Master of Science / Department of Agronomy / Robert M. Aiken / Increasing crop water use efficiency (WUE), the amount of biomass produced per unit water consumed, can enhance crop productivity and yield potential. The objective of the first study was to evaluate the factors affecting water productivity among eight sorghum (Sorghum bicolor (L.) Moench) genotypes, which differ in canopy architecture. Sorghum genotypes, grown under field conditions, showed significant differences in (a) biomass production, (b) water use, (c) intercepted radiation, (d) water productivity and (e) radiation use efficiency (RUE; the amount of biomass produced per unit of intercepted radiation which is suitable for photosynthesis). WUE and RUE were more strongly correlated to biomass production than to water use or intercepted radiation, respectively. RUE was positively correlated to WUE and tended to increase with internode length, the parameter used to characterize canopy architecture. These results demonstrate that increased utilization of radiation can increase water productivity in plants. Sorghum canopies that increase light transmission to mid−canopy leaves can increase RUE and also have the potential to increase crop productivity and WUE. The objective of the second study was to develop a quantitative model to predict leaf area index (LAI), a common quantification of canopy architecture, for sorghum from emergence to flag leaf stage. LAI was calculated from an algorithm developed to consider area of mature leaves (leaves with a ligule/collar), area of expanding leaves (leaves without a ligule/collar), total leaf area per plant and plant population. Slope of regression of modeled LAI on observed LAI varied for photoperiod sensitive (PPS) and insensitive (non−PPS) genotypes in 2010. A good correlation was found between the modeled and observed LAI with coefficient of determination (R[superscript]2) 0.96 in 2009 and 0.94 (non−PPS) and 0.88 (PPS) in 2010. These studies suggest that canopy architecture has prominent influence on water productivity of crops and quantification of canopy architecture through an LAI simulation model has potential in understanding RUE, WUE and crop productivity.

<p>In the scope of future population support, agricultural productivity, in particular in sub-Saharan Africa, has to increase drastically to meet the UN’s millennium development goals of eradicating extreme poverty and hunger by 2015. Water availability in the root-zone limits crop production in large parts of the developing world. As competition for fresh water increases, water of lower quality, for example saline or polluted water, is often used for irrigation. Low-cost drip systems are suitable for saline water irrigation because they effectuate a minimisation of salt accumulation, leaf burn and peaks in salt concentration. Nonetheless, all types of saline water irrigation contain the risk for causing soil salinisation. Thus, in order to achieve long-term sustainability of these systems, appropriate management strategies are needed. The choice of management practices may be influenced by local conditions such as climate, soil and irrigation water salinity. A litera-ture review showed that there is a potential for saline water irrigation in sub-Saharan Africa in water scarce areas. Low-cost drip irrigation with saline water (6 dS m-1) was successfully used to irrigate two consecutive crops of tomato in semi-arid South Africa. An integrated ecosystems model was developed to simulate long-term yield and salt accumulation in a drip-irrigated agricultural system for a range of salinities, climates and management techniques. Crop, salt and water balance data from two field experiments conducted in Israel and South Africa, respectively, were used to parameterise and test the model. Emphasis was placed on testing the usability of the model as a tool for evaluating the importance of certain plausible management options of low-cost, drip-irrigation systems. Therefore, particular focus was directed towards correctly describing soil salinity stress on plant growth and soil evaporation from a distributed (wetted and dry) surface. In addition, the model was developed to function for different climates without having to change any other parameters or variables except for the actual climatic data. Simulations were subsequently run over a 30-year period to study long-term yield and salt accumulation in the soil profile for two sites in South Africa, demonstrating the applicability of the model. Model simulations showed that high soil salinities reduced crop growth and thus increased both drainage and soil evaporation. Further, covering the soil with a plastic sheet led to a reduction of soil evaporation and a subsequent increase in both transpiration and drainage. Rainfall was crucial for the leaching of salts from the soil, and thus in regions with low levels of rainfall, a higher leaching fraction of supplied saline irrigation water has to compensate for the lack of rain. However, a high leaching fraction also causes large amounts of salt leaching, which could potentially pollute underlying groundwater and downstream ecosystems. This risk can be mitigated using mulching, which minimises non-productive water losses, thereby lowering irrigation water needs. The choice of irrigation water salinity, frequency of irrigation and soil coverage may differ between the farmer and the regional water manager due to different preferences. Furthermore, the study highlighted how environmental variables such as water use efficiency and radiation use efficiency can be used as indicators of system performance. Whereas the latter is first and foremost a general stress indicator, water use efficiency more precisely describes specific factors such as plant size, allocation patterns and evaporative demand, which will affect the exchange of carbon dioxide and water through the stomata.</p>

This thesis deals with the estimation of plant-atmosphere trace gas exchange and isotopic discrimination from atmospheric concentration measurements. Two space scales were investigated: canopy and regional. The canopy-scale study combined a Lagrangian model of turbulent dispersal with ecophysiological principles to infer vertical profiles of fluxes of CO2, H2O and heat as well as carbon and oxygen isotope discrimination during CO2 assimilation, from concentration measurements within a forest. The regional-scale model used a convective boundary layer budget approach to infer average regional isotopic discrimination and fluxes of CO2 and sensible and latent heat from the evolution during the day of boundary layer height and mean concentrations of CO2 and H2O, temperature and carbon and oxygen isotope composition of CO2. For the canopy study, concentrations of five scalar quantities, CO2, 13CO2, C18O16O, H2O and temperature, were measured at up to nine heights within and above a mixed fir and spruce forest in central Siberia over several days just after snow melt in May 2000. Eddy covariance measurements of CO2, H2O and heat fluxes were made above the canopy over the same period, providing independent verification of the model flux estimates. Photosynthesis, transpiration, heat exchange and isotope discrimination during CO2 assimilation were modelled for sun and shade leaves throughout the canopy through a combination of inversion of the concentration data and principles of biochemistry, plant physiology and energy balance. In contrast to the more usual inverse modelling concept where fluxes are inferred directly from concentrations, in this study the inversion was used to predict unknown parameters within a process-based model of leaf gas and energy exchange. Parameters relating to photosynthetic capacity, stomatal conductance, radiation penetration and turbulence structure were optimised by the inversion to provide the best fit of modelled to measured concentration profiles of the five scalars. Model results showed that carbon isotope discrimination, stomatal conductance and intercellular CO2 concentration were depressed due to the low temperatures experienced during snow melt, oxygen isotope discrimination was positive and consistent with other estimates, radiation penetrated further than simple theoretical predictions because of leaf clumping and penumbra, the turbulence coherence was lower than expected and stability effects were important in the morning and evening. For the regional study, five flights were undertaken over two days in and above the convective boundary layer above a heterogeneous pine forest and bog region in central Siberia. Vertical profiles of CO2 and H2O concentrations, temperature and pressure were obtained during each flight. Air flask samples were taken at various heights for carbon and oxygen isotopic analysis of CO2. Two budget methods were used to estimate regional surface fluxes of CO2 and plant isotopic discrimination against 13CO2 and C18O16O, with the first method also used to infer regional sensible and latent heat fluxes. Flux estimates were compared to ground-based eddy covariance measurements. Model results showed that afternoon estimates for carbon and oxygen isotope discrimination were close to those expected from source water isotopic measurements and theory of isotope discrimination. Estimates for oxygen isotope discrimination for the morning period were considerably different and could be explained by contrasting influences of the two different ecosystem types and non-steady state evaporative enrichment of leaf water.

In the scope of future population support, agricultural productivity, in particular in sub-Saharan Africa, has to increase drastically to meet the UN’s millennium development goals of eradicating extreme poverty and hunger by 2015. Water availability in the root-zone limits crop production in large parts of the developing world. As competition for fresh water increases, water of lower quality, for example saline or polluted water, is often used for irrigation. Low-cost drip systems are suitable for saline water irrigation because they effectuate a minimisation of salt accumulation, leaf burn and peaks in salt concentration. Nonetheless, all types of saline water irrigation contain the risk for causing soil salinisation. Thus, in order to achieve long-term sustainability of these systems, appropriate management strategies are needed. The choice of management practices may be influenced by local conditions such as climate, soil and irrigation water salinity. A litera-ture review showed that there is a potential for saline water irrigation in sub-Saharan Africa in water scarce areas. Low-cost drip irrigation with saline water (6 dS m-1) was successfully used to irrigate two consecutive crops of tomato in semi-arid South Africa. An integrated ecosystems model was developed to simulate long-term yield and salt accumulation in a drip-irrigated agricultural system for a range of salinities, climates and management techniques. Crop, salt and water balance data from two field experiments conducted in Israel and South Africa, respectively, were used to parameterise and test the model. Emphasis was placed on testing the usability of the model as a tool for evaluating the importance of certain plausible management options of low-cost, drip-irrigation systems. Therefore, particular focus was directed towards correctly describing soil salinity stress on plant growth and soil evaporation from a distributed (wetted and dry) surface. In addition, the model was developed to function for different climates without having to change any other parameters or variables except for the actual climatic data. Simulations were subsequently run over a 30-year period to study long-term yield and salt accumulation in the soil profile for two sites in South Africa, demonstrating the applicability of the model. Model simulations showed that high soil salinities reduced crop growth and thus increased both drainage and soil evaporation. Further, covering the soil with a plastic sheet led to a reduction of soil evaporation and a subsequent increase in both transpiration and drainage. Rainfall was crucial for the leaching of salts from the soil, and thus in regions with low levels of rainfall, a higher leaching fraction of supplied saline irrigation water has to compensate for the lack of rain. However, a high leaching fraction also causes large amounts of salt leaching, which could potentially pollute underlying groundwater and downstream ecosystems. This risk can be mitigated using mulching, which minimises non-productive water losses, thereby lowering irrigation water needs. The choice of irrigation water salinity, frequency of irrigation and soil coverage may differ between the farmer and the regional water manager due to different preferences. Furthermore, the study highlighted how environmental variables such as water use efficiency and radiation use efficiency can be used as indicators of system performance. Whereas the latter is first and foremost a general stress indicator, water use efficiency more precisely describes specific factors such as plant size, allocation patterns and evaporative demand, which will affect the exchange of carbon dioxide and water through the stomata. / QC 20101102

Ozonation has been utilized for water treatment for over 100 years. During that time, the range of applications has grown considerably, and includes the remediation of nursery and greenhouse irrigation water. Ozone is dissolved into irrigation water to kill pathogens and degrade chemical contaminants. By convention, growers remove ozone from solutions, prior to distribution to the crop, to avoid phytotoxic effects. The available literature regarding aqueous ozone (O3(aq)) phytotoxicity is limited, making this a sagacious practice, although the removal does preclude any ancillary benefits beyond the point of treatment. The effects of applying O3(aq) under two irrigation systems are examined. Initial studies suggested O3(aq) concentrations as high as 20 mg⋅L-1 could be applied directly to mineral wool substrate in a limited (one time) fashion without a negative response. To be effective as a remediation tool, however, ozone would need to be applied more frequently (e.g. daily). The effects of daily O3(aq) application, via drip irrigation in mineral wool hydroponic tomato culture, was examined. In the first of two studies, daily applications of 3.0 mg⋅L-1 O3(aq) elicited an overall positive growth response. In a follow-up study, 6.0 mg L-1 elicited a negative response. Nursery operators often utilize overhead irrigation. A study was conducted to determine if overhead irrigation utilizing O3(aq) was compatible with select woody perennial nursery species. The amount of ozone lost from solution during application was examined, as well as crop response to the ozone environment generated. It was shown that 60 to 70% of the ozone was unaccounted for at canopy level, while phytotoxic effects were elicited at emitter concentrations above 1.5 mg L-1. Marchantia polymorpha is a significant weed species in greenhouse and nursery production; a species with few control options. Anatomical features of M. polymorpha suggested sensitivity to O3(aq). Studies were performed to examine contact time (CT) and exposure frequencies required for M. polymorpha suppression. A CT of 0.84 mg⋅L-1⋅min at an application frequency of 3-times/week achieved measurable suppression. / Natural Science and Engineering Research Council (NSEARC); Ontario Ministry of Agriculture Food and Rural Affairs (OMAFRA); Ontario Centres of Excellence (OCE); Purification Research Technologies INC (PRTI); Flowers Canada (Ontario).

No description available.

Diss. (sammanfattning). Umeå : Sveriges lantbruksuniv. / Härtill 5 uppsatser.

Made available in DSpace on 2014-06-11T19:32:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-02-03Bitstream added on 2014-06-13T19:22:14Z : No. of bitstreams: 1 mucoucah_mfs_dr_botfca.pdf: 847058 bytes, checksum: b7d3981d242b8be0200b777f5d74745d (MD5) / Universidade Estadual Paulista (UNESP) / Foi estudada a influência de cinco profundidades de lençol freático no desenvolvimento de bulbos de calla (Zantedeschia sp). As características avaliadas foram: área foliar, número de folhas, número de flores, altura da haste floral, ciclo da cultura, ganho de massa verde do bulbo, evapotranspiração da cultura e eficiência do uso da água. As callas foram cultivadas em estufa de vidro com 50% de redução na radiação interna, plantadas em vasos construídos de tubos de pvc de diâmetro nominal de 150 mm preenchidos com substrato, os bulbos utilizados apresentavam massa verde inicial variando de 10 a 12 g. Os vasos foram colocados em bandejas, com capacidade para seis vasos, as mesmas apresentavam um sistema automático para o abastecimento de água por um reservatório conectado diretamente às bandejas com uma bóia para manutenção do nível do lençol freático constante. As profundidades dos lençóis freáticos foram: 10, 17, 24, 31 e 38 cm. As características referentes ao desenvolvimento da planta foram verificadas ao longo do ciclo, por meio de nove avaliações efetuadas durante o cultivo. A evapotranspiração foi medida diariamente e computada semanalmente e ao término do ciclo. O ganho de massa verde dos bulbos foi avaliado ao final do ciclo de cultivo pela relação entre a massa verde inicial e a massa verde final. A eficiência do uso da água foi checada com base na evapotranspiração da cultura (L.planta-1) e na massa verde final do bulbo (g). Os resultados referentes à área foliar foram variáveis de 1.011,6 a 2.016,3 cm2. O número de folhas emitidas variou de 7,5 a 13,8 folhas por bulbo. Ao longo de todo o ciclo de cultivo o número médio de flores emitidas foi de 0,8 a 1,2 flores por bulbo. Os bulbos apresentaram um aumento variável de 21,7 a 11,7 vezes em relação ao tamanho inicial, ou seja, o ganho de massa verde ao final do cultivo foi na ordem de 2.173 a 1.170%. / The objective was to determine the influence of 5 different table water levels in the crop development of Calla. The parameter evaluated were leaf area, number of leaves, number of flowers, flowers height, growth cycle, tuber increment rate, evapotranspiration of the culture and efficiency in water use. The study was conducted in glass greenhouse with 50% percent of sunlight reduction. The plants were grown in PVC pots with diameter of 150 mm, which were filled with substrate. The plant tubers weigthed from 10 g to 12 g. The pots were placed within containers, at a rate of six per container, where the water replacement was authomatically determined by a buoy, which kept the water level constant. The table water levels used were 10, 17, 24, 31 and 38 cm. The crop development parameters were checked in nine evaluations during the growth cycle. Evapotranspiration was evaluated weekly and at the end of the cycle. The increment in tuber weigth was determined from the initial and final fresh weight. The water use efficiency was determined from the culture evapotranspiration (mm) and from the final fresh weigth (g). The results show that leaf area varied between 1,011.6 and 2,016.3 cm2. The number of leaves varied from 7.5 and 13.8 leaves per tuber. The number of flowers produced per tuber throughout their whole life cycle was 0.8 and 1.2. The plant tubers presented a size increment which ranged from 21.7 times to 11.7 times their initial size, which represented an increment of fresh weigth at the end of the culture of 2,173% and 1,170%. The evapotranspiration of the whole culture was 46.14 L/planta and 26.89 L/planta. The efficiency in water use varied between 4.5 g/L and 6.9 g/L. The data set was submitted to the F and Tukey statistical tests, to allow for comparisons of average results. Was found statistical discrepancy in the growth cycle parameter, between 38 cm table water level, which life cycle was 281 days, and 10 and 24 cm table water levels.

Made available in DSpace on 2015-03-26T13:50:07Z (GMT). No. of bitstreams: 1 texto completo.pdf: 790288 bytes, checksum: 9e23155ca85ebc80cb22cb64e76f4448 (MD5) Previous issue date: 2011-02-17 / Fundação de Amparo a Pesquisa do Estado de Minas Gerais / The aim of this study was to analyze the growth and water use efficiency of maize and cowpea crops under different irrigation water depths in sole and intercropping systems in a semi-arid region. The experiment was carried out at the Experimental Field Station of Bebedouro (09 ° 09'S, 40 ° 22'W) Embrapa Semiarido, located at Petrolina-PE. The cowpea and maize in different cropping systems (sole and intercropping) were subjected to five different irrigation water depths applied shortly after tasseling in corn and flowering stage in cowpea 40 days after sowing. Combining the three settings of cropping systems and the five different irrigation water depths, the crops of maize and cowpea were subjected to 15 different treatments. Three different methods were used to obtain the values of crop coefficient (Kc): Soil water balance method, using the equation proposed by FAO bulletin 56, and Kc adjusted according to degree days values. To attain these objectives, the access tubes were settled down in each experimental treatment to a depth of 1.0 m for monitoring the soil water content in daily basis through an access tube model Diviner 2000 (Sentek Pty Ltd., Australia). The measurements were taken on weekly basis and the total biomass yield at the end of crop cycle (at 102 and 78 days for maize and cowpea, respectively). Morphophysiological indices were calculated to characterize the growth of corn and cowpea in different cropping systems. Indicators of the response of crop production and performance of water application in the cropping system were calculated by using data of total income, the relationship between the prices of commercial grain production for both crops, as well as amounts of precipitation (P) and volume of water applied by irrigation (I). The consortium has significantly reduced the total dry matter of shoots, leaf area index, the rate of crops growth, leaf weight and leaf area ratio of maize and cowpea. The coefficient of sole crop system showed values of 0.86, 1.10 and 0.52 for corn and 0.68, 1.04, 1.06 and 0.63 for cowpea, respectively, for phases beginning, middle and end. Intercropping system these values were 0.90, 1.30 and 0.72 for corn and 0.86 1.30 and 0.91 for cowpea, for these phases in the order they were mentioned. The grain yield of corn and cowpea in response to soil water availability was reduced in mixed stands in relation to unique plantings and water use efficiency of corn and cowpea planting was higher in exclusive compared to intercropping. Even so, in economic terms the adoption of the consortium was more advantageous in all treatments. This information is of great importance to support the improvement of water management in the Semiarid Northeast Brazil. / O objetivo desse trabalho foi analisar o crescimento, as necessidades hídricas e a eficiência do uso de água das culturas do milho e do feijão-caupi, submetidas a diferentes lâminas de água nos sistemas de plantio, exclusivo e consorciado, no Semiárido brasileiro. O experimento foi conduzido no Campo Experimental de Bebedouro (09°09 S; 40°22 W, 365,6m) da Embrapa Semiárido, localizado no município de Petrolina-PE. As culturas, nos diferentes sistemas de plantio (exclusivo e consorciado), foram submetidas a cinco lâminas de irrigação, aplicadas logo após o pendoamento no milho e na fase de floração do feijão-caupi aos 40 dias depois da semeadura. Combinando as configurações de sistema de cultivo e as diferentes lâminas de irrigação, as culturas do milho e do feijão-caupi foram submetidas a 15 tratamentos distintos. Foram utilizados três diferentes métodos para obtenção dos valores de coeficiente de cultura (Kc): balanço hídrico no solo, utilização da equação proposta pela FAO56 e ajuste da variável graus-dia aos valores de Kc. Para tanto, o monitoramento do teor de água no solo foi realizado diariamente por meio de uma sonda modelo Diviner 2000 (Sentek Pty Ltd., Austrália) e tubos de acesso instalados em cada tratamento. Realizaram-se medições de biomassa em intervalos semanais e de rendimento ao final do ciclo das culturas, que ocorreram aos 109 e 76 dias, para o milho e o feijão-caupi, respectivamente. Foram calculados índices morfofisiológicos para caracterizar o crescimento das culturas do milho e feijão-caupi nos diferentes sistemas de plantio. Além disso, foram utilizados indicadores que consideram a resposta produtiva da cultura e o desempenho de aplicação de água no sistema deprodução, que foram calculados por meio dos dados de rendimento total, da relação entre os preços da produção comercial de grãos de ambas as culturas, bem como dos valores de precipitação (P) e do volume de água aplicado por irrigação (I). O consorcio reduziu significativamente a fitomassa seca total da parte aérea, o índice de área foliar, a taxa de crescimento da cultura, a razão de massa foliar e a razão de área foliar do milho e feijão-caupi. O coeficiente de cultura em sistema exclusivo apresentou valores médios de 0,86, 1,10 e 0,52 para o milho e de 0,68, 1,04, 1,06 e 0,63 para o feijão-caupi, respectivamente para as fases inicial, intermediária e final. No sistema consorciado esses valores foram de 0,90, 1,30 e 0,72 para o milho e 0,86, 1,30 e 0,91 para o feijão-caupi, para as referidas fases na ordem que foram mencionadas. A produtividade de grãos das culturas do milho e feijão-caupi em resposta à disponibilidade hídrica no solo foi reduzida nos plantios consorciados em relação aos plantios exclusivos e a eficiência de uso de água das culturas do milho e do feijão-caupi foi superior no plantio exclusivo em relação ao consorciado. Mesmo assim, em termos econômicos a adoção do consórcio mostrou ser mais vantajosa em todos os tratamentos. Essas informações são de grande importância para subsidiar a melhoria do manejo da água no Semiárido do Nordeste brasileiro.

Orientador: Antonio Evaldo Klar / Banca: João Carlos Cury Saad / Banca: Magali Ribeiro da Silva / Banca: Rubens Duarte Coelho / Banca: Tais Tostes Graziano / Resumo: Foi estudada a influência de cinco profundidades de lençol freático no desenvolvimento de bulbos de calla (Zantedeschia sp). As características avaliadas foram: área foliar, número de folhas, número de flores, altura da haste floral, ciclo da cultura, ganho de massa verde do bulbo, evapotranspiração da cultura e eficiência do uso da água. As callas foram cultivadas em estufa de vidro com 50% de redução na radiação interna, plantadas em vasos construídos de tubos de pvc de diâmetro nominal de 150 mm preenchidos com substrato, os bulbos utilizados apresentavam massa verde inicial variando de 10 a 12 g. Os vasos foram colocados em bandejas, com capacidade para seis vasos, as mesmas apresentavam um sistema automático para o abastecimento de água por um reservatório conectado diretamente às bandejas com uma bóia para manutenção do nível do lençol freático constante. As profundidades dos lençóis freáticos foram: 10, 17, 24, 31 e 38 cm. As características referentes ao desenvolvimento da planta foram verificadas ao longo do ciclo, por meio de nove avaliações efetuadas durante o cultivo. A evapotranspiração foi medida diariamente e computada semanalmente e ao término do ciclo. O ganho de massa verde dos bulbos foi avaliado ao final do ciclo de cultivo pela relação entre a massa verde inicial e a massa verde final. A eficiência do uso da água foi checada com base na evapotranspiração da cultura (L.planta-1) e na massa verde final do bulbo (g). Os resultados referentes à área foliar foram variáveis de 1.011,6 a 2.016,3 cm2. O número de folhas emitidas variou de 7,5 a 13,8 folhas por bulbo. Ao longo de todo o ciclo de cultivo o número médio de flores emitidas foi de 0,8 a 1,2 flores por bulbo. Os bulbos apresentaram um aumento variável de 21,7 a 11,7 vezes em relação ao tamanho inicial, ou seja, o ganho de massa verde ao final do cultivo foi na ordem de 2.173 a 1.170%. / Abstract: The objective was to determine the influence of 5 different table water levels in the crop development of Calla. The parameter evaluated were leaf area, number of leaves, number of flowers, flowers height, growth cycle, tuber increment rate, evapotranspiration of the culture and efficiency in water use. The study was conducted in glass greenhouse with 50% percent of sunlight reduction. The plants were grown in PVC pots with diameter of 150 mm, which were filled with substrate. The plant tubers weigthed from 10 g to 12 g. The pots were placed within containers, at a rate of six per container, where the water replacement was authomatically determined by a buoy, which kept the water level constant. The table water levels used were 10, 17, 24, 31 and 38 cm. The crop development parameters were checked in nine evaluations during the growth cycle. Evapotranspiration was evaluated weekly and at the end of the cycle. The increment in tuber weigth was determined from the initial and final fresh weight. The water use efficiency was determined from the culture evapotranspiration (mm) and from the final fresh weigth (g). The results show that leaf area varied between 1,011.6 and 2,016.3 cm2. The number of leaves varied from 7.5 and 13.8 leaves per tuber. The number of flowers produced per tuber throughout their whole life cycle was 0.8 and 1.2. The plant tubers presented a size increment which ranged from 21.7 times to 11.7 times their initial size, which represented an increment of fresh weigth at the end of the culture of 2,173% and 1,170%. The evapotranspiration of the whole culture was 46.14 L/planta and 26.89 L/planta. The efficiency in water use varied between 4.5 g/L and 6.9 g/L. The data set was submitted to the F and Tukey statistical tests, to allow for comparisons of average results. Was found statistical discrepancy in the growth cycle parameter, between 38 cm table water level, which life cycle was 281 days, and 10 and 24 cm table water levels. / Doutor