Browsing by Author "Sofkova-Bobcheva S"
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- ItemCharacterization of the Volatile Profiles of Six Industrial Hemp (Cannabis sativa L.) Cultivars(American Society of Agronomy, 2022-10-27) Sofkova-Bobcheva SVolatile organic compounds (VOCs) play an important role in plant ecology and can be useful in pest management. This work characterises, for the first time, the VOC emissions of six industrial hemp (Cannabis sativa L.) cultivars grown in New Zealand: CFX-2, CRS-1, Ferimon 12, Katani, Futura 75, and Finola. Volatiles emitted from flowers and foliage of eight-week-old plants were collected using a dynamic headspace sampling method and analysed using gas chromatography coupled to mass spectrometry. We assessed the effect of cultivar, sex (monoecious, male, and female), and site (i.e., two sites differing in soil types, maintained under irrigation and rain-fed conditions) on VOC emissions. Thirty-five volatile compounds were tentatively identified from the headspace samples of hemp plants, but none of the cultivars emitted all 35 compounds. β-Myrcene was the most abundant compound in most cultivars. Overall, there was a significant effect of sex, and the interaction of sex and cultivar on the volatile profiles, but no effect of site. Female plants typically emitted more volatiles than their male counterparts and monoecious cultivars. The main compounds driving the difference between cultivars and sexes were (Z)- and (E)-β-ocimene. We hypothesize that differences in emission emerged as a defence strategy to protect costly female flowers from herbivores (since C. sativa is wind pollinated), but this hypothesis needs further testing. We recommend additional studies exploring how biotic and abiotic factors influence hemp VOC emissions, changes in VOCs throughout the crop cycle, the role of VOCs in plant-insect interactions and their use in pest management.
- ItemInfluence of water loss on mechanical properties of stored blueberries(Elsevier, 2021-02-27) Rivera S; Kerckhoffs H; Sofkova-Bobcheva S; Hutchins D; East AMoisture loss is considered a main cause of blueberry softening during postharvest storage. However, the causal relationship between softening and water loss has only previously been described by force to 1 mm compression. This study was performed to identify suitable instrumental tests that allow the separation of blueberries with different water loss values during storage. Mechanical properties were measured by double compression (Texture Profile Analysis) and puncture test. Variability on blueberry mechanical properties was created by regulating storage humidity and consequently water loss. As water loss increases during storage, hardness slope (slope of a straight line drawn between the trigger force of 0.06 N and the force at 15 % strain) obtained by the compression test reduces, and the displacement at berry skin break obtained by puncture test, increases. Therefore, these parameters can be potentially used to quantify mechanical changes in stored blueberries.
- ItemMoringa oleifera L.: A Potential Plant for Greenhouse Gas Mitigation in Temperate Agriculture Systems(Versita, 2022-07-28) Sofkova-Bobcheva SThe earth’s climate is changing because of the increase in greenhouse gas (GHG) concentration, to which livestock is a major contributor. Methane produced from cattle can be reduced by using high quality forages. This study compared the GHG produced from M. oleifera in an artificial ruminant system with two high quality pasture species, ryegrass and white clover. Methane and total gas production were measured using an in vitro batch culture system. A preliminary screening using oven dried M. oleifera planted in field and greenhouse, and a main experiment using six provenances of M. oleifera, a composite sample and M. oleifera leaves from greenhouse was undertaken. Both experiments compared the M. oleifera from different sources with high quality ryegrass and white clover. Real time gas production was recorded for 48 h, total gas production, methane analysed at 12 and 24 h. Short chain fatty acids concentration were also determined at the end of the fermentation. Preliminary results showed that M. oleifera leaves grown in field and greenhouse have lower gas and methane production compared with ryegrass, but similar to white clover. The differences were driven by a high production of propionic and butyric acids. The six M. oleifera provenances also produced less methane than ryegrass but were similar to white clover at 12 and 24 h after the start of fermentation. M. oleifera fermented faster than ryegrass or white clover. Hydrogen production from fermentation of M. oleifera might not have been diverted to methane production but removed by other compounds. In vitro fermentation showed differences in methane production across provenances. This suggests that it may be possible to select for low methane genotypes.
- ItemYield and tuber quality variability in commercial potato cultivars under abiotic stress in New Zealand.(2018) Siano A; Kerckhoffs LHJ; Roskruge N; Sofkova-Bobcheva S