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Under storage conditions of ambient temperature and relative humidity in South Africa, seed-associated mycoflora proliferates. Fusarium moniliforme is ubiquitous in newly-harvested maize, persisting for variable periods in storage, while Aspergillus flavus may represent the final group of species in the succession of aspergilli after grain storage under high temperature and/or high humidity. Many strains of these fungi produce toxigenic secondary metabolites (mycotoxins) under local storage conditions. Since pathogenic fungi may be present within the tissues of stored seeds, these contaminants will not be eradicated by external fungicide treatment, therefore a possible alternative is biological control. The aim of the present investigation was to ascertain whether certain strains and/or species of Trichoderma have potential as biocontrol agents against the seed-associated pathogenic fungi, Aspergillus flavus and Fusarium moniliforme. A study of the fungal growth in dual cultures revealed that from nine isolates of Trichoderma spp. (T harzianum and T viride), four had a noticeable inhibitory effect on the growth of the pathogenic fungi. Scanning electron microscopical investigation of fungal interaction demonstrated no obvious hyphal penetration by - Trichoderma spp. In addition, significant alteration of Fusarium hyphae, with pronounced collapse and loss of turgor, and production of aberrant conidial heads and microheads by A. flavus were observed. Evidence derived from some biochemical studies revealed that antibiosis (by production of extracellular enzymes, volatile compounds and possible antibiotics) is probably the mechanism involved in the antagonistic effect of the four aggressive Trichoderma spp. The in vitro studies demonstrated that the use of Trichoderma spp. as biocontrol agents against A. flavus and F. moniliforme appears promising. / Thesis (M.Sc.)-University of Natal, 1995.

ABSTRACT The aim of this work was to produce enzymatic hemp seed protein hydrolysates (HPH) followed by bioassay guided fractionation to identify antioxidant and antihypertensive peptides. Therefore, simulated gastrointestinal digestion of isolated hemp seed proteins was conducted using consecutive actions of pepsin and pancreatin to produce HPH, which was then separated by membrane ultrafiltration to obtain peptide sizes of <1, 1-3, 3-5, and 5-10 kDa. Evaluation of HPH and its membrane fractions for antioxidant and antihypertensive properties showed that they significantly (P<0.05) scavenged radicals, reduced and strongly chelated metal ions as well as inhibited lipid oxidation. During a 24-hr test, the HPH reduced systolic blood pressure (SBP) of spontaneously hypertensive rats (SHR) after oral administration by a maximum of -30 mmHg when compared to -15 mmHg for the membrane fractions. To reduce production cost, hemp seed protein meal (HPM) was directly hydrolyzed to a protein hydrolysate (HMH) and was shown to also reduce SBP during 4-8 weeks of dietary feeding. The attenuation of SBP correlated to suppressed plasma levels (0.047-0.059 U/mL and 0.040-0.054 µg/mL) of angiotensin converting enzyme (ACE) and renin, respectively, when compared to the control rats (0.123 U/mL and 0.151 µg/mL). A total of 23 peptides were identified to be present in the HPH. WVYY and PSLPA showed superior in vitro antioxidant properties, while ACE activity was inhibited by WYT (89%), WVYY (91%) and PSLPA (90%). Renin activity was inhibited by WYT (77%), SVYT (87%) and IPAGV (75%). However, oral administration to SHR showed that the pentapeptides (PSLPA and IPAGV) were more effective SBP-reducing agents (-40 mm Hg) when compared to the tri- (-13 mmHg) and tetrapeptides (-36 mmHg). These results show for the first time in literature, the bioactive properties of hemp seed peptides and indicate their potential use as ingredients to formulate antioxidant and antihypertensive functional foods and nutraceuticals.

In this study, pollen contamination (measured by the number of seeds pollinated by pollen not belonging to any of the clones on the seed orchard) is compared between open pollination and isolated pollination environments in a Scots pine (Pinus sylvestris) seed orchard called Västerhus, located outside Önsköldsvik. In this seed orchard a tent experiment is taking place. Skogforsk has built six large tents covering 12-14 trees with each tent. Fertilization patterns were compared between one tree in a tent with a supplementation of pollen from five clones not represented in the tent and another tree of the same clone subject to open pollination outside the tents. By using DNA markers the paternity was determined for 48 seeds from each tree. The results show a big difference in pollen contamination between the two trees. The tree inside the tent showed a contamination rate of 0% and the tree from the open pollination had a contamination rate of 20,5%. No difference was found in the numbers of different fathers although the selfing rate of 4,26% was higher in the tent than the selfing rate of 2,56% observed in the open pollination environment. These results match the results of other studies done on the same orchard pretty well and therefore tent isolation with a supplementary pollination can be a good way to reduce unwanted pollen contamination.

In this study, pollen contamination (measured by the number of seeds pollinated by pollen not belonging to any of the clones on the seed orchard) is compared between open pollination and isolated pollination environments in a Scots pine (Pinus sylvestris) seed orchard called Västerhus, located outside Önsköldsvik. In this seed orchard a tent experiment is taking place. Skogforsk has built six large tents covering 12-14 trees with each tent. Fertilization patterns were compared between one tree in a tent with a supplementation of pollen from five clones not represented in the tent and another tree of the same clone subject to open pollination outside the tents. By using DNA markers the paternity was determined for 48 seeds from each tree. The results show a big difference in pollen contamination between the two trees. The tree inside the tent showed a contamination rate of 0% and the tree from the open pollination had a contamination rate of 20,5%. No difference was found in the numbers of different fathers although the selfing rate of 4,26% was higher in the tent than the selfing rate of 2,56% observed in the open pollination environment. These results match the results of other studies done on the same orchard pretty well and therefore tent isolation with a supplementary pollination can be a good way to reduce unwanted pollen contamination.

Inconsistent seed germination poses a problem for efficient seedling production of Echinacea species. Evidence suggests that ethylene can be effective for improving germination in Echinacea species. The objectives of this research were: to develop an ethylene pre-germination treatment that enhances germination in Echinacea species that is retained following drying and storage, and to determine if the ethylene effect on enhanced germination was an important mode of action for dormancy release. Four species of Echinacea (E. purpurea, E. tennesseensis, E. angustifolia and E. simulata) treated with 1-aminocyclopropane-1-carboxylic acid (ACC) or ethephon resulted in faster and generally higher germination. Pre-treatment of seeds with ACC or ethephon followed by drying was as effective as chilling stratification for enhancing germination depending on the species. While ethylene pretreatments did increase germination to some extent depending on species, it was concluded that 60-day stratification alone was a more commercially-viable treatment. Ethylene production or perception was not necessary for germination in untreated or stratified seeds as shown by aminoethoxyvinylglycine (AVG), silver thiosulfate (STS), and 1-methylcyclopropene (MCP) treatments. Both stratification and ACC treatment reduced Echinacea seed sensitivity to ABA and could be a common mechanism for enhanced germination. However, it does not appear that the increased germination seen after stratification was mediated through ethylene production because final germination percentages were generally unchanged following inhibition of ethylene production or action. In contrast, inhibition of ethylene production and perception reduced early 3-day germination suggesting that ethylene was more involved in seed vigor than final germination. It was determined that there is no physiological significance of ethylene for dormancy release in these Echinacea species.

Research objective. The study was aimed to establish development and distribution patterns of cabbage stem weevil (Ceutorhynchus pallidactylus), cabbage seed weevil (C. obstrictus) and Brassica pod midge (Dasineura brassicae) in winter and spring oilseed rape crops, to estimate insect damage, to compare the efficacy of insecticides of different mode of action and to determine the optimal timing of insecticide application. Research tasks. 1. To determine species abundance and diversity of Ceutorhynchus spp. infesting oilseed rape crops. 2. To study cabbage stem weevil’s (C. pallidactylus) biology (migration activity of adult insects, embryonic and post-embryonic development) in winter and spring oilseed rape crops and to estimate insect injury. 3. To establish the patterns of distribution of adults of cabbage seed weevil (C. obstrictus) as well as those of embryonic and post-embryonic development in winter and spring oilseed rape crops and to estimate insect injury. 4. To explore the biology of Brassica pod midge (Dasineura brassicae), to identify distribution and development peculiarities and damage done to winter and spring oilseed rape. 5. To determine biological and economic efficacy and optimal application timing of insecticides of different mode of action against stem (C. pallidactylus) and pod (C. obstrictus and D. brassicae) insect pests in winter and spring oilseed rape. / Tyrimų tikslas. Nustatyti kopūstinių stiebinių paslėptastraublių (Ceutorhynchus pallidactylus), ankštarinių paslėptastraublių (C. obstrictus) ir ankštarinių gumbauodžių (Dasineura brassicae) plitimo ir vystymosi ypatumus žieminiuose ir vasariniuose rapsuose bei žalingumą, palyginti skirtingo poveikio insekticidų efektyvumą ir nustatyti optimalų insekticidų naudojimo laiką nuo šių kenkėjų. Tyrimų uždaviniai. 1. Nustatyti žieminių ir vasarinių rapsų pasėliuose plintančių paslėptastraublių (Ceutorhynchus spp.) rūšių gausumą ir įvairovę. 2. Ištirti kopūstinių stiebinių paslėptastraublių (C. pallidactylus) biologiją (suaugėlių migracijos aktyvumą, embrioninį ir poembrioninį vystymąsi) žieminiuose ir vasariniuose rapsuose, įvertinti šių kenkėjų žalingumą. 3. Nustatyti ankštarinių paslėptastraublių (C. obstrictus) suaugėlių paplitimo, embrioninio ir poembrioninio vystymosi ypatumus žieminiuose ir vasariniuose rapsuose bei jų žalingumą. 4. Ištirti ankštarinių gumbauodžių (Dasineura brassicae) biologiją, nustatyti jų žalingumą bei vystymosi ypatumus žieminiuose ir vasariniuose rapsuose. 5. Nustatyti skirtingo poveikio insekticidų biologinį ir ūkinį efektyvumą ir optimalų jų naudojimo laiką nuo stiebų (C. pallidactylus) ir ankštarų kenkėjų (C. obstrictus ir D. brassicae) žieminiuose ir vasariniuose rapsuose.

ABSTRACT The aim of this work was to produce enzymatic hemp seed protein hydrolysates (HPH) followed by bioassay guided fractionation to identify antioxidant and antihypertensive peptides. Therefore, simulated gastrointestinal digestion of isolated hemp seed proteins was conducted using consecutive actions of pepsin and pancreatin to produce HPH, which was then separated by membrane ultrafiltration to obtain peptide sizes of <1, 1-3, 3-5, and 5-10 kDa. Evaluation of HPH and its membrane fractions for antioxidant and antihypertensive properties showed that they significantly (P<0.05) scavenged radicals, reduced and strongly chelated metal ions as well as inhibited lipid oxidation. During a 24-hr test, the HPH reduced systolic blood pressure (SBP) of spontaneously hypertensive rats (SHR) after oral administration by a maximum of -30 mmHg when compared to -15 mmHg for the membrane fractions. To reduce production cost, hemp seed protein meal (HPM) was directly hydrolyzed to a protein hydrolysate (HMH) and was shown to also reduce SBP during 4-8 weeks of dietary feeding. The attenuation of SBP correlated to suppressed plasma levels (0.047-0.059 U/mL and 0.040-0.054 µg/mL) of angiotensin converting enzyme (ACE) and renin, respectively, when compared to the control rats (0.123 U/mL and 0.151 µg/mL). A total of 23 peptides were identified to be present in the HPH. WVYY and PSLPA showed superior in vitro antioxidant properties, while ACE activity was inhibited by WYT (89%), WVYY (91%) and PSLPA (90%). Renin activity was inhibited by WYT (77%), SVYT (87%) and IPAGV (75%). However, oral administration to SHR showed that the pentapeptides (PSLPA and IPAGV) were more effective SBP-reducing agents (-40 mm Hg) when compared to the tri- (-13 mmHg) and tetrapeptides (-36 mmHg). These results show for the first time in literature, the bioactive properties of hemp seed peptides and indicate their potential use as ingredients to formulate antioxidant and antihypertensive functional foods and nutraceuticals.

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