CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A falta de um manejo adequado da irrigaÃÃo por parte da maioria dos produtores instalados nos perÃmetros pÃblicos irrigados no estado do Cearà à considerado como o principal fator com interferÃncia direta na produtividade, custo de produÃÃo, qualidade dos produtos comercializados e principalmente na questÃo ambiental, onde o uso inadequado da Ãgua de nossos mananciais poderà comprometer seriamente nossas geraÃÃes futuras. A iniciativa de desenvolvimento de ferramentas para auxiliar o produtor a realizar um manejo de irrigaÃÃo satisfatÃrio, que seja acessÃvel e de fÃcil operaÃÃo à uma meta que devemos sempre definir como prioritÃria. Esse trabalho visa o desenvolvimento de um aplicativo para dispositivos mÃveis, capaz de utilizar uma base de dados prÃpria na realizaÃÃo do cÃlculo do tempo diÃrio de irrigaÃÃo para cada cultura em uma determinada data. Foram utilizadas tÃcnicas e ferramentas de desenvolvimento de software, especÃficas para a plataforma mÃvel Android. O aplicativo visa auxiliar na conduÃÃo de um manejo com uso racional de Ãgua nos perÃmetros irrigados localizados no estado de CearÃ, semiÃrido nordestino, mitigando a falta da assistÃncia tÃcnica especializada em agricultura de precisÃo, utilizando bancos de dados com informaÃÃes necessÃrias para o cÃlculo da necessidade hÃdrica e posterior recomendaÃÃo do tempo de irrigaÃÃo. Entre os bancos de dados instalados, conta-se com as series histÃricas da âevapotranspiraÃÃo potencial de referÃnciaâ dos Ãltimos dez anos nas regiÃes representativas onde se encontram implantados os oito principais perÃmetros irrigados do estado do CearÃ: Curu-Paraipaba, Pentecostes, Baixo AcaraÃ, Araras Norte, Jaguaribe Apodi, Morada Nova, Tabuleiros de Russas e IcÃ-Lima Campos, alÃm dos bancos de dados com informaÃÃes relativas ao âcoeficiente de cultivoâ e âPercentual de coberturaâ dos principais cultivos explorados nos perÃmetros. O sistema desenvolvido apresenta uma nova abordagem para o manejo da irrigaÃÃo, fazendo uso da mobilidade disponÃvel em celulares para permitir que os usuÃrios realizem o cÃlculo do tempo de irrigaÃÃo diÃrio em qualquer um dos perÃmetros irrigados do estado do CearÃ. A utilizaÃÃo do aplicativo em simulaÃÃo para o PerÃmetro Irrigado Baixo AcaraÃ, demonstrou uma reduÃÃo de aproximadamente 26 % em relaÃÃo a utilizaÃÃo atual de Ãgua na irrigaÃÃo, permitindo concluir-se que o seu uso proporciona um bom manejo de irrigaÃÃo e poderà resultar em uma economia de Ãgua necessÃria para reduÃÃo dos impactos recorrentes dos longos e repetitivos perÃodos de estiagem sobre os recursos hÃdricos do estado do CearÃ. / The lack of a proper irrigation management by the majority of producers in irrigated public areas in the state of Cearà is considered the main factor with direct influence on productivity, cost of production, quality of products, and especially in the environmental issue, where the inappropriate use of water from our springs could seriously compromise our future generations. The initiative in the development of tools to assist the producer to carry out a satisfactory irrigation management that is accessible and of easy operation is a goal that should always be set as a priority. This work aims to develop an application for mobile devices, able to use its own database in the realization of the daily irrigation time calculation for each crop on a certain date. Techniques and software development tools were used specificly for the Android mobile platform. The application intends to assist in conducting a management with rational use of water in irrigated areas in the state of CearÃ, semi-arid northeast, mitigating the lack of technical assistance specialized in precision farming, using databases with information necessary for the calculation of the need water and subsequent irrigation time recommendation. Among the installed databases, it has historical series of "potential reference evapotranspiration" for the past ten years in representative regions where the eight main irrigation schemes of the Cearà state: Curu-Paraipaba, Pentecostes, Baixo AcaraÃ, Araras Norte, Jaguaribe Apodi, Morada Nova, Tabuleiros de Russas e IcÃ-Lima Campos are located and also databases with information on the "crop coefficient" and "coverage percentage" of major crops exploited on the perimeters. This application was developed to present a new approach to irrigation management, making use of the available mobile phones in order to allow users to perform the calculation of the daily irrigation time in any of the irrigated perimeters of the Cearà state. The use of the application in simulation for the Irrigated Perimeter Baixo Acaraà demonstrated a reduction of approximately 26% over the current use of water in irrigation, allowing its use be concluded that provides good irrigation management and could result in an economy of water required to reduce the impact of recurring long and repetitive periods of drought on water resources of the state of CearÃ.

A series of field, rainshelter, growth cabinet and modelling studies were conducted to investigate hot pepper response to different irrigation regimes and row spacings; to generate crop-specific model parameters; and to calibrate and validate the Soil Water Balance (SWB) model. Soil, climate and management data of five hot pepper growing regions of Ethiopia were identified to develop irrigation calendars and estimate water requirements of hot pepper under different growing conditions. High irrigation regimes increased fresh and dry fruit yield, fruit number, harvest index and top dry matter production. Yield loss could be prevented by irrigating at 20-25% depletion of plant available water, confirming the sensitivity of the crop to mild soil water stress. High plant density markedly increased fresh and dry fruit yield, water-use efficiency and dry matter production. Average fruit mass, succulence and specific leaf area were neither affected by row spacing nor by irrigation regimes. There were marked differences among the cultivars in fruit yields despite comparable top dry mass production. Average dry fruit mass, fruit number per plant and succulence were significantly affected by cultivar differences. The absence of interaction effects among cultivar and irrigation regimes, cultivars and row spacing, and irrigation regimes and row spacing for most parameters suggest that appropriate irrigation regimes and row spacing that maximize productivity of hot pepper can be devised across cultivars. To facilitate irrigation scheduling, a simple canopy cover based procedure was used to determine FAO-type crop factors and growth periods for different growth stages of five hot pepper cultivars. Growth analysis was done to calculate crop-specific model parameters for the SWB model and the model was successfully calibrated and validated for five hot pepper cultivars under different irrigation regimes or row spacings. FAO basal crop coefficients (Kcb) and crop-specific model parameters for new hot pepper cultivars can now be estimated from the database, using canopy characteristics, day degrees to maturity and dry matter production. Growth cabinet studies were used to determine cardinal temperatures, namely the base, optimum and cut-off temperatures for various developmental stages. Hot pepper cultivars were observed to require different cardinal temperatures for various developmental stages. Data on thermal time requirement for flowering and maturity between plants in growth cabinet and open field experiments matched closely. Simulated water requirements for hot pepper cultivar Mareko Fana production ranged between 517 mm at Melkassa and 775 mm at Alemaya. The simulated irrigation interval ranged between 9 days at Alemaya and 6 days at Bako, and the average irrigation amount per irrigation ranged between 27.9 mm at Bako and 35.0 mm at Zeway. / Thesis (PhD)--University of Pretoria, 2010. / Plant Production and Soil Science / unrestricted