Orientador: Adalton Mazetti Fernandes / Resumo: A otimização do manejo da adubação nitrogenada com fornecimento do nitrogênio (N) no período de maior demanda pelas plantas pode ser uma estratégia para maximizar a produtividade e a qualidade de tubérculos na cultura da batata (Solanum tuberosum L.). Dessa forma, objetivou-se com este trabalho avaliar a produtividade e a qualidade físico-química e nutricional dos tubérculos das cultivares de batata Agata e Markies submetidas a diferentes formas de manejo da adubação nitrogenada tradicional combinada com a aplicação de doses de N na fase de enchimento de tubérculos. Foram conduzidos quatro experimentos, com as cultivares Agata e Markies durante a safra de inverno dos anos de 2017 e 2018. A área de 2018 não foi a mesma do ano anterior, e ambos experimentos localizavam-se em áreas comerciais de produção de batata em Botucatu-SP. O delineamento experimental adotado em todos experimentos foi em blocos ao acaso com esquema fatorial 4 x 4, com quatro repetições. As formas de manejo da adubação nitrogenada tradicional foram: M1 = 160 kg ha-1 de N no plantio; M2 = 80 kg ha-1 de N no plantio; M3 = 40 kg ha-1 de N no plantio e 120 kg ha-1 de N na amontoa; M4 = 80 kg ha-1 de N no plantio e 80 kg ha-1 de N na amontoa, combinadas com as doses de 0, 20, 40 e 80 kg ha-1 de N aplicadas na fase de enchimento dos tubérculos. As formas de manejo da adubação nitrogenada tradicional combinadas com as doses de N na fase de enchimento de tubérculos, não causaram deficiência de N nas plantas de bata... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Optimizing the management of nitrogen (N) fertilization with supply of N in the period of greatest demand for plants can be a strategy to maximize the yield and quality of tubers in the potato crop (Solanum tuberosum L.). Thus, the objective of this work was to evaluate the yield and the physico-chemical and nutritional quality of the tubers of potato cultivars Agata and Markies submitted to different forms of management of traditional N fertilization combined with N application rates at the tuber bulking stage. Four experiments were conducted with the cultivars Agata and Markies during the winter growing season of the 2017 and 2018 years. The 2018 area was not the same as the previous year, and both experiments were located in potato producer areas in Botucatu-SP. The experimental design adopted in all experiments was in randomized blocks with a 4 x 4 factorial scheme, with four replications. The forms of management of traditional N fertilization were: M1 = 160 kg N ha-1 at planting; M2 = 80 kg N ha-1 at planting; M3 = 40 kg N ha-1 at planting plus 120 kg N ha-1 at hilling; M4 = 80 kg N ha-1 at planting plus 80 kg N ha-1 at hilling, combined with rates of 0, 20, 40, and 80 kg N ha-1 applied at tuber bulking stage. The forms of traditional N fertilization management combined with the N rates at tuber bulking stage did not cause N deficiency in potato plants in both cultivars, when leaf sampling was performed at the time indicated for the crop. In the cultivar Markies, applica... (Complete abstract click electronic access below) / Doutor

O presente trabalho teve como objetivo avaliar aspectos fisiológicos e bioquímicos de batatas cv. Ágata, Asterix e Monalisa minimamente processadas. Primeiramente foram estudadas variáveis fisiológicas e microbiológicas de batatas armazenadas a 5, 15 e 25ºC. As batatas \'Asterix\' apresentaram as maiores taxas respiratórias em relação a \'Ágata\' e \'Monalisa\', independente da temperatura de armazenamento. As contagens de bactérias psicrotróficas e coliformes totais, para todas as cultivares armazenadas a 5oC durante 9 dias de armazenamento, mantiveram-se dentro dos padrões aceitáveis. O armazenamento a 5oC foi eficiente no controle da atividade metabólica e na segurança de batatas minimamente processadas. No segundo experimento, o ensaio enzimático realizado teve como objetivo verificar o efeito de diferentes cultivares e de temperaturas de armazenamento (5 e 15ºC) sobre a atividade das enzimas fenilalanina amônia-liase (PAL), polifenoloxidase (PPO) e peroxidase (POD). As atividades enzimáticas aumentaram para todas as cultivares na temperatura de 15ºC. Batatas \'Ágata\' e \'Asterix\' são mais indicadas para processamento mínimo do que \'Monalisa\', sendo esta mais susceptível ao escurecimento enzimático. O terceiro experimento avaliou os níveis de carboidratos não estruturais em batatas minimamente processadas e armazenadas a 5 e 15ºC. A maior degradação de amido em batatas \'Asterix\' armazenadas a 5ºC esteve relacionada com o aumento do teor de açúcares solúveis verificado para este tratamento. Foi observado um aumento nos teores de amido para a cultivar \'Ágata\' armazenada a 5ºC. Os teores de sacarose decresceram para todas as cultivares armazenadas a 5ºC e houve manutenção nos teores deste carboidrato quando armazenadas a 15ºC. No quarto experimento foram testadas diferentes combinações de antioxidantes nas três cultivares armazenadas a 5ºC. Batatas \'Monalisa\' apresentaram os maiores teores de fenóis totais e valores de atividade da PAL, POD e PPO independente do tratamento. Batatas \'Ágata\' tratadas com ácido ascórbico 2% + cisteína 0,5% e cisteína 0,5% + 4-hexilresorcinol 0,01% apresentaram os menores valores de atividade da PAL, POD e PPO. Para as cultivares Asterix e Monalisa os melhores resultados obtidos foram nas combinações com 4-hexilresorcinol e cisteína, respectivamente. / The purpose of the present work was to evaluate physiological and biochemical aspects of minimally processed Agata, Asterix and Monalisa potato cultivars. First physiological and microbiological variables of fresh-cut potatoes stored at 5, 15 and 25ºC were evaluated. Potatoes \'Asterix\' showed the highest respiratory rates when compared to potatoes cv. Agata and Monalisa, regardless of the storage temperature. Psychrotrophic bacteria and total coliforms counts were within acceptable limits for all cultivars stored at 5oC during 9 days of storage. Storage at 5oC was effective to control the metabolic activity and to keep food safety of minimally processed potatoes. In a second experiment, the effect of different cultivars and storage temperatures (5 and 15ºC) on the enzymatic activity of phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) was studied. Enzymatic activity increased in all cultivars at 15ºC. \'Agata\' and \'Asterix\' potatoes were more suitable for minimal processing than \'Monalisa\'. This last cultivar is more susceptible to enzimatic browning. The third experiment was aimed at evaluating non-structural carbohydrates levels in mimally processed potatoes stored at 5 and 15ºC. The highest starch degradation rate was observed in potatoes \'Asterix\' stored at 5ºC, which was related to the increase in the soluble sugar amount verified in this experiment. There was an increase in starch content in \'Agata\' potatoes stored at 5ºC. Sucrose contents decreased in all cultivars stored at 5ºC and remained constant in cultivars stored at 15ºC. In a fourth experiment, different combinations of antioxidants in the three potato cultivars stored at 5ºC were studied. Potatoes \'Monalisa\' showed the highest total phenol amounts and the highest activities of PAL, PPO and POD, regardless of treatment. \'Agata\' potatoes treated with ascorbic acid 2% + cysteine 0.5% and cysteine 0.5% + 4-hexylresorcinol 0.01% showed the lowest valves activities of PAL, POD and PPO. For the Asterix and Monalisa cultivars, the best results were obtained when combinations of 4-hexylresorcinol and cysteine were used, respectively.

O presente trabalho teve como objetivo avaliar aspectos fisiológicos e bioquímicos de batatas cv. Ágata, Asterix e Monalisa minimamente processadas. Primeiramente foram estudadas variáveis fisiológicas e microbiológicas de batatas armazenadas a 5, 15 e 25ºC. As batatas \'Asterix\' apresentaram as maiores taxas respiratórias em relação a \'Ágata\' e \'Monalisa\', independente da temperatura de armazenamento. As contagens de bactérias psicrotróficas e coliformes totais, para todas as cultivares armazenadas a 5oC durante 9 dias de armazenamento, mantiveram-se dentro dos padrões aceitáveis. O armazenamento a 5oC foi eficiente no controle da atividade metabólica e na segurança de batatas minimamente processadas. No segundo experimento, o ensaio enzimático realizado teve como objetivo verificar o efeito de diferentes cultivares e de temperaturas de armazenamento (5 e 15ºC) sobre a atividade das enzimas fenilalanina amônia-liase (PAL), polifenoloxidase (PPO) e peroxidase (POD). As atividades enzimáticas aumentaram para todas as cultivares na temperatura de 15ºC. Batatas \'Ágata\' e \'Asterix\' são mais indicadas para processamento mínimo do que \'Monalisa\', sendo esta mais susceptível ao escurecimento enzimático. O terceiro experimento avaliou os níveis de carboidratos não estruturais em batatas minimamente processadas e armazenadas a 5 e 15ºC. A maior degradação de amido em batatas \'Asterix\' armazenadas a 5ºC esteve relacionada com o aumento do teor de açúcares solúveis verificado para este tratamento. Foi observado um aumento nos teores de amido para a cultivar \'Ágata\' armazenada a 5ºC. Os teores de sacarose decresceram para todas as cultivares armazenadas a 5ºC e houve manutenção nos teores deste carboidrato quando armazenadas a 15ºC. No quarto experimento foram testadas diferentes combinações de antioxidantes nas três cultivares armazenadas a 5ºC. Batatas \'Monalisa\' apresentaram os maiores teores de fenóis totais e valores de atividade da PAL, POD e PPO independente do tratamento. Batatas \'Ágata\' tratadas com ácido ascórbico 2% + cisteína 0,5% e cisteína 0,5% + 4-hexilresorcinol 0,01% apresentaram os menores valores de atividade da PAL, POD e PPO. Para as cultivares Asterix e Monalisa os melhores resultados obtidos foram nas combinações com 4-hexilresorcinol e cisteína, respectivamente. / The purpose of the present work was to evaluate physiological and biochemical aspects of minimally processed Agata, Asterix and Monalisa potato cultivars. First physiological and microbiological variables of fresh-cut potatoes stored at 5, 15 and 25ºC were evaluated. Potatoes \'Asterix\' showed the highest respiratory rates when compared to potatoes cv. Agata and Monalisa, regardless of the storage temperature. Psychrotrophic bacteria and total coliforms counts were within acceptable limits for all cultivars stored at 5oC during 9 days of storage. Storage at 5oC was effective to control the metabolic activity and to keep food safety of minimally processed potatoes. In a second experiment, the effect of different cultivars and storage temperatures (5 and 15ºC) on the enzymatic activity of phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) was studied. Enzymatic activity increased in all cultivars at 15ºC. \'Agata\' and \'Asterix\' potatoes were more suitable for minimal processing than \'Monalisa\'. This last cultivar is more susceptible to enzimatic browning. The third experiment was aimed at evaluating non-structural carbohydrates levels in mimally processed potatoes stored at 5 and 15ºC. The highest starch degradation rate was observed in potatoes \'Asterix\' stored at 5ºC, which was related to the increase in the soluble sugar amount verified in this experiment. There was an increase in starch content in \'Agata\' potatoes stored at 5ºC. Sucrose contents decreased in all cultivars stored at 5ºC and remained constant in cultivars stored at 15ºC. In a fourth experiment, different combinations of antioxidants in the three potato cultivars stored at 5ºC were studied. Potatoes \'Monalisa\' showed the highest total phenol amounts and the highest activities of PAL, PPO and POD, regardless of treatment. \'Agata\' potatoes treated with ascorbic acid 2% + cysteine 0.5% and cysteine 0.5% + 4-hexylresorcinol 0.01% showed the lowest valves activities of PAL, POD and PPO. For the Asterix and Monalisa cultivars, the best results were obtained when combinations of 4-hexylresorcinol and cysteine were used, respectively.

Abstract The plant can be considered a superorganism that consists of the plant per se and numerous populations of pro- and eukaryotic microorganisms. The interactions between the plant and endophytic microorganisms colonizing plant internal tissues are typically commensalistic or mutualistic. However, information on the role of endophytes in plant defense is limited because pathways are only partly known and systemic responses are typically not seen. The aim of this thesis was to study the priming capacities of endophytic Methylobacterium sp. IMBG290 on potato (Solanum tuberosum L.). Priming of plants by non-pathogenic bacteria allows the host to save energy and to reduce time needed for development of defense reaction during a pathogen attack. Priming phenomenon was demonstrated for Methylobacterium sp. IMBG290 as an activation of salicylic acid and jasmonate/ethylene-dependent defense pathways after challenge inoculation with the pathogen. Moderate activation of plant antioxidant system may also contribute to resistance induction by the strain. The viable but nonculturable state is presumably a survival strategy observed for the majority of bacterial endophytes. Pathogen attack or environmental changes can activate these quiescent forms. Thus Methylobacterium+ sp. IMBG290 became cultivable upon plant inoculation by nonpathogenic bacteria. I observed that the composition of the endophyte community changed in response to Methylobacterium sp. IMBG290 inoculation in shoot tissues and correlated with potato disease resistance and growth promotion. Therefore, the activation of endophytic bacterial populations as a putative mechanism of plant disease resistance was proposed. Endophytes have a high agricultural potential. Growth- and resistance-promoting capacities of Methylobacterium sp. IMBG290 on potato were highly variable depending on the cultivar, pathogen, inoculum density, and environmental conditions. Context-dependent efficacy requires more attention when designing complex microbial inoculants capable influencing positively plant growth, resistance, and nutritional properties. / Tiivistelmä Kasvia voidaan pitää superorganismina, joka koostuu kasvista itsestään ja lukuisista pro-ja eukaryottisista mikrobipopulaatioista. Kasvin ja sen sisäosia asuttavien endofyyttisten mikro-organismien väliset vuorovaikutukset ovat yleensä kommensalistisia tai mutualistisia. Endofyyttien rooli kasvin puolustuksessa on kuitenkin huonosti tunnettu, koska reitit tiedetään vain osittain eikä järjestelmällisiä vasteita usein havaita. Tämän väitöskirjatyön tavoitteena oli tutkia endofyyttisen Methylobacterium sp. IMBG290-kannan kykyä vahvistaa perunan (Solanum tuberosum L.) puolustusta. Tautia aiheuttamattomat bakteerit kykenevät vahvistamaan kasvien puolustusta, mikä auttaa isäntäkasvia säästämään energiaa ja nopeuttamaan puolustusreaktiota patogeenihyökkäyksen aikana. Methylobacterium sp. IMBG290-kannan vahvistuskyvyn osoitettiin perustuvan salisyylihappo- ja jasmonaatti/etyleeni-riippuvaisten puolustusreittien aktivoimiseen patogeeni-istutuksen jälkeen. Antioksidanttijärjestelmän lievä aktivoituminen voi myös vaikuttaa kannan aiheuttamaan vastustuskyvyn lisääntymiseen. Suurimmalle osalle bakteeriendofyyteistä ‘elävä mutta viljelemätön’-olotila on luultavasti selviytymisstrategia. Patogeenihyökkäys tai muutokset ympäristössä voivat aktivoida tällaiset hiljaiset olomuodot. Methylobacterium sp. IMBG290-kanta muuttui viljeltävissä olevaan muotoon kun kasviin istutettiin tautia aiheuttamaton bakteeri. Selvitin, että endofyytti-yhteisön koostumus muuttuu vasteena Methylobacterium sp. IMBG290-kannan istuttamiseen kasvin verson solukoissa, korreloiden lisääntyneen perunan vastustuskyvyn ja kasvun kanssa. Siksi endofyyttisten bakteeripopulaatioiden aktivoitumista esitettiin uutena kasvin puolustusmekanismina. Endofyyteillä on suuret mahdollisuudet maataloudessa. Methylobacterium sp. IMBG290-kannan kasvua ja vastustuskykyä lisäävät ominaisuudet perunalla vaihtelivat lajikkeen, patogeenin, lisätyn bakteeriympin ja ympäristöolosuhteiden mukaan. Suunniteltaessa monimutkaisia bakteeriymppejä kasvien kasvin, vastustuskyvyn ja ravintosisällön lisäämiseksi, täytyy tällainen tilanteesta riippuva tehokkuus ottaa enemmän huomioon.

Abstract Seed potato is the starting point in the potato (Solanum tuberosum L.) production chain. In order to secure potato production in a variety of production conditions, plant diseases must be controlled and the yield characteristics of the used cultivars ensured. In addition, production must be cost-effective. Characteristics particular to northern production conditions include long periods of daylight and a short growing season as well as a several months long seed potato storage period. The focus of the present study is on northern production conditions and methods, including haulm killing and sprout control, which are presumed to affect seed potato quality, as well as the initial stages of the seed potato production chain, i.e. micro- and minituber production, which could influence cost-effectiveness and propagation. Haulm killing is one of the methods used in seed potato production to regulate tuber size. It is often carried out on unsenesced plants. The present results, however, indicate that cultivar properties have a greater effect on the sprouting and crop yield of seed potatoes than production-phase haulm killing or temperature sum accumulation. Nevertheless, haulm killing carried out three weeks after flowering (75 DAP) accelerated emergence. When the effect of haulm killing methods on seed potatoes was compared with natural haulm senescence, haulm killing was shown to increase disease pressure. Black scurf (Rhizoctonia Solani) was present in seed tubers whose haulm had been destroyed by mechanical or mechanical-chemical haulm killing. Naturally senesced haulm had less black scurf, and crop quantity and starch content developed to a level typical of the cultivar. Storage periods lasting several months make controlling seed potato sprouting more challenging. Therefore, use of the plant hormone gibberellic acid (GA) in sprout control was investigated. GA treatments at lower concentration (100 mM) increased the number of tubers in the cultivar Fambo. Thus, the timing of haulm killing and in the case of Fambo, GA treatment influenced the characteristics of seed potatoes. Conventionally, the first tuber generation is produced using microplants to produce minitubers in greenhouses. This production method is, however, labour-intensive, and energy and investment costs are high. With the aim of increasing production efficiency in northern production conditions, the production of minitubers in the laboratory using a novel bioreactor technology and in growth rooms using the hydroponic technique was investigated. The Liquid LabTM Rocker bioreactor system was used in vitro, all the cultivars examined (Asterix, Timo, Van Gogh and Velox) produced microtubers. The quantity of tubers produced per dish varied between 30 (for the cultivar Asterix in eight weeks) and 75 (for the cultivar Velox in 11 weeks). The results showed hydroponic production of minitubers to be successful in indoor conditions: the cultivars Desiree and Van Gogh developed their first tuber three weeks faster than Asterix, and the minituber yield was 4.5 per plant for Desiree, 7.5 for Van Gogh and 4.0 for Asterix. When the results indicate that both the Liquid LabTM Rocker production method and the hydroponic production method are suitable for mass production of seed potatoes. / Tiivistelmä Siemenperuna on lähtökohta perunan (Solanum tuberosum L.) tuotantoketjussa. Jotta perunantuotanto turvataan eri tuotanto-olosuhteissa, on hallittava siemenperunan kasvitaudit, taattava sadontuotto-ominaisuudet ja tuotannon on oltava lisäksi kustannustehokasta. Pohjoisissa tuotanto-olosuhteissa erityispiirteinä ovat valoisuudeltaan pitkät päivät ja kestoltaan lyhyet kasvukaudet. Lisäksi siemenperunoiden varastointijakso kestää useita kuukausia. Tässä tutkimuksessa selvitettiin vaikuttavatko pohjoiset tuotanto-olosuhteet tai tuotannossa käytetyt varsistonhävitys tai itämisen hallinta siemenperunoiden laatuominaisuuksiin. Lisäksi selvitettiin siemenperunoiden ensimmäisen mukulasukupolven (mikro- ja minimukula) tuotantoa eri tekniikoilla. Siemenperunatuotannossa varsistonhävitystä käytetään mukulakoon säätelykeinona. Varsistonhävitys tehdään usein tuleentumattomaan kasvustoon. Saatujen tulosten perusteella lajikeominaisuudet vaikuttivat itämiseen ja sadontuotto-ominaisuuksiin enemmän kuin varsistonhävitys tai mukuloihin kerääntynyt lämpösumma. Varsistonhävitys kolme viikkoa kukinnasta (75 päivää istutuksen jälkeen) nopeutti kuitenkin siemenperunoiden taimettumista. Vertailtaessa varsistonhävitysmenetelmien vaikutusta siemenperunaan verranteena kasvuston luontainen tuleentuminen, varsistonhävitys lisäsi kasvitautipainetta. Mekaanis-kemiallisesti ja mekaanisesti varsistonhävityissä satomukuloissa tuli esiin seittirupea (Rhizoctonia solani). Luontaisesti tuleentuneen kasvuston sadoissa oli seittirupea vähemmän ja myös sadon määrä ja tärkkelyspitoisuus kehittyivät lajikkeelle luontaiselle tasolle. Useiden kuukausien varastointijakso vaikeuttaa siemenperunoiden itämisen hallintaa. Kun tutkittiin gibberelliinihapon (GA) käyttöä itämisen hallintaan, alhaisemman konsentraation (100mM) GA –käsittely lisäsi Fambo –lajikkeen mukulalukumäärää. Tulosten perusteella varsistonhävityksen ajoittamisella ja GA –käsittelyllä (Fambo –lajike) vaikutettiin siemenperunoiden ominaisuuksiin. Siemenperunan ensimmäisen mukulasukupolven eli minimukuloiden tuottaminen tapahtuu perinteisesti kasvihuonekasvatuksena mikrokasveista. Tuotantotapa on työvoima-, energia- ja invetointikustannuksia vaativaa. Tuotannon tehostamiseksi pohjoisissa tuotanto-olosuhteissa tutkittiin mikro- ja minimukuloiden tuotantoa eri teknologioilla. Mikromukuloita tuotettiin bioreaktorimenetelmällä laboratoriossa ja minimukuloita hydroponisella menetelmällä kasvatushuoneissa. Tulokset osoittavat, että kaikki tutkitut lajikkeet (Asterix, Timo, Van Gogh ja Velox) tuottivat bioreaktorissa mikromukuloita. Mikromukuloiden määrä vaihteli 30:sta (Asterix, 8 viikon kasvatus) 75:een (Velox, 11 viikon kasvatus). Myös minimukuloiden hydroponinen tuotanto sisätiloissa on mahdollista; kaikki lajikkeet muodostivat mukuloita, Desiree ja Van Gogh 3 viikkoa nopeammin kuin Asterix. Desiree tuotti minimukuloita 4.5 kpl/kasvi, Van Gogh 7.5 ja Asterix 4.0. Tulokset osoittavat, että molemmat menetelmät (bioreaktori ja hydroponinen) soveltuvat mikro- ja minimukuloiden massatuotantoon.

High temperature limit successful potato cultivation in the lowlands of tropical regions. One effect of high temperature may be an increase in gibberellin activity that is inhibitory to tuberization. Paclobutrazol blocks gibberellin biosynthesis and reduces its level in the plant. The effect of paclobutrazol on potato was examined under non-inductive conditions in a greenhouse and under field conditions in the hot tropical lowlands of eastern Ethiopia. Paclobutrazol was applied as a foliar spray or soil drench at rates equivalent to 0, 2, 3, and 4 kg a. i. per ha. Paclobutrazol increased chlorophyll a and b content, and photosynthetic efficiency, enhanced early tuber initiation, delayed physiological maturity, and increased tuber fresh mass, dry matter content, specific gravity and crude protein content. It reduced the number of tubers per plant and extended the tuber dormancy period. Paclobutrazol reduced shoot growth, and plant height, and increased the partitioning of assimilates to the tubers while reducing assimilate supply to the leaves, stems, roots and stolons. Stomatal conductance and the rate of transpiration were reduced. In addition, paclobutrazol treatment increased tuber N, Ca and Fe content while reducing P, K and Mg content. Growth analyses indicated that paclobutrazol decreased leaf area index, crop growth rate, and total biomass production. It increased specific leaf weight, tuber growth rate, net assimilation rate, and partitioning coefficient (harvest index). Microscopic observations showed that leaves of treated plants developed thicker epicuticular wax layers. The epidermal, palisade and spongy mesophyll cells were larger. It increased the thickness of the cortex and the size of vascular bundles and pith cells of the stem. It also increased the width of the cortex and favoured the formation of more secondary xylem vessels, resulting in thicker roots. Deposition of starch grains in the stem pith cells, and cortical cells of the stem and root, were stimulated in response to paclobutrazol treatment. In most instances the method of application did not affect the efficiency of paclobutrazol. The effect of cultivar and reproductive growth on growth, photosynthetic efficiency, water relations, dry matter production, tuber yield and quality of potato was also the subject of investigation. Non-flowering, flowering and fruiting plants of cultivars Al-624, Al-436, CIP-388453-3(A) and CIP-388453-3(B) were evaluated under field conditions of a sub-humid tropical highland of eastern Ethiopia. Cultivars exhibited differences with respect to leaf stomatal conductance, rate of transpiration, net photosynthesis, biomass production and allocation, tuber yield, tuber size distribution, specific gravity, dry matter content and nutrient composition. Fruiting plants had higher leaf stomatal conductance, and higher rates of transpiration and photosynthesis rates. The leaf area index, tuber growth rate, and partitioning coefficient (harvest index) of the fruiting plants were reduced, but crop growth rates and net assimilation rates were higher. Without affecting total dry matter production, fruit development reduced the amount partitioned to the leaves, stems, roots, and tubers. Fruit development reduced total and marketable tuber mass and tuber numbers. The effect of MCPA and paclobutrazol were studied under greenhouse and field conditions. Single foliar sprays were applied during the early and full bud development stages at rates of 0, 250, 500, and 750 g a.i. ha-1. Both MCPA and paclobutrazol greatly reduced the number of flowers and completely inhibited berry set. MCPA did not affect the number, yield, dry matter content and specific gravity of tubers. Without affecting the number of tubers, paclobutrazol increased tuber yield, dry matter content and specific gravity. / Thesis (DPhil (Horticultural Science))--University of Pretoria, 2007. / Plant Production and Soil Science / unrestricted

Pour cette étude, dans un premier temps, une caractérisation physico-chimique et rhéologique des amidons natifs de deux cultivars locaux de pomme de terre (Sipiera et Tselefou) et de trois de manioc (2425, 4115 et Seedling) a été faite avant leur incorporation dans du pâté de bœuf à 20, 30, 40 et 50g/kg de mêlée. L’influence du type d’amidon et de leur taux d’incorporation sur les propriétés physico-chimiques et texturales des pâtés a été évaluée. Les résultats ont montré que les propriétés physiques, fonctionnelles et rhéologiques des amidons sont étroitement liées à leur origine botanique. L’Analyse en Composantes Principales (ACP) laisse paraître que de tous les amidons natifs, celui du cultivar de pomme de terre Sipiera se rapproche le plus du témoin. Une fois incorporé dans les pâtés ; l’ACP de tous les paramètres texturaux des pâtés aux amidons natifs indique que le pâté à l’amidon du cultivar de manioc Seedling à de 40g/kg de mêlée (PS40), est celui qui se rapproche le plus du pâté témoin. Dans un deuxième temps, les amidons de pomme de terre (Sipiera) et de manioc (2425) ont été sélectionnés pour la modification (acétylation). Ces amidons acétylés ont par la suite fait l’objet des mêmes analyses que les amidons natifs et incorporés dans les pâtés aux mêmes taux que les amidons natifs. Des résultats, il ressort que les propriétés fonctionnelles des amidons natifs sont fortement influencées par l’acétylation et le temps d’acétylation. Les essais d’incorporation des amidons acétylés dans les pâtés montrent que l’amidon Sipiera/20 à un taux d’incorporation de 40g/kg de mêlée ne se distingue pas significativement (p>0,05) du pâté témoin / The first part of this work deals with the physico-chemical and rheological characterisation of native starches of two local cultivars of Irish potatoes (Sipiera and Tselefou) and three cultivars of cassava (2425, 4115 and Seedling) before they are incorporated into beef patty at 20, 30, 40 and 50g/kg ground meat. The influence of the type of starch and the amount of incorporation on the physico-chemical and textural properties of patties was evaluated. Results show that the physical, functional and rheological properties of starches are closely related to their botanical origin. Principal Component Analysis (PCA) showed that Irish potato cultivar Sipiera had properties that were close to reference. The PCA of all the textural properties of patties with native starches show that patty from starch of cassava cultivar Seedling at 40g/kg (PS40) was closest to the reference. In the second part of the work, the starch Sipiera and 2425 were selected for modification. These two starches were then acetylated for 10 and 20min. and this permitted us to have Sipiera/10, Sipiera/20, 2425/10 and 2425/20. The functional properties of the native starches were however strongly influenced by acetylation and the time of acetylation. Incorporation trials of this acetylated starches at different amounts in patty showed that Sipiera/20 starch at an incorporation rate of 40g/kg ground meat is not significantly different from the reference patty

The potato (Solanum tuberosum L.) has great importance in human nutrition where it occupies the fourth place among the most consumed foods in the world. It is a highly demanding culture technology especially in the nutritional point of view. Despite the titanium (Ti) is not considered a nutrient, studies have shown beneficial effects of this element when applied to plants. The application of Ti leaf can be an alternative for this element is slightly movable in the soil and is generally present in insoluble forms. Thus, the objective was to evaluate the influence of application rates of Ti foliar in the potato crop. We conducted an experiment in the period from August to November 2014, installed at the experimental station Udi Pesquisa e Development in Uberlândia-MG, with kind Ágata. Variables related to metabolism were evaluated: SPAD chlorophyll content, nitrate reductase activity (NRA), lipid peroxidation (LP), urease, proline, catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD). Nutritional factors such as levels of nutrients nitrogen (N), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) present in leaves and tubers were measured stages of growth, tuber and tuber filling. At the end of the crop cycle was quantified the average mass, diameter, commercial classification and productivity of tubers. The design was a randomized block design with four replications and six treatments. The supply of the Ti compound fertilizer was through for 5% of magnesium oxide, 10% sulfur trioxide and 0,85% titanium complex and the treatments was: T1 - without the application of Ti, T2 -10.2; T3 - 15.3; T4 - 20.4; T5 - 22.9 and T6 - 25.5 g Ti ha-1 divided into three equal applications during the growth phase, tuber and tuber filling. It was concluded that in the growth phase the foliar application of Ti reduces the Mn content in the leaves and there is increased activity of POD and ANR and reduced urease activity. In the tuberization phase the Fe absorption, SOD activity and POD response to increasing Ti dose. In tubers filling stage foliar application of Ti increases chlorophyll levels (Spad value). The application of Ti in the leaf growth stages, tuber and tuber filler results in a lower Zn content in the tubers. The average tuber weight, the average diameter of tubers and the total productivity of tubers are affected by foliar application of Ti. The dose Ti foliar applied for further tuber yield is 5.74 g Ti ha-1. / A batata (Solanum tuberosum L.) tem grande importância na alimentação humana onde ocupa o quarto lugar entre os alimentos mais consumido no mundo. É uma cultura altamente exigente em tecnologias especialmente sob o ponto de vista nutricional. Apesar do titânio (Ti) não ser considerado um nutriente, trabalhos demonstram efeitos benéficos deste elemento quando aplicado às plantas. A aplicação de Ti foliar pode ser uma alternativa pois este elemento é pouco móvel no solo e geralmente está presente em formas insolúveis. Desta forma, objetivou-se avaliar a influência da aplicação de doses de Ti via foliar na cultura da batata. Realizou-se um experimento no período de agosto a novembro de 2014, instalado na estação experimental Udi Pesquisa e Desenvolvimento em Uberlândia-MG, com utilização da cultivar Ágata. As variáveis relacionadas ao metabolismo avaliadas foram: teor clorofila SPAD, atividade da nitrato redutase (ANR), peroxidação lipídica (PL), urease, prolina, catalase (CAT), superóxido desmutase (SOD) e peroxidase (POD). Aspectos nutricionais como os teores dos nutrientes nitrogênio (N), cobre (Cu), ferro (Fe), manganês (Mn) e zinco (Zn) presentes em folhas e tubérculos foram mensurados fases de crescimento, tuberização e enchimento de tubérculos. Ao final do ciclo da cultura foi quantificada a massa média, diâmetro médio, classificação comercial e a produtividade dos tubérculos. O delineamento foi o de blocos casualizados, com quatro repetições e seis tratamentos. O fornecimento do Ti foi através de fertilizante composto por 5% de óxido de magnésio, 10% de trioxido enxofre e 0,85% de complexo de titânio com os seguintes tratamentos: T1 sem aplicação de Ti, T2 -10,2; T3 -15,3; T4 - 20,4; T5 - 22,9 e T6 - 25,5 g de Ti ha-1 divididos em três aplicações iguais durante a fase de crescimento, tuberização e enchimento de tubérculos. Concluiu-se que os teores de Cu não são influenciados pelas doses de Ti nas fases avaliadas. Na fase de crescimento a aplicação foliar de Ti reduz o teor de Mn nas folhas e há aumento da atividade da POD e ANR e redução da atividade da urease. Na fase de tuberização a absorção de Fe e atividade de enzimas SOD e POD tem resposta ao aumento da dose de Ti. Na fase de enchimento de tubérculos a aplicação foliar de Ti incrementa os teores de clorofila (valor Spad). A aplicação de Ti foliar nas fases de crescimento, tuberização e enchimento de tubérculos resulta em menor teor de Zn nos tubérculos. A massa média de tubérculos, o diâmetro médio de tubérculos e a produtividade total de tubérculos são influenciados pela aplicação foliar de Ti. A dose de Ti aplicada via foliar para maior produtividade de tubérculos é de 5,74 g de Ti ha-1. / Mestre em Agronomia

No description available.

The overall aim of this research was to improve the understanding of the ecology and diversity of Trichoderma species within the soil and rhizosphere of onion (Allium cepa L.) and potato (Solanum tuberosum L.) under intensive management in New Zealand. The indigenous Trichoderma population was measured in a field trial at Pukekohe over a three year period under six different crop rotation treatments. The treatments included two continuous onion and potato rotations (intensive), two onion/potato mixed rotation (conventional), and two green manure rotations (sustainable). Results showed that Trichoderma populations were stable in both the rhizosphere and bulk soil (1.5 x 10² to 8.5 x 10³ CFU g⁻¹ ODS). The planting and incorporation of an oat (Avena sativa L.) green manure in the sustainable rotations positively increased Trichoderma colony forming unit (CFU) numbers in the rhizosphere soil from 3.4 x 10² to 2.5 x 10³ g⁻¹ ODS. A Trichoderma species identification method was developed based on colony morphology. Representative isolates were verified using restriction fragment length polymorphism (RFLP) and DNA sequencing. The method allowed for rapid and reliable identification of isolated Trichoderma species. Five species were identified in the Pukekohe soil: T. asperellum, T. atroviride, T. hamatum, T. harzianum and T. koningii. Results showed identical species diversity between the rhizosphere, rhizoplane and bulk soil. The species did not strongly compete between each other for the rhizosphere ecological niche and differences in species proportions seemed to be caused by environmental factors rather than the rotation treatments. The incorporation of oat green manure in pots did not significantly promote the indigenous Trichoderma population size and diversity in the rhizosphere of onion plants up to 4 months old. The identified species were the same as in the field trial. The incorporation of onion scale residues was shown to result in low Trichoderma and high Penicillium CFU numbers and a reduction in plant size. Additionally, the presence of high levels (6.0 x 10⁵ CFU g⁻¹ ODS) of Penicillium CFU was negatively correlated with the presence of Trichoderma CFU. The effect of oat incorporation on Trichoderma saprophytic growth was also investigated in a soil sandwich assay and revealed no significant differences. A series of experiments indicated that onion extract obtained from dry onion scale residues had no antifungal activity against either Trichoderma or Penicillium and instead tended to promote their hyphal growth and sporulation. It also showed that competition between Penicillium and Trichoderma isolates was limited despite the ability of Penicillium to produce a wide range of inhibitory substances. Four indigenous Trichoderma species (T. atroviride, T. hamatum, T. harzianum and T. koningii) were shown to be rhizosphere competent in a split tube experiment over a 6 week period. The results of this experiment revealed that, the Trichoderma species clearly displayed differences in their ability to colonise the rhizosphere of young onion seedlings. Species such as T. koningii had the greatest rhizosphere colonising ability regardless of soil depth while T. harzianum displayed the weakest ability. Results also indicated that when inoculated as a mixture the four species competed with one another to colonise the rhizosphere. Overall, this research indicated that the studied crop rotation treatments and the use of oat as a green manure did not strongly promote indigenous Trichoderma populations. Species diversity was constant throughout the research with T. hamatum and T. koningii being the most frequently isolated species.