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Citrus rootstock production in Brazil commonly uses manual overhead irrigation systems to water plants. Manual irrigation systems present low efficiency, apply more water than needed, and result in release of nutrients and pesticides into the soil with a potential to contaminate groundwater. Closed irrigation systems that avoid the disposal of nutrient solutions like subirrigation can be used to increase production efficiency and reduce the environmental contamination. Our objective was to evaluate the effect of subirrigation applied by a prototype tray on plant growth and morphological and physiological responses of Rangpur lime (Citrus limonia Osbeck ‘Limeira’) seedlings subjected to different water levels in conic containers filled with pine bark substrate. We tested three treatments: T1) subirrigation with water reaching two-thirds of the container height (8 cm); T2) subirrigation with water reaching one-third of the container height (4 cm); and T3) control with manual overhead irrigation. Subirrigation resulted in higher plant growth of Rangpur lime seedlings. At 90 days after sowing (DAS), we observed significant effects of T1 over the other treatments on plant growth, as indicated by higher total dry mass (P = 0.0057), shoot/root ratio (P = 0.0089), shoot height (P = 0.0004), leaf area (P = 0.0005), and root length (P = 0.0333). The number of bifurcations was 400% higher in T3 than at the subirrigated treatments, which can lead to an increase in the labor costs for pruning. Seedlings grown under T1 presented leaf water potential 13% higher compared with T3 at predawn, which was the time of highest stomatal efficiency, presenting the lowest water loss, maximum stomatal closure, and higher transpiration at lower stomatal resistance. T2 plants displayed intermediate water status with a water potential 5% higher than T3. T3 plants showed a higher transpiration rate under maximum stomatal closure, reducing leaf water potential. The subirrigated treatment with water level of two-thirds of container height (8 cm) induced higher plant growth and shortened the crop cycle, anticipating the transplanting to the next phase (grafting) with the possibility of reducing production costs in the nursery.

O tamanho médio de partículas e a porosidade dos substratos condicionam as propriedades matriciais, interferindo na capacidade de retenção e de transmissão da água no meio. O conhecimento desses atributos é fundamental em processos de irrigação por capilaridade, para que o molhamento atinja as camadas superiores dos recipientes com níveis de tensão de água facilmente disponível. O presente trabalho teve como objetivo estudar a ascensão de água por capilaridade para determinar a posição mais apropriada do nível de saturação na ascensão capilar em recipientes com substratos de coco e pinus, de textura grossa e fina. Foram efetuados experimentos avaliando a ascensão de água por capilaridade em colunas segmentadas preenchidas com os substratos. Os valores de umidade em cada segmento foram calculados gravimetricamente e relacionados aos de tensão estimados pela curva de tensão dos substratos. Os substratos com textura fina apresentaram melhor elevação de água por capilaridade, com melhor elevação da umidade em níveis de tensão de água disponível. O substrato de coco fino apresentou água disponível em todo o perfil do recipiente, enquanto o de pinus apresentou as camadas superiores do recipiente com água retida em tensões abaixo do ponto de murcha permanente. O substrato fino de coco apresentou os melhores resultados para aplicação na irrigação por capilaridade, permitindo recomendar o seu uso com o nível de saturação posicionado a cinco centímetros do fundo do recipiente por quinze minutos. The average particle size and porosity of substrates affects the matrix properties of root growth media, interfering in water holding and water conductivity capacity through substrates. The knowledge of these attributes is essential in capillary irrigation processes to allow the wetting front reaches upper layers under easily available water tension. The present work had the objective to study the water rise by capillary processes to determine the most favorable position of the saturation level for contained plants for two substrates: coconut fiber and pine bark, with two grain particle sizes: fine and coarse textures. Water rise trails were carried out in segmented columns filled with substrates. The water content in each column segment was estimated in weight basis and related to the values of water tension estimated by the water tension curve for each evaluated substrate. The results showed that fine substrates presented higher water rise with adequate levels of easily available water. The fine coconut substrate presented easily available water in the entire substrate column, unlike pine bark substrate that showed the upper layer with moisture below the wilting point. The fine coconut substrate showed the best results for capillary application, allowing to recommend irrigation schedule using the saturation level at 5 cm during 15 minutes.

TÉCNICA DE AVALIAÇÃO DE BULBO ÚMIDO POR MÚLTIPLOS CORTES EM TRINCHEIRA Carlos Vinícius Garcia Barreto; Emílio Sakai; Regina Célia de Matos Pires; Flávio Bussmeyer ArrudaSeção de Ecofisiologia e Biofísica, Instituto Agronômico, Campinas, emilio@iac.sp.gov.br 1 Resumo A técnica de estudo de bulbos úmidos por trincheira no solo é recomendada como parte do manejo de água em lavouras cultivadas sob gotejamento. O aprimoramento desta técnica com a realização de cortes em diferentes distâncias em relação ao emissor pode trazer informações adicionais além do diâmetro e profundidade. As áreas molhadas superficial e subsuperficial, com sua profundidade média, perfil do bulbo úmido ao longo da linha sob perspectiva são possíveis de ser obtidos. O objetivo do presente trabalho foi avaliar as características dos bulbos úmidos formados por diferentes configurações de gotejamento utilizando múltiplas medições de secções do bulbo com construção de figura do bulbo úmido em três dimensões. As configurações de gotejamento utilizaram 2 fatores, distância entre emissores de mesma vazão, 50cm de espaçamento (50) e80 cmde espaçamento (80), e profundidade de instalação do tubogotejador, na superfície do solo 0, enterrado a10 cm(10) e a20 cm(20) totalizando 6 configurações: T1 (50 – 0), T2 (50 – 10), T3 (50 –20), T4 (80 – 0), T5 (80 – 10) e T6 (80 – 20). Os principais resultados observados foram a menor área molhada superficial para gotejamento enterrado, tendências de perda de água em profundidade e menor continuidade de área molhada subsuperficial para gotejadores de80 cmde espaçamento. A técnica apresentou-se adequada para fins de manejo de irrigação por gotejamento. Unitermos: gotejamento, área molhada, irrigação subterrânea, manejo de irrigação. Barreto. C.V.G.; Sakai, E.; Pires, R.C. de M.; Arruda, F.B.WET BULB EVALUATION TECHNIQUE USING MULTIPLE SLICES ON SOIL PITS 2 Abstract Technique of soil pit for wet bulbs studies is recommended as one of the many practices in water management on plantations under trickle irrigation. The development of this technique with multiple slices on pit wall at different distances from the emitters allows gathering more data besides the ones on diameter and depth of the wet bulb. The superficial and subsuperficial wet areas and their depths as well as the wet bulb profile along the irrigation line were obtained. The aim of this study was to evaluate the characteristics of wet bulb formed under different configurations of trickle irrigation during the braking of bud dormancy in coffee plantation. The treatments used two factors, distance between emitters (50 cm(50) and80 cm(80)) and installation depth (superficial installation (0), buried installation at10 cm(10) and buried installation at20 cm(20)) in six treatments, T1 (50-0), T2 (50-10), T3 (50-20), T4 (80-0), T5 (80-10) and T6 (80-20). The principal observed results showed a smaller superficial wet area for subsuperficial trickle irrigation, tendency for percolation and bad continuity of wet zone in the soil along the 80-cm lines. This technique is appropriate for trick irrigation management KEY WORDS: trickle irrigation, wet areas, buried irrigation, irrigation management.

The aim of this study was to design and characterize hydraulic subirrigation equipment for the citrus rootstocks production of to allow the water capillary rise for the seedling stage. This equipment was designed since the citrus seedling phase occurs in plastic containers with substrate, and because there is a need to increase the irrigation efficiency in this sector. The methodology consisted of: (i) identification and characterization of the irrigation methods used in the citrus rootstocks production; (ii) the design of subirrigation equipment prototype; and, (iii) the construction and hydraulic evaluation of the prototype equipment. After a model was designed, 10 prototypes were built with two different dimensions (44 × 29 × 15 cm and 62 × 41 × 15 cm), and the theoretical and experimental relationships of flow and operating pressure were determined. The proposed equipment was designed according to engineering criteria that allows its evaluation for commercial use, although additional field trials are required for its final adjustment. Moreover, the theoretical equation of flow rate was validated for small-immersed orifices in thin walls, as an operational condition of the developed subirrigation equipment.