. This was supported by the induced expression of both the
OEE2 and HCF136 genes.
This study concludes that the 60% pure SS extract, of which glycerol trilinoleate is the active
ingredient, cannot be used as a bio-stimulant independently. It is proposed that during the
purification of the crude SS extract, additional components responsible for increasing yield in
wheat, was lost and thereby its ability to increase yield. This product could however be of
value when used in combination with other compounds that is able to facilitate yield
increases.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-08212014-141230 |
| Date | 21 August 2014 |
| Creators | Viljoen, Riana |
| Contributors | Prof JC Pretorius, Dr B Visser |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-08212014-141230/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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