In order to make feasible the use of irrigated areas of the Pontal Sul Irrigation Scheme in Petrolina, State of Pernambuco, Brazil, modelling of real evapotranspiration (ET) and plant biomass production (BIO) at a large scale was performed with associated agro-meteorological data and the algorithm SAFER (Simple Algorithm For Evapotranspiration Retrieving) using MODIS images for the years 2010–2017. The year 2012 presented the highest ET average with 3.15 mm day⁻¹ in the rainy season, reaching a maximum of 6 mm day⁻¹. The lowest mean ET was recorded in the year 2013, with 0.08 mm day⁻¹ in the dry season, and the maximum recorded for the period was 3.40 mm day⁻¹ in the irrigated agricultural area. For BIO, the highest average was 104.82 kg ha⁻¹ day⁻¹, during the rainy season of 2012, reaching a maximum value of 252 kg ha⁻¹ day⁻¹. The lowest average was for the dry period of 2013, with a value of 0.93 kg ha⁻¹ day⁻¹, and a maximum of 112.51 kg ha⁻¹ day⁻¹ in the irrigated agricultural area. The higher ET results represent moisture in the root zone, provided by rainfall and/or irrigation, showing maximum values in the rainy season. The results obtained for BIO suffer greatly from perimeter water availability. The present study becomes very important to the management of water resources, as it provides an increase in water productivity for food production.

The objective of this work was to evaluate the growth of sugar-apple seedlings under irrigation management with saline water in a substrate with soil amendment. Treatments were obtained from the arrangement between polymer doses (0, 0.2, 0.6, 1.0 and 1.2 g dm^-3) and levels of irrigation water electrical conductivity (0.3, 1.1, 2.7, 4.3 and 5.0 dS m^-1), associated with irrigation frequencies (daily and every alternate day), and two additional treatments to evaluate container volume (1.30 and 0.75 dm³), using a randomized complete block design, with four replicates. At 120 days after sowing, the variables substrate salinity, stem diameter, plant height, number of leaves and Dickson quality index were determined. Data were submitted to analyses of variance, regression and contrast. Substrate salinity increased with the increase in irrigation water electrical conductivity and polymer doses. Growth and quality of the seedlings were reduced with increasing irrigation water salinity, and highest values of the variables were obtained in seedlings under daily irrigation. Container with larger volume led to higher growth. The use of hydrated polymer at the adopted levels had no effect on growth and quality of seedlings, requiring further studies. To produce sugar-apple seedlings with better quality, irrigation frequency should be daily and water electrical conductivity should be lower than 2 dS m^-1.

Geoestatística aplicada à uniformidade de aplicação de água em sistema de irrigação por gotejamento usado e novo - DOI: 10.7127/rbai.v9n300298

Application of saline water causes water and salt stress, changing the behavior of the plants. The aim of this work was to evaluate the accumulation and allocation of biomass in sugar-apple seedlings under frequencies of irrigation with saline water in a substrate with soil conditioner, as well as the effect of container volume. The treatments were obtained from the arrangement between polymer doses (0, 0.2, 0.6, 1.0 and 1.2 g dm^-3) and electrical conductivity of irrigation water (0.3; 1.1; 2.7; 4.3 and 5.0 dS m^-1), associated with irrigation frequencies (daily and alternated), plus two additional treatments to evaluate container volume (0.75 and 1.30 dm³), distributed in blocks. The evaluations were performed at 120 days after sowing. Irrigation frequency affected the variables, and the highest values ​​were obtained with daily irrigation, except for root/shoot dry matter ratio. Increase in the electrical conductivity of the irrigation water inhibited biomass accumulation. The effect of the container was significant for daily irrigation; higher volume led to higher root, shoot and total biomass. Polymer doses did not affect the biomass of the seedlings. Daily irrigation with non-saline water favored biomass production in sugar-apple seedlings. In the production of sugar-apple seedlings, water with electrical conductivity below 1.0 dS m^-1 should be used on a daily frequency of application in 1.30 dm³ containers.

A estimativa da evapotranspiração é um relevante componente no manejo da irrigação e, sua mensuração envolve diversos parâmetros que podem dificultar na sua obtenção. O trabalho objetivou comparar modelos matemáticos para determinação da evapotranspiração de referência para o município de Apodi, RN. Foram utilizados dados atmosféricos dos meses de setembro à dezembro de 2008 e 2009, fornecidos pelo Instituto Nacional de Meteorologia (INMET). A evapotranspiração de referência foi estimada pelos modelos de Penman-Monteith (Padrão da FAO), Jensen-Haise, Hargreaves-Samani e Makkink. Foi realizada análise de regressão linear entre os métodos alternativos e o método de Penman-Monteith com os dados de 2008. A partir dos modelos de regressão, os dados foram ajustados pelo coeficiente de regressão para os anos de 2008 e 2009. A partir desses dados simulados, calculou-se os índices de Willmott (d), de Pearson (), de confiabilidade e, a percentagem do desvio (PD). Resultados mais precisos foram encontrados em modelos que utilizam a radiação solar como variável, diferentemente daquele que utilizou apenas a temperatura do ar e a umidade relativa do ar. Os melhores desempenhos foram encontrados para os métodos de Jensen-Haise e Makkink, obtendo correlações classificados como “muito alta”. Contudo, os melhores métodos a serem aplicados para a região de Apodi-RN, entre os meses de setembro e dezembro, são o de Jensen-Haise ajustado pelo fator de 0,65 e o de Makkink.