Thesis (M. A. Agriculture (Plant Protection)) -- University of Limpopo, 2019 / Potato (Solanum tuberosum L.) is highly susceptible to root-knot (Meloidogyne species)
nematodes, with no known nematode resistant genotypes. In Limpopo Province, two
cucurbitacin-containing phytonematicides had been researched and developed. The
active ingredients of the cucurbitacin-containing phytonematicides are cucurbitacins,
which are allelochemicals that could induce phytotoxicity on crops being protected against
nematode damage. The objectives of this study were to determine: (1) mean
concentration stimulation point (MCSP) of Nemarioc-AL phytonematicide on potato
cultivar ꞌMondial G3ꞌ for managing M. javanica and (2) application interval of Nemarioc
AL phytonematicide on potato cultivar ꞌMondial G3ꞌ. Sprouted tubers were planted in 10
cm deep/pot with each pot filled with steam-pasteurised soil and Hygromix at 3:1 (v/v)
ratio in the field under microplot conditions. After 100% emergence (2 weeks), each plant
was inoculated with 5 000 M. javanica eggs and second-stage juveniles (J2). Seven
treatments, namely, 0, 2, 4, 8, 16, 32 and 64% Nemarioc-AL phytonematicide were
arranged in a randomised complete block design, with 11 replications. In Objective 2, four
treatments, namely, 1, 2, 3 and 4 weeks were arranged in randomised complete block
design, with 15 replications. Plant variables and nutrient elements were subjected to the
Curve-fitting Allelochemical Response Data (CARD) model to generate biological indices
used to compute MCSP using the relation MCSP = Dm + Rh/2 and the overall sensitivity
value (∑k). The MCSP for plant variables and nutrient elements, were empirically derived
as 4.31% and 1.33%, with the ∑k of 18 and 4 units, respectively. Nematode variables and
increasing concentrations of Nemarioc-AL phytonematicide exhibited negative quadratic
relations where eggs, J2 in soil and roots and total population (Pf) were optimised at
xv
14.43, 28.23, 23.30 and 13.55%. To conduct Objective 2 which is application interval,
empirically derived MCSP value of 4.31% from Objective 1 was used. Application interval
was optimised using the concept of 1, 2, 3, and 4 weeks in weeks-per-month-of-30-days.
The application interval of 4.31% was established at 2.43 weeks which translated to 18
days [(2.43 weeks/4 weeks) × 30 days]. All nematode variables in Objective 2 were not
significantly different at all intervals. In, conclusion Nemarioc-AL phytonematicide can be
used at 4.31% concentration to control nematodes population densities without being
phytotoxic to crops at 18 days application interval. / National Research Foundation (NRF) ,
Agricultural Research Council (ARC) and the Flemish
Interuniversity Council of Belgium
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ul/oai:ulspace.ul.ac.za:10386/3170 |
| Date | January 2019 |
| Creators | Kobe, Selaelo Patrisia |
| Contributors | Pofu, K. M., Mashela, P. W. |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | xv, 68 leaves |
| Relation | Adobe Acrobat Reader |
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