Student Number : 9907276D - MSc Dissertation - School of Animal, Plant and Environmental Sciences - Faculty of Science / The broad aim of this study was to measure the ecosystem repair of the Sabie River (which traverses through both the grassland and savanna biomes) riparian environment in Mpumalanga, South Africa, in response to the clearing of alien plants by the Working for Water (WfW) alien plant clearing programme. This was done in order to assess the effectiveness of the WfW clearing on the Sabie River riparian plant community composition and associated environmental factors. Although “effectiveness” can be assessed in various ways, in this study it included determining whether there was a reduction in the invasion intensity (defined as the percentage aerial cover of woody alien plants) after clearing. This broad aim was achieved by studying the impacts of the WfW alien plant clearing programme, as well as the invasion of alien plants, on the plant species composition, diversity and vegetation structure of riparian ecosystems on the Sabie River. Hence, in 2005 40 modified Whittaker nested plots were sampled. The impacts on the Sabie River riparian environment were also assessed by measuring various environmental variables that are likely to change as a result of clearing, such as the ground cover (percentages of exposed soil, rock, litter, herbaceous vegetation and grass), as well as various soil chemical and physical properties. Twenty plots were surveyed along the Sabie River in the Hazeyview region (savanna biome), ten in the Sabie region (grassland biome) and ten in the Graskop region (grassland biome). The response of the Sabie River riparian community to invasive alien plant clearing by WfW (and the alien plant invasion itself) was also assessed over time, by comparing the 2005 study with one done in 1996, which used the same plots. In 2005, a cumulative total of 282 species were found, 222 (79%) of which were indigenous and 60 (21%) alien. The grassland sites had a higher cumulative total of 222 species compared with the 171 species in the savanna sites. A total of 112 (39%) species were common between the biomes, 86 (30%) of which were indigenous and 26 (9%) alien. At the 1000 m2 scale, the indigenous species richness (32.4 ± 1.4 (S.E.)) was significantly higher than the alien species richness (12.0 ± 0.5) (P < 0.001). Of the 60 alien species, 17 (28%) were shrubs and 15 (25%) trees. The grassland sites were more species rich at the 1000 m2 scale (48.8 ± 1.8) and diverse at the 100 m2 scale (Simpson’s index of alpha diversity of 0.90 ± 0.01) than the savanna sites (species richness of 40.0 ± 2.1 and alpha diversity of 0.85 ± 0.02; P = 0.003 for species richness and P = 0.04 for alpha diversity). The Sabie sites were more species rich at the 1000 m2 scale (52.6 ± 2.8) than the Graskop sites (45.0 ± 1.4) (P = 0.12). The higher species richness in the Sabie region contributed to the higher total species richness in the grasslands relative to the savanna sites. At the 1000 m2 scale, the overall beta diversity (Sorenson’s coefficient of community) between the biomes was 0.57, and the species complementarity (the Marczewski-Steinhaus distance) between the biomes was 0.60, indicating that the biomes were not that similar in terms of species composition. Even though the grassland was more rich and diverse in terms of species than the savanna, the overall relative abundances of plant species in each biome was very similar (species evenness (Simpson’s measure of evenness), at the 100 m2 scale, of 0.52 ± 0.03 in the grassland and 0.51 ± 0.03 in the savanna; P = 0.74). The savanna tended to have a higher degree of invasion intensity (aerial cover of woody alien plants of 34.4 ± 4.6% compared to 29.4 ± 4.5% in the grassland; P = 0.44), possibly due to its position lower in the catchment, and hence a sink for upstream alien plant propagules. It was hypothesized that higher plant species richness and/or diversity should enhance community resistance to alien plant invasions, in both the grassland and savanna biomes. In the Sabie (grassland) region, there was a negative correlation between the indigenous and alien species richness, thus indicating that the Sabie region plant community may have been more resistant to the invasion of alien plants than the other two regions. Therefore, the hypothesis was not rejected for the Sabie region. On the other hand, in the Graskop (grassland) and Hazeyview (savanna) regions, there were positive correlations between the indigenous and alien species richness, thus indicating that these plant communities may not have been as resistant to the invasion of alien plants. Therefore, the hypothesis was rejected for both the Graskop and Hazeyview regions. When considering the biome scale, the hypothesis was not rejected as the increase in total species richness with increasing invasion intensity in the grassland (which was more diverse than the savanna) indicated that it may have been more resistant to the invasion of alien plants than the savanna, which had a total species richness that decreased with increasing invasion intensity. In 2005, exposed soil, litter and grass covers tended to be slightly higher in the savanna (14.4 ± 1.6%; 43.5 ± 3.0%; 21.8 ± 1.7% respectively) than in the grassland (12.1 ± 2.5%; 43.2 ± 4.2%; 20.1 ± 2.3% respectively) (P = 0.43, 0.96 and 0.56 respectively). Rock and herbaceous covers were higher in the grassland (4.3 ± 1.6% and 20.3 ± 1.7% respectively) than in the savanna (0.8 ± 0.2% and 19.5 ± 2.2% respectively), but only rock cover was significantly different (P = 0.04) (P = 0.76 for herbaceous cover). These patterns in ground cover may have been a response to the slightly higher invasion intensity in the savanna. The hypothesis that the lower the degree of alien plant invasion, the higher the understorey vegetation cover, which may result in reduced cover of exposed soil and litter, in both the grassland and savanna biomes, was not rejected as the grassland tended to have a lower degree of alien invasion (although not significant), a higher cover of herbaceous vegetation, and corresponding lower covers of exposed soil and litter. The biomes (in 2005) did not differ significantly in soil pH (grassland pH: 4.6 ± 0.1; savanna pH: 4.8 ± 0.1; P = 0.34). However, the grassland soils were generally more fertile than the savanna soils, i.e. higher organic matter (4.5 ± 0.2% versus 3.3 ± 0.4%; P = 0.01) and total nitrogen (0.3 ± 0.02% versus 0.2 ± 0.02%; P = 0.03). The concentrations (mg/l) of most of the nutrients were also higher in the grassland. The lower fertility of the savanna soils may have been related to the higher litter cover of the savanna immobilizing a larger amount of available nutrients than the grassland; another possibility may have been slower rates of soil organic matter decomposition in the slightly cooler (higher altitude) grassland regions. The soils of the grassland sites tended to be more compacted (0.8 ± 0.1 kg/cm2) (but not significantly) than those of the savanna sites (0.7 ± 0.1 kg/cm2) (P = 0.43), and the savanna plots were on significantly steeper ground (12.8 ± 1.7º) than the grassland plots (4.8 ± 1.1º) (P < 0.001), which may have also contributed to lower fertility through greater leaching and erosion losses. From the detrended correspondence analysis (DCA) of the species by plot data, there were no distinct plant communities separating out between the biomes and regions. This is probably because the Sabie River riparian environment essentially supports a riparian forest/woodland, rather than reflecting the species typically found in the adjoining (more upland) grasslands and savannas. Hence, the species composition of the riparian environment was fairly uniform throughout the study area. The canonical correspondence analysis (CCA), which also incorporates the environmental variables, showed that altitude, exposed soil cover, soil pH, organic carbon content and slope steepness were the variables that most closely (and significantly) correlated with the species composition, and two of these variables relate directly to soil fertility, and the other three are indirectly related to soil fertility. Of the original “treatments” of the 1996/1997 study, namely (A) biome (grassland versus savanna), (B) invasion intensity (high (> 50%) versus low (< 50%)), and (C) clearing (cleared versus uncleared), the legacy of the latter two did not persist over time, as there was little or no clear overall relationship between the 1996 and 2005 data when analysed by ANCOVA. The cumulative total species richness sampled in the 40 plots increased from 163 species in 1996, to 282 in 2005 (42% increase). Mean species richness (at the 1000 m2 scale) was 24.1 ± 1.0 in 1996 and 44.4 ± 1.5 in 2005 (P < 0.001). Trees increased from 28 species in 1996 to 46 in 2005 (39% increase), shrubs from 44 to 82 (46%), herbaceous plants from 71 to 121 (41%), and grasses from 20 to 33 (39%). However, even though the species richness of each growth form increased over time, the proportion of each growth form remained approximately the same, i.e. in 1996, 17% of the species were trees, 27% shrubs, 44% herbaceous and 12% grasses; whereas in 2005, 16% were trees, 29% shrubs, 43% herbaceous and 12% grasses. The greatest increase over time was for category 1, 2 and 3 weed species, namely 25 in 1996 to 50 in 2005, a 50% increase. Although mean alpha diversity was higher in 2005 (0.9 ± 0.01 compared to only 0.3 ± 0.03 in 1996 (at the 100 m2 scale); P < 0.001), overall beta diversity over time (a change from 1996 to 2005) was relatively low, indicating a small change in overall species composition, despite the increase in species richness. The invasion intensity (percentage aerial cover of woody alien plants) was similar between the years, i.e. 30.0 ± 4.6% in 1996 and 31.9 ± 3.2% in 2005 (P = 0.73). When comparing the invasion intensity between the three original treatments over time, the invasion intensity of the 1996 grassland and savanna plots remained unchanged. The invasion intensity of the 1996 high invaded plots also remained unchanged over time, however the low invaded plots had a significantly higher invasion intensity in 2005 (P = 0.004). The invasion intensity of the 1996 uncleared plots remained unchanged over time, whereas the cleared plots had a significantly higher invasion intensity in 2005 (P = 0.03). These results clearly show that the legacy of the original invasion intensity and clearing treatments measured in the 1996/1997 study did not persist over time, whereas the inherent differences between the biomes did. The hypothesis that higher plant species richness and/or diversity should enhance community resistance to alien plant invasions was rejected, as both the 1996 and 2005 plant communities were not that resistant to the invasion of alien plants, even though there was a significantly higher species richness and diversity in 2005 than in 1996. It is concluded that because of both the similar growth form composition and invasion intensity over time, the WfW clearing efforts are not succeeding in the primary aim of controlling aliens, particularly woody alien species. However, there was a considerable decrease in the aerial cover of large alien plants, namely (a) alien plants > 5 m decreased from 15.8 ± 4.1% in 1996 to 5.8 ± 1.2% in 2005 (P = 0.02), and (b) those between 2 – 5 m tended to decrease from 13.3 ± 2.8% in 1996 to 11.1 ± 2.4% in 2005 (P = 0.55). However, these decreases were balanced by a considerable increase in the aerial cover of alien plants < 2 m in height, which increased from 3.9 ± 1.0% in 1996 to 15.0 ± 2.1% in 2005 (P < 0.001). This therefore showed that the WfW clearing programme is succeeding, to some extent, in removing most of the larger alien plants but not in controlling the regenerating plants, which recover through post-clearing resprouting and/or newly established seedlings. Exposed soil, rock and litter covers were higher in 2005 (13.3 ± 1.5%; 2.5 ± 0.8%; 43.3 ± 2.5% respectively) than in 1996 (2.1 ± 0.5%; 0.9 ± 0.3%; 16.4 ± 2.7% respectively) (P < 0.001 for soil and litter covers, and 0.07 for rock cover). Herbaceous and grass covers were significantly higher in 1996 (47.8 ± 2.8% and 32.8 ± 2.6% respectively) than in 2005 (20.0 ± 1.4% and 20.9 ± 1.4% respectively) (P < 0.001 for herbaceous and grass covers). These differences in the ground covers between the years may have partially been a response to the major February 2000 flood event, which cleared a large proportion of the vegetation, resulting in much greater rates of erosion and deposition of soils. The WfW clearing operations also removed a significant proportion of the vegetation, and disturbed much that remained, thus modifying the environment. The increase in litter cover may have also been due to the slightly higher invasion intensity in 2005 than in 1996. Soil pH remained unchanged over time (both years had a pH of 4.7 ± 0.1; P = 0.99), indicating that pH was unaffected by the invasion and subsequent clearing of alien plants, as well as the 2000 flood event which moved a tremendous amount of sediment. The hypothesis that the lower the degree of alien plant invasion, the higher the understorey vegetation cover, in both 1996 and 2005, was not rejected as the plots in 1996 had a lower degree of alien invasion (although not significant), a higher cover of herbaceous vegetation, and corresponding lower covers of exposed soil and litter. Along the Sabie River, the alien tree and shrub species with the greatest densities were Rubus cuneifolius (American bramble) (1828 plants/ha), Lantana camara (Lantana) (1760), Solanum mauritianum (Bugweed) (838), Indigofera macrophylla (640), Eucalyptus grandis (Saligna gum) (560), Caesalpinia decapetala (Mauritius thorn) (403), Agrimonia odorata (Agrimonia) (220), Lilium formosanum (St. Joseph’s lily) (218), and Populus x canescens (Grey popular) (125). Focusing the clearing efforts on these species will help to reduce the frequency of re-invasions, reduce costs, and increase ease of clearing. The primary aim of the WfW programme is to increase water supplies by controlling woody alien plants. Therefore, it is concluded that the WfW clearing along the Sabie River has been partially successful, as there has been a significant decrease in the invasion intensity of large (> 5 m) alien trees (which tend to have the highest transpiration rates) over time from 1996 to 2005. In 1996, these large alien trees were represented mainly by Eucalyptus spp. However, the WfW programme was not effective in terms of ecosystem repair, as the invasion intensity increased slightly from 1996 to 2005, largely as a result of the significant increase in the aerial cover of smaller alien shrubs (< 2 m). If left unchecked, these will probably in time result in even higher levels of invasion intensity when the individual plants increase in size and cover. Furthermore, the growth form composition remained relatively unchanged over time, and more than half of the alien species found in 2005 were tree and shrub species. Therefore, little or no ecosystem repair has occurred along the Sabie River. In order to improve the effectiveness of the WfW programme, various detailed recommendations are included, which largely revolve around improvements in follow-up treatments.

Recentemente houve a divisão de Simaba sensu lato em Simaba sensu stricto e Homalolepis (Simaroubaceae), dois gêneros Sul-Americanos que estão presentes em diferentes domínios morfoclimáticos e biomas. Apesar de suas filogenias estarem quase que totalmente esclarecidas, algumas espécies ainda necessitam de atenção. Em alguns estudos, as ceras cuticulares mostraram-se úteis na resolução de algumas filogenias. Há décadas, diferentes espécies de Simaroubaceae vêm sendo estudadas devido à presença de substâncias amargas com grande atividade biológica. Entretanto, não há estudos na família voltados a caracterização química e morfológica das ceras cuticulares. Deste modo, este trabalho analisou a composição química e morfologia das ceras cuticulares foliares de 119 indivíduos pertencentes a 20 espécies de Homalolepis, quatro de Simaba s.s. e três de grupos próximos. As ceras foram extraídas em diclorometano e analisadas através de cromatografia a gás acoplada a espectrometria de massas. O estudo da morfologia das ceras epicuticulares foi realizado através de microscopia eletrônica de varredura. Foram identificadas 71 substâncias nas ceras, pertencendo principalmente à classe dos ácidos graxos, alcanos, álcoois primários, esteroides e tocoferóis. As classes mais abundantes encontradas nas ceras foram os ácidos graxos e alcanos, sendo que a primeira estava presente em maior quantidade nas espécies de Homalolepis e a segunda nas de Simaba s.s. Esta diferença de proporção permitiu a diferenciação destes dois gêneros. Entretanto, qualitativamente, as ceras das diferentes espécies estudadas mostraram-se bastante semelhantes, assim como sua caracterização morfológica, não sendo possível a distinção dos indivíduos em nível de espécie. A partir das análises das ceras em relação aos domínios morfoclimáticos, observou-se que os indivíduos coletados nos domínios Atlântico e Amazônico apresentaram teores menores que os coletados no Cerrado. Entretanto, não foi possível, de maneira geral, o estabelecimento da relação das classes de substâncias das ceras com os domínios de coleta, exceto aquelas coletadas no domínio Amazônico que apresentaram maior proporção de alcanos em relação às outras classes / Simaba sensu lato was recently splited in two distinct genera, Simaba senso strictu and Homalolepis, both with South American distribution occuring in different environments and morphoclimatic areas. Although their phylogenies are almost fully understood, some species still require attention. Studies with cuticular waxes have showed the usefulness of these characters in some phylogenies. Despite the great number of data concerning the chemical analysis of species of Simaroubaceae related to quassinoid composition, for the best of our knowledge there is no study with the chemical and morphological characterization of the cuticular waxes on this family. Therefore, in the present study, the chemical composition and the morphology of the leaf cuticular waxes of 119 specimens belonging to 20 species of Homalolepis, four from Simaba s.s. and three from related genera were analyzed. The waxes were extracted with dichloromethane and analyzed by gas chromatography coupled to mass spectrometry. The morphology of the epicuticular waxes was analyzed by scanning electron microscopy. Seventy-one compounds were identified in the waxes, comprising fatty acids, alkanes, primary alcohols, steroids and tocopherols. The most abundant classes were the fatty acids and alkanes. While fatty acids were the major class in Homalolepis, alkanes were more abundant in Simaba s.s. This quantitative distinction allowed the differenciation of the two genere. Notwithstanding, the composition of the waxes were very similar, as well as their morphology. Consequently, these data were not helpful in distinguishing the species. Concerning the wax composition in relation to the morphoclimatic areas, the speciemens collected in the Atlantic and Amazonian domains had thiner wax loads than those collected in the Cerrado. However, almost none correlation was found between wax chemical classes and the morphoclimatic area, except for the predominance of alkanes in the specimens collected in the Amazonian domain

The hemlock-silverbell (Tsuga canadensis-Halesia tetraptera) forest type is known to exist in only two places, the Great Smoky Mountains National Park (GRSM) and the Joyce Kilmer National Memorial Forest. The hemlock component of this forest type is currently threatened by the hemlock woolly adelgid (Adelgis tsugae), an invasive aphid-like insect native to Japan. This current status has given rise to the need to investigate the ecological resources of this rare forest type before the hemlock component dies out. The objectives of this study were to determine the nature of the plant/environment and plant/plant associations within this forest type. Within this forest type hemlock was negatively related to protection, aspect, and slope steepness and silverbell was positively related to aspect and slope steepness. This study also identified some interspecific associations such as the negative relationship in the understory between hemlock and striped maple, and provided evidence that understory stems are exhibiting a growth response to hemlock decline in these stands. The information obtained from this study characterizing the plant/environment interactions and even the structural and species components of this forest type will serve as a baseline of data from which to measure change and will provide insight into the mechanisms of species distribution and perhaps into short term scenarios of forest response to hemlock decline and mortality.

Orientador: José Luiz Stape / Resumo: O Brasil é um dos líderes mundiais na produção de celulose, papel e painéis de madeira. Este sucesso se deve a diversos fatores, tais como: às condições edafoclimáticas favoráveis ao desenvolvimento de espécies de alto rendimento; aos investimentos nos setores de pesquisa e inovação; ao estabelecimento de parcerias entre empresas e instituições de pesquisa e ensino. Desde a chegada das primeiras árvores de eucalipto, no início do século XX, a produtividade da espécie e a quantidade de área plantada cresceram no país, por outro lado, a busca por melhorias deve ser constante. O uso de modelos baseados em processos tem sido direcionado à compreensão da influência de fatores edafoclimáticos em parâmetros da espécie. Desta forma, é possível simular ambientes em situações adversas e prever possíveis impactos das mudanças climáticas na produtividade da espécie, assim como selecionar áreas aptas à cultura, além de determinar fatores que limitam o crescimento. Os objetivos deste trabalho foram parametrizar e validar o modelo 3-PG para o clone de eucalipto de maior plasticidade fenotípica para diferentes regiões do Brasil; e estimar a produtividade deste mesmo clone para diferentes ciclos climáticos em uma região onde a setor de florestas plantadas ainda não está estabelecido, como o estado de Rondônia. A parametrização do modelo foi eficiente quanto a predição de produção de biomassa de lenho (R2 = 0,93), diâmetro a altura do peito (R2 = 0,94) e área basal (R2 = 0,93), o mesmo não aco... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Brazil is one of the world leaders in the production of pulp, paper and wood panels. This success is due to several factors, such as: the edaphoclimatic conditions favorable to the development of high yield species; the investments in research and innovation sectors; the establishment of partnerships between companies, research and education institutions. Since the arrival of the first Eucalyptus trees at the beginning of the 20th century, the productivity of the species and the amount of planted area have grown in the country, in addition, the search for improvement must be constant. Technologies related to remote sensing, genetic sequencing, genetically modified organisms, ecophysiology and modeling of forest systems enable the filling of previously unknown gaps. The use of process-based models has been directed at understanding the influence of edafoclimatic factors on species parameters. In this way, it is possible to simulate environments in adverse situations and predict possible impacts of climate change on the productivity of the species, as well as to select areas suitable for cultivation, and to determine factors that limit growth. The objectives of this study were to parameterize and validate the 3-PG model for the Eucalyptus clone of higher phenotypic plasticity for different regions of Brazil; and to estimate the productivity of this same clone for different climatic cycles in a region where the planted forest sector is not yet established, state of Rondônia. The... (Complete abstract click electronic access below) / Doutor

Made available in DSpace on 2015-03-26T13:50:11Z (GMT). No. of bitstreams: 1 texto completo.pdf: 3004018 bytes, checksum: 8f3143541f68816827525828eba9c677 (MD5) Previous issue date: 2012-07-20 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The main objectives of the present study were: 1) to evaluate the goodness of fit of growth models to determine the variation of the dry mass for sugarcane, cultivars RB92579, RB867515, RB928064 and RB855453; and 2) determine the growth rates of the mentioned cultivars subjected to different levels of water stress, denoted in the present work as: unstressed (10 kPa), mild (60 kPa), moderate (90 kPa) and severe (120 kPa). Two independent experiments were carried out: the first one under field conditions and the second one in a greenhouse, both located at the Federal University of Viçosa (Brazil). Environmental and plant data were collected from October 26 (2011) to May 18 (2012) for the first experiment and December 18 (2011) to May 22 (2012) for the second experiment. In the first experiment, the growth models (expolinear, logístico and Gompertz) were capable of simulating well accumulated dry matter of the cultivars, during the studied period. Values of the adjusted determination coefficient were above 92.09% for all evaluated models. Based on the adjusted parameters of the expolinear model, it was observed, at the end of the experimental period, that the dry mass was lightly superior for the cultivar RB855453 compared to RB867515, which outperformed the cultivars RB928064 and RB92579. Due to the water stress effect on the growth and accumulated dry mass of sugarcane under greenhouse conditions, it was observed that the sigmoid model with three parameters provided the best fit to the growth and data of plant heights. In the treatments without water stress, the maximum values of culture growth rate (TCC) ranged between 0.22 and 0.31 g°Cd-1, while the maximum values of stem elongation rate (TEC) were between 0.20 and 0.25 cm°Cd-1, regardless of cultivar. In contrast, under severe water xviii stress, the maximum values of the TCC ranged between 0.050 and 0.068 g°Cd-1 and the TEC were between 0.07 and 0.09 cm°Cd-1, also regardless of the evaluated cultivar. For the treatment without water stress, the maximum TCC for the RB867515 cultivar were larger then RB855453, RB92579 and RB928064, corresponding to 7.5, 36.8 and 40.8 %, respectively. In that condition, the cultivar RB867515 reached the maximum TEC only at 1100°Cd, while for the others, the maximum values were observed at 900 °Cd, approximately. / O presente estudo teve como objetivos principais: 1) Ajustar os modelos de crescimento expolinear, logístico e Gompertz ao acúmulo de matéria seca da parte aérea da cana-de-açúcar para os cultivares RB92579, RB855453, RB867515 e RB928064; e 2) Determinar as taxas de crescimento dos cultivares mencionadas sob distintos níveis de estresse hídrico, referidos no presente trabalho como: ausência de estresse (10 kPa), estresse leve (60 kPa), moderado (90 kPa) e severo (120 kPa). Foram conduzidos dois experimentos independentes, sendo o primeiro em condições de campo, e o segundo em casa-de-vegetação, ambos localizados na Universidade Federal de Viçosa. Os dados do ambiente e da planta foram coletados no período de 26/08/11 até o dia 18/05/12 (primeiro experimento) e 18/12/11 até 22/05/12 (segundo experimento). No primeiro experimento, os modelos de crescimento (expolinear, logístico e Gompertz) foram capazes de simular bem a matéria seca acumulada pelos cultivares ao longo do período estudado. Os valores de coeficiente de determinação ajustado (R2aj) estiveram acima de 92,09% para todos os modelos avaliados. A partir do ajuste dos parâmetros do modelo de crescimento expolinear, constatou-se que, ao final do período experimental, a massa seca foi ligeiramente maior para o cultivar RB855453 em comparação ao RB867515, os quais se destacaram em relação aos cultivares RB928064 e RB92579. Em decorrência do efeito do estresse hídrico no crescimento e acúmulo de massa seca da parte aérea da cana-de-açúcar sob condições de casa-de-vegetação, foi constatado que o modelo sigmoidal com três parâmetros proporcionou melhor ajuste aos dados de matéria seca e de estatura dos colmos. Na ausência de estresse hídrico, os valores máximos da taxa de crescimento da cultura (TCC) estiveram compreendidos entre 0,22 e 0,31 g°Cd-1, enquanto os valores máximos da taxa de elongação do colmo (TEC) estiveram compreendidos entre 0,20 e 0,25 cm°Cd-1, independente da cultivar. Em contraste, sob estresse severo, os valores máximos da TCC estiveram entre 0,050 e 0,068 g°Cd-1 e da TEC entre 0,07 e 0,09 cm°Cd-1, também independente do cultivar avaliado. Sob ausência de estresse hídrico, a TCC máxima do cultivar RB867515 foi em média cerca de 7,5, 36,8 e 40,8 % maior que a TCC máxima dos cultivares RB855453, RB92579 e RB928064, respectivamente. Nessa condição, esse cultivar alcançou a TEC máxima somente aos 1100 °Cd, enquanto para os demais cultivares, os valores máximos foram observados aos 900 °Cd, aproximadamente.

Made available in DSpace on 2015-03-26T13:50:17Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1468096 bytes, checksum: 821c125478c701b474e99866d66afebc (MD5) Previous issue date: 2013-07-26 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objective of this study was to quantify evapotranspiration and growth of clones of irrigated forage cactus during the first production year of the second crop cycle (March 2012 to February 2013). The experiment was carried out in Serra Talhada - PE, located in the Brazilian Semiarid region. A randomized block design with three replications was used in a factorial arrangement (3x3), in which the plots consisted of three conditions of soil water availability, determined by applying a fixed irrigation depth (L: 7.5 mm) with three frequencies (F: 7, 14 and 28 days), and subplots were three forage cactus clones (IPA: IPA Sertânia; MIU: Tiny and, OEM: Mexican Elephant Ear). The soil water content was monitored from June 2012 to February 2013 with a capacitive probe (Diviner 2000 @ Sentek Pty Ltd, Australia.) using an average time interval of three days. Daily meteorological data were obtained from an automatic weather station and used to determine the reference evapotranspiration (ETo), according to the Penman-Monteith method, parameterized in the 56 FAO Bulletin. In addition to meteorological data, physical and hydraulic properties of the soil, a soil water budget (SWB) was performed every 14 days, and the components were accumulated subsequently in nine periods of 28 days. The actual crop evapotranspiration (ETr) was estimated as a residual of the SWB to determine the relationship ETr/ETo. After 150 days from the first cut, eight biometric campaigns were carried out in each thirty day time intervals for cladodes and plant morphological analysis. With these data, morphogenetic rates were determined over time for the three forage cactus clones. All data were compared by analysis of variance test and the Tukey test at the 5% level of significance. Evapotranspiration and other SWB components showed significant differences among clones and irrigation conditions over time. However, for values accumulate during the crop cycle, only the soil water flow for clone IPA, under the F14 condition (-66.5 mm), differed from the other two clones showing the highest flow value. The average ETr for irrigated forage cactus was 1.5 mm day-1 during the analysis period, based on an average atmospheric demand of 5.1 mm day-1. The ratio ETr / ETo for the clones showed low magnitude of the imposed conditions (ambient together with the irrigation), providing values of 0.27 ± 0.12, 0.30 ± 0.14 and 0.29 ± 0.12 for IPA, and OEM MIU, respectively. It was found that the evaluated conditions of water availability did not affect significantly (P> 0.05) most of the absolute and relative values of the growth variables of the three clones significantly. When different clones were compared, regardless of water availability conditions, it was observed that, in terms of absolute values, the OEM presented the highest means. Evaluations in the long run showed that there was a significant increase in the growth of clones in the last months of the first year of production. However, this occurred due to rainfall events which, together with the application of the irrigation treatments, provided greater growth increase for the OEM and IPA clones, in this order, reaching 70% and 60% of the total rate for height, and 37.0 % and 45.3% for plant width. Thus, it can be concluded that the different conditions of the soil water availability did not affect evapotranspiration and growth of forage cactus clones. Nevertheless, the OEM and IPA clones had the best growth performances when compared to the MIU clone, which was the one that showed the lowest growth under irrigated conditions of the Brazilian Semiarid region. / O objetivo deste estudo foi quantificar a evapotranspiração e o crescimento de clones de palma forrageira irrigada durante o primeiro ano produtivo do segundo ciclo da cultura (março de 2012 a fevereiro de 2013). O experimento foi conduzido em Serra Talhada PE, localizada no Semiárido brasileiro. Utilizou-se o delineamento em blocos ao acaso, com três repetições, em arranjo fatorial (3x3), no qual as parcelas foram compostas por três condições de disponibilidade de água, resultantes da aplicação de uma lâmina fixa (L: 7,5 mm) em três frequências (F: 7, 14 e 28 dias), e as subparcelas por três clones de palma forrageira (IPA: IPA Sertânia; MIU: Miúda; e OEM: Orelha de Elefante Mexicana). Foi realizado, durante o período de junho de 2012 a fevereiro de 2013, o monitoramento do conteúdo de água no solo com auxílio de uma sonda capacitiva (Diviner 2000@ SentekPty Ltda. Austrália), no intervalo médio de três dias. Dados diários dos elementos meteorológicos foram obtidos a partir de uma estação automática, visando determinar a evapotranspiração de referência (ETo) pelo método de Penman-Monteith, parametrizado no Boletim 56 da FAO. Por meio desses dados e de propriedades físico-hídricas do solo, foi realizado o balanço de água no solo (BAS) a cada 14 dias, sendo que os componentes foram acumulados, posteriormente, em nove períodos de 28 dias. Por resíduo do BAS, estimou-se a evapotranspiração real da cultura (ETr) para determinação da relação ETr/ETo. Após 150 dias do primeiro corte, foram realizadas oito campanhas biométricas, com intervalos de trinta dias cada, para análises morfológicas da planta e dos cladódios. Com esses dados, foram determinadas as taxas morfogênicas ao longo do tempo para o ciclo dos clones. Todos os dados foram comparados pela análise de variância e pelo teste de médias de Tukey, ao nível de 5% de significância. A evapotranspiração e os demais componentes do BAS apresentaram diferenças significativas entre os clones e condições de irrigação ao longo do tempo. Entretanto, para os valores acumulados ao longo do ciclo, apenas o fluxo de água no solo do clone IPA, na condição F14 (-66,5 mm), diferenciou-se dos demais clones, apresentando o valor mais alto de fluxo. A ETr média da palma forrageira irrigada, durante o período de análise foi de 1,5 mm dia-1 para uma demanda atmosférica média de 5,1 mm dia-1. A relação ETr/ETo dos clones apresentou baixa magnitude nas condições impostas (ambiente em conjunto com a irrigação), proporcionando valores de 0,27±0,12; 0,30±0,14 e 0,29±0,12 para a IPA, MIU e OEM, respectivamente. Constatou-se que as condições de disponibilidade de água avaliadas também não afetaram significativamente (P>0,05) a maioria dos valores absolutos e relativos das variáveis de crescimento dos três clones. Quando se compararam os diferentes clones, independentemente da condição de disponibilidade de água, observou-se que, em termos de valores absolutos, a OEM apresentou as maiores médias. Na avaliação ao longo do tempo, houve evolução significativa do crescimento dos clones nos últimos meses do primeiro ano produtivo. Porém, isso ocorreu devido aos eventos de precipitação pluviométrica, que em conjunto com a aplicação dos tratamentos de irrigação, promoveram maiores incrementos nos clones OEM e IPA, nessa ordem, atingido 70% e 60% da taxa total para a altura, e 37,0% e 45,3% para a largura da planta. Assim, conclui-se que as diferentes condições de disponibilidade de água no solo não influenciaram a evapotranspiração e o crescimento dos clones de palma forrageira. Todavia os clones OEM e IPA tiveram os melhores desempenhos de crescimento em relação ao MIU, que foi o que apresentou o menor crescimento sob condições irrigadas do Semiárido brasileiro.