Soil water potential during different phenological phases of coffee irrigated by center pivot

Irrigation management can be established, considering the soil water potential, as the limiting factor for plant growth, assuming the soil water content between the field capacity and the permanent wilting point as available water for crops. Thus, the aim of this study was to establish the soil water potential interval during four different phenological phases of coffee irrigated by center pivot. The experiment was set at the experimental area of the Engineering Department at the Federal University of Lavras, in Brazil. The coffee variety planted is designated as Rubi, planted 0.8 meters apart, with rows spaced 3.5 meters apart. The treatments corresponded to the water depths applied based on different percentages of Kc and reference evapotranspiration (ET0) values. Sensors were used to measure the soil water potential interval, installed 25 centimeters depth. In order to compare the results, it was considered as the best matric potential the one that was balanced with the soil water content that resulted in the largest coffee productivity. Based on the obtained results, we verified that in the phases of fruit expansion and ripening, the best results were obtained, before the irrigations, when the soil water potential values reached -35 and -38 kPa, respectively. And in the flowering, small green and fruit expansion phases, when the values reached -31 and -32 kPa, respectively.

Root system distribution of sugarcane irrigated with domestic sewage effluent aplication by subsurface drip system

Irrigation with domestic sewage effluent (DSE) has been recommended by subsurface dripping, as it can obtain a high rate of irrigation efficiency and faster use of salts in comparison with other irrigation methods. The study aimed at evaluating the area, the length and the effective depth of the root system of sugarcane irrigated with DSE by subsurface drip system and with different irrigation rates at depths of 0.00-0.20, 0.20-0.40, 0.40-0.60 and 0.60-0.80m. The experiment was carried out in the municipality of Piracicaba, in the state of São Paulo (SP), Brazil, in a sugarcane area irrigated with DSE in a completely randomized blocks set up in furrows, with three replications and four treatments, which are: one area without irrigation (AWI) and three irrigated areas meeting 50% (T50%), 100% (T100%) and 200% (T200%) of the crop's water need between each round of irrigation. T100% and T200% provided smaller areas and lengths of roots in the two deepest layers, as compared to AWI and T50%, which stimulated the development of deeper roots due to the water stress. TWI, T100% and T200% presented 80% of the roots up to a depth of 0.40m and T50% treatment presented 76.43% of roots total.

Technical and economic indicators of the yellow passion fruit tree irrigated with underground water supply

The research aimed to quantify technical and economic indicators of yellow passion fruit tree irrigated with fractions of irrigation with underground source of water, to generate information that helps farmers in decision making on the implementation of investment in irrigated fruit growing (yellow passion fruit). For this purpose, we used the passion fruit crop irrigated with Microjet type irrigation system, with conducting system in simple espaliers. The treatments consisted of five hours of application of the depth of water required by the crop with irrigation frequency of two days. The results showed that the highest yield (16660kg ha-1) was obtained with the fractionation of irrigation twice a day (50% to 7h and 50% to 21h30), which provided an increase in productivity of 54%, demonstrating the financial viability and being highly profitable to the interest rate of 2% per year, with low sensitivity of financial risk to real interest rates above the prevailing market.

Geostatistics and remote sensing methods in the classification of images of areas cultivated with citrus

This study compares the precision of three image classification methods, two of remote sensing and one of geostatistics applied to areas cultivated with citrus. The 5,296.52ha area of study is located in the city of Araraquara - central region of the state of São Paulo (SP), Brazil. The multispectral image from the CCD/CBERS-2B satellite was acquired in 2009 and processed through the Geographic Information System (GIS) SPRING. Three classification methods were used, one unsupervised (Cluster), and two supervised (Indicator Kriging/IK and Maximum Likelihood/Maxver), in addition to the screen classification taken as field checking.. Reliability of classifications was evaluated by Kappa index. In accordance with the Kappa index, the Indicator kriging method obtained the highest degree of reliability for bands 2 and 4. Moreover the Cluster method applied to band 2 (green) was the best quality classification between all the methods. Indicator Kriging was the classifier that presented the citrus total area closest to the field check estimated by -3.01%, whereas Maxver overestimated the total citrus area by 42.94%.

Energy demand in citrus production under varied operational efficiency values

Citrus orchards are very important in Brazil, especially in São Paulo State, where occupy an area of 600,000 ha approximately. To identify sustainability degree of citrus production system, an energy analysis allows evaluating efficiency of direct and indirect applied inputs. Thus, this study aimed to evaluate citrus production system under energetic point of view, in which invested energy is paid back with citrus production; being compared within three scenarios for operational field efficiency. As result, by sensitivity analysis was determined that fuel was the main energy demander, followed by pesticides and fertilizers. In operational work capacity analysis, all combinations between efficiency (minimum, typical and maximum) and yield levels became positive in the seventh year, except for the combination minimum efficiency and 10 % less yield, positive in the eighth year. The best combination (maximum efficiency and 10 % more yield) has promoted investment payoff around the sixth and seventh year. By this study, it is possible to determine the total energy demand to produce citrus and indentify the applied inputs that need more attention by the decision-makers. Labor and seedlings can be ommited for further studies with citrus, since they were irrelevant. Management of agricultural machinery may pose an important role on decreasing environmental impact of citrus production.

Estimated production and evapotranspiration of irrigated bean cultivars

The current study intended to determine the optimum water depth, yield and evapotranspiration (ETc) for bean cultivars. The experiment was conducted in the Campus of Unit I of the Triângulo Mineiro Federal Education and Technology Institute in Uberaba, MG, in a completely randomized design with three replications. The treatments consisted of four water-replacing levels in the soil (70, 100, 130 and 160% of the crop evapotranspiration) and four bean cultivars (Pérola, BRSMG Madrepérola, BRSMG Majestoso and IAC Alvorada). The average values of ETc obtained for soil water balance for the cultivars Pérola, BRSMG Madrepérola, BRSMG Majestoso and IAC Alvorada were, respectively, of 5.25 mm day-1, 4.59 mm day-1, 4.54 mm day-1 and 4.77 mm day-1. The water depths which provided the highest yields were for the cultivars Pérola, BRSMG Madrepérola, BRSMG Majestoso and IAC Alvorada of 451.61 mm, 454.41 mm, 504.71 mm and 344.30 mm, respectively. The maximum yields found were 4597.87 kg ha-1 (Pérola), 4546.27 kg ha-1 (BRSMG Madrepérola), 4253.39 kg ha-1 (BRSMG Majestoso) and 3958.50kg ha-1 (IAC Alvorada).

IDENTIFICATION OF SUITABLE AREAS FOR IRRIGATED RICE CROPPING USING MODIS IMAGES AND HAND MODEL

ABSTRACT One of the most relevant activities of Brazilian economy is agriculture. Among the main crops in Brazil, rice is one of high relevance. The state of Rio Grande do Sul, in Southern Brazil, is responsible for 68.7% of domestic production (IBGE, 2013). The goal of this study was to develop a low-cost methodology with a regional scope to identify suitable areas for irrigated rice cropping in this state, using spectro-temporal behavior of vegetation index by means of MODIS images and HAND model. The rice-cropped area of this study was the southern half of the State. Using the HAND model, flood areas were mapped to identify irrigated rice cultivation. We used multi-temporal images of vegetation index from MODIS sensor, covering the period from August 2001 to May 2012. To assess the results, we used data collected in the fields and cropped area information from IBGE. The results showed that the proposed methodology was satisfactory, with Kappa 0.92 and global accuracy of 98.18%. As result, MODIS sensor data and flood areas delineation by means of HAND model generated the estimate irrigated rice area for the area of study.

Characterization of capacitive sensors for measurements of the moisture in irrigated soils

The irrigation is a technique developed to supply the hydric needs of the plants. The use of the water should be optimized so that the culture just has enough for its growth, avoiding waste. The objective of this work was to characterize the behavior of capacitive sensors of humidity to monitor the moisture in the soils. In first instance, it was appraised sensors with dielectric built of synthetic pomes stone (Rd = 0,4 and Rd = 0,8) and of soil samples (Rd = 0,8 and Rd = 1,0), being the Rd parameter a geometric factor that relates the distance between the capacitor plates with radius of the plates. For the calibration, the sensors were installed in PVC recipient of cylindrical shape, filled with soil. The set (sensor and soil) was humidified by capillary effect and submitted by a natural drying very slowly. The parameter readings were taken daily, which allowed obtain the curves relating the humidity percentage, expressed in terms of dry weight, with the output voltage fort the sensor. The experiments were performed in sand soil and in dark red latossolo. The obtained results allowed to infer that the behavior of the sensor has a specific feature for each type of soil, being, therefore, necessary to develop a own calibration curve for the sensor, when used in soil with specific characteristic.

Misturas de herbicidas para o controle de plantas daninhas anuais na cultura de citrus (Citrus sinensis (L.) Osbeck)

Com o objetivo de se avaliar a eficiência das misturas de glyphosate com diuron ou simazine para o controle de plantas daninhas anuais na cultura de citrus, foram conduzidos dois experimentos durante o ano agrícola 83/84, sendo um em Jaguariúna e outro em Catanduva, ambos no estado de São Paulo. Os resultados obtidos mostraram que, embora todos os tratamentos tenham sido altamente eficientes, o controle de Digitaria horizontalis, Brachiaria plantaginea e portulaca oleracea aos 10 DAT foi um pouco inferior quando se aplicou as misturas de tanque (glyphosate + diuron ou simazine), em relação à aplicação seqüencial desses mesmos produtos. A adição do sulfato de amônio nas misturas de tanque minimizou esse problema, o qual não foi observado na avaliação realizada aos 30 DAT. Ainda com relação às misturas, o controle das gramíneas foi superior quando se utilizou diuron em relação à simazine. As misturas de herbicidas residuais com glyphosate proporcionaram melhor controle aos 60 DAT quando comparados às aplicações de glyphosate isoladamente.

Efeito de herbicidas residuais, aplicados por vários anos consecutivos, na distribuição do sistema radicular da laranjeira Natal (Citrus sinensis.(L.) osbeck)

O presente trabalho foi desenvolvido com o objetivo de verificar a influência do uso contínuo de vários herbicidas residuais, sobre a distribuição das radicelas de laranjeiras Natal (Citrus sinensis (L.) Osbeck) enxertadas sobre limão Cravo (Cithus limonia Osbeck) e plantadas em janeiro de 1970. O experimento foi instalado no pomar de produção da Faculdade de Ciências Agrárias e Veterinárias do Campus de Jaboticabal (UNESP), em Latossol Roxo distrófico, com 1,6% de matéria orgânica e 51% de argila. O delineamento experimental utilizado foi o de blocos ao acaso, dentro de um esquema fatorial 11x 3x2x2, com três repetições. Os tratamentos utilizados, com as respectivas doses em kg do i.a/ha foram: fluometuron a 4,2; simazíne a 4,8; atrazine a 4,8; bromacil a 3,2;bromacil (40%) + diuron (40%) a 4,8; bromacil (53,3%) + diuron (27,6%) a 4,8; terbacil a 3,2; oxadiazon a 1,5; dichlobenil a 3,0 e 6,0; além de uma testemunha capinada. O estudo das radicel as foi feito pelo "método do trado", tendo sido tomadas amostras de solo contendo radicelas, nas distâncias de 80, 160 e 240 cm do tronco, nas camadas de 0 a 15 cm e 15 a 30 cm de profundidade e em duas direções distintas (entrelinhas e entreplantas). Os resultados mostraram que as radicelas localizam-se superficialmente, com 70% delas nos primeiros 15 cm, do total encontrado na camada superficial de 0 a 30 cm de profundidade do solo. Cerca de 75% das radicelas situam-se até a distância de 160 cm do tronco. Na camada mais superficial do solo (0 a 15 cm), a quantidade de radicelas diminuiu de maneira acentuada, à medida que se afastou do tronco. Na camada de 15 a 30 cm de profundidade, ocorreu uma distribuição horizontal mais uniforme, comparada com a da camada de 0 a 15 cm. As radicelas das plantas do cultivar Natal distribuiram-se uniformemente, tanto na direção das plantas da linha vizinha, quanto nas das plantas de uma mesma linha, para o espaçamento de 7,0 m x 7,2 m. Não se detectaram diferenças estatisticamente significativas nas quantidades de radicelas entre as parcelas dos vários tratamentos com herbicidas, excluindo-se desta forma, qualquer efeito negativo de tais produtos químicos sobre o sistema radicular das laranjeiras.

Uso contínuo de herbicidas em citrus (Citrus sinensis (L ) Osbeck), I - efeitos no controle de plantas daninhas

A presente pesquisa foi conduzida no município de Conchal - SP, Brasil, em um Latossolo Vermelho Amarelo com 1,75% de matéria orgânica, com o objetivo de verificar o efeito do uso continuo dos principais herbicidas, no controle de plantas daninhas em um pomar de laranja 'Pera' (Citrus sinensis (L.) Osbeck, enxertada sobre limão cravo (Citrus limonia Osbeck). O delineamento experimental adotado foi o de blocos ao acaso, com 12 parâmetros e 4 repetições. Os tratamentos utiliza dos com as respectiva s dose s do i.a. em kg/ha foram: terbacil a 3,2; simazine a 4,0; ametryne + secbumetone a 4,5; dichlobenil a 5,0; diuron a 3,2; bromacil a 3,2; bromacil + diuron a 3,2; paraqua t a 0,6; glyphosate a 1,61 e MSMA a 1,77, além de uma testemunha que recebia uma capina anualmente e outra que era capinada sempre que a cobertura pelas plantas daninhas atingia 25% da área da parcela. O pomar foi plantado em maio/75 e a 14 aplicação foi realizada em outubro de 1977. As parcelas continham 4 plantas em uma área de 3,0 x 18,0 m (54 m2). A última foi realizada em 1986. O efeito dos tratamentos no controle das plantas daninhas foi avaliado pela contagem por espécie botânica, assim como por avaliações visuais. Todos os herbicidas utilizados apresentaram controle de aceitável a excelente, dependendo da composição específica das plantas daninhas, e aqueles cue apresentaram os melhores índices de controle das plantas daninhas, assim como efeitos residuais mais prolongados, foram bromacil + diuron, diuron, bromacil, ametryne + secbumetone e terbacil. herbicidas aplicados em pósemergência os melhores índices de controle foram obtidos com glyphosate e paraquat.

Uso contínuo de herbicidas em citrus (Citrus sinensis L.) osbeck ): II. Efeitos no desenvolvimento, produção e qualidade dos frutos

A presente pesquisa foi conduzida no município de Conchal - SP, Brasil, em um Latossol Vermelho Amarelo com 1,75% de matéria orgânica com o objetivo de veri fic ar o efeito do uso cont inuo dos principais herbicidas no desenvolvimento, produção e qualidade dos frutos em um pomar de laranja 'Pera' Citrus sinensis (L.) Osbeck), en xertada sobr e limão cravo (Citrus lionia Osbeck). O delineamento experimental adotado foi o de blocos ao acaso, com 12 tratamentos e 4 repetições. Os tratamentos utilizados com as respectivas doses do i. a. em kg/h a foram: terbacil a 3,2; simazine a 4,0; ametryne + secbumetone 4,5; dichlobenil a5,0 ; diuron a3,2 ; bromacila 3,2; bromacil + diuron a 3,2; paraquat a 0,6; glyphosate a 1,61 e MSMA a 1,77 alem de uma testemunha que recebia uma capina anualmente, e outra que era capinada sempre que a cobertura pelas plantas daninhas atingia 25% da área da parcela. O pomar foi plantado em meio/ 75 e a 1a aplicação dos herbicidas foi realizada em outubro de 1977. As parcelas continham 4 plantas em uma area de 3,0 x 18,0 m (54 m2). A última aplic ação foi realizada em 1992. O efeito no desenvolvimento foi feito pela medida do diâmetro do caule a 10 m acima do ponto de enxertia, pelo diâmetro da copa na altura mediana e pela altura das plantas. Todas essas medidas eram realizadas 2 vezes por ano. Para avaliação da produção, eram colhidos os frutos de quatro plantas por parcela. A qualidade dos frutos foi avaliada através das medidas do diâmetro longitudinal e transversal, albedo, peso e número de sementes, peso médio dos frutos, % de suco, % de sólidos solúveis e % de acidez. Pelos dados obtidos , verifica - se que não houve influência dos herbicidas no desenvolvimento das plantas de citros, e na produção. As influencias na qualidade dos frutos foram mínimas, e dependeram do ano de amostragem.

Possíveis efeitos alelopaticos de Brachiaria decumbens sobre o crescimento inicial de limão cravo (Citrus limonia)

Foram estudados os possíveis efeitos alelopáticos da incorporação da matéria seca da parte aérea de Brachiaria decumbens, ao substrato, nas concentrações de 0, 1,5 e 3,0% (p/p) sobre o crescimento inicial de limão cravo (Citrus limonia Osbeck), em casa-de-vegetação. Foram determinados os parâmetros biométrico s e algumas propriedades físico-químicas da solução do solo. A maior quantidade de matéria seca incorporada causou redução de 44, 42, 57 e 55% das médias da altura, teor de clorofila, área foliar e acúmulo de matéria seca total, respectivamente. O potencial osmótico, pH, condutividade elétrica e os teores de nutrientes da solução do solo foram alterados. Provavelmente, a redução do crescimento observada seja devida a deficiência de N causada por alterações na dinâmica do N-solo em função da incorporação de B. decumbens.

Effects of irrigated rice sowing season and imazapyr + imazapic time of application on rice grain yield and red rice management

Irrigated rice sowing season and red rice competition are among the main factors affecting grain yield. The objective of this work was to evaluate the sowing date of irrigated rice and moments of application of the herbicide imazapyr + imazapic to control red rice management and irrigated rice grain yield. Eight experiments were performed at the following dates (09/30, 10/19, 11/08 and 12/01) for the 2010/2011 harvest season and (09/27, 10/17, 11/08 and 12/05) for the 2011/2012 harvest season. The treatments were: application of the herbicide imazapyr + imazapic at doses of 105+35 g ha-1 in pre-emergence (PRE); 52.5+17.5 g ha‑1 in pre-emergence and 52.5+17.5 g ha-1 in post-emergence (PRE + POST); and 105+35 g ha-1 in post- emergence (POST), and a control without application and no weeding. The cultivar Puitá Inta CL was used and a randomized block design with four replicates. A joint analysis of the experiments was carried out. There was less emergence of red rice and higher grain yield of the irrigated rice at the early periods (09/30/10 and 09/27/11), with 10,578 and 8,653 kg ha-1, respectively. At the end of the season (12/01/10 and 12/05/11), there was greater reduction of the red rice seed bank. Sowing at the beginning of the recommended period provided more irrigated rice grain yield. The application of imazapyr + imazapic at a dose of 52.5+17.5 g ha-1 in PRE + 52.5+17.5 g ha-1 POST, and 105+35 g ha-1 only in PRE and POST was effective in the control of red rice.

Initial growth and competitive ability of yellow nutsedge and irrigated rice

Weeds cause significant reduction in the irrigated rice crop yield. Cyperus esculentus (yellow nutsedge) is adapted to irrigate environment. Information on the competitive ability of the weed to the culture, and their environmental adaptation, are scarce. In this study, we sought to determine the initial growth and competitive ability of yellow nutsedge and irrigated rice, as a function of cultivar growth cycle. Initial growth and competition studies were conducted in a randomized complete design in a greenhouse in the agricultural year 2010/11. For the initial growth study, the treatments consisted of a factorial combination of a biotype of yellow nutsedge and two rice cultivars in the function of the vegetative cycle (BRS Querência: early cycle - IRGA 424: intermediate cycle) and six evaluation times (10, 20, 30, 40, 50, and 60 days after emergence). Were evaluated: plant height, leaf area, aboveground dry biomass and root dry biomass. In the competitive ability study in the replacement series, the cultivar BRS Querência (early cycle) and yellow nutsedge were utilized and tested in different proportions of competition (100:0, 75:25, 50:50, 25:75, and 0:100). Were evaluated leaf area and aboveground dry biomass. In general, rice cultivars have an adaptive value equivalent to yellow nutsedge. IRGA 424 cultivar has less height than weed, becoming the weed control more important in this cultivar. For rice crop, intraspecific competition is more important, whereas for the weed, interspecific competition is the most pronounced.