Thesis(M.Sc.( Agriculture, Horticulture)) -- University of Limpopo, 2019 / Worldwide, tomato (Solanum lycopersicum L.) is one of the most important crops grown
for nutritional value and health benefits, and are highly susceptible to root-knot
(Meloidogyne species) nematodes. Following the withdrawal of synthetic chemical
nematicides, Nemarioc-AL and Nemafric-BL phytonematicides have been researched
and developed as alternatives to synthetic chemical nematicides. However, Nemarioc-AL
and Nemafric-BL phytonematicides contains allelochemicals namely, cucurbitacin A
(C32H46O9) and cucurbitacin B (C32H46O8) as their active ingredients. Therefore, the
objective of this study was to determine whether increasing concentration of Nemarioc
AL and Nemafric-BL phytonematicides would result in cucurbitacin residues in tomato
plant, to generate mean concentration stimulation point (MCSP) values, overall sensitivity
(∑k) and selected foliar mineral elements of tomato plant. Two parallel trials of Nemarioc
AL and Nemafric-BL phytonematicides were conducted under field conditions, with each
validated the next season. Each trial had seven treatments, namely, 0, 2, 4, 8, 16, 32 and
64% of Nemarioc-AL or Nemafric-BL phytonematicide concentrations, arranged in a
randomised complete block design (RCBD), with five replications. In each trial, the
seasonal interaction on variables was not significant and therefore data were pooled
across the two seasons (n = 70). In both phytonematicides, the cucurbitacin residues
were not detected in soil and tomato fruit. Plant variables and selected foliar nutrient
elements were subjected to the Curve-fitting Allelochemical Response Data (CARD)
model to generate biological indices which allowed for the calculation of MCSP of
phytonematicides on tomato and their ∑k values of tomato to Nemarioc-AL and Nemafric
BL phytonematicides. In Nemarioc-AL phytonematicide experiment, MCSP for tomato plant variables was at 1.13%, with the ∑k of 60 units, while the MCSP for selected tomato
nutrient elements in leaf tissues was at 2.49%, with the ∑k of 21 units. Plant height,
chlorophyll content, stem diameter, number of fruit, dry fruit mass, dry shoot mass and
dry root mass each with increasing concentration of Nemarioc-AL phytonematicide
exhibited positive quadratic relations with a model explained by 95, 82, 96, 89, 83, 83 and
92%, respectively. Similarly, K, Na and Zn each with increasing Nemarioc-AL
phytonematicide concentration exhibited positive quadratic relations with a model
explaining a strong relationship by 91, 96 and 89%. In Nemafric-BL phytonematicide
experiment, MSCP for tomato plant variables was at 1.75%, with the ∑k of 45 units,
whereas MCSP for selected tomato nutrient elements in leaf tissues was at 3.72% with
the ∑k of 33 units. Plant height, chlorophyll content, stem diameter, number of fruit, dry
fruit mass, dry shoot mass and dry root mass and increasing Nemafric-BL
phytonematicide concentration exhibited positive quadratic relations with the model
explaining a strong relationship by 92, 83, 97, 96, 87, 94 and 96%. Likewise, Na and Zn
each with increasing Nemafric-BL phytonematicide concentration exhibited positive
quadratic relations with a model explaining their relationship by 93 and 83%, respectively.
In contrast, K with increasing Nemafric-BL phytonematicide concentration exhibited
negative quadratic relations with a model explaining the relationship by 96%. In
conclusion, tomato plant variables and selected foliar nutrient elements over increasing
concentration of phytonematicides exhibited DDG patterns, characterised by three
phases, namely, stimulation, neutral and inhibition. The developed non-phytotoxic
concentration would be suitable for successful tomato production under field conditions.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ul/oai:ulspace.ul.ac.za:10386/3157 |
| Date | January 2019 |
| Creators | Bango, Happy |
| Contributors | Shadung, K. G., Mashela, P. W. |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | xiv, 64 leaves |
| Relation |
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