Orientador: Dinival Martins / Banca: Raimundo Leite Cruz / Banca: Emerson Galvani / Resumo: Um ensaio, com amendoim (Arachis hypogaea L.), cv. IAC-TATUST, foi conduzido, na área experimental do Setor de Ciências Ambientais (21,85° S; 48,43° W; 786 m), FCA/UNESP, em Botucatu, SP, em parcela única sob "tratamento úmido" durante o período de 11/02/2001 a 06/06/2001. Durante todas as fases de crescimento das plantas foram monitoradas as radiações fotossinteticamente ativa incidente, refletida e transmitida, bem como a produção semanal da biomassa acumulada e sua energia química, incluindo raízes, hastes, folhas, flores, frutos e sementes, com o objetivo de determinar a eficiência de uso da radiação (EUR) e a eficiência de conversão da radiação interceptada (ECR) pelas plantas cultivadas. Os resultados mostraram que a EUR média foi de 1,33 g MJ-1 e a ECR foi de 2,5%, cujos valores estão coerentes com aqueles encontrados em literatura. Nas condições de Botucatu, a cultura do amendoim interceptou, aproximadamente 600 MJ m-2 de radiação PAR, de modo que no final do seu ciclo a energia da biomassa atingiu a magnitude de 18 MJ m-2. Em termos médios, o coeficiente de extinção da luz (k) foi de 0,68, o índice de colheita, em base de energia, foi de 0,38 e a produtividade obtida, do amendoim em casca, foi equivalente a 4,5 t ha-£. / Abstract: A trial, with peanut (Arachis hypogaea L.), cv. IAC-TATU-ST, was carried out, in experimental area of Setor de Ciências Ambientais (21,85° S; 48,43° W; 786 m), FCA/UNESP, in Botucatu, SP, in single section with "humid treatment" during the period from 11/02/2001 to 06/06/2001. For all growth phases of peanut crop, the incident, reflected and transmitted photosynthetically active radiations were monitored, as well as the weekly production of the accumulated biomass, chemical energy, including roots, stems, leaves, flowers, fruits and seeds, with purpose of determining the radiation use efficiency and the radiation conversion efficiency of intercepted PAR for the cultivated plants. The results showed that EUR was about 1,33 g MJ-1 and ECR was about 2,5%. The values are coherent with those found in literature. In Botucatu conditions, the peanut crop intercepted, more or less 600 MJ m-2 of PAR, so that in the end of cycle, the biomass energy reached to 18 MJ m-2. In standard terms, the light extinction coefficient (k) was about 0.68, the harvest index, in energy basis, was about 0.38 and peanut yield, in peel, was equivalent to 4.5 t ha-£. / Mestre

As mudanças climáticas globais e a expansão da cultura da cana-de-açúcar para regiões com menor suprimento hídrico elevaram a importância de estimativas consistentes das necessidades de água da cultura. Na tentativa de contribuir nesse campo, o presente trabalho buscou analisar o consumo hídrico da cana-de-açúcar em três diferentes escalas espaciais: folha, planta e dossel, além de uma ferramenta de simulação (DSSAT/CANEGRO) quanto ao seu desempenho na estimativa do consumo hídrico da cana-de-açúcar. Foram realizadas medidas de evapotranspiração do dossel pelo método do balanço de energia-razão de Bowen (MRB) e de transpiração das plantas por meio do balanço de calor nos colmos (BC) e das folhas com um analisador de gás à infravermelho (IRGA). Duas áreas experimentais foram utilizadas, sendo a primeira com a variedade CTC 12, na safra 2011/2012, irrigada por gotejamento subsuperficial; a segunda área com a variedade RB867515, irrigada por aspersão por meio de um pivô central, na safra 2012/2013. O acoplamento planta-atmosfera também foi avaliado. As análises do MRB indicaram um fluxo de calor latente médio de 70% da energia disponível no ambiente, com 25% de fluxo de calor sensível e 5% no fluxo de calor no solo. Com a mesma metodologia a evapotranspiração da cultura média (ETc) foi estimada em 3,92 e 3,25 mm dia-1 para as variedades CTC 12 e RB867515, respectivamente, resultando em um coeficiente de cultura (Kc) médio de 1,37, na fase de pleno desenvolvimento vegetativo. No período experimental, o canavial permaneceu mais acoplado à atmosfera (Ω médio=0,37) e a transpiração avaliada pelo BC chegou a 4,7 e 3,62 mm dia-1, respectivamente para CTC 12 e RB867515. A metodologia do IRGA resultou em perda de água ao nível foliar da faixa de até 1 mm h-1. Conforme a demanda atmosférica, o Kc da cultura apresentou-se variável em função da evapotranspiração de referência (ETo). O modelo DSSAT/CANEGRO mostrou-se eficiente na simulação da ETc e transpiração do canavial, com resultados mais satisfatórios (R2=0,59) quando utiliza-se a metodologia FAO 56 nas simulações. / Global climate change and the sugarcane crop expansion to regions with lower water supply became more important the real estimate of crop water requirements. This study aimed to contribute on this regard by analyzing the sugarcane water consumption at three different spatial scales: leaf, plant and canopy. The DSSAT/CANEGRO crop model was also evaluated with respect to sugarcane transpiration and evapotranspiration. Bowen ratio energy balance (BREB) method was performed to measure crop canopy evapotranspiration and the transpiration were measured with sap flow by stem heat balance for plant scale and infra-red gas analyzer (IRGA) for leaf scale. Two experimental sites were used: the first with CTC 12 cultivar and drip irrigation, on 2011/2012 season; in the second experiment the RB867515 variety was grown under sprinkler irrigation by a central pivot, on the 2012/2013 growing season. The plant-atmosphere decoupling factor was also evaluated. BREB method showed latent heat flux representing 70% of the available energy, 25% for sensible heat flux, and 5% for soil heat flux. BREB crop evapotranspiration (ETc) ranged from 3.92 to 3.25 mm day-1 for CTC 12 and RB867515, respectively, resulting in a mean crop coefficient (Kc) of 1.37 at the full vegetative growth stage. In the experimental period, sugarcane crop was coupled to the atmosphere (Ω=0.37) and transpiration assessed by HB reached 4.7 and 3.62 mm day-1 for CTC 12 and RB867515, respectively. IRGA method showed a leaf water loss up to 1 mm h-1. Kc varied with reference evapotranspiration (ETo) The DSSAT/CANEGRO crop model was efficient in the ETc and transpiration simulation, with better results (R2=0.59) when using FAO 56 ETo method in the simulations.

O tomate (Lycopersicum esculentum Mill) é um dos vegetais mais populares e amplamente consumidos e que faz parte importante na dieta diária. A maioria das áreas cultivadas com a cultura é usando irrigação por sulcos e com menor proporção irrigada por gotejamento. Além de baixa eficiência no uso da água, o sistema de irrigação por sulcos possui impacto ambiental negativo, tornando assim o gotejamento um sistema alternativo viável. O experimento foi conduzido com o objetivo de se avaliar o efeito de quatro lâminas de irrigação por gotejamento, três doses de potássio e a presença de cobertura plástica sobre as características agronômicas do tomateiro L. esculentum, cultivar Débora Plus. Foi utilizado um delineamento experimental inteiramente casualizado, em um esquema fatorial 4x3x2, com três repetições. Os tratamentos consistiram de lâminas de irrigação equivalentes a 125, 100, 75 e 50 % da necessidade hídrica da cultura, com doses de potássio de 208, 416 e 624 kg ha-1, com e sem cobertura do solo ("mulching"). A lâmina de irrigação foi aplicada mediante sistema de gotejamento quando a tensão da água no solo estava entre 10 e 15 kPa. As lâminas de irrigação afetaram significativamente os parâmetros de crescimento vegetativo e produtividade. O potássio, o mulching, as interações de irrigação e potássio, de irrigação e mulching, de irrigação, potássio e mulching influenciaram a altura das plantas aos 90 dias após o transplante (DAT), a massa de matéria fresca das plantas e a produção. A eficiência do uso da água (EUA) diminuiu com o aumento das lâminas de irrigação, sendo que a produtividade máxima foi obtida com a aplicação de 0,57 L.dia-1.planta-1. As maiores produtividades total e comercial foram de 86,20 e 79,73 Mg.ha-1, obtidas da combinação de 54,36 L.planta-1. ciclo-1 e dose de potássio de 416 kg.ha-1, sob condições de solo coberto com mulching. / Tomato is one of the most popular and widely consumed vegetable which forms a major part of daily diet. Most of the crop is irrigated by furrow irrigation system with fewer experiences with drip irrigation. Apart from low water use efficiency, the main irrigation system posses negative environmental impact thus making drip irrigation viable alternative. The objectives of the study was to evaluate the effect of four drip irrigation levels, three potassium doses and the presence of plastic mulching on water use efficiency and the agronomic characteristics of tomato, Lycopersicon esculentum Mill, variety, Débora Plus. The experimental design was a randomized complete design in a 4 x 3 x 2 factorial scheme with three replications. The treatments consisted of irrigation water levels equivalent to 125, 100, 75 and 50% of crop water requirement with potassium doses of 208, 416 and 624 kg ha-1. Irrigation was applied through drip irrigation system when soil water tension was between 10-15 kPa. Irrigation water levels significantly affected crop development parameters and production. Potassium, mulching, interactions of irrigation and potassium, irrigation and mulching, irrigation, potassium and mulching influenced plant height at 90 days after transplant , fresh plant mass and production. Water use efficiency decreased with increase in irrigation levels with daily recommended irrigation water of 0,57 L plant-1 cycle-1. The highest total and commercial yield were 86,20 and 79,73 t ha-1 both obtained with 54,36 L plant-1 cycle-1 and potassium dose 416 kg ha-1 with mulching.

Understanding the mechanism of photosynthetic seasonality in Amazonian evergreen forests is critical for its formulation in global climate and carbon cycle models. However, the control of the unexpected photosynthetic seasonality is highly uncertain. Here we use eddy-covariance data across a network of Amazonian research sites and a novel evapotranspiration (E) and two-leaf-photosynthesis-coupled model to investigate links between photosynthetic seasonality and climate factors on monthly scales. It reproduces the GPP seasonality (R-2=0.45-0.69) with a root-mean-square error (RMSE) of 0.67-1.25gCm(-2)d(-1) and a Bias of -0.03-1.04gCm(-2)d(-1) for four evergreen forest sites. We find that the proportion of diffuse and direct sunlight governs the photosynthetic seasonality via their interaction with sunlit and shaded leaves, supported by a proof that canopy light use efficiency (LUE) has a strong linear relationship with the fraction of diffuse sunlight for Amazonian evergreen forests. In the transition from dry season to rainy season, incident total radiation (Q) decreased while LUE and diffuse fraction increased, which produced the large seasonal increase (similar to 34%) in GPP of evergreen forests. We conclude that diffuse radiation is an important environmental driver of the photosynthetic seasonality in tropical Amazon forests yet depending on light utilization by sunlit and shaded leaves. Besides, the GPP model simulates the precipitation-dominated GPP seasonality (R-2=0.40-0.69) at pasture and savanna sites. These findings present an improved physiological method to relate light components with GPP in tropical Amazon. Plain Language Summary Understanding the mechanism of photosynthetic seasonality in Amazonian evergreen forests is critical for its formulation in global climate and carbon cycle models. However, the control of the unexpected photosynthetic seasonality is highly uncertain. Here we use eddy-covariance data across a network of Amazonian research sites and a novel evapotranspiration (E) and two-leaf-photosynthesis-coupled model to investigate links between photosynthetic seasonality and climate factors on monthly scales. It reproduces the GPP seasonality (R2= 0.45-0.69) for four evergreen forest sites. We find that the proportion of diffuse and direct sunlight governs the photosynthetic seasonality via their interaction with sunlit and shaded leaves, supported by a proof that canopy light-use efficiency (LUE) has a strong linear relationship with the fraction of diffuse sunlight for Amazonian evergreen forests. We conclude that diffuse radiation is an important environmental driver of the photosynthetic seasonality in tropical Amazon forests yet depending on light utilization by sunlit and shaded leaves. Besides, the GPP model simulates the precipitation-dominated GPP seasonality (R2= 0.40 similar to 0.69) at pasture and savanna sites. These findings present an improved physiological method to relate light components with GPP in Amazon.

The literature suggests that grain number largely determines and as such limits yield in barley. Many of the reported studies were conducted in relatively low yielding environments and it is unclear if grain number is also a limiting factor in high yield potential climates. Nor is it known with certainty what physiological or morphological traits must be targeted in order to increase grain number. There may be a degree of trade-off between yield components whereby grain number is adjusted according to resource availability to the plant, either pre- or post-anthesis, in a way that ensures consistently well-filled grains at harvest. If mechanisms exist for adjusting grain numbers or grain storage capacity after anthesis to match assimilate availability, this may place limits on how far yield can be increased without increasing post-anthesis assimilate production. In order to determine the scope for increasing the yield potential of barley a more thorough understanding of the potential trade-offs between grain number, grain storage capacity and post-anthesis assimilate supply is required. The aim of research reported in this thesis was to establish what determines the yield of spring barley in Ireland and to investigate the timing and possible mechanisms involved in regulating grain number and grain storage capacity in relation to the supply of photoassimilates. Field experiments were carried out on spring barley (Hordeum vulgare L., cv. Quench) at several locations in Ireland from 2011 to 2013. A sub-set of experiments involving destructive sampling and in-field assessments on plots managed as per current best farm practice gathered crop growth, development, and yield component data across sites and seasons in order to establish what determines yield under typical crop production conditions. Separate experiments artificially manipulated the source:sink ratio of plots via shading and seed rate treatments to investigate in more detail the mechanisms determining grain number and grain weight and any potential trade-off between the two components. Grain number accounted for most of the variation in yield across 9 site/seasons of crops managed as per current best practice in Ireland (P < 0.001; R2 = 0.84) while grain weight remained relatively conserved. Ear number accounted for most of the variation in grain number (P = 0.002; R2 = 0.75) and ear number itself was largely determined by shoot survival from an early season peak through to harvest (P <0.001; R = 0.96). Shoot size and weight at the beginning of stem extension had the largest influence on shoot survival. Shading treatments were used to test whether there was a mechanism for adjusting grain numbers after anthesis to match the availability of assimilate for grain filling. Substantial post-anthesis reductions in assimilate supply during grain filling in 2011 and 2012 did not significantly reduce grain number (P > 0.05). A small reduction in grain number (8%) was found in response to shading for a two week period early post-anthesis in 2013, however this was likely a reduction in grain set in shoots or spikelets that reached anthesis after the treatment was imposed rather than a post-anthesis abortion or down-regulation of grain number. Percentage light interception by well managed (unshaded) canopies shortly after anthesis was generally greater than 93% across several sites and seasons, therefore increasing grain numbers to increase sink capacity would likely be associated with an unavoidable decrease in the amount of light intercepted per grain during the early grain development period. However, experiments showed that grain weight at harvest was neither reduced nor increased in response to variations in light interception during this period of endosperm development (P > 0.05), because soluble sugar concentrations in the grain were maintained at the expense of storage reserve deposition in the stems. Results suggest that grain number and grain storage capacity may both be determined pre-anthesis resulting in a trade-off during stem extension whereby grain numbers are adjusted in a way that helps conserve grain weight. A strong negative relationship between ear number and grain number per ear (P < 0.001; R2 = 0.81) across two sites of seed rate experiments in 2013 resulted in a plateau in overall grain number of approximately 18,000 grains m-2 suggesting that there may be a limit to how many grains can be established in a given environment; this was achieved with an ear number of approximately 1000 ears m-2. Yield potential for Irish conditions was estimated at 12.29 t ha-1 at 85% dry matter based on estimates of potential assimilate supply during grain filling; with a grain number of 26,481 m-2 required to utilise this. These estimates are both 44% higher than the mean yield and grain number achieved in crops managed as per current best farm practice. Once high potential ear numbers are secured (> 1000 m-2), breaking the negative relationship between ear number and grain number per ear may hold the key to further increasing grain number and hence yield potential. Increasing assimilate production and partitioning to ears during stem extension, either through increases in the duration of stem extension or solar radiation use efficiency, may enable larger grain numbers to be produced whilst maintaining or increasing individual grain storage capacity and deposition of stem storage reserves. Water and nutrient availability, as well as susceptibility to lodging may present further limitations to yield in the future.

Exploring how drought influences growth, performance, and survival in different species is crucial to understanding the impacts of climate change on forest ecosystems. Here, we investigate the responses of two co-occurring pines (Pinus nigra and Pinus sylvestris) to interannual drought in east-central Spain by dendrochronological and wood anatomical features integrated with isotopic ratios of carbon (delta C-13) and oxygen (delta O-18) in tree rings. Our results showed that drought induces both species to allocate less carbon to build tracheid cell-walls but increases tracheid lumen diameters, particularly in the transition wood between early and latewood, potentially maximizing hydraulic conductivity but reducing resistance to embolism at a critical phase during the growing season. The thicker cell-wall-to-lumen ratio in P. nigra could imply that its xylem may be more resistant to bending stress and drought-induced cavitation than P. sylvestris. In contrast, the higher intrinsic water-use efficiency (iWUE) in P. sylvestris suggests that it relies more on a water-saving strategy. Our results suggest that narrower cell-walls and reduced growth under drought are not necessarily linked to increased iWUE. At our site P. nigra showed a higher growth plasticity, grew faster and was more competitive than P. sylvestris. In the long term, these sustained differences in iWUE and anatomical characters could affect forest species performance and composition, particularly under increased drought stress.

The complex interaction of genetics, environment and management in determination of crop yields can interfere with selection progress in breeding programs. Specifically, the impact on selection for nitrogen use efficiency (NUE) in wheat (Triticum aestivum L.) under changing climatic conditions can be confounded by these interactions. Temperature increases for the southeastern United States are projected to range from 1-3°C by 2050 with nighttime temperatures increasing more rapidly than day temperatures. High temperatures are known to affect crop development and breeding for tolerance to heat stress is difficult to achieve in field environments. We utilized a multi-environment trial to assess variation in traits associated with NUE based on interactions of genotype x environment x management (G×E×M). All genotypes in the study responded favorably to lower than recommended nitrogen rates. Incremental application of N rates increased yield and post-anthesis N uptake significantly. Additionally, two multi-year studies investigating the effects of heat stress on soft red winter wheat varieties were conducted during the 2015-2016 growing seasons at the University of Kentucky Spindletop Research Farm in Lexington, KY. Thirty-six to 40 genotypes were chosen based on the combination of traits for vernalization and photoperiod sensitivity determined using marker analysis. Warmed environments were created through active and passive warming. Heading date, averaged across genotypes, shifted 1-5 days earlier in the actively warmed environment compared to the ambient environment across both years (p ≤0.05). Grain yield, averaged across genotypes, was significantly reduced in the actively warmed environment by 211.41 kg ha-1 (p ≤0.05) or 4.84%; however yield response to environment varied among genotypes with several genotypes displaying an increased yield in the warmed environment. Night temperature increases ranged from 0.27-0.75 °C above ambient temperature in the passively warmed environment. Grain yield, averaged across genotypes, was significantly reduced in the passively warmed environment by 224.29 kg ha-1 (p ≤0.05) or 6.44%; however, yield response to environment varied among genotypes with several genotypes displaying an increased yield in the warmed environment. Yield reductions are attributed to nitrogen utilization being reduced by 9.4% (p ≤0.001) under increased night temperatures.

Understanding the effects of water stress on wheat growth, yield and quality is essential for good irrigation management. In South Africa most of the wheat production areas are vulnerable to drought stress during crop development. That causes substantial reduction in grain yield, depending on the developmental stage at which water stress occurred. Supplemental irrigation is the main strategy for adaptation and stabilisation of yield under water stress. However, agriculture is the leading single water-use sector locally, consuming about 60% of total available water. Therefore, the need to improve water use efficiency (WUE) in crop production is clear, since South Africa is classified as a water-scarce country. Experiments were conducted under a rain shelter at Hatfield Experimental Farm, University of Pretoria, in the 2010 and 2011 seasons. The main objective of the study was to evaluate the effects of water stress at different stages on growth, yield, and quality of three wheat cultivars, namely Duzi, Steenbras and SST 843. Water stress was imposed by withholding water at either of three growing stages. The first treatment was stressed during tillering stages to flag leaf (stem elongation (SNN)), followed by water stress from flag leaf to the end of flowering (flowering stage (NSN)), and lastly water stress from grain filling to physiological maturing (grain-filling stage (NNS)), whereas optimal supply of water was maintained throughout the season by weekly irrigating to field capacity for the control treatment (NNN). Irrigation treatments and cultivars influenced growth, yield and quality, depending on the developmental stage at which irrigation was withheld. The control treatment (NNN) and the treatment stressed in the flowering stage (NSN) had highest and lowest grain yield respectively in both seasons. Water stressed treatment NSN reduced grain yield by 33% and 35% in the 2010 and 2011 seasons respectively, when compared with the control treatment (NNN). Reduction of grain yield due to stress in the flowering stage (NSN) was ascribed to reduction in the number of seeds per ear, number of ears per unit area, ear length, and flag-leaf photosynthesis rate (Pn). In the flowering stage (NSN) water stress reduced Pn by 59% which was due to increased leaf temperature because of lower transpiration (E) and stomatal conductance (gs). The water stress treatment NSN reduced transpiration by 72% and stomatal conductance by 84% in the flowering stage. Plant height was reduced by 23% because of water stress imposed in the flowering stage (NSN), which consequently decreased biomass yield by 29% in the 2011 season. Growth and yield parameters showed dramatic recovery when stress was terminated during the flag-leaf stage (SNN). The cultivar Steenbras had lower yield reduction under stress, whereas Duzi and SST 843 had higher yield potential under the well-watered conditions (NNN). In the 2011 season SST 843 had higher WUE of 14.2 kg ha-1 mm, which corresponded to higher grain yield of 7210 kg ha-1 and higher ET of 509 mm. Water-stress treatment SNN gave the highest WUE of 14.9 kg ha-1 mm, which corresponded to a total water use (ET) of 451 mm and grain yield of 6738 kg ha-1. Water stress treatments SNN and NNS reduced ET by 27% and 17%, respectively, which translated to 173 mm and 105 mm water saved by each treatment correspondingly. Grain protein content (GPC) was reduced most by the treatment exposed to stress in the stem elongation stage (SNN). However, the GPC was acceptable (>12%) in all treatments in both seasons. Hectolitre mass was reduced most by water stress imposed during grain filling (NNS). Water stress treatment NNS lowered the hectolitre mass by 3% and 4% in the 2010 and 2011 seasons respectively. Generally all quality parameters in the present study were acceptable for all irrigation treatment and cultivars. The hypothesis that water stress in the stem elongation and grain-filling stages will have little effect on yield and improve WUE was accepted. Therefore it can be recommended that supplemental irrigation should be applied from flag leaf to end of flowering (NSN) stages of wheat in order to minimise grain yield losses in the absence of rainfall. Further research should focus on extrapolation of these results to other production regions using crop models. / Dissertation (MInstAgrar)--University of Pretoria, 2013. / Plant Production and Soil Science / unrestricted

Thesis (MSc .(Agronomy)) -- University of Limpopo, 2015 / The changes in climate, especially poor rainfall patterns and distributions are key issues posing major agricultural challenges for food security and threaten the rural livelihoods of many communities in the Limpopo Province. Rainfall (P) is low and limited. These limited P is mostly lost through runoff and evaporation, which result in low soil moisture availability and possible crop failure. Therefore, techniques that reduce these water losses are important for improving dryland crop production and rainwater productivity (RWP). The objectives of this study were to determine the potential and effectiveness of rainwater harvesting and conservation techniques (RWH&CT’s) to conserve and improve plant available water (PAW) for dryland maize production and also determine the efficiency of the RWH&CT’s to improve dryland maize yield and RWP compared to conventional tillage (CON). The study was conducted over a period of two growing seasons (2008/09; 2009/10) using maize as indicator crop at the Towoomba Research Station of the Limpopo Department of Agriculture in the Limpopo Province of South Africa, on an Arcadia ecotope. The experiment was laid out in a randomized complete block design, with four replications and five treatments. The five treatments used in the study were; conventional tillage (CON), No-till (NT), In-field rainwater harvesting (IRWH), Mechanized basins (MB) and Daling plough (DAL). The IRWH and DL were classified as rainwater harvesting techniques (RWHT’s), whilst MB and NT were classified as water conservation techniques. Two access tubes were installed at each treatment to measure the soil water content (SWC) at four different soil depths of 150, 450, 750 and 1050 mm using the neutron water meter. The data collected included climatic data, soil and plant parameters. The data were subjected to analysis of variance through NCSS 2000 Statistical System for Windows and GENSTAT 14th edition. Mean separation tests were computed using Fisher's protected least significant difference test. The SWC of IRWH, DAL and MB were about 510 and 490 mm higher compared to CON and NT treatment during the 2008/09 and 2009/10 seasons, respectively. The PAWT of the IRWH, MB and DAL was significantly different from the CON treatment during the 2008/09 season. For both seasons the biomass yield of the IRWH treatment was significantly different from the NT treatment, producing 23 and 50% more biomass in the 2008/09 and 2009/10 growing seasons, respectively. The grain yield under IRWH was significantly different from the NT treatment during both 2008/09 and 2009/10 seasons. The highest maize grain yield of IRWH was achieved during the 2009/10 season with 56% higher grain yield than the NT treatment. RWP from various RWHT’s were significantly different from the NT treatment. These results indicate that IRWH and DAL were 12 and 2% more effective in converting rainwater into harvestable grain yield than the CON treatment. R2 values of 68.6 and 78.4% for SWC and transpiration (Ev) were obtained when correlated with maize grain yield respectively. This indicates the importance of moisture conservation for improved dryland maize production under low P areas. Therefore, the use of appropriate RWHT’s by smallscale farmers maybe crucial to improve dryland maize production. IRWH outperformed all other treatments in terms of the soil parameters and plant parameter measured during the period of this study. Therefore, these results suggest IRWH has potential of sustaining maize yields under low rainfall conditions. Key words: Rainwater harvesting, conservation techniques, ecotope, rainwater productivity, maize yield, precipitation use efficiency.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第22782号 / 農博第2425号 / 新制||農||1081(附属図書館) / 学位論文||R2||N5302(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 中村 公人, 教授 星野 敏, 教授 藤原 正幸 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM