University of Stellenbosch. Faculty of Agrisciences. Dept. of Agronomy. / Thesis (MScAgric (Agronomy)--University of Stellenbosch, 2007. / Calcium (Ca) is an important plant nutrient with many functions, such as strengthening of cell walls and maintaining membrane stability and cell integrity. A greenhouse experiment was conducted using an aeroponic production system, to evaluate the influence of different Ca: K & Mg ratios (consisting of a control [100% Ca], and three treatments in which the Ca levels were changed to 33%, 66% and 133% of the control, while the K and Mg levels were adjusted to compensate for the change in Ca) and two different irrigation methods (irrigation on roots only, and irrigation on roots and stolons) on tuber yield and mineral concentration. The treatment that received the highest Ca: K & Mg ratio had significantly more larger tubers than the lowest Ca treatment, although there was no significant difference in total tuber number between treatments. The high Ca treatment also had a significantly higher Ca concentration in the skin than the low Ca treatment. The site of irrigation did not have a significant effect on the total tuber number per plant, or on the Ca content of the tubers that were produced. The tubers produced in the first experiment were divided into two weight classes, and stored at three different temperatures. The percentage weight loss during storage was determined by weighing the tubers before, and again after storage. The firmness of the tubers was also measured after storage. Tubers were then stored in a dark room at room temperature to allow sprouts to develop. The sprouts of each tuber were counted and weighed. Weight loss was the lowest for tubers stored at 3oC. Firmness of the tubers increased as the Ca: K & Mg ratio of the nutrient solution used during production was increased. Number of sprouts was the highest for tubers stored at 6oC. Sprout number was also significantly higher for the larger tubers compared to the smaller ones. Total sprout weight was the highest for the tubers stored at 6oC, and was also the highest for the larger tubers. After sprouts started to develop, the tubers were planted again in the greenhouse, in sawdust and irrigated with a complete Steiner nutrient solution at 1.5 mS cm-1. After these plants were harvested, the leaf area and dry weight of the leaves were determined. The first generation tubers were counted and weighed. The only factor that had a significant influence on the growth of the plants, was the size of the seed tubers that were used. The larger seed tubers produced plants that had significantly higher leaf areas, dry weight of leaves, as well as higher yields than that of the plants produced from the smaller seed tubers. From the results of this study, it can be concluded that Ca has a definite positive effect on the quality of seed potatoes as well as the size of the tubers that are produced. This study also supported that seed tubers should be stored at low temperatures, around 3oC, to maintain the highest quality, while larger tubers proved to out-yield smaller ones.

Seed tubers conditioned to 0, 200 or 400 day-degrees above 4t were grown in land infested with Q. pallida. Plants from 400 day-degree seed emerged earlier, had larger canopies and greater dry weights early in the growing season than plants from 0 day-degree seed. However, physiological ageing reduced peak percentage ground cover and advanced crop senescence so that similar quantities of solar radiation were intercepted over the whole growth period. Overall, total and ware yields were not affected much by seed tuber physiological age. The partially resistant cultivars tested were more tolerant than the non resistant cultivars but tolerance was not usually affected by physiological age of seed tubers. The effects of nematicide treatment, initial Q. pallida population density, cultivar maturity class, cultivar resistance status and planting date on nematode multiplication, plant growth and tolerance of attack by Q. pallida are discussed. Using data from a variable temperature water bath experiment, probability and regression analysis estimated mean basal temperatures for the development of Q. pallida and Q. rostochiensis at 2.5 and S.rCi least variance analysis estimates were 3.5 and 4.rC respectively. Approximately 200 day-degrees above 3.5 and 4.rC were required from the inoculation of JJ2 of Q. pallida and G. rostochiensis to the peak numbers of JJ5 found in potato roots. From a range of chemicals tested for their ability to release antigen from Q. pallida cysts, sodium hypochlorite was found to be the most effective. Released antigen was detected using polyclonal antisera and monoclonal antibodies in an ELISA test. The potential for the development of an ELISA based diagnosis test for PCN using species-specific antibodies is discussed.

Topinambų (Helianthus tuberosus L.) gumbų laikymo sąlygų optimizavimas 2006 m. Lietuvos žemės ūkio universiteto pomologiniame sode išaugintoje topinambų veislėje ‘Swojecki’ tirta laikomų sandėlyje gumbų cheminė sudėtis. Standartiniais metodais žaliavoje nustatyti sausųjų medžiagų, tirpių sausųjų medžiagų, bendrojo, redukuojančių sacharidų bei sacharozės, žalios ląstelienos, žaliųjų proteinų, amino rūgščių kiekiai bei laikymo metu susidarę masės nuostoliai. Tyrimų duomenų vidurkiai bei standartiniai nuokrypiai statistiškai apdoroti programa „Microsoft Excel“. Skirtumų esmingumas (P≤0,05) apskaičiuotas programa „Statistica“. Nustatyta, kad po keturių mėnesių sausųjų medžiagų kiekis topinambų gumbuose, laikytuose polipropileniniuose maišuose, buvo 2,2 karto didesnis nei laikytuose durpėse ar smėlyje. Esminiai didžiausios tirpių sausųjų medžiagų, žalios ląstelienos ir žaliųjų proteinų kiekių netektys (atitinkamai 4,0%, 1,5 % ir 4%.) po keturių laikymo mėnesių nustatyta gumbuose, laikytuose polipropileniniuose maišuose. Esminiai mažiausi bendrųjų sacharidų ir sacharozės kiekiai nustatyti po dviejų mėnesių topinambų gumbuose, nepriklausomai nuo to, kur jie buvo laikyti. Esminiai didžiausi per visą tyrimo laikotarpį redukuojančiųjų sacharidų kiekiai nustatyti polipropileniniuose maišuose, laikytuose topinambų gumbuose. Visu tyrimų laikotarpiu daugiausiai laikomuose topinambų gumbuose, nepriklausomai kur jie buvo laikomi, buvo sukaupta nepakeičiamosios amino rūgšties arginino ir... [toliau žr. visą tekstą] / The chemical composition during storage of tuber in Jerusalem artichoke cv. ‘Swojecki’, grown on pomological garden of Lithuanian University of in 2006 was assayed. By means of Standard methods the quantity of dry substance, soluble dry substance, total, reducing sugar, sucrose, raw fibre, raw proteins, amino acids also mass losses were estimated. For statistic analysis arithmetic average and standard deviation was calculated using MC EXCELL. To evaluate data validity statistic (P≤0,05) program „Statistica“ were used. It was established, that after four storage month the amount of dry matter in tubers which have been storage in polypropylene bags was 2,2 time bigger if compare those with tubers in peat or sand. Essential largest losses amounts of soluble dry matter, raw fibre also raw proteins (correspondingly 4,0%, 1,5 % and 4%) have been estimated in tubers which were storage in polypropylene bags. According results the essential smallest amounts of total saccharides, also sucrose where accumulated in tubers after two moth independent where they have been storage. Essential largest amounts of reducing sugars during all storage period have been estimated in tubers which were storage in polypropylene bags. During all storage period independent storage method the largest indispensable amino acid arginine also replaceable glutamine and the smallest amounts of methyonine and tyrosine have been established. The smallest mass losses during all storage period have been identify... [to full text]

Orientador: Adalton Mazetti Fernandes / Coorientador: Rogério Peres Soratto / Banca: Marcelo de Almeida Silva / Banca: Pablo Forlan Vargas / Resumo: A produtividade da batata depende da capacidade da planta sintetizar carboidratos nas folhas e mobilizá-los para os tubérculos em crescimento. Assim, o crescimento foliar excessivo nos estágios tardios do ciclo da cultura pode afetar negativamente a produtividade de tubérculos. Em condições favoráveis ao crescimento da parte aérea das plantas, o uso de retardantes ou reguladores do crescimento vegetal pode ser uma alternativa para melhorar a produtividade da cultura, através da redução no porte das plantas e do aumento na alocação de matéria seca (MS) para os tubérculos em crescimento. Desta forma, objetivou-se com este trabalho avaliar o efeito dos reguladores de crescimento vegetal cloreto de mepiquat, cloreto de chlormequat, proexadiona cálcica e placobutrazol, no crescimento, produtividade e qualidade de tubérculos das cultivares de batata Agata e Mondial. Foram conduzidos dois experimentos independentes, um com a cultivar Agata e outro com a cultivar Mondial. Ambos os experimentos foram instalados no delineamento experimental de blocos ao acaso no esquema fatorial 4x5+1, com quatro repetições. Os tratamentos foram representados por quatro reguladores vegetais (cloreto de mepiquat, cloreto de chlormequat, paclobutrazol e proexadiona cálcica), aplicados nas doses de 25, 50, 100, 200 e 400 g ha-1 do i.a., além do tratamento controle (sem aplicação de regulador vegetal). Na cultivar Agata todos os reguladores de crescimento tiveram efeito semelhante sobre as características ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Potato yield depends on the plant's ability to synthesize carbohydrates in the leaves and mobilize them for growing tubers. Thus, excessive leaf growth in the late stages of the crop cycle can negatively affect tuber yield. Under conditions favorable to shoot growth, the use of retarders or plant growth regulators may be an alternative to improve crop yield by reducing plant size and increasing dry matter (DM) the growing tubers. Thus, the aim of this work was evaluate the effect of plant growth regulators mepiquat chloride, chlormequat chloride, prohexadione calcium and placobutrazol on the growth, yield and quality of potato tubers of Agata and Mondial cultivars. Two independent experiments were conducted, one with the cultivar Agata and the other with the cultivar Mondial. Both experiments were installed in a randomized complete block design in the 4x5+1 factorial scheme, with four replications. The treatments were represented by four plant regulators (mepiquat chloride, chlormequat chloride, paclobutrazol and proexadione calcium), applied at the rates of 25, 50, 100, 200 and 400 g ha-1 of i.a., in addition to the control treatment (without the application of plant growth regulator). In the Agata cultivar, all growth regulators had a similar effect on the growth and yield characteristics of tubers, but the prohexadione calcium regulator decreased the postharvest quality of the tubers. In the Mondial cultivar the growth regulator paclobutrazol was more efficient in reducing the vegetative growth of the plants and maintaining the postharvest quality of the tubers. In both cultivars the greatest effects on growth and commercial yield of tubers occurred between the rates of 50 and 100 g ha-1 of i.a.. In the cultivar Agata the rates of growth regulators reduced the commercial yield of tubers, but in the cultivar Mondial the commercial yield of tubers increased with the application ... / Mestre

Yield and marketing characteristics of set of ware potatoes species were evaluated in this diploma thesis. Samples of potatoes, on which was the measurement executed, were forked out on the field in Košetice in Vysočina region. This region is typical potatoe area and has significant share on the national production of ware potatoes, starch potatoes and seed potatoes with different lenght of vegetation season. The inception of major phenological phase of growth, the quantity of plants on area, the quantity of stalks of a single plant and the overall appereance of growth were valuated in the vegetation process of individual species. The quantity of tubers on one plant, the quantity of tubers on one stalk and the average weight of one tuber were evaluated after the harvest. Then was defined the overall yield of tubers, the yield of marketing tubers and their overall revenue share. The appearence of tubers, their health condition and the amount of mechanical damage was discribed in detail for every species. The final results were processed to charts and graphs and they were statistically evaluated. The medium late and the semi-early species had achieved the best results for growing. The very early and the early species had lower yield and larger share of waste.

The thesis is focused on fertilization of the potato by leaf nutrition. The aim of the experiment was to evaluate how the selected varieties of potatoes respond on the application of leaf fertilizers. There were evaluated the effects of the application of urea, Energenu Foliar and Lignohumate NPK in varieties with different growing season Magda - very early, Adele - mid-early, Jasmine early to mid-early and late Laura. These varieties are evaluated by the proportion of emerged plants, tuber yield, proportion of consume size tubers, number of tubers in a bunch, the average weight of one tuber, number of stems per plant and starch content. From the results, it was found that all varieties responded positively to the application of leaf fertilizers. The effects on the potatoes were influenced by used variation of the fertilizer and by the different growing season of each potato variety

Made available in DSpace on 2016-06-07T17:12:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-27. Added 1 bitstream(s) on 2016-06-07T17:16:46Z : No. of bitstreams: 1 000863925.pdf: 1291594 bytes, checksum: deb5e65e57e298b3299eb33c094e853a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O Brasil destaca-se dentro do setor florestal quanto ao desenvolvimento e produção de espécies de interesse econômico. Em parceria com empresas do ramo florestal, a Universidade Estadual Paulista (UNESP - Campus de Botucatu) vem desenvolvendo projetos de identificação de características relacionadas ao estresse abiótico em eucalipto. A presença de lignotúber é um caráter que confere a essas espécies maior tolerância a níveis de estresse. Os objetivos deste estudo foram: compreender a relação do lignotúber com o estresse e as características silviculturais por meio das estimativas de correlações fenotípicas e parâmetros genéticos. Os experimentos foram conduzidos com duas espécies de eucaliptos e seus híbridos, em dois ambientes contrastantes quanto aos aspectos edafoclimáticos. Avaliaram-se dois caracteres de crescimento: altura (ALT) e circunferência à altura do peito (CAP) e a presença de lignotúber. De posse dos parâmetros genéticos estimados, não foi detectada manifestação de heterose e epistasia nos materiais em questão. As análises conjuntas dos experimentos indicaram significância para os tratamentos, quanto a presença de lignotubérculo. Deste modo, a correlação fenotípica foi significativa, indicando que na presença de estresse biótico/abiótico existe a associação entre as características silviculturais e a presença de lignotúber. As plantas que apresentaram esta estrutura possuem menor crescimento vegetativo. Estes resultados evidenciam que o lignotúber é uma estrutura de grande importância nas plantas e fator determinante na escolha de genótipos para regiões onde o estresse é alto / Brazil stands out in the forest sector by the development and production of species with economic interests. In partnership with forestry companies, the University of Sao Paulo State (UNESP- Botucatu) has been developing studies to identifying traits related to abiotic stress in Eucalyptus. The presence of lignotuber is a character that gives to these species tolerance to different levels of stress. Our aim was to understand the relationship of lignotuber with stress and silvicultural characteristics by estimating the genetic parameters and phenotypic correlations. Experiments were conducted with two eucalyptus species and their hybrids in two contrasting environments as the edaphoclimatic aspects. We evaluated two characters of growth: height (ALT), circumference at breast height (CAP) and presence of lignotuber. The estimation of the genetic parameters did not detect heterosis and epistasis in these materials. Joint analysis of the experiments indicated significance for the treatments, as for the presence of lignotubercle. Thus, the phenotypic correlation was significant, indicating that in the presence of biotic/abiotic stress, exist association between silvicultural traits and the presence of lignotuber. Plants with this structure showed less vegetative growth. These results show that the lignotuber is an important structure in plants and an important factor to be considered in choosing genotypes for regions where stress is high

Orientador: Celso Luis Marino / Banca: Douglas Domingues da Silva / Banca: Evandro Wagner Tambarussi / Banca: Mario Teixeira Moraes / Banca: Iraê Amaral Guerrini / Resumo: O Brasil destaca-se dentro do setor florestal quanto ao desenvolvimento e produção de espécies de interesse econômico. Em parceria com empresas do ramo florestal, a Universidade Estadual Paulista (UNESP - Campus de Botucatu) vem desenvolvendo projetos de identificação de características relacionadas ao estresse abiótico em eucalipto. A presença de lignotúber é um caráter que confere a essas espécies maior tolerância a níveis de estresse. Os objetivos deste estudo foram: compreender a relação do lignotúber com o estresse e as características silviculturais por meio das estimativas de correlações fenotípicas e parâmetros genéticos. Os experimentos foram conduzidos com duas espécies de eucaliptos e seus híbridos, em dois ambientes contrastantes quanto aos aspectos edafoclimáticos. Avaliaram-se dois caracteres de crescimento: altura (ALT) e circunferência à altura do peito (CAP) e a presença de lignotúber. De posse dos parâmetros genéticos estimados, não foi detectada manifestação de heterose e epistasia nos materiais em questão. As análises conjuntas dos experimentos indicaram significância para os tratamentos, quanto a presença de lignotubérculo. Deste modo, a correlação fenotípica foi significativa, indicando que na presença de estresse biótico/abiótico existe a associação entre as características silviculturais e a presença de lignotúber. As plantas que apresentaram esta estrutura possuem menor crescimento vegetativo. Estes resultados evidenciam que o lignotúber é uma estrutura de grande importância nas plantas e fator determinante na escolha de genótipos para regiões onde o estresse é alto / Abstract: Brazil stands out in the forest sector by the development and production of species with economic interests. In partnership with forestry companies, the University of Sao Paulo State (UNESP- Botucatu) has been developing studies to identifying traits related to abiotic stress in Eucalyptus. The presence of lignotuber is a character that gives to these species tolerance to different levels of stress. Our aim was to understand the relationship of lignotuber with stress and silvicultural characteristics by estimating the genetic parameters and phenotypic correlations. Experiments were conducted with two eucalyptus species and their hybrids in two contrasting environments as the edaphoclimatic aspects. We evaluated two characters of growth: height (ALT), circumference at breast height (CAP) and presence of lignotuber. The estimation of the genetic parameters did not detect heterosis and epistasis in these materials. Joint analysis of the experiments indicated significance for the treatments, as for the presence of lignotubercle. Thus, the phenotypic correlation was significant, indicating that in the presence of biotic/abiotic stress, exist association between silvicultural traits and the presence of lignotuber. Plants with this structure showed less vegetative growth. These results show that the lignotuber is an important structure in plants and an important factor to be considered in choosing genotypes for regions where stress is high / Doutor

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Potato is an important food source for the world, and to evaluate the effect of the percentage of potassic sources (double sulphate of potassium and magnesium and potassium chloride) Atlantic cultivar, the experiment was conducted in Whermann farm, located in Cristalina-GO, from 19 July to 19 November 2011. The experimental design was a randomized block design with seven treatments (T1=100%K2SO4MgSO4;T2=12,5%KCl/87,5%K2SO4MgSO4;T3=25%KCl/75%K2SO4MgSO4;T4=50%KCl/50%K2SO4MgSO4;T5=75%KCl/25%K2SO4MgSO4;T6=12,5%KCl/87,5%K2SO4MgSO4 e T7=100%KCl) and four replications in a factorial design with split plot. The plots were related to treatments and the subplots at times (26, 47, 68, 89 and 110 DAP). The percentages of double sulphate of potassium and magnesium (K2SO4MgSO4) and potassium chloride in the accumulation of potassium, sulfur and chlorine in the leaves and tubers as well as the main productive characteristics as soluble solids, classification of tubers, tuber number and yield were evaluated. At 56 and 75 DAP , it was found accumulated in leaves higher levels of 1.22 and 11.1 g plant - 1 potassium and chlorine, respectively. The accumulation of S on leaf potato was influenced by potassium fertilization at 89 DAP where differences between treatments were observed, with the greatest concentration of 4, while the lowest was 7, did not differ from the others. In tuber treatments 7, 1 and 2 were higher, and at about 91 DAP at the maximum rate was 1.31 g plant - 1. Treatments 1 and 2 had higher accumulations of S, where the DAP 110 reached 1.12 g plant - 1. The highest values of accumulation of chlorine in tubers during the cycle were 0.10, 0.90, 0.10, 0.13, 0.13 and 0.13 g plant - 1 at 92, 104, 88, 87, 86 and 82 DAP, respectively, with the 47, 68 and 89 DAP, differences between treatments. The treatments had no influence on the content of soluble solids classification and productivity. The numbers of tubers suffered interference of treatments in the last two collections, where the 110 DAP showed 18.22, 19.70, 19.96, 20.39, 19.20, 16.01 and 13.79 tubers plant - 1 for treatments 1, 2, 3 , 4, 5, 6 and 7 respectively. The potato cultivar Atlantic was influenced by potassium fertilization on accumulation of nutrients from leaves and tubers and number of tubers plant - 1, which was not influenced in the standings, the soluble solids and tuber yield. / A batata é uma fonte alimentar muito importante para o mundo, e objetivando avaliar o efeito da porcentagem de fontes potássicas (sulfato duplo de potássio e magnésio e cloreto de potássio) na cultivar Atlantic, o experimento foi conduzido na fazenda Whermann, localizada no município de Cristalina-GO, no período de 19 julho a 19 novembro de 2011. O delineamento experimental utilizado foi o de blocos ao acaso, com sete tratamentos (T1=100%K2SO4MgSO4; T2=12,5%KCl/87,5%K2SO4MgSO4; T3=25%KCl/75%K2SO4MgSO4;T4=50%KCl/50%K2SO4MgSO4;T5=75%KCl/25%K2SO4MgSO4;T6=12,5%KCl/87,5%K2SO4MgSO4 e T7=100%KCl) e quatro repetições, em esquema fatorial com parcela subdividida. As parcelas referiam-se aos tratamentos, e as subparcelas às épocas (26, 47, 68, 89 e 110 DAP). Foram avaliadas as porcentagens de sulfato duplo de potássio e magnésio (K2SO4MgSO4) e cloreto de potássio no acúmulo de potássio, enxofre e cloro nas folhas e tubérculos bem como nas principais características produtivas como sólidos solúveis, classificação de tubérculos, número de tubérculos e produtividade. Aos 56 e 75 DAP, encontrou-se acumulado nas folhas níveis mais elevados de 1,22 e 11,1 g planta-1 de potássio e cloro, respectivamente. O acúmulo de S na folha batata foi influenciado pela adubação potássica onde aos 89 DAP foram observadas diferenças entre os tratamentos, tendo o 4 o maior acúmulo, enquanto que o 7 foi o menor, não diferindo dos demais. No tubérculo, os tratamentos 7, 1 e 2 apresentaram maiores valores, sendo que por volta dos 91 DAP à taxa máxima foi de 1,31g planta-1. Os tratamentos 1 e 2 apresentaram maiores acúmulos de S, onde aos 110 DAP alcançou 1,12 g planta-1. Os maiores valores de acúmulo de cloro nos tubérculos durante o ciclo foram 0,10, 0,90, 0,10, 013, 0,13 e 0,13, g planta-1 aos 92, 104, 88, 87, 86 e 82 DAP respectivamente, apresentando aos 47, 68 e 89 DAP, diferenças entre tratamentos. Os tratamentos não influenciaram quanto ao teor de sólidos solúveis classificação e produtividade. Os números de tubérculos sofreram interferência dos tratamentos nas duas últimas coletas, onde aos 110 DAP apresentou 18,22; 19,70;19,96;20,39;19,20;16,01 e 13,79 tubérculos planta-1 para os tratamentos 1, 2, 3, 4, 5, 6 e 7 respectivamente. A cultivar de batata Atlantic sofreu influência da adubação potássica nos acúmulos de nutrientes das folhas e tubérculos e no número de tubérculos planta-1, não sofrendo influência na classificação, nos sólidos solúveis e produtividade de tubérculos. / Mestre em Agronomia

The distribution, absorption, metabolism and tissue binding of radioactivity were studied in hamsters after oral and intraperitoneal administration of alpha-chaconine- (3H). The material was well absorbed from the gastrointestinal tract and nearly 22 percent of the label was excreted via urine and feces in 7 days. The excretion was higher in urine (21 percent) than in feces ( < 1 percent). Tissue concentrations of radioactivity peaked at 12 hours following oral administration, with the highest concentrations found in lungs, liver, spleen, skeletal muscle, kidney and pancreas, with heart and brain containing moderate amounts. Concentrations of radioactivity in tissues following intraperitoneal administration were significantly higher than those observed after oral treatment. Excretion of chloroform-soluble products in the feces was 10 times higher than that of the chloroform-insoluble metabolites after both oral and intraperitoneal administration. In the urine, the activity was predominantly in the chloroform-insoluble form and the chloroform-soluble metabolites were relatively minor in amounts (0.27, 0.85, and 2.45 percent versus 0.005, 0.14 and 0.19 percent of dose for 12, 24 and 72 hours, respectively). After 7 days, the chloroform-soluble metabolites in urine increased to 20 percent of the excreted radioactivity, while the amount of chloroform-insoluble metabolites was less than 1 percent. Subcellular distribution of the labeled compound indicated the highest concentration of radioactivity in the nuclear and microsomal fractions of brain, liver and heart tissues. A small amount of radioactivity, shown by a minor peak, was also observed in the fractions between the mitochondrial and microsomal fractions on a sucrose gradient. Binding of radioactivity was observed in brain, testes, kidney, lung, liver and heart . All of the label in the brain appeared to be in the bound form . The results indicated that alpha-chaconine is slowly absorbed from the gastrointestinal tract after oral administration, and persists in various tissues, much of it in bound (non-extractable) form (in nuclear and microsomal fractions). Excretion of alpha-chaconine- (3H) and its metabolites was investigated after oral and intraperitoneal administration in hamsters. The separation of the glycoalkaloid and its metabolites in feces and urine was accomplished by thin-layer chromatography. An increase in the concentration of excreted alpha-chaconine metabolites in feces and urine was observed. In urine over 50 percent of the eliminated radioactivity during the initial 24 hours was due to the aglycone, solanidine. The fraction of the total dose administered which was excreted represented only 27 percent (26 percent in feces and less than 1 percent in urine) during the 7 day test period. Contrary to the general belief that potato glycoalkaloid absorption is poor following oral administration, only 5 percent or less was excreted in feces during the initial 72 hours, a fact explained by the binding of radioactivity to tissues. Inhibition of acetylcholinesterases by alpha-chaconine was studied. The inhibition of purified erythrocyte acetylcholinesterase and horse serum cholinesterase by alpha-chaconine was found to be a mixed-type with kinetic constants. An inhibition constant (Ki) for both the specific and pseudocholinesterases was 8.3 x 10-6 M and 4.0 x 10-4 M, respectively. Kinetic constants obtained for both enzymes were as follows: Vmax of 7.14 x 10-5 and 3.76 x 10-4 max moles/liter/min, respectively, and Km of 6.2 x 10-5 and 1.33 x 10-4, respectively. The distribution of acetylcholinesterase among the subcellular fractions of rat brain homogenate separated by sucrose density gradient centrifugation was determined, as well as the inhibition pattern of these fractions following in vitro incubation with 0.016 M alpha-chaconine. Enzyme activity was found to be distributed equally between the mitochondrial and microsomal fractions, with the nuclear fraction having the least activity. Percentage inhibition of the various fractions obtained was: whole homogenate 43, nuclear fraction 55, mitochondria 35, and microsomes 33. Brain acetyl cholinesterase activity of animals given intraperitoneal doses (10, 30, 60 mg / Kg) of alpha-chaconine was 79, 55 and 18 percent of the control group. Acetylcholinesterase activity of heart and plasma of animals administered alpha-chaconine did not show the dose-related response observed in the brain. Inhibition of heart acetylcholinesterase was 61 percent, while plasma gave 51 percent for the rats given a dose of 10 mg/Kg and no inhibition for rats given 30 mg/ Kg. Acrylamide gel electrophoretic separation of cholinesterases in aqueous homogenates from whole brain and heart of adult male rats administered alpha-chaconine was investigated. Brain acetylcholinesterase isoenzymes were found to be inhibited by 30 and 60 mg/ Kg dosage levels of alpha-chaconine administered intraperitoneally. Electrophoretic separation of plasma from the treated animals resulted in five anodally migrating zones having properties of cholinesterases. These sites hydrolyze acetylthiocholine and alpha-naphthylacetate, and all were inhibited by alpha-chaconine except the slowest migrating band (band 5). Inhibition of isoenzyme activity of bands 1 and 2 is observed for the groups administered 10 and 30 mg/Kg alpha-chaconine with the percentage inhibition of both bands (l and 2) being 40 and 77 percent for animals given 10 mg/Kg and 100 and 75 percent for the latter group. Isoenzyme bands 3 and 4 were completely absent in the alkaloid treated animals. Inhibition of non-specific cholinesterase isoenzymes (butyrylthiocholine hydrolyzable bands) by alpha-chaconine was clearly demonstrated. In vitro inhibition of plasma, erythrocyte and brain esterase isoenzymes was estimated by incubating gels with 10-4 M alpha-chaconine after the electrophoretic separations. With this concentration of alpha-chaconine, the various isoenzymes in rat plasma, erythrocyte and brain showed some response to the inhibitory potency of alpha-chaconine. The slower-moving isoenzyme bands were inhibited to 100 percent with the different concentrations of inhibitor. The fast migrating isoenzyme bands in plasma and erythrocytes were least affected by alpha-chaconine (10-4 M), with no inhibition. Plasma protein isoenzymes from adult male rats were not affected by alphachaconine.