Thesis (MScAgric.)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Experi!11entsin KwaZulu-Natal showed that seed treatment with molybdenum
(Mo) could double the yield and increase the protein content by 1.9% of
soybeans grown on acidic soils. However, it was also found that soybean yield at
five of the localities was reduced on average by 8% after Mo seed treatment. It
was surmised that the yield reductions observed after Mo seed treatment were
connected to the quality of the seed used for planting. The aim of this project was
to assess the relationship between seed quality and Mo seed treatment and find
a fast, easy quality assessment test that could be used to adapt Mo treatments
according to seed quality.
The first investigation entailed assessing the quality of the seed obtained, from
various seed lots, for planting. A number of different seed quality testing
techniques were performed and they included the accelerated ageing test,
tetrazolium test, conductivity test, standard germination test and an emergence
. test planted at different depths with incubation at different temperatures. All the
test results were compared with the accelerated ageing test results, to find the
test most closely correlated to the accelerated ageing test, which is regarded as
the most accurate indicator of soybean seed vigour. It was found that the
emergence test where the seeds where planted at 10 cm presented a close
correlation with the accelerated ageing test. An assessment of seed quality
revealed that the four different seed lots provided seed of three significantly
different levels of quality, which could be used for further investigations.
The second investigation was concerned with the reaction of the seed of different
quality levels to Mo seed treatment. Firstly, seeds from four different seed lots
were treated with five different concentrations of Mo and planted under acidic
conditions. The establishment was monitored up until six weeks, at which point
the experiment was terminated. In the second planting, seeds from the four
different seed lots were treated with six different concentrations of Mo and planted under optimum pH conditions. Emergence was monitored and after
thinning out the remaining plants were left to mature and produce seed. The
emergence percentage results from both of these two plantings did not reveal the
alleged positive effect Mo seed treatment has produced in the field and no
definite relationship between seed quality and Mo seed treatment was observed.
The third investigation was concerned with the effect that osmoconditioning had
on the reaction of seed to Mo seed treatment. Seeds from two seed lots, one of
very poor quality and the other of good quality, were pre-treated with four
different levels of poly-ethylene glycol (PEG 6000) and then treated with four
concentrations of Mo. They were planted under optimum pH conditions and
establishment was monitored. After being thinned out the remaining plants were
allowed to mature and produce seed. The emergence percentage results
revealed that the PEG pre-treatments greatly improved emergence percentages,
especially in the poor quality seed. There were some positive effects of Mo seed
treatment observed where the lower concentrations of Mo were used, but again,
no definite relationship between seed quality and Mo seed treatment was found.
PEG pre-treatment appeared to help make the seeds more "resistant" to the
harmful effects of Mo. / AFRIKAANSE OPSOMMING: Navorsing in KwaZulu-Natal het aangetoon dat saadbehandeling met molibdeen
(Mo) die opbrengs van sojabone op suurgrond kan verdubbel en die
proteieninhoud met tot 1.9% kan verhoog. Daar is egter ook gevind dat
sojaboonopbrengs op vyf lokaliteite met gemiddeld 8% gedaal het na
saadbehandeling met Mo. "nVermoede bestaan dat die opbrengsverlagings wat
voorgekom het na saadbehandeling met Mo verband hou met die kwaliteit van
saad wat vir die aanplantings gebruik is. Die doel van die projek was om vas te
stel wat die verband tussen saadkwaliteit en Mo saadbehandeling is en om "n
vinnige en maklike toets te vind om saadkwaliteit te bepaal om sodoende Mo
behandelings aan te pas volgens saadkwaliteit.
In die eerste eksperiment is die kwaliteit van verskillende saadlotte wat verkry is,
getoets. "n Aantal verskillende tegnieke om saadkwaliteit te bepaal is uitgevoer.
Die tegnieke was die versnelde verouderingstoets, tetrazoliumtoets,
konduktiwiteitstoets, standaard ontkiemingstoets en "n vestigingstoets waar saad
op verskillende dieptes geplant en by verskillende temperature geïnkubeer is.
Die resultate van die verskillende toetse is gekorreleer met die resultate van die
versnelde verouderingstoets, wat beskou word as die toets wat die beste
aanduiding gee van saadgroeikragtigheid. Daar is gevind dat sade wat 10 cm
diep in sand geplant is, se opkoms die beste korrelasie met die versnelde
verouderingstoets toon en dus as "n goeie aanduiding van die kwaliteit van saad
beskou kan word. Daar is gevind dat daar drie saadlotte is met duidelike
kwaliteitsverskille wat gebruik kon word in verdere eksperimente.
Die tweede eksperiment het die reaksie van saad van verskillende
kwaliteitsvlakke teenoor molibdeen saadbehandeling ondersoek. Eerstens is
saad van vier verskillende saadlotte behandel met vyf verskillende konsentrasies
Mo en onder baie suur toestande geplant. Die vestiging is gemonitor vir ses
weke waarna die eksperiment gestaak is. Daarna is saad van dieselfde vier saadlotte behandel met ses verskillende Mo konsentrasies en onder optimum pH
toestande geplant. Vestiging is gemonitor en na ses weke is die plante uitgedun
en twee plante per pot is gelaat om saad te produseer. Die
~
vestigingspersentasie van beide die eerste en tweede plantings het nie die
verwagte positiewe effek teenoor Mo saadbehandeling getoon nie en geen
betekenisvolle verwantskap tussen saadkwaliteit en Mo saadbehandeling kon
waargeneem word nie.
Die derde eksperiment het die invloed van osmokondisionering op die reaksie
van saad op Mo saadbehandeling ondersoek. Saad van twee saadlotte, een van
goeie kwaliteit en een van swak kwaliteit, is voorafbehandel met poli-etileen glikol
(PEG 6000) en daarna met vier konsentrasies van Mo behandel. Die sade is
onder optimum pH toestande geplant en die vestiging is gemonitor. Nadat dit
uitgedun is, is die oorblywende twee plante gelaat om saad te produseer. Die
vestigingspersentasies het getoon dat PEG voorafbehandelings vestiging
betekenisvol verbeter, veral in die geval van lae kwaliteit saad. Daar was 'n
. positiewe effek van Mo saadbehandeling waar relatief lae konsentrasies
molibdeen toegedien is, maar daar kon weereens nie 'n duidelike verwantskap
tussen saadkwaliteit en Mo saadbehandeling waargeneem word nie. Dit blyk dat
PEG voorafbehandeling die sade meer bestand teen die skadelike invloed van
Mo gemaak het.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52010 |
| Date | 12 1900 |
| Creators | Bilbe, Sara Ann |
| Contributors | Pieterse, P. J., Stellenbosch University. Faculty of AgriSciences. Dept. of Agronomy. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 62 p. : ill. |
| Rights | Stellenbosch University |
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