Please read the abstract in the section 00front of this document / Thesis (PhD (Soil Science))--University of Pretoria, 2007. / Plant Production and Soil Science / unrestricted

Submitted by MIRIAM BÜCHLER TARUMOTO null (miriamtarumoto@gmail.com) on 2016-03-30T21:54:43Z No. of bitstreams: 1 DissertaçãoTarumoto2016.pdf: 1751155 bytes, checksum: c28f218af2401297106ae7c562f5cb51 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-04-01T20:17:28Z (GMT) No. of bitstreams: 1 tarumoto_mb_me_bot.pdf: 1751155 bytes, checksum: c28f218af2401297106ae7c562f5cb51 (MD5) / Made available in DSpace on 2016-04-01T20:17:28Z (GMT). No. of bitstreams: 1 tarumoto_mb_me_bot.pdf: 1751155 bytes, checksum: c28f218af2401297106ae7c562f5cb51 (MD5) Previous issue date: 2016-02-26 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Existindo diferentes comportamentos na absorção e utilização de fósforo entre genótipos, e devido à importância deste elemento para a cana de açúcar, objetivou-se por meio do acompanhamento do desenvolvimento inicial de plantas de cana-de-açúcar cultivadas em solução nutritiva, avaliar parâmetros nutricionais e biométricos de dois genótipos de cana-de-açúcar quando submetidas a condições distintas de disponibilidade de fósforo. O delineamento experimental foi inteiramente casualizado, em esquema fatorial (2x2), composto por duas variedades: 1- RB966928 (variedade classificada como precoce e exigente) e 2- RB867515 (variedade classificada como tardia e rústica) submetidas a duas concentrações de P nas soluções nutritivas de crescimento, consideradas de baixa (2 mg L-1) e alta (16 mg L-1) disponibilidade. Foram cultivadas cinco repetições por tratamento, perfazendo-se 20 unidades experimentais. Os resultados do trabalho mostraram que a variedade RB867515 é mais eficiente em usar P em condições limitantes. Porém, em condições de alta disponibilidade de fósforo a variedade RB966928 é mais eficiente. Apesar da variedade RB867515 ser responsiva quando submetida à alta disponibilidade de P, apresenta maior influência das variações do teor de fósforo em cana-de-açúcar, quando comparada à variedade RB966928, que se mostrou responsiva e não exigente, ou seja, é menos sensível a diferentes teores de fósforo em cana-de-açúcar. Em início de desenvolvimento há diferença entre as variedades para parâmetros biométricos e nutricionais da planta e morfológicos de raiz de cana-de-açúcar cultivada em solução nutritiva em níveis de fósforo, sendo a variedade RB966928 mais responsiva. O nível de alta disponibilidade de fósforo proporciona maiores parâmetros morfológicos de raiz, massa de matéria seca da planta e reduz a relação raiz/parte aérea; aumenta o acúmulo de N, P, K, Ca, Mg, S, Cu, Zn, Mn, Fe; aumenta a absorção de N, P, K, Ca, Mg, S, Zn, Mn e Fe por metro de raiz. A eficiência da utilização de nitrogênio, fósforo e zinco foi prejudicada em condições de alta disponibilidade de fósforo. A variedade RB966928 apresenta maior acúmulo de nutrientes por planta, maior absorção de nutrientes por comprimento de raiz e é mais eficiente no uso de N, Ca, Mg, S, Cu, Zn, Mn, Fe. / Existing different behavior in the absorption and utilization of phosphorus among genotypes, and because of its importance for sugarcane, aimed to by monitoring the initial development of sugarcane plants cultivated in nutrient solution, to evaluate nutritional and biometric parameters of two genotypes of sugarcane when subjected to distinct conditions of phosphorus availability. The experimental design was completely randomized in a factorial scheme (2x2), composed of two varieties: 1- RB966928 (variety classified as early and demanding) and 2- RB867515 (variety classified as late and rustic) submitted to two concentrations of P in solutions nutritive growth considered low (2 mg L-1) and high (16 mg L-1) availability. Five replicates per treatment were grown, making up 20 experimental units. Our results showed that RB867515 variety is more efficient in use of P in limiting conditions. However, in high availability of phosphorus conditions RB966928 variety is more efficient. Despite the variety RB867515 be responsive when subjected to the high availability of P, has greater influence of phosphorus variations in sugarcane compared to the variety RB966928, which proved to be responsive and unfussy, meaning it is less sensitive the different levels of phosphorus in sugarcane. In the beginning of development there are differences between varieties for biometric and nutritional plant parameters and morphological root sugarcane grown in nutrient solution in phosphorus levels, and the RB966928 is more responsive. The phosphorus high availability provides greater morphological parameters of root, dry weight of the plant and reduces the root/shoot; increases the accumulation of N, P, K, Ca, Mg, S, Cu, Zn, Mn, Fe; increases the absorption of N, P, K, Ca, Mg, S, Zn, Mn and Fe by roots length. The efficient use of nitrogen, phosphorus and zinc was impaired in high availability phosphorus conditions. The RB966928 variety has a higher accumulation of nutrients per plant, increased nutrient uptake by root length and is more efficient in the use of N, Ca, Mg, Cu, Zn, Mn, Fe.

Although silicon (Si) has not yet been recognized as an essential nutrient element, its application to sugarcane (Saccharum officinarum L.) has proved to be beneficial. Since optimum crop production depends on the maintenance of adequate plant nutrients in the soil, there is a need in the South African sugar industry for a reliable index for assessing the requirement for supplemental silicon (Si) in soils, particularly in reducing the risk of Eldana saccharina stalk borer infestation in cane. The objective of this study was to assess Si availability in soils, to select a suitable Si extraction method and a critical value for determining when a response is likely. For this purpose, five acid soils (representing. some of the most important agricultural soil groups used for sugarcane production in the sugar belt) were used in October 2004, in the lAKE WILSON glasshouse of the South African Sugarcane Research Institute (SASRI) based at Mount Edgecombe. Except for the Arcadia form soil with an initial Si content of 1.2 mmol kg- I as estimated using the O.OlM H2S04 + (NH4)zS04) extractant, soils representing the other five soil forms namely Cartref, Glenrosa, Longlands and Nomanci; exhibited a sub-optimal Si content of not more than 4.0 mmol kg-I. Sorghum was used as a plant crop and sugarcane as a ratoon crop because of their Si accumulator status. Three different Si sources: calmasil, slagment and wollastonite; with respectively 9.85, 15.20, and 5.25% Si content were applied at increasing rates of 0, 3 and 6 tons ha- 1 as Si fertilizers. Silicon (Si) was extracted from untreated and treated soils by utilizing six different extractants, (1) O.OlM H2S04 + (NH4)2S04; (2) Distilled water; (3) 0.025M H2S04; (4) 0.5M CH3COOH; (5) 0.5M CH3COONH4pH 4.8; and (6) O.OlM CaCh.2H20. The amount of soil Si extracted followed the order: 0.025M H2S04 > 0.5M CH3COOH > O.OlM H2S04 + (NH4)2S04 > O.OlM CaCh.2H20 > 0.5M CH3COON~ pH 4.8 > distilled water. Soil Si extracted by 0.025M H2S04 was significantly correlated with soil exchangeable cations,. CEC, clay content, cane biomass yield, cane Si uptake and increasing rates of applied Si. Averaged over all soil forms investigated, the increases in dry biomass yield and Si uptake ranged. from 18% to 154% for sorghum; and from 23% to 85% for cane respectively. Even though the highest increases (%) in cane biomass yield and Si uptake were obtained on a Nomanci form soil with initial poor fertility status, the highest means were obtained on an Arcadia form soil with the highest Si initial content. There was no difference between different Si sources in their ability to influence cane biomass yield and Si uptake, and therefore the supply to the soils. Even though the lower and higher Si source rates were not different from each other, they increased cane yield and Si uptake, indicating that Si was undoubtedly beneficial for sugarcane. The Si critical levels for different soils as estimated by 0.025M H2S04 were 6.0 mmol kg-1 (168 mg kg-I) for Arcadia; 2.6 mmol kg-I (64 mg kg-I) for Cartrel; 2.5 mmol kg-I (64 mg kg-I) for Glenrosa; 1.6 mmol kg-I (45 mg kg-I) for Longlands; and 2.4 mmol kg-I (67 mg kg-i) for Nomanci form soils. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.