Thesis (M. Agricultural Management (Animal Production)) -- University of Limpopo, 2016 / Cultivated potato (Solanum tuberosum L.) cultigens do not have resistant genotypes
to root-knot (Meloidogyne species) nematodes. Currently, efforts are underway to
introgress nematode resistance in potato breeding programmes, whereas other
environment-friendly nematode management strategies are being assessed in
various cultigens. Nemafric-BL and Nemarioc-AL phytonematicides have being
researched and developed for managing the root-knot nematode whereas Biocult
Mycorrhizae are intended to enhance crop productivity through improved absorption
of P, which is inherently low in most South African soils. The objectives of the study,
therefore, were: (1) to determine the interactive effects of Nemacur (N), Biocult
Mycorrhizae (B) and Nemarioc-AL or Nemafric-BL phytonematicide (P) on population
densities of M. javanica and growth of potato plants, (2) to investigate the effects of
Nemacur (N), Velum (V), Biocult Mycorhizae (B) and Nemarioc-AL or Nemafric-BL
phytonematicide (P) on population densities of M. javanica and growth of potato
plants. For the microplot experiment, potato cv. ‘Mondial G3’ seeds were sown in 25
cm-diameter plastic pots with 5 000 ml steam-pasteurised river sand and Hygromix-T
at 3:1 (v/v) growing mixture in autumn (March-May) 2015. Pots were buried 80%
deep into the soil in with 0.5 m inter-row and 0.5 m intra-row spacing. Potato cv.
‘Mondial G3’ seeds were dipped in a mixture of Mancozeb with a wettener for
disease management prior to sowing. Appropriate treatments were applied soon
after emergence of leaves. Each plant was inoculated by dispensing a mixture of 5
000 eggs and M. javanica J2. Eight treatments, control (N0B0P0), Nemacur (N1B0P0),
Biocult (N0B1P0), phytonematicide (N0B0P1), Nemacur × Biocult (N1B1P0), Nemacur ×
phytonematicide (N1B0P1), Biocult × phytonematicide (N0B1P1) and Nemacur ×
Biocult × phytonematicide (N1B1P1), were arranged in a randomised complete block
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design (RCBD) with 8 replications (n= 64). Under field conditions the study was
conducted in summer (October 2015 - January 2016), with 30-cm furrows dug and
potato seeds placed in the soil with 30 cm inter-row and 40 cm intra-row spacing.
The four treatments, namely, (1) untreated control, (2) Nemacur or Velum (3) Biocult
Mycorrhizae and (4) Nemarioc-AL or Nemafric-BL phytonematicide, were arranged
in RCBD, replicated three times for the Velum experiment and five times for the
Nemacur experiment. At 56 days after inoculation, the second order interaction
(N1B1P1) was highly significant (P ≤ 0.01) for eggs in root and total nematodes,
contributing 13 and 12% to total treatment variation (TTV) of the two variables,
respectively, in the Nemarioc-AL phytonematicide study. Relative to untreated
control, the second order interaction (N1B1P1) reduced eggs in root and total
nematodes by 42 and 36%, respectively. In both Nemarioc-AL and Nemafric-BL
phytonematicide experiments, the combination of phytonematicide and Biocult
Mycorrhizae reduced gall rating. Nemacur, Biocult and Nemarioc-AL
phytonematicide, the treatment effects were highly significant on eggs, J2 in root and
total nematodes, contributing 53, 68 and 57% to TTV of the three variables,
respectively. Nemacur, Biocult and Nemafric-BL phytonematicide treatments each
was not significant (P ≤ 0.05) for nematodes variables. Both treatments for Nemacur,
Biocult and Nemarioc-AL or Nemafric-BL phytonematicides were significant for gall
rating, contributing 92 and 70% to TTV of the variable, respectively. In Nemarioc-AL
phytonematicide, relative to the untreated control, gall rating was reduced by 48 to
56%, whereas in Nemafric-BL phytonematicide the variable was reduced by 33 to
56%. In the Velum study, Biocult and Nemarioc-AL or Nemafric-BL phytonematicide,
the treatment effects in both experiments were highly significant (P ≤ 0.01) on eggs
in root, contributing 88% to TTV of the variable. Both treatments from Nemarioc-AL
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and Nemafric-BL phytonematicides had no significant effects on all plant variables
measured. In microplot, the second order interaction (Nemacur × Biocult ×
Nemarioc-AL phytonematicide) was highly significant for nematode eggs in root and
total nematode. In a three-way matrix, the N1B1P1 interaction had the highest effects
on eggs, followed by Biocult alone, then Nemacur alone and then the
phytonematicide. The same trend was observed in the three-way matrix for total
nematodes. However, in two-way matrix for eggs, Biocult outperformed Nemacur, as
was the phytonematicide on J2. In another microplot study, the second order
interaction (Nemacur × Biocult × Nemafric-BL phytonematicide) was significant for J2
in soil and roots, with the three-way matrix showing, that Biocult alone had higher
effects than the N1B1P1 interaction on J2 in root. A three-way matrix also showed that
Nemacur was outperformed by the phytonematicide alone, Biocult alone and the
interactions on J2 in soil. In conclusion, Nemarioc-AL and Nemafric-BL
phytonematicides could each be used with Biocult Mycorrhizae in the management
of population densities of M. javanica in potato production since the impact from
Nemacur which is a synthetic nematicide does not have that much difference from
that of phytonematicides interacted with Biocult Mycorrhizae. / Agricultural Research Council
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ul/oai:ulspace.ul.ac.za:10386/2003 |
| Date | January 2016 |
| Creators | Seshweni, Mosima Dorcus |
| Contributors | Pofu, K. M., Mashela, P. W. |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | xxvii, 110 leaves |
| Relation | Adobe Acrobat Reader |
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