Does the tolerance of sugarcane to excess water in the soil depend on the stage of development? / A tolerância da cana-de-açúcar ao excesso de água no solo depende do estádio de desenvolvimento?

Soil waterlogging reduces the availability of oxygen to the roots of the plants, which makes necessary an efficient drainage system for correction. Thus, the objective of this study was to evaluate the tolerance of sugarcane in flooded crop with different velocities of lowering the groundwater in three stages of ratoon sugarcane development. The experiment was carried out in a randomized complete block design (3 x 5 + 1), with three developmental stages (44, 210 and 305 days after planting) and five groundwater falling velocities (30 cm in 3, 6, 9, 12 and 15 days) and the control (irrigation without flooding the soil). There was a significant effect for groundwater retraction velocities and evaluation periods for leaf area (LA) and leaf area index. The treatments P1V4 and P2V3 presented the highest LAs (0.91 m²). The first sugarcane ratoon was tolerant to soil waterlogging at different stages of development and to different groundwater falling velocities, with no major losses in plant development and productivity, however, for total recoverable sugar cane ratoon was more sensitive when the flood occurred in the regrowth stage.

Moisture limits and potassium concentrations in soil solution in crop lisianthus (Eustoma grandiflorum) fertigated in greenhouse conditions

O lisianthus (Eustoma grandiflorum) vem despertando grande interesse, pela beleza das cores das flores, firmeza das hastes e durabilidade pós-colheita. No entanto, o conhecimento da irrigação e da fertirrigação do lisianthus, fatores de alto impacto na produção e na qualidade das hastes e dos botões florais, têm-se apoiado, geralmente, no empirismo ou em recomendações de outros países, resultando na aplicação de quantidade insuficiente ou excessiva de água e fertilizantes. Este trabalho teve como objetivo estabelecer parâmetros para o manejo racional da fertirrigação do lisianthus (var. Casablanca e var. Excalibur) sob ambiente protegido, por meio da determinação do melhor limite inferior de umidade no solo, associado à determinação da concentração ótima de potássio a ser mantida na solução do solo. A pesquisa foi conduzida em dois ambientes protegidos, localizados na área experimental do Departamento de Engenharia de Biossistemas da Escola Superior de Agricultura \"Luiz de Queiroz\", Universidade de São Paulo (ESALQ/USP). Os tratamentos foram constituídos de cinco limites de umidade no solo para início da irrigação (T1 = 0,20, T2 = 0,15, T3 = 0,13, T4 = 0,11 e T5 = 0,09 cm3 cm-3) e cinco concentrações de potássio na solução do solo (K1 = 50, K2 = 100, K3 = 150, K4 = 200 e K5 = 250 mg dm-3). As parcelas foram dispostas no delineamento em blocos completos inteiramente casualizados, arranjados em esquema fatorial de 5 x 5 (cinco limites de umidade e cinco concentrações de potássio na solução do solo), com quatro repetições, totalizando 100 parcelas experimentais. Durante a fase de crescimento e de produção do lisianthus, foi monitorada a solução no solo, medindo-se as concentrações de potássio (K+), bem como a condutividade elétrica (CE) da solução, nas profundidades, de 0,15 e 0,30 m, por meio de extratores de solução do solo e de um reflectômetro TDR100 (Campbell Scientific, Logan-Utah). No primeiro ciclo (ciclo de outono-inverno) foram obtidos turnos de regas médios equivalentes a 6, 10, 12, 12 e 12 dias para limites de umidade do solo iguais a 0,20, 0,15, 0,13, 0,11 e 0,09 cm3 cm-3 respectivamente. Já no segundo ciclo (ciclo de primavera verão) os limites de umidades estudados resultaram em intervalos entre fertirrigações (turnos de rega médios) de aproximadamente 7, 11, 14, 17 e 23 dias. O cultivo do lisianthus sob o limite inferior de umidade do solo igual a 0,20 cm3 cm-3 resultou na aplicação de lâminas de irrigação de até 16% (primeiro ciclo) e 26% (segundo ciclo) superiores em relação às lâminas médias dos demais limites de umidade do solo. Após a obtenção de boa aproximação entre os valores esperados e obtidos das concentrações de potássio (K+) e da condutividade elétrica da solução do solo (CEes) no início do ciclo, foi possível, por meio do uso de extratores de cápsula porosa e TDR, a manutenção das concentrações de K+ e CEes em níveis próximos aos estabelecidos pelos tratamentos, garantindo o paralelismo dos perfis ao longo do tempo. A ordem de predominância dos nutrientes nas plantas de liasianhtus colhidas no final do segundo ciclo foi K>N>S>Mg>Ca>P, para os macros e Fe>Mn>B>Zn>Cu para os micronutrientes, além disso, verificou-se também que, as diferentes concentrações de potássio na solução do solo não resultou em diferenças expressivas nos teores deste nas plantas. As principais características de crescimento e produção da cultura do lisianthus apresentaram resposta linear decrescente em função da redução dos valores de umidade do solo tidos como limites para início da irrigação. O uso de extratores de capsulas porosas associado ao monitoramento da umidade do solo com a TDR e a utilização da equação do balanço de massas possibilitou um manejo satisfatório das concentrações de potássio e da condutividade elétrica da solução do solo no cultivo do lisianthus fertirrigado em ambiente protegido. Além disso, para todas as variáveis de interesse comercial e de rendimento total, os melhores resultados foram obtidos quando a cultura do lisianthus foi submetida a maiores frequências de fertirrigação. As características de rendimento e de qualidade das hastes florais não foram influenciadas pelas concentrações de potássio na solução do solo.Lisianthus (Eustoma grandiflorum) has had attracting great interest by the beauty of the flowers colors, firmness of stems and post-harvest durability. However, knowledge of irrigation and fertigation of lisiathus, high impact factors in the production and quality of stems and flower buds, have had based it generally on empiricism or recommendations from other countries, resulting in insufficient or excessive application of water and fertilizer. This study aimed to establish parameters for the appropriated management of lisianthus fertigation (var. Casablanca and var. Excalibur) under protected environment by determining the best soil moisture lower boundary associated with the optimum concentration of potassium which have be maintained in the soil solution. The research was conduct in two greenhouses, located in the experimental area of the Department of Biosystems Engineering from Escola Superior de Agricultura \"Luiz de Queiroz\", University of São Paulo (ESALQ / USP). The treatments were compose of five soil moisture limits to start fertigation (T1 = 0.20, T2 = 0.15, T3 = 0.13, T4 = 0.11 and T5 = 0.09 cm3 cm-3) and five concentrations of potassium in the soil solution (K1 = 50, K2 = 100, K3 = 150, K4 = 200 and K5 = 250 mg dm-3). The plots were arrange in completely randomized block design and factorial scheme of 5 x 5 (five moisture limits and five concentrations of potassium in the soil solution), with four repetitions, totaling 100 plots. During the growth and production phases of lisianthus, the soil solution was monitoring by measuring of potassium concentration (K+) and electrical conductivity (EC) at 0.15 to 0.30 m of depth through soil solution extractors and TDR100 Reflectometer (Campbell Scientific, Logan, Utah). In the first cycle (autumn-winter), average scheduling irrigation equivalent to 6, 10, 12, 12 and 12 days were obtained for soil moisture limits equal to 0.20, 0.15, 0.13, 0, 11 and 0.09 cm3 cm-3 respectively. And the second cycle (summer-spring) the limits of moisture studied resulted in intervals between fertigations (average scheduling irrigation) of approximately 7, 11, 14, 17 and 23 days. Cultivation of lisianthus under the lower soil moisture limit of 0.20 cm3 cm-3 resulted in the application of irrigation depth of up to 16% (first cycle) and 26% (second cycle) higher than the average irrigation depth of the others limits of soil moisture. At the beginning of the cycle, after obtaining a good approximation between the expected and observed values of the potassium (K+) and the electrical conductivity of the soil solution, it was possible the maintenance of the concentrations of K+ and CEs at levels close to those established by the treatments through the use of porous capsule extractors and TDR, guaranteeing the parallelism of the profiles over the time. The nutrients order predominance in the lisianthus plants harvested at the end of the second cycle was K> N> S> Mg> Ca> P, for the macros and Fe> Mn> B> Zn> Cu for micronutrients. It was also observed that, the different concentrations of potassium in the soil solution did not result in significant differences in contents of that nutrient in the plants. The main growth and yield characteristics of the lisianthus crop showed a linear decreasing response as a function of the reduction of the soil moisture values considered as limits for the beginning of irrigation. The use of porous capsules extractors associated with soil moisture monitoring with TDR and the mass balance equation enabled satisfactory management of potassium and electrical conductivity concentrations of the soil solution in the grown crop of lisianthus. Furthermore, the best results were obtain when lisianthus was subject to higher frequencies of fertigation for all variables of commercial interest and total yield. The yield and quality characteristics of the flower stems were not influenced by the potassium concentrations in the soil solution

UTILIZAÇÃO DO REJEITO DA DESSALINIZAÇÃO DA ÁGUA NA PRODUÇÃO DE MUDAS DE ESPÉCIES DA CAATINGA

Waste brine from water desalination is a highly salty residue that can be used to grow crops if carefully managed. The aim of this research was to examine the response of two species of the Caatinga (Mimosa caesalpiniifolia Benth and Mimosa tenuiflora (Willd.)Poir) to five salinity levels [0.46 (control), 3.2, 3.78, 5.02 and 5.96 dS m-1] of irrigation water obtained by dilution of the waste brine from water desalination. The 2 x 5 factorial treatments were arranged according to a completely randomized design with three replications. At 81 days of cultivation, plants of sabiá and jurema preta were sensitive to salinity increase with the addition of waste water in irrigation, especially the sabiá, which decreases more intensely its dry weight of roots and leaves and leaf area. This decrease however, does not rule out the possibility of production of forest tree seedlings using reject water desalination

BELL PEPPER CULTIVATION WITH BRINE FROM BRACKISH WATER DESALINATION

In desalination process, besides the potable water, highly salty and pollutant water (brine) is generated, which can be used for producing crops since it is carefully monitored. In order to test this hypothesis, bell pepper plants, cv. 'Margarita', were grown in coconut fiber substrate under greenhouse and were irrigated with nutrient solutions prepared with tap water, brine from desalination plant, and its dilution with tap water at 75, 50 and 25%, giving a range of electrical conductivities of the nutrient solution (ECs) of 2.6, 3.1, 6.6, 10.0 and 12.2 dS m-1 after the dilutions and fertilizers addition. Completely randomized blocks design was used with 5 treatments (salinity levels of the nutrient solutions) and six replications. Leaf area, number of marketable fruit, total and marketable yield were reduced with ECs increase. The marketable yield of bell pepper 'Margarita' reduced 6.3% for each unitary increase of ECs above 2.6 dS m-1 (threshold salinity) and the results suggest that in hydroponic system, the reduction of marketable yield with increasing ECs is promoted by reduction of the number of fruits per plant instead of a reduction of fruit mean weight

Cotton production using secondary domestic sewage - doi: 10.4025/actascitechnol.v35i2.13157

This study was performed at the campus of the Semiarid Rural Federal University in Mossoró, State of Rio Grande do Norte, and aimed to evaluate the behavior of cotton (Gossypium hirsutum L. race latifolium Hatch), cultivar 8h as for growth and yield when fertirrigated with secondary domestic sewage. The experiment consisted of a randomized block split plot design, with dilutions of domestic effluents tested at plot level [25% - T1, 50% - T2, 75% - T3, 100% of secondary domestic sewage - T4 and 100% water supply with soil mineral fertilization – T5] on soils of different textures. The plant height was significantly greater at only at 15 and 30 DAP, reaching a maximum value of 67.30 cm with 100% wastewater on the 50th DAP. The cotton production was not influenced by the application of different levels of secondary domestic sewage; but a linear increase of productivity was observed in the sandy soil, reaching 1,363.45 kg ha-1 with the application of 100% of domestic sewage. On the Cambisol, the cotton plant presented the best results in terms of morphology.

Concentração salina e fases de exposição à salinidade do meloeiro cultivado em substrato de fibra de coco Salt concentration and phases of exposure tosalinity of melon grown in coconut fiber substrate

No semiárido, a escassez de água de boa qualidade faz com que os produtores utilizem água salobra para preparar a solução nutritiva. Com o objetivo de investigar a utilização de água salobra na irrigação de meloeiro (Cucumis melo L., cv. AF 015) cultivado em substrato de fibra de coco em casa de vegetação, plantas foram nutridas com soluções salinas de condutividades elétricas (CEs) 1,1 (testemunha); 2,5; 4,0 e 5,5 dS m-1 aplicadas durante as fases: crescimento vegetativo (10-30 dias após o transplantio-DAT); florescimento (31-50 DAT) e frutificação e maturação (51-70 DAT). O delineamento experimental foi o inteiramente casualizado, com 12 tratamentos arranjados em um esquema fatorial 4x3 (níveis de salinidade x tempo de exposição dos sais), com três repetições. Houve correlação na perda relativa por incremento de CEs das variáveis de crescimento e de produção do meloeiro em função da salinidade da solução nutritiva para cada fase de exposição. As soluções nutritivas preparadas com água salobra podem ser utilizadas no cultivo do meloeiro em substrato de fibra de coco com o mínimo de perdas relativas de massa média de frutos por incremento de CEs, quando aplicadas na fase de florescimento.<br>Scarcity of good water quality in semiarid region causes producers to use brackish water to prepare the nutrient solution. In order to investigate the use of brackish water in irrigation of greenhouse-melon (Cucumis melo L., cv. AF 015) grown in coconut fiber substrate, plants were irrigated with saltine nutrient solutions of electrical conductivities (ECs) of 1.1 (control), 2.5, 4.0 and 5.5 dS m-1, applied during the phases of vegetative growth (10-30 days after transplanting, DAT), flowering (31-50 DAT) and fruiting and ripening (51-70 DAT). The design was completely randomized, with 12 treatments arranged in a 4x3 factorial design (salinity levels x exposure time of the salts), with three replications. There was a correlation in the reduction relative to each increased de ECs of the growth and yield variables of melon in function of ECs for each phase of exposure. The nutrient solutions prepared with brackish water can be used to grow melons in coconut fiber substrate with minimal reduction relative of mean fruit weight with increasing ECs applied during flowering

PRODUÇÃO DE ALFACE HIDROPÔNICA E MICROCLIMA DE AMBIENTE PROTEGIDO SOB MALHAS TERMO-REFLETORAS

The thermo-reflective and black screens was used for shading for plants and they has private properties that improve the microclimate conditions, it was aimed to evaluate the growth and yields in hydroponic lettuce production (Lactuca sativa L, cv. Olinda), under effect of the thermo-reflective with different percentages of attenuation of the solar radiation. The treatments were and thermo black screens 50% with four different percentages of attenuation of the solar radiation, being meshes 40, 50, 60 and 70%. It was observed significant differences in function of the treatments for all the analyzed characteristics number of leaf, diameter of stem, fresh and dry matter biomass, leaf area and distances of internodes. The meshes thermo-reflective 40 and 50%, it had provided better development for lettuce, in relation to expression of the economical characteristics, being suitable to supply shading in greenhouse conditions at Northeastern semi-arid areas. However, it's improved the most control of the solar radiation, temperature and relative humidity, with micro weather conditions the best for growth and yields of Lettuce

USE OF REJECT BRINE FROM DESALINATION ON DIFFERENT DEVELOPMENT STAGES OF HYDROPONIC LETTUCE

In order to evaluated the impact of the high salinity reject brine from reverse osmosis desalination on hydroponics lettuce cultivated in greenhouse an investigation was carried out in Mossoro, Northeast of Brazil (5º11'S, 37º20'O and 18m above sea). Two lettuce cultivars ('Verônica' and 'Babá de verão') were cultivated with a basic nutrient solution with 1.1 dS m-1 (control) during the crop cycle (1-28 days after transplanting - DAT) - T0 and with basic nutrient solution containing 50% of the reject water from desalinization with 4.8 dS m-1 exposed during 1-7, 21-28, 7-14 e 1-28 DAT (T1, T2, T3 and T4, respectively). The addition of 50% of brine reject from desalination into the hydroponic nutrient solution allows grow only 'Verônica' lettuce with no reduction in fresh biomass. This lettuce cultivar shows to be more tolerant to salinity for all exposure time with reject brine in the nutrition solution, despite the fact that 'Babá de Verão' cultivar is more productive

EFEITOS DOS SISTEMAS DE CULTIVO E MANEJO DA CAATINGA ATRAVÉS DA ANÁLISE DOS INDICADORES QUIMICOS DE QUALIDADE DO SOLO NA PRODUÇÃO AGRÍCOLA EM APODI, RN

The sustainable management of savanna reduces the devastation of semiarid and aims based agricultural guided by systematic principles of agroecology. In that connection we evaluated the effects of cropping systems and management of savanna through the analysis of chemical indicators of soil quality in agricultural production in Apodi, RN. . The systems were evaluated: 1 - management area of savanna with 5 (five) years (MAS5), 2 - management area of savanna with 7 (seven) years (MAS7), 3 - conventional system (CSA) and 4 - native forest (NF). The chemical analysis revealed that the management of savanna for five to seven years is a beneficial way contributed to conservation of soil

PRODUÇÃO DE ALFACE HIDROPÔNICA UTILIZANDO BIOFERTILIZANTE COMO SOLUÇÃO NUTRITIVA

To evaluate the utilization of the biofetilizer substituting nutrient solution in hydroponic lettuce was carried out the study in greenhouse at Environmental Science Departament of the UFERSA, located in Mossoró, Rio Grande do Norte State, Brazil. The statistical test was realized in randomized blocks, with thee repetitions. Treatments were composed of five nutrient solution (Biofertilizer - T1; Biofertilizer + 25% of the mineral nutrient solution - T2; Biofertilizer + 50% of the mineral nutrient solution - T3; Biofertilizer + 75% of the mineral nutrient solution - T4 and mineral nutrient solution - T5). The fresh and matter biomes, leaf area, diameter of caulis and number of leaf was analyzed. The T5 treatment showed better response in relation to growth parameters and production of hydroponic lettuce, demonstrating that in a hydroponic requires high levels of nutrients readily available to meet the rapid and high nutrient demand