Lythrum salicaria is an invasive plant in North America. The study is focused on carbohydrate reserves (especially starch) in below-ground plant organs of the named species. These energy sources are considered as possible contributors of invasive behaviour both in short and long time periods. Another question is whether these storages can be influenced by other factors. These ideas were tested in common garden experiments.

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Please read the abstract in the section 00front of this document / Dissertation (MSc (Agric) Horticultural Science)--University of Pretoria, 2005. / Plant Production and Soil Science / unrestricted

Thesis (PhD(Agric))--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Water scarcity is a key limiting factor for viticulture in dry regions. Traditionally drought sensitive varieties have the potential to grow in dry areas, however in most situations, through the use of rootstocks. Drought-tolerant rootstocks are expected to improve grapevine response to water deficit by improving the water uptake and transport and by reducing the water loss in leaves by root-to-shoot signalling. The mechanisms of rootstocks’ tolerance to drought are not yet fully understood. The main aim of this study was to improve the understanding of the rootstock/scion-cultivar interaction in the regulation of grapevine water use and leaf stomatal behaviour. Irrigated field vines without any water constraint were compared to rain-fed grapevines subjected to moderate water constraint. To better manage vine water status, reduce variability, and compare more rootstocks, greenhouse trials were also conducted where plants were well watered or subjected to severe water constraints. Pinotage grapevines (Vitis vinifera L.) grafted onto 110 Richter, 140 Ruggeri and 1103 Paulsen rootstocks were used for field experiments whereas Pinotage grapevines grafted onto 99 Richter, 110 Richter, 140 Ruggeri, 1103 Paulsen and Ramsey were used for greenhouse experiments. Our study suggested the influence of rootstocks on scion-cultivar water status and leaf stomatal size and density and gas exchange of the scion, implying an influence on water uptake and transport and a tight regulation of the stomatal conductance. Our data supported the hypothesis that the influence of rootstock in response to drought seemed to be higher under increasing water deficit up to a point where the plant water status is the main driver of the stomatal conductance and therefore photosynthesis regulation, considering the plant water status thresholds. In addition, the results suggested that stomatal development is affected by light, drought and possibly by rootstocks. Nevertheless, it is still not clear how the rootstock affects stomatal development and the link with scion-cultivar water use. It seems that the transpiration rate of leaves is more related to stomatal size than density. Thus one possible mechanism of Pinotage leaf adaptation to water constraints was structural during leaf growth, with a reduction in pore size to reduce plant water loss. The results showed that the rootstock is regulating the cultivar's stomatal size (anatomical changes during leaf growth) and functioning (stomatal regulation) through a complex signalling process. The effect of light on stomatal development is interesting in the context of canopy microclimate and canopy manipulation (choice of the vine architecture vs canopy size, in the context of climate change versus the possible increase in drought and water scarcity). The use of rootstocks is a long term investment which aims to provide resistance to soil pests and pathogens and to confer to the scion-cultivar drought and salt tolerance. The use of drought tolerant rootstocks is actually one of the most relevant practical solutions in dry terroir – units and in situations where water availability is limited. The understanding of the physiological and genetic mechanisms which govern scion-cultivar drought tolerance/behaviour induced by rootstocks is critical in terms of rootstocks choice in interaction with the scion-cultivar and is critical to assist breeding programs to create/select drought tolerant rootstocks.

Spring shock syndrome (SSS) is a condition where flowering and leaf development in peach and nectarine trees is delayed and those leaves that do develop are often small and discoloured. Trees experiencing spring shock syndrome yield poorly. To learn more about the development of this syndrome, this thesis has examined the influence of root zone temperature (RZT) and genotype on the growth of peach rootstocks and the scions grafted onto them. Other factors that influence the quality of peach seedling rootstocks were also examined. Initial trials examined the influence of Okinawa (a low chill cultivar) and Golden Queen (a high chill cultivar)rootstocks on the expression of SSS. Studies found that multiple stems could originate from either multiple seeds within a single stone or from axils originating from the base of cotyledons. The incidence of both conditions was heavily influenced by variety, thus suggesting that an active selection program based on the elimination of these traits would be beneficial to the stone fruit nursery industry. / Doctor of Philosophy (PhD)

S'avaluaren 58 soques de Pseudomonas fluorescens i Pantoea agglomerans per la seva eficàcia en el biocontrol de la malaltia causada per l'oomicet Phytophthora cactorum en maduixera i pel nematode formador de gal·les Meloidogyne javanica en el portaempelt GF-677.Es desenvolupà un mètode ex vivo d'inoculació de fulla amb l'objectiu de seleccionar soques bacterianes com a agents de control biològic de P. cactorum en maduixera. Tres soques de P. fluorescens es seleccionaren com a soques eficaces en el biocontrol del patogen en fulles i en la reducció de la malaltia en plantes de maduixera. La combinació de soques semblà millorar la consistència del biocontrol en comparació amb les soques aplicades individualment.Tres soques de P. fluorescens es seleccionaren per la seva eficàcia en la reducció de la infecció de M. javanica en portaempelts GF-677. La combinació d'aquestes soques no incrementà l'eficàcia del biocontrol, però semblà reduir la seva variabilitat. / 58 Pseudomonas fluorescens and Pantoea agglomerans strains were evaluated for their biocontrol efficacy against the oomycete Phytophthora cactorum in strawberry and the root-knot nematode Meloidogyne javanica in GF-677 rootstocks.An ex vivo detached leaf inoculation method was developed to select bacterial strains as biological control agents of P. cactorum in strawberry. Three P. fluorescens strains were selected as effective in biocontrol of the pathogens on leaves and in disease reduction in strawberry plants. Combination of strains improved biocontrol consistency compared to strains applied individually. Three P. fluorescens strains were selected for their efficacy in M. javanica infection reduction in GF-677 rootstocks. Combination of these strains did not increase biocontrol efficacy, but reduced its variability.

Thesis (MScAgric (Horticulture))--University of Stellenbosch, 2007. / Most nectarine orchards in South Africa are currently planted at a distance of 4 x 1.5 m (2 500 trees/ha). These trees are mainly sylleptically trained to a central leader, although many producers also use the proleptic route. The former produces relatively high yields early in the lifetime of the orchard. A problem with nectarine production in South Africa is the lack of efficient rootstocks in terms of aspects such as size-control and the use of nematode-resistant rootstocks. The aim of this study is to evaluate different training systems for nectarine production and to investigate the role of three rootstocks that play a dominant role in the peach industry in South Africa. ‘Alpine’ nectarines were planted in the winter of 2002 at Lushof near Ceres, Western Cape, South Africa (33º18’S, 19º20’E). The trees were trained according to four different training systems: a four-leader system (5 x 3 m; 667 trees/ha), a two-leader system (5 x 1.5 m; 1 333 trees/ha), a proleptically trained central leader (5 x 1 m; 2 000 trees/ha), and a sylleptically trained central leader (5 x 1 m; 2 000 trees/ha). The trees were planted on three different rootstocks: GF 667; SAPO 778; Kakamas seedling. The time spent per tree on pruning, thinning and picking was recorded. During harvest, the number of fruit and fruit mass per tree were recorded. Light measurements were recorded annually after summer pruning. The measurements were taken at different heights and at different depths in the canopy. To compare the training systems on an economic basis, the data from the trial together with projected data gathered from farmers and advisors were used to calculate the net present value (NPV) and internal rate of return (IRR) for each training system. The results showed that rootstock only played a significant role when it came to fruit mass (fruit size). Fruit from trees on SAPO 778 were heavier, indicating bigger fruit, than fruit from trees on Kakamas seedling rootstocks and this can play a role in packout percentage and income. In terms of the training system, the four-leader system took the most time to manage per tree. However, this system took the least time to manage per hectare during the initial years. No differences were found between the two central leaders. They both took the longest time to manage per hectare. The four-leader system produced significantly less fruit than any of the other systems during the first two years of production. In the third year of production, there was no significant difference found between the systems. Light penetration seemed to be the poorest at the middle and bottom of the canopy for trees trained to a central leader. Because of the open centre of the four-leader system, light penetration into the middle of these trees was good, but poor light penetration occurred in the upper and outer parts of the canopy underneath the scaffold branches. Poor light penetration occurred in the parts lower than 1.5 m from the ground for all the systems. This was the area that was measured in this study. The result of an economic comparison showed that according to the IRR rating, the fourleader system should be preferred. The final decision should however be made according to the NPV rating. Results obtained from NPV calculations did not lead to the same conclusions as could be made from the IRR calculations. According to the rating of the NPV at five percent discounting rate, the two-leader should be the preferred system, while the proleptically trained central leader system should be preferred at a ten percent discounting rate. This implies that when the opportunity cost is low, the two-leader system should be preferred, and when the opportunity cost is high, the proleptically trained central leader system should be preferred.

Resumo: O presente trabalho teve por objetivos avaliar: 1 - a utilização de aspersão de água e o repouso das suspensões de ovos e juvenis de Meloídogyne spp. pelos períodos de O; 5; 10; 15; 20; 25 e 30 minutos, na eliminação de espumas retidas sobre estes; 2 - a resistência a Me/oidogyne incogníta de 64 genótipos de pimenta Capsícum chínense; cinco da C. annuum; dois da C. baccatum e um da C. frutescens, e de dez cultivares comerciais de pimentão; 3 - a resistência a M. javaníca e a M. mayaguensis dos genótipos resistentes a M. íncognita; 4 - a compatibilidade da enxertia, dos genótipos resistentes a M. íncogníta, com os híbridos de pimentão Rubia R, Margarita e Maximos, nas fases de muda, de crescimento e na produtiva, e 5 - a manutenção da resistência dos porta-enxertos a M. íncogníta, ao final do ciclo da cultura. Os experimentos de aspersão de água e de repouso das suspensões foram conduzidos no Laboratório de Nematologia da UNESP-FCAV, em Jaboticabal-SP, no ano de 2004. Após a trituração das raízes de Capsicum spp., no experimento de aspersão de água, as suspensões foram vertidas na peneira com orifícios de 0,074 mm (200 mesh) sobre a peneira com orifícios de 0,025 mm (500 mesh) e lavadas, sendo as espumas, retidas sobre os ovos e juvenis na peneira de 500 mesh, aspergidas ou não com 50 mL de água, por 20 segundos. No experimento de repouso, após a trituração, as suspensões ficaram em repouso pelos períodos estabelecidos, sendo, na seqüência, vertidas sobre as peneiras e lavadas. Os experimentos de resistência de Capsicum spp. a Meloidogyne spp., de compatibilidade de enxertia e de manutenção da resistência a nematóides de galha, foram conduzidos em casa de vegetação, em Jaboticabal-SP, entre os anos de 2004 e 2005... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of the present work was to study: 1 - the utilization of water sprinkling and letting suspensions of eggs and juveniles of Meloidogyne spp. stand for periods of O; 5; 10; 15; 20; 25 and 30 min, to eliminate foam remaining on them; 2 resistance to Me/oidogyne incognita in 64 pepper genotypes of the species Capsicum chinense, five of C. Annuum, two of C. baccatum and one of C. frutescens, and of ten commercial pepper cultivars; 3 - resistance to M. javanica and M. mayaguensis in genotypes resistant to M. incognita; 4 - compatibility of grafting of genotypes resistant to M. incognita with the bell pepper hybrids Rubia R, Margarita and Maximos, during seedling, growth and productive phases; and 5 - maintenance of resistance of rootstocks to M. incognita at the end of the cultivation cycle. The experiments studying water sprinkling and letting suspensions stand were conducted in the Nematology Laboratory of UNESP-FCAV, at Jaboticabal-SP, during 2004. In nematode application with water sprinkling, the roots of Capsicum spp. were triturated, and the suspensions were poured over a sieve with a pore size of 0.074 mm (200 mesh) on top of a sieve with a pore size of 0.025 mm (500 mesh) and washed; the foam retained on the eggs and juveniles on the 500-mesh was sprinkled or not using 50 mL of water. In the experiment of letting suspensions stand, after trituration the suspensions were allowed to stand for the periods established, after which they were poured over the sieves and washed. The experiments on the resistance of Capsicum spp. to Meloidogyne spp., the compatibility of grafting and the maintenance of resistance to root-knot nematodes were conducted in a greenhouse, at Jaboticabal-SP, between 2004 and 2005. In experiments on resistance of the genotypes to Meloidogyne spp., ten plants were used per genotype, where each plant was considered a repetition... (Complete abstract click electronic access below) / Orientadora: Leila Trevizan Braz / Coorientador: David Ariovaldo Benzatto / Coorientador: Jaime Maia dos Santos / Banca: Arthur Bernardes Cecílio Filho / Banca: Clélia Aparecida Iunes Lapera / Banca: Rumy Goto / Banca: Izabel Cristina Leite / Doutor

Made available in DSpace on 2014-06-11T19:26:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-23Bitstream added on 2014-06-13T20:54:58Z : No. of bitstreams: 1 palangana_fc_me_botfca.pdf: 1558586 bytes, checksum: 9baaaa39eb027b263cb88fc95e6dc206 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Avaliou-se o efeito da utilização do bioestimulante Stimulate® em plantas de pimentão enxertadas e não enxertadas, em ambiente protegido, no aumento de produção. Seis doses do Stimulate® (0; 75; 100; 125; 150 e 175 mL p.c. 100 L H2O-1) foram aplicadas via pulverização foliar sete vezes, quinzenalmente, em plantas de pimenteiro resultando em um esquema fatorial (2 x 6) e delineamento experimental de blocos casualizados com quatro repetições. As plantas enxertadas foram mais produtivas em relação às plantas pé-franco, produzindo frutos de características agronômicas superiores. No geral, 100 e 125-150 mL p.c. 100 L H2O-1 de Stimulate® promoveram incremento positivo na produção de pimenteiro enxertado e pé-franco, respectivamente / It was evaluated the effect of using the Stimulate® biostimulant in grafted and non grafted plants of sweet pepper in a protected environment, to increase production. Six doses of Stimulate® (0; 75; 100; 125; 150 e 175 mL p.c. 100 L H2O-1) were applied by foliar sprays seven times, fortnightly, in sweet pepper plants resulting in a factorial (2 x 6) and randomized block design with four replications. The grafted plants were more productive than non grafted plants, producing fruits with better agronomic characteristics. In general, 100 and 125-150 mL p.c. 100 L H2O-1 of Stimulate® promoted a positive increase in the production of grafted and non grafted sweet pepper plants, respectively

Made available in DSpace on 2014-06-11T19:33:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-02-22Bitstream added on 2014-06-13T19:23:54Z : No. of bitstreams: 1 oliveira_cd_dr_jabo_prot.pdf: 6450834 bytes, checksum: 54ef6c225a3ecd6cbc9589a230eb0ac4 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente trabalho teve por objetivos avaliar: 1 - a utilização de aspersão de água e o repouso das suspensões de ovos e juvenis de Meloídogyne spp. pelos períodos de O; 5; 10; 15; 20; 25 e 30 minutos, na eliminação de espumas retidas sobre estes; 2 - a resistência a Me/oidogyne incogníta de 64 genótipos de pimenta Capsícum chínense; cinco da C. annuum; dois da C. baccatum e um da C. frutescens, e de dez cultivares comerciais de pimentão; 3 - a resistência a M. javaníca e a M. mayaguensis dos genótipos resistentes a M. íncognita; 4 - a compatibilidade da enxertia, dos genótipos resistentes a M. íncogníta, com os híbridos de pimentão Rubia R, Margarita e Maximos, nas fases de muda, de crescimento e na produtiva, e 5 - a manutenção da resistência dos porta-enxertos a M. íncogníta, ao final do ciclo da cultura. Os experimentos de aspersão de água e de repouso das suspensões foram conduzidos no Laboratório de Nematologia da UNESP-FCAV, em Jaboticabal-SP, no ano de 2004. Após a trituração das raízes de Capsicum spp., no experimento de aspersão de água, as suspensões foram vertidas na peneira com orifícios de 0,074 mm (200 mesh) sobre a peneira com orifícios de 0,025 mm (500 mesh) e lavadas, sendo as espumas, retidas sobre os ovos e juvenis na peneira de 500 mesh, aspergidas ou não com 50 mL de água, por 20 segundos. No experimento de repouso, após a trituração, as suspensões ficaram em repouso pelos períodos estabelecidos, sendo, na seqüência, vertidas sobre as peneiras e lavadas. Os experimentos de resistência de Capsicum spp. a Meloidogyne spp., de compatibilidade de enxertia e de manutenção da resistência a nematóides de galha, foram conduzidos em casa de vegetação, em Jaboticabal-SP, entre os anos de 2004 e 2005... / The aim of the present work was to study: 1 - the utilization of water sprinkling and letting suspensions of eggs and juveniles of Meloidogyne spp. stand for periods of O; 5; 10; 15; 20; 25 and 30 min, to eliminate foam remaining on them; 2 resistance to Me/oidogyne incognita in 64 pepper genotypes of the species Capsicum chinense, five of C. Annuum, two of C. baccatum and one of C. frutescens, and of ten commercial pepper cultivars; 3 - resistance to M. javanica and M. mayaguensis in genotypes resistant to M. incognita; 4 - compatibility of grafting of genotypes resistant to M. incognita with the bell pepper hybrids Rubia R, Margarita and Maximos, during seedling, growth and productive phases; and 5 - maintenance of resistance of rootstocks to M. incognita at the end of the cultivation cycle. The experiments studying water sprinkling and letting suspensions stand were conducted in the Nematology Laboratory of UNESP-FCAV, at Jaboticabal-SP, during 2004. In nematode application with water sprinkling, the roots of Capsicum spp. were triturated, and the suspensions were poured over a sieve with a pore size of 0.074 mm (200 mesh) on top of a sieve with a pore size of 0.025 mm (500 mesh) and washed; the foam retained on the eggs and juveniles on the 500-mesh was sprinkled or not using 50 mL of water. In the experiment of letting suspensions stand, after trituration the suspensions were allowed to stand for the periods established, after which they were poured over the sieves and washed. The experiments on the resistance of Capsicum spp. to Meloidogyne spp., the compatibility of grafting and the maintenance of resistance to root-knot nematodes were conducted in a greenhouse, at Jaboticabal-SP, between 2004 and 2005. In experiments on resistance of the genotypes to Meloidogyne spp., ten plants were used per genotype, where each plant was considered a repetition... (Complete abstract click electronic access below)