RESUMO Em regiões áridas e semiáridas do planeta, a elevada demanda evaporativa e as características pedogenéticas dos solos, associadas a deficiências no sistema de drenagem de alguns perímetros irrigados, contribuem para um elevado potencial de salinização desses solos. Assim, constituíram objetivos deste estudo determinar o grau de salinização na área irrigada e avaliar o processo de acumulação de sais no período seco e o potencial de lixiviação destes pela água das chuvas no Perímetro Irrigado Califórnia, em Sergipe. Medidas da condutividade elétrica do extrato de saturação do solo (CEes), em dS m-1 a 25 ºC, foram efetuadas no início e final do período chuvoso dos anos de 2008 e 2009. A densidade amostral foi igualmente distribuída em toda área do Perímetro. Os dados foram submetidos à análise geoestatística e gerados mapas da distribuição espacial da CEes por meio do programa ArcGis®. Os valores médios da CEes obtidos revelaram que, apesar da prática de agricultura irrigada intensiva por longo período, o processo de acumulação de sais não foi significativo, tanto na camada superficial (0-0,20 m) quanto em subsuperfície (0,20-0,40 m). Os valores médios da CEes em superfície variaram de 0,47 a 1,10 dS m-1, ficando abaixo de valores da salinidade limiar para a maioria das culturas anuais e perenes.

INFLUÊNCIA DE ÉPOCAS DE PLANTIO NA EFICIÊNCIA DO USO DA ÁGUA DA CHUVA EM CULTIVO IRRIGADO DE CANA-DE-AÇÚCAR THAIS NASCIMENTO MENESES¹ E RONALDO SOUZA RESENDE² ¹Mestre em Recursos Hídricos, PRORH/UFS- São Cristóvão, SE, th41s.nascimento@gmail.com.²Pesquisador da Embrapa Tabuleiros Costeiros, Aracaju, SE, professor colaborador do PRORH/UFS- São Cristóvão, SE.  1 RESUMO A otimização da água de irrigação pode ser alcançada com base na época de plantio que resulte no maior aproveitamento da água da precipitação, através da sincronização das fases fenológicas de maior demanda hídrica da cultura com a estação de maior disponibilidade hídrica. Este estudo visou avaliar o efeito de cinco épocas de plantio que resulte no maior aproveitamento da água da chuva, maximização da produtividade agroindustrial e eficiência do uso da água em cultivo irrigado de cana-de-açúcar. Para tanto, foram conduzidos dois experimentos, um com a variedade de cana-de-açúcar RB92579 e outro com a RB962962, em área da Usina Coruripe, Alagoas. O delineamento estatístico dos experimentos foi em blocos ao acaso, com os tratamentos constituídos pelas épocas de plantio em outubro (E1), novembro (E2), dezembro (E3) de 2012; janeiro (E4) e fevereiro (E5) de 2013, com quatro repetições. Analisou-se ao final do primeiro ciclo de cultivo a produtividade em toneladas de colmos (TCH) e toneladas de açúcar (TAH) por hectare, e o açúcar total recuperável (ATR) das variedades de cana-de-açúcar, bem como, a eficiência de uso da água, em relação à água que entrou no sistema de produção, seja incluindo a chuva efetiva [EUA(Pe+I)] ou a precipitação total [EUA(P+I)]. O plantio em novembro maximizou o aproveitamento de água da precipitação. As épocas de plantio E1, E2 e E4 resultaram em maiores produtividades de colmo e de açúcar de ambas as variedades. O plantio em janeiro favoreceu o aumento da EUA, tanto em produtividade de colmo como de açúcar, enquanto a época menos favorável foi o plantio em fevereiro. A variedade RB92579 apresentou resultados absolutos superiores em relação aos componentes de produção e EUA, quando comparada a RB962962. Palavras-Chave: Saccharum ssp., precipitação efetiva, irrigação plena, potencial produtivo.  MENESES, T.N.; RESENDE, R.S.PLANTING PERIOD INFLUENCE ON THE EFFICIENCY OF RAIN WATER USE IN SUGAR CANE IRRIGATED CROPS  2 ABSTRACT The optimization of irrigation water can be achieved based on the planting month that results in better use of water from precipitation, by synchronizing the phenological phases of higher crop water demand with higher rainwater availability season. This study aims to evaluate the effect of five planting month that results in better use of water from precipitation, maximizing the agro-industrial productivity and rainwater use efficiency in irrigated sugarcane. In order to do so, two experiments were carried out, each with a different cultivar of sugarcane, RB92579 and RB962962, in the experimental area of the Coruripe Mill, Alagoas Sate, Brazil. The statistical delimitation was by randomized blocks design, and termed the treatments according to the planting month October (E1), November (E2), December (E3) – 2012; January (E4) and February (E5) – 2013) with four repetitions, based in variety. In the end of the first cropping cycle, tons of sugarcane stalks (TSS) and tons of sugar per hectare (TSH), and total recoverable sugar (TRS), and efficiency of water use in relation to water that entered the production system, either including the effective rainfall [WUE (Pe - I)] or total precipitation [WUE (P + I)] of the varieties of sugarcane analyzed were evaluated. The sugarcane planted in November maximize the use of water from precipitation. Treatments E1, E2 and E4 resulted in higher stalks and sugar yields for both varieties. Planting January increasing WUE, both in stem stalk biomass and sugar biomass basis. February was the least favorable month of planting. The variety RB92579 presented superior results related to physical productivity and the water use efficiency, when compared to the RB962962 variety. Keywords: Saccharum ssp., efficient precipitation, full irrigation, productive potential.

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The objective of this work was to evaluate the vegetative vigor and root architecture of ‘Pera CNPMF D-6’ sweet orange grafted on Rangpur lime at early stage of development, submitted to different planting methods (planting of nursery trees produced in a protected environment-PNT and planting of seeds at the definitive place-PS) and soil preparation with and without subsoiling. The experiment was carried out at the Lagoa do Coco Farm, Rio Real, Bahia, Brazil. Biometric evaluations were performed to estimate the variables: canopy volume (CV), vegetative vigor index (VVI) and canopy cover rates in the planting row (CCR-R) and interrow (CCR-I). Root samples were also collected up to a depth of 1.45 m at five points in the planting row. The roots were digitized and processed to obtain total root length (TRL), root length density (RLD), average root diameter (RD) and root length for the diameter classes. Plants produced in protected environment exhibit greater shoot vegetative and root development compared to those produced by sowing at the definitive place, at least for the young orchard and under rainfed conditions. Subsoiling did not affect root system distribution and PNT favored the increase in TRL along the soil profile compared to PS, for all diameter classes evaluated, contributing to the increase in vegetative vigor observed in the plants. Regardless of the management practices adopted, roots were concentrated in the first 0.35 m of the vertical soil profile, due to physical impediment caused by the presence of cohesive horizons.

Root architecture affects plant growth and agricultural productions. Although it is related to genetic factors, soil physical limitations can affect the root system and volume of explored soil, compromising plant growth and fruit production. Considering the need to mitigate these restrictions, the objective of the present study was to evaluate two planting types (planting of protected seedlings and planting of seeds in definitive place) and two scion-rootstock combinations (‘Pera’ sweet orange, CNPMF D-6 selection, combined with ‘Santa Cruz Rangpur’ lime and ‘Sunki Tropical’ mandarin rootstocks). The experiment was conducted at the Lagoa do Coco Farm, Rio Real, BA, Brazil, in a Oxisol under rainfed conditions. Biometric, physiological, and soil water content evaluations were made during the experiment. Soil mechanical resistance to root penetration and root system characteristics were also evaluated. Roots were concentrated on the soil surface layers (0-0.40 m), extending horizontally up to 1.50 m from the plant, regardless of the management practices used. The total root length in each root diameter classes studied, root length density, and total root mean diameter were higher for planting of protected seedling, resulting in greater root development. Plants from ‘Pera’ sweet orange scion grafted on ‘Santa Cruz Rangpur’ lime rootstock had earlier production and were more vigorous. Soil structure affects root growth, and the root distribution up to 0.40 m depth is correlated with plant vigor, yield, and water status under rainfed conditions.

Well-operated and calibrated weighing lysimeters reliably determine the water demand of agricultural crops, and the quality of the data is evaluated through the error analyses attributed to the instrument. The objective of this study was to determine performance parameters of a weighing lysimeter and to evaluate its adequacy for the direct determination of cocoa crop evapotranspiration. The lysimeter with 1.44 m2 surface, supported on four load cells installed in the experimental area of the Graduate Program in Agricultural Engineering of the Universidade Federal do Recôncavo da Bahia, was calibrated at 3:00 a.m., using known masses at intervals of 02 minutes in five cycles of addition and removal. Data were collected using a datalogger coupled to four load cells with an individual capacity of 1000 kg, programmed to perform readings every 01 second, storing the averages of 15 minutes. The lysimeter showed excellent accuracy, with r2greater than 0.99 in the correlation between the standard masses and the signal of the load cells and standard error of linear regression estimate of 0.03 mm. The combination of repeatability and hysteresis errors with an uncertainty of 0.19% showed that the load cells have accuracy of ±0.07 mm, with resolution of 0.00033 mV, and sensitivity to detect mass changes below 0.1 mm, the system is adequate for direct measurement of cocoa ETc at time intervals of less than one hour.

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