The welfare of mankind is intimately bound up with the welfare of soils and plants as all of man's food comes, in the, first instance, from plants. Much research has been done to increase yields but little is known of the nutrient values of plants. Since little is known about potassium's effect on the nutrient value of plants, and because carrots have a high Vitamin A precursor content and radishes have a higher Vitamin C content, the author decided to determine what level of potash fertilization should be applied for optimum nutrient value in carrots and radishes. His decisions were, that while the addition of potash to land containing sufficient readily available potassium appears to tend to reduce yields, it does increase the mineral content of the produce. It also increases the total sugar up to a point after which it inhibits the carbohydrate formation. The author also found that additional potassium has no effect on the nitrogen content and, while it has no significant effect on the Vitamin A content it does have a very definite upward trend to produce more with the increases of potassium applied. The addition of potash increases the trend to produce more Vitamin C to the extent that high and very high levels of potassium applications become significant. The author found that correlation exists between the application of potassium and the protective nutrient value in plants. / Land and Food Systems, Faculty of / Graduate

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Ph. D.

Three crops of corn (<i>Zea mays</i> L.) were grown on four Coastal Plain soils in a greenhouse study to determine the effects of increasing rates of Kon corn growth, elemental composition of corn tissue and soil nutrient levels. Plant height and production of dry matter were measured to determine the effect of K application on corn yield. Plant tissue concentrations of Ca, Mg and K were determined, as were NH₄OAc extractable soil Ca, Mg and K. Potassium, as KCl, was applied at rates of 0, 100, 200, 300 and 400 ppm K to the first corn crop. Potassium application of 100 ppm increased corn yield on the Kenansville and Uchee soils, but no further increase or decrease in yield occurred at higher K rates. Increasing K rates caused an increase in plant tissue Kand a simultaneous decrease in plant tissue Mg. Plant tissue Ca was also reduced in plants grown on the Kenansville and Uchee soils. Magnesium deficiency symptoms were observed on corn plants grown at K rates greater than 100 ppm Kon the Goldsboro, Kenansville, and Uchee soils. Magnesium deficiency was confirmed by plant tissue analysis which revealed plant Mg levels as low as 0.07% on the Goldsboro soil. A second corn crop was grown in the previously amended soil. Results were similar to the first crop with yield increasing with the application of 200 ppm K on the Kenansville and Uchee soils. Yields did not significantly increase or decrease at higher K rates. Plant tissue K increased with increasing K rates with a simultaneous decrease in plant tissue Mg in plants grown on three of the four soils. Potassium, as K₂SO₄•2MgSO₄, was applied to a third corn crop at the same K rates as the first crop (ie. 0, 100, 200, 300, and 400 ppm K). Application of K₂SO₄•2MgSO₄ also supplied Mg at rates of 0, 60, 120, 180 and 240 ppm Mg. Plant yield increased at the 100 ppm K application rate on the Kenansville and Uchee soils, but decreased at rates of 300 ppm Kor greater on the Kenansville and at rates of 200 ppm Kor greater on the Uchee soil. Plant tissue K increased in plants grown on all soils, and Mg increased in plants grown on three of the four soils. However, Ca levels in plant tissue were reduced with increasing Kand Mg application in plants grown on all soils. Reduction in yield on the Kenansville and Uchee soils coincided with Ca levels of 0.3% or less. These Ca levels are considered to be insufficient for proper plant growth and decreases in plant yield were attributed to Ca deficiency. Excessive rates of K as K₂SO₄•2MgSO₄ (300 and 400 ppm K) were necessary to induce Ca deficiency. / M. S.

Orientador: Adalton Mazetti Fernades / Coorientador: Pablo Forlan Vargas / Banca: Roberto Lyra Villas Bôas / Banca: Fábio Rafael Echer / Resumo: Para a maioria das hortaliças que produzem raízes tuberosas, o potássio (K) é o nutriente mineral exigido em maior quantidade. Entretanto, a aplicação de doses elevadas desse nutriente pode prejudicar o desenvolvimento das plantas, devido ao aumento da concentração salina ou mesmo decorrer em grandes perdas por lixiviação, especialmente em solos arenosos. Desta forma, o objetivo deste trabalho foi avaliar o crescimento e a produtividade da batata-doce submetida a doses e formas de parcelamento da adubação potássica em solos com diferentes teores iniciais de potássio (K). Foram conduzidos quatro experimentos em áreas com diferentes disponibilidades iniciais de K no solo (baixa = 0,7 mmolc dm-3; média = 1,4 e 1,5 mmolc dm-3 e alta = 3 mmolc dm-3) entre os anos de 2016 e 2018. O delineamento experimental utilizado foi o de blocos ao acaso, no esquema fatorial 3x4+1. Os tratamentos foram representados por três doses de K2O (60, 120 e 240 kg ha-1) combinadas com quatro formas de parcelamento (1 = 100% no plantio; 2 = 1/2 no plantio + 1/2 aos 40 dias após o plantio (DAP), 3 = 1/2 no plantio + 1/2 aos 90 DAP; 4 = 1/3 no plantio + 1/3 aos 40 DAP + 1/3 aos 90 DAP), além da testemunha sem K. O crescimento das plantas, em termos de biomassa produzida, aumenta em solos com baixo e médio teor inicial de K até as doses de 145 e 115 kg ha-1 de K2O, respectivamente. Em solos com alto teor inicial de K (≥ 3,0 mmolc dm-3), a adubação potássica não contribuiu para o acúmulo de matéria seca da p... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Among the majority of tuberous roots vegetables, potassium (K) is the most required mineral nutrient. However, the application of high rates of this nutrient may harm the plants development, due to the increase in saline concentration or even in large losses by leaching, especially in sandy soils. Thus, the purpose of this work was to evaluate the growth and yield of sweet potato submitted to rates and forms of K split application in soils with different K concentration. Four experiments were carried out in areas with different initial K availability in the soil (low = 0.7 mmolc dm-3, medium = 1.4 and 1.5 mmolc dm-3 and high = 3 mmolc dm-3) between 2016 and 2018. The experimental design was a randomized block design in the 3x4 + 1 factorial scheme. The treatments were represented by three doses of K2O (60, 120 and 240 kg ha-1) combined with four forms of plotting (1 = 100% at planting, 2 = 1/2 at planting + 1/2 at 40 days after planting (DAP), 3 = 1/2 at planting + 1/2 at 90 DAP, 4 = 1/3 at planting + 1/3 at 40 DAP + 1/3 at 90 DAP), in addition to the control without K. In terms of biomass produced, the plant growth increases in soils with low and medium initial K concentration up to 145 and 115 kg ha-1 of K2O, respectively. In soils with a high initial concentration of K (≥ 3.0 mmolc dm-3), K fertilization did not contribute to the accumulation of dry matter of the plant, but reduces the biomass accumulation in the tuberous roots. In soil with low initial K concentration, the commercial yield increases up to 171 kg ha-1 of K2O, and in soils with a medium initial K concentration, the increase in commercial yield reaches rates between 106 and 111 kg ha-1 of K2O. However, under high initial availability of K, the commercial yield reduces with the potassium fertilization until the rate of 60 kg ha-1 of K2O. The split application of K (planting + 40 + 90DAP) was shown to be more efficient in increasing ... / Mestre

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Orientador: Marco Antonio Tecchio / Banca: Hélio Grassi Filho / Banca: Luiz Antonio Junqueira Teixeira / Resumo: Objetivou-se avaliar a influência de porta-enxertos, fontes e doses de potássio na duração dos estádios fenológicos, na produção e nas características físicas e químicas dos cachos e bagas da uva 'Niagara Rosada'. O experimento foi realizado nos ciclos produtivos de 2016 e 2017 na Faculdade de Ciências Agronômicas - UNESP, no município de Botucatu-SP, situado a 22º 51' 55" S e 48º 27' 22" O e a 810 m. O sistema de condução utilizado nas videiras foi a espaldeira baixa no espaçamento de 2,0 x 0,8 m. O delineamento experimental foi de blocos casualizados em esquema fatorial 4 x 2 x 2, sendo quatro doses (0, 75, 150, 300 kg K2O ha1), duas fontes de potássio (cloreto de potássio e sulfato de potássio) e dois porta-enxertos ('IAC 572' e 'IAC 766'). Em cada ciclo de produção, a aplicação dos tratamentos foi parcelada em duas vezes durante o ciclo, sendo a metade da dose aplicada na época da poda e outra no início da maturação dos frutos. As variáveis analisadas durante os ciclos foram a avaliação dos estádios fenológicos, análise de K disponível no solo e diagnose foliar. Na colheita foram avaliadas: produção, produtividade, massa fresca, comprimento e largura dos cachos, massa fresca de bagas e engaços. No mosto da uva foram avaliados o teor de sólidos solúveis (SS), Acidez titulável (AT), relação (SS/AT) e pH. Concluiu-se que, a adubação potássica incrementou os teores de potássio no solo nas camadas de 0-20 e 20-40 cm, e os teores de potássio e cálcio nas folhas na época da flor... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to evaluate the influence of rootstocks, sources and rates of potassium in the production and physicochemical characteristics of bunches and berries of grape 'Niagara Rosada'. The experiment was conducted in the productive cycles of 2016 and 2017 at the Experimental Farm of the Faculty of Agricultural Sciences- UNESP, located in Botucatu, SP (22º 51' 55" S and 48º 27' 22" O and 810 m). The plants were spaced 2,0 x 0,80 m, in espalier support system low. The experimental design was a randomized complete block design in a 4 x 2 x 2 factorial scheme, with four rates (0, 75, 150, 300 kg K20 ha-1), two potassium sources (potassium chloride and potassium sulfate) and two rootstocks ('IAC 572' and 'IAC 766'). The application of the treatments were divided in two times in the cycle, half of the rate in the season of pruning and another half in the beginning of the maturation of the fruits. During the cycle were evaluated the phenological stages, potassium contents in the soil and nutritional leaf samples. At harvest, were evaluated: production; productivity; fresh weight, length and width of bunches, weight of berries and stems. The must grape was evaluated for soluble solids (SS), titratable acidity (TA), relationship SS/TA and pH. It was concluded that, potassium fertilization increased the potassium contents in the layers of 0-20 and 20-40 cm, and in the potassium contents and leaf compensation at the time of flowering. Potassium fertilization is not influential in production, productivity and physical and chemical characteristics ... / Mestre

Thesis (Ph.D.)--University of Hawaii at Manoa, 1994. / Includes bibliographical references (leaves 97-114). / Microfiche. / xiii, 114 leaves, bound ill. 29 cm

Typescript. / Thesis (Ph. D.)--University of Hawaii, 1967. / Bibliography: leaves 145-152. / xiii, 152 l illus., tables