Dissertation (PhD (Agric))--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Orientador: Roberto Lyra Villas Boas / Banca: Dirceu Maximino Fernandes / Banca: Antonio Enebi Boaretto / Banca: Francisco Antonio Monteiro / Banca: William Natale / Resumo: O nitrogênio é o elemento que proporciona as maiores respostas no crescimento das gramas e a adubação nitrogenada adequada pode proporcionar a formação do tapete em menor tempo, com boa qualidade. Para testar esta hipótese, o experimento teve como objetivos: (a) determinar a dose de N que permita a produção de tapetes, de boa qualidade, das gramas Zoysia japonica (Esmeralda) e Stenotaphrum secundatum (Santo Agostinho) em menor tempo de produção; (b) estudar a respostas dessas gramas em relação às doses de N; (c) estudar características das gramas que possam auxiliar no manejo da adubação nitrogenada. Foram instalados dois experimentos em fazenda de produção de grama, em Itapetininga, SP, no ano de 2003. O delineamento experimental adotado em ambos experimentos foi em blocos casualizados com quatro repetições. O primeiro foi realizado em uma área de produção de grama Esmeralda, em esquema fatorial 4 x 2 com quatro doses de N: 150, 300, 450 e 600 kg ha-1, divididos em três ou seis aplicações, mais um tratamento que não recebeu N. O segundo experimento foi realizado em uma área de cultivo de grama Santo Agostinho aplicando quatro doses de N: 150, 300, 450 e 600 kg ha-1, divididas em três aplicações, mais um tratamento que não recebeu N. O aumento das doses de N influenciou a taxa de cobertura do solo pela grama Santo Agostinho e Esmeralda reduzindo o tempo para formação do tapete. A concentração de N na folha e da cor verde da grama foram influenciadas pelas doses de N, em ambas espécies, podendo ser utilizadas para auxiliar na recomendação das doses de N. A imagem digital mostrou-se adequada para indicar a taxa de cobertura do solo e a cor verde da folha das gramas Santo Agostinho e Esmeralda. Doses de N entre 350 e 400 kg ha 1 proporcionaram a produção de tapetes de grama Santo Agostinho e Esmeralda... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Nitrogen is the nutrient that provides the largest responses in turfgrass growth and the adequate N fertilization may provide sod production in shorter period, with good quality. To test this hypothesis the experiment had as objectives: (a) to determine the N rate that improves Zoysia japonica (Zoysiagrass) and Stenotaphrum secundatum (St. Augustinegrass) sod quality production, in a shorter period; (b) to study the answers of turfgrass as function of N rates; (c) to study turfgrass characteristics that may help in N fertilization management. Two experiments were conducted in a sod production farm, in Itapetininga, São Paulo State, Brazil, in the year of 2003. The experiments were set in complete blocks design, with four replications. The first experiment was developed in Zoysiagrass sod production area, in a factorial 4 x 2, with four N rates: 150, 300, 450 e 600 kg ha-1, splitting in three or six applications, plus a treatment that didn't receive N. The second experiment was developed in St. Augustinegrass sod production area, with four N rates: 150, 300, 450 e 600 kg ha-1, splitting in three applications, plus a treatment that didn't receive N. The increasing of N rates influenced the soil cover rate by the St. Augustinegrass and Zoysiagrass, reducing the sod production period. The N concentration in leaf and turfgrass green color were influenced by the N rates, in both species and may be used to help in the N rate recommendation. The digital image showed to be adequate to measure the soil cover rate and the green color of St. Augustinegrass and Zoysiagrass leaves. The N rates between 350 and 400 kg ha-1 promoted the St. Augustinegrass and Zoysiagrass sod production, with good quality. Splitting N rates, in three or six applications, hasn't changed the Zoysiagrass sod production period. / Doutor

Made available in DSpace on 2014-06-11T19:30:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-03-23Bitstream added on 2014-06-13T20:00:33Z : No. of bitstreams: 1 godoy_ljg_dr_botfca.pdf: 2954029 bytes, checksum: 81cadea9f84428b17c7c5c0cf69a2fc6 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O nitrogênio é o elemento que proporciona as maiores respostas no crescimento das gramas e a adubação nitrogenada adequada pode proporcionar a formação do tapete em menor tempo, com boa qualidade. Para testar esta hipótese, o experimento teve como objetivos: (a) determinar a dose de N que permita a produção de tapetes, de boa qualidade, das gramas Zoysia japonica (Esmeralda) e Stenotaphrum secundatum (Santo Agostinho) em menor tempo de produção; (b) estudar a respostas dessas gramas em relação às doses de N; (c) estudar características das gramas que possam auxiliar no manejo da adubação nitrogenada. Foram instalados dois experimentos em fazenda de produção de grama, em Itapetininga, SP, no ano de 2003. O delineamento experimental adotado em ambos experimentos foi em blocos casualizados com quatro repetições. O primeiro foi realizado em uma área de produção de grama Esmeralda, em esquema fatorial 4 x 2 com quatro doses de N: 150, 300, 450 e 600 kg ha-1, divididos em três ou seis aplicações, mais um tratamento que não recebeu N. O segundo experimento foi realizado em uma área de cultivo de grama Santo Agostinho aplicando quatro doses de N: 150, 300, 450 e 600 kg ha-1, divididas em três aplicações, mais um tratamento que não recebeu N. O aumento das doses de N influenciou a taxa de cobertura do solo pela grama Santo Agostinho e Esmeralda reduzindo o tempo para formação do tapete. A concentração de N na folha e da cor verde da grama foram influenciadas pelas doses de N, em ambas espécies, podendo ser utilizadas para auxiliar na recomendação das doses de N. A imagem digital mostrou-se adequada para indicar a taxa de cobertura do solo e a cor verde da folha das gramas Santo Agostinho e Esmeralda. Doses de N entre 350 e 400 kg ha 1 proporcionaram a produção de tapetes de grama Santo Agostinho e Esmeralda... / Nitrogen is the nutrient that provides the largest responses in turfgrass growth and the adequate N fertilization may provide sod production in shorter period, with good quality. To test this hypothesis the experiment had as objectives: (a) to determine the N rate that improves Zoysia japonica (Zoysiagrass) and Stenotaphrum secundatum (St. Augustinegrass) sod quality production, in a shorter period; (b) to study the answers of turfgrass as function of N rates; (c) to study turfgrass characteristics that may help in N fertilization management. Two experiments were conducted in a sod production farm, in Itapetininga, São Paulo State, Brazil, in the year of 2003. The experiments were set in complete blocks design, with four replications. The first experiment was developed in Zoysiagrass sod production area, in a factorial 4 x 2, with four N rates: 150, 300, 450 e 600 kg ha-1, splitting in three or six applications, plus a treatment that didn't receive N. The second experiment was developed in St. Augustinegrass sod production area, with four N rates: 150, 300, 450 e 600 kg ha-1, splitting in three applications, plus a treatment that didn't receive N. The increasing of N rates influenced the soil cover rate by the St. Augustinegrass and Zoysiagrass, reducing the sod production period. The N concentration in leaf and turfgrass green color were influenced by the N rates, in both species and may be used to help in the N rate recommendation. The digital image showed to be adequate to measure the soil cover rate and the green color of St. Augustinegrass and Zoysiagrass leaves. The N rates between 350 and 400 kg ha-1 promoted the St. Augustinegrass and Zoysiagrass sod production, with good quality. Splitting N rates, in three or six applications, hasn't changed the Zoysiagrass sod production period.

Species possess characteristics that are considered adapted to burning and these allow them to outcompete species and dominate in fire prone environments. It has therefore been proposed that fire might have played a critical role in the observed expansion of the grasslands, during the late Miocene. The aim of this study was (i) to investigate whether plant response to fire was a result of physiology or (ii) whether it was due to phylogenetic history. This was achieved by doing a pair-wise comparison between Panicoideae (and Panicoideae) and non-Panicoideae (Danthonioideae and Aristidoideae) species. Pre-fire characteristics, that would enhance fire frequency and assist with plant recovery after burning, were compared across phylogenies and photosynthetic type. Post fire plant recovery was then followed in a field and pot comparison which examined the re-growth of the leaf canopy area, leaf mass, above-ground biomass and the cost of this to the below-ground biomass. The pre-fire characteristics showed both a photosynthetic and phylogenetic response. It was found that the species showed a greater canopy death during winter and had a lower moisture content than the species. These characteristics would potentially contribute towards a larger fuel load in the species. However, the comparison of the dead standing biomass at the end of winter and the below-ground biomass, showed a phylogenetic response with the Panicoideae having a proportionally larger dead standing biomass and below-ground biomass than the non-Panicoideae. These results suggest that not only did the Panicoideae have a larger potential fuel load but that they also shunted carbon below-ground, enabling a fast recovery after being burned. The post-fire results were more strongly determined by phylogeny than by photosynthetic type. The Panicoideae recovered faster and more completely than the non-Panicoideae grasses, possibly contributing to their success and expansion under conditions of increased fire frequency. Although recovery of the and Panicoideae were similar, frequently burnt grasslands are dominated by the Panicoideae. Hence, this dominance cannot be explained by differences in their fire responses and may be determined by the post-fire environmental conditions that potentially advantage species possessing the photosynthetic pathway. Panicoideae dominance is limited to mesic environments where fire is the likely driver of grassland expansion while more arid environments are dominated by non-Panicoideae species. Representative species from these non-Panicoid subfamilies showed poor recovery after fire. This suggests that factors other than fire were the likely drivers of these xeric grassland expansions. The ability of these subfamilies, and particularly the species, to cope with drought remains a likely selective mechanism that requires further research.

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