Effect of partial soil wetting on transpiration, vegetative growth and root system of young orange trees

The wetted area fraction is a factor critical to the success of drip irrigation. This study aimed to evaluate the effect of partial soil wetting on transpiration, vegetative growth and root system of young orange trees. The experiment was carried out in a greenhouse where plants were grown in 0.5 m3boxes internally divided into compartments. The wetting of 12 % of soil area was tested on two types of soil cultivated with ‘Valencia’ orange trees grafted onto Rangpur lime and ‘Swingle’ citrumelo rootstocks. Transpiration was determined in 40 plants. Water extraction and root density were evaluated in the compartments. Transpiration is reduced by restriction in wetted soil area, and such reduction is influenced by the number of days after the beginning of partial irrigation, atmospheric evaporative demand and plant phenological stage. Mean transpiration of plants with partial irrigation was equivalent to 84 % of the mean transpiration of plants with 100 % of wetted soil area in the period studied. However, after 156 days of imposing partial irrigation there was no difference in transpiration between treatments. Plant acclimation was caused by an increase in root concentration in the irrigated area. After a period of acclimation, if the entire root system is wetted, soil water extraction becomes proportional to the percentage of wetted area after a short period of time. Despite the reduction in transpiration, there was no difference between treatments with 12 % and 100 % of wetted soil area in terms of vegetative growth

Tensiometria aplicada na estimativa do consumo hídrico do cafeeiro irrigado por gotejamento

O cafeeiro está entre as principais culturas irrigadas do Brasil e o seu consumo de água tem sido quantificado, principalmente, pelo uso de variáveis climatológicas, como a evapotranspiração de referência (ETo) e o coeficiente de cultura (Kc). Os coeficientes utilizados no manejo da irrigação e na estimativa da evapotranspiração (ET) do cafeeiro são, atualmente, objetos de pesquisa de muitos cientistas, que procuram caracterizar regionalmente esses fatores. O objetivo deste trabalho foi estimar os parâmetros característicos das necessidades hídricas do cafeeiro, ou seja, a ET e o Kc, com base em dois métodos de estimativa de ETo e tensiometria. O estudo foi realizado em Piracicaba-SP, utilizando a espécie Coffea arabica da variedade Catuaí Vermelho IAC 144, o sistema de irrigação adotado foi o gotejamento e o manejo foi feito por tensiometria. Foram utilizados dois métodos para a estimativa da ETo, Penman-Monteith e Priestley Taylor. As lâminas de irrigação necessárias para o suprimento hídrico da cultura variaram entre 1,73 e 2,67 mm d-1, em média, ao longo do período de avaliação. Concluiu-se que o Kc estimado com base na tensiometria e em estimativas de ETo (Penman-Monteith e Priestley Taylor) apresentou valores que variaram de 0,59 (época 4) a 0,98 (época 2)

Effect of partial soil wetting on transpiration, vegetative growth and root system of young orange trees

The wetted area fraction is a factor critical to the success of drip irrigation. This study aimed to evaluate the effect of partial soil wetting on transpiration, vegetative growth and root system of young orange trees. The experiment was carried out in a greenhouse where plants were grown in 0.5 m3boxes internally divided into compartments. The wetting of 12 % of soil area was tested on two types of soil cultivated with ‘Valencia’ orange trees grafted onto Rangpur lime and ‘Swingle’ citrumelo rootstocks. Transpiration was determined in 40 plants. Water extraction and root density were evaluated in the compartments. Transpiration is reduced by restriction in wetted soil area, and such reduction is influenced by the number of days after the beginning of partial irrigation, atmospheric evaporative demand and plant phenological stage. Mean transpiration of plants with partial irrigation was equivalent to 84 % of the mean transpiration of plants with 100 % of wetted soil area in the period studied. However, after 156 days of imposing partial irrigation there was no difference in transpiration between treatments. Plant acclimation was caused by an increase in root concentration in the irrigated area. After a period of acclimation, if the entire root system is wetted, soil water extraction becomes proportional to the percentage of wetted area after a short period of time. Despite the reduction in transpiration, there was no difference between treatments with 12 % and 100 % of wetted soil area in terms of vegetative growth

Effect of partial soil wetting on transpiration, vegetative growth and root system of young orange trees

The wetted area fraction is a factor critical to the success of drip irrigation. This study aimed to evaluate the effect of partial soil wetting on transpiration, vegetative growth and root system of young orange trees. The experiment was carried out in a greenhouse where plants were grown in 0.5 m3boxes internally divided into compartments. The wetting of 12 % of soil area was tested on two types of soil cultivated with ‘Valencia’ orange trees grafted onto Rangpur lime and ‘Swingle’ citrumelo rootstocks. Transpiration was determined in 40 plants. Water extraction and root density were evaluated in the compartments. Transpiration is reduced by restriction in wetted soil area, and such reduction is influenced by the number of days after the beginning of partial irrigation, atmospheric evaporative demand and plant phenological stage. Mean transpiration of plants with partial irrigation was equivalent to 84 % of the mean transpiration of plants with 100 % of wetted soil area in the period studied. However, after 156 days of imposing partial irrigation there was no difference in transpiration between treatments. Plant acclimation was caused by an increase in root concentration in the irrigated area. After a period of acclimation, if the entire root system is wetted, soil water extraction becomes proportional to the percentage of wetted area after a short period of time. Despite the reduction in transpiration, there was no difference between treatments with 12 % and 100 % of wetted soil area in terms of vegetative growth

LISÍMETRO DE PESAGEM E DE LENÇOL FREÁTICO DE NÍVEL CONSTANTE PARA USO EM AMBIENTE PROTEGIDO

This paper had as objective to build and to calibrate weight lysimeters of low capacity and to establish comparisons between the working status of constant level water table lysimeters. Two weight lysimeters of 15-L and 50-L and two constant level water table lysimeters of 15-L and 50-L were built at Embrapa Mandioca & Fruticultura Irrigation and Fertirrigation Laboratory, Cruz das Almas - BA, Brazil. Linearity, repetitivity and hysteresis errors in the range of reading of the weight lysimeter. Simultaneously measurements of soil evaporation were performed on bare soil with the two lysimeters in a 1-h interval. Afterwards, orange transpiration was measured by using lysimeters and by using a heat balance sap flow equipment. Results showed that the relation between analogical signals and the standard mass in the lysimeter provided linear equation with reasonable goodness of fit. The systematic and random errors were larger in the lysimeters of larger capacity. The instruments were able to make readings with good stability during the days of measurements and were also able to detect mass variation due to hourly transpiration. However, the measurements were in agreement if comparing average three day data

Aproveitamento térmico de coletor solar na desinfestação de substrato

Disinfestation of the substrate is mandatory in the production of healthy and vigorous seedlings. However, conventional treatment with agrochemicals can be unsatisfactory, due to the costs and risks of biological vacuum and intoxication. To minimize these limitations, solarization emerges as a potentially viable technique. Therefore, this work evaluated the energy conversion of a solar collector and its capacity for disinfesting substrate with cricket (Gryllus assimilis(Fabr. 1775)). The equipment was built with a wooden box, with six galvanized steel tubes inside. The face of the box facing the sun had transparent glass, which allowed the entry of shortwave solar radiation and restricted the outflow of hot air masses. A completely randomized experimental design was used, with four solar radiation exposure treatments, each with five replications. During the experiment, it was found that the maximum temperature of the substrate was 70.4 °C, with a maximum thermal amplitude of 38.6 °C, between the interior and exterior of the equipment. The thermal variation, per unit of incident solar radiation, reached a maximum value of 1.61°C.W-1.m-2. The quickest extermination of the insects occurred with two hours of exposure to solar radiation. The substrate temperatures inside the solar collector and the control, were on average 60.4 and 25.0 ºC, respectively.A desinfestação do substrato torna-se obrigatória na produção de mudas sadias e com vigor. No entanto, o tratamento convencional com agroquímicos pode ser insatisfatório, devido aos custos e aos riscos de vácuo biológico e intoxicação. Para minimizar essas limitações, a solarização surge como uma técnica potencialmente viável. Por conseguinte, esse trabalho avaliou a conversão energética de um coletor solar e a sua capacidade de desinfestação de substrato com grilo (Gryllus assimilis(Fabr. 1775)). O equipamento foi construído com uma caixa de madeirite, com seis tubos de aço galvanizado em seu interior. A face da caixa voltada para o Sol possuía vidro transparente, que permitia a entrada de radiação solar de ondas curtas e restringia a saída de massas de ar quente. Empregou-se o delineamento experimental inteiramente casualizado, com quatro tratamento de exposição à radiação solar, cada um com cinco repetições. Durante o experimento, constatou-se que a temperatura máxima do substrato foi de 70,4°C, com uma amplitude térmica máxima de 38,6°C, entre o interior e exterior do equipamento. A variação térmica, por unidade de radiação solar incidente atingiu valor máximo de 1,61°C.W-1.m-2. O extermínio mais rápido dos insetos ocorreu com duas horas de exposição à radiação solar. As temperaturas do substrato no interior do coletor solar e da testemunha, foram em média de 60,4 e 25,0 ºC, respectivamente

A Multicriteria Model for Estimating <i>Coffea arabica</i> L. Productive Potential Based on the Observation of Landscape Elements

Understanding a crop’s productive potential is crucial for optimizing resource use in agriculture, encouraging sustainable practices, and effectively planning planting and preservation efforts. Achieving precise and tailored management strategies is equally important. However, this task is particularly challenging in coffee cultivation due to the absence of accurate productivity maps for this crop. In this article, we created a multicriteria model to estimate the productive potential of coffee trees based on the observation of landscape elements that determine environmental fragility (EF). The model input parameters were slope and terrain shape data, slope flow power, and orbital image data (Landsat 8), allowing us to calculate the NDVI vegetation index. We applied the model developed to coffee trees planted in Bambuí, Minas Gerais, Brazil. We used seven plots to which we had access to yield data in a recent historical series. We compared the productivity levels predicted by the EF model and the historical productivity data of the coffee areas for the years 2016, 2018, and 2020. The model showed a high correlation between the calculated potential and the annual productivity. We noticed a strong correlation (R2) in the regression analyses conducted between the predicted productive potential and the actual productivity in 2018 and 2020 (0.91 and 0.93, respectively), although the correlation was somewhat weaker in 2016 (0.85). We conclude that our model could satisfactorily estimate the yearly production potential under a zero-harvest system in the study area

Effect of water stress on renewable energy from sugarcane biomass

The higher heating value (HHV) of sugarcane biomass components has been well documented; however, the effect of different soil water levels (abiotic stress) during the growing season on HHV has not been assessed for this energy crop. Drip irrigation in sugarcane production presents a potential to be a disruptive technology for sugarcane mills in terms of water-energy-nexus, making this inextricable relationship more efficient. The objective of this article was to quantify the higher heating value and useful energy from biomass partitions of different sugarcane varieties (Saccharum spp.) drip irrigated at four water levels and four maturation processes (drying off intensity prior to harvesting time); this information is not available in literature to date. The contribution of this article to the state of the art of knowledge are: a) the heating values for sugarcane partitions: bagasse, leaves and pointers did not vary significantly for varieties, water stress levels under drip irrigation and maturation processes; conversely, the heating value for the sheath biomass partition vary significantly for varieties. The average heating values for all treatments for the bagasse, sheaths, leaves and pointers were 18.16, 17.21, 17.64 and 17.84 MJ kg−1 respectively; b) the useful energy in sugarcane is almost totally dependent on the biomass produced per unit of area; drip irrigation levels and sugarcane variety traits are important in establishing the bioenergy productivity per area; the average value obtained for all treatments was 660.29 GJ ha−1 year−1 (36.90 Mg dry mass ha−1 year−1). Drip irrigated sugarcane crops at higher water levels in the soil, resulted a higher intensive land use and less deforestation pressure at sugarcane bioenergy production areas