Bioaccumulation of 60Co2+ ions in tobacco plants

Tobacco has previously been used in investigations of metals and radionuclide uptake. This study presents determination of bioaccumulation and translocation of 60Co2+ ions in tobacco plants (Nicotiana tabacum L.) grown in Hoagland’s nutrient solution. Cobalt concentration in tobacco plants increased with increasing concentration in nutrient solution. Bioaccumulation from the initial concentration C0 = 0.96 μM Co reached 90% after 7 day cultivation. Only small amounts of Co accumulated in roots, up to 2 - 4 % were removable from roots by washing with 0.1 M CoCl2, indicating that this portion of Co is bound to the root surface in ion-exchangeable form. Tobacco roots retained approximately 2/3 of accumulated cobalt and 1/3 was transported to shoots. Autoradiography revealed that 60Co was preferentially localized in younger leaves. Prolongation of cultivation time did not change the [Co]roots : [Co]shoots ratio significantly. Relationships between growth rate, transpiration rate, uptake and distribution of cobalt in plant tissue are discussed.

Effect of Cl- and Na+ ratios in nutrient solutions on tomato (Solanum lycopersicum L.) yield in a hydroponic system

Intensive tomato (Solanum lycopersicum L.) production in coastal areas of Sinaloa is exposed to significant amounts of Cl and Na deposited by sea breezes and irrigation water, which affects the yield of this vegetable. The aim of this study was to evaluate three percentage ratios of Cl-/anions (25/100, 50/100 and 75/100) and three percentage ratios of Na+/cations (25/100, 50/100 and 75/100) in the nutrient solution on mineral composition, dry matter production and yield of tomato. The experimental design was completely randomized with a 32 factorial arrangement and four replications. Analysis of variance and mean comparisons were performed (Tukey, P ≤ 0.05). Cl and Na concentrations in tomato leaves, stems and fruits increased significantly with increasing ratios of Cl-/anions and Na+/cations in the nutrient solution. The 75/100 Cl-/anions ratio reduced (P ≤ 0.05) the Ca concentration in leaves, while the 75/100 Na+/cations ratio decreased (P ≤ 0.05) K concentrations in leaves and stems. Both ratios reduced aerial dry biomass (48 and 25.8 %, respectively) and tomato yield (50.8 and 45.7 %, respectively). The results indicate that tomato plants grown with the 75/100 percentage ratio of Cl-/anions or the 75/100 percentage ratio of Na+/ cations absorb excessive amounts of Cl or Na, which causes ionic imbalance (especially of K+ and Ca2+) and affects dry matter production and yield.

Preplant Fertilization Increases Substrate Microbial Respiration But Does Not Affect Southern Highbush Blueberry Establishment in a Coconut Coir-based Substrate

Coconut coir is widely used as a substrate component for southern highbush blueberry [(SHB) Vaccinium corymbosum L. interspecific hybrids] cultivation in containers. Coconut coir-based substrates can exhibit high potassium (K), sodium (Na), and chlorine (Cl) concentrations. Sodium in the substrate is particularly problematic because it can cause salinity stress and nutritional imbalances in young blueberry plants. Thus, Na removal is important to ensure transplant success. We hypothesized that preplant fertilization with large volumes of nutrient solution can reduce substrate salinity, replace Na with nutritional cations, and enhance blueberry establishment. We tested this hypothesis in a greenhouse experiment with ‘Snowchaser’ SHB grown in rhizoboxes filled with a 7:3 mix of coconut coir and perlite. Four different treatments were delivered every 24 hours starting 72 hours before transplant. Treatments included 1.75 g⋅L–1 calcium nitrate (CN), 2.38 g⋅L–1 monoammonium phosphate (MAP), deionized water, and well water. One rooted cutting was transplanted to each rhizobox. Rhizoboxes were fertigated during the 7-week cultivation period. We found that preplant fertilization increased nitrogen (N), phosphorus (P), and calcium (Ca) concentrations in the substrate without replacing Na. Thus, preplant fertilization increased substrate salinity. Preplant fertilization also promoted microbial respiration in the substrate at the start of the experiment. Treatments did not affect SHB root architecture, leaf area index, leaf greenness, or biomass accumulation, likely because nutrients delivered by the fertigation solution provided the plants with homogeneous optimal conditions. These findings suggest that preplant fertilization with large volumes of nutrient solution does not enhance blueberry establishment in coconut coir-based substrates.

Fuzzy Logic Controller for Automating Electrical Conductivity and pH in Hydroponic Cultivation

This study proposes a fuzzy logic controller for adjusting the electrical conductivity (EC) and pH of the nutrient solution in a hydroponic system. The proposed control system detects the EC and pH of the solution through sensors and adjusts the working time of the solution pump through the fuzzy controller. Specifically, the EC and pH of the nutrient solution are maintained at specific values. A Raspberry Pi3 development board is used in the proposed control system to realize and solve the problem of adjusting the EC and pH of the solution. In the fuzzy controller, the inputs are EC and pH sensors, and the output is the operating time of the pump. Experimental results indicate that the proposed control system can effectively reduce the measurement burden and complex calculations of producers by adjusting nutrient solutions.

High NH4+/NO3− Ratio Inhibits the Growth and Nitrogen Uptake of Chinese Kale at the Late Growth Stage by Ammonia Toxicity

The aim of this study was to determine the effects of various NH4+/NO3− ratios in a nutrient solution on the growth and nitrogen uptake of Chinese kale under hydroponic conditions. The four NH4+/NO3− ratios in the nutrient solution were CK (0/100), T1 (10/90), T2 (25/75), and T3 (50/50). An appropriate NH4+/NO3− ratio (10/90, 25/75) promoted the growth of Chinese kale. T2 produced the highest fresh and dry weight among treatments, and all indices of seedling root growth were the highest under T2. A high NH4+/NO3− ratio (50/50) promoted the growth of Chinese kale seedlings at the early stage but inhibited growth at the late growth stage. At harvest, the nutrient solution showed acidity. The pH value was the lowest in T3, whereas NH4+ and NH4+/NO3− ratios were the highest, which caused ammonium toxicity. Total N accumulation and N use efficiency were the highest in T2, and total N accumulation was the lowest in T3. Principal component analysis showed that T2 considerably promoted growth and N absorption of Chinese kale, whereas T3 had a remarkable effect on the pH value. These findings suggest that an appropriate increase in NH4+ promotes the growth and nutrient uptake of Chinese kale by maintaining the pH value and NH4+/NO3− ratios of the nutrient solution, whereas excessive addition of NH4+ may induce rhizosphere acidification and ammonia toxicity, inhibiting plant growth.

CARACTERIZAÇÃO FÍSICO-QUÍMICA DE SUBSTRATO DE FIBRA DE CASCA DE COCO APÓS O CULTIVO HIDROPÔNICO DE PIMENTÃO COM ÁGUA DE REÚSO E DIFERENTES LÂMINAS DE SOLUÇÃO NUTRITIVA

CARACTERIZAÇÃO FÍSICO-QUÍMICA DE SUBSTRATO DE FIBRA DE CASCA DE COCO APÓS O CULTIVO HIDROPÔNICO DE PIMENTÃO COM ÁGUA DE REÚSO E DIFERENTES LÂMINAS DE SOLUÇÃO NUTRITIVA1 RENATA DA SILVA CUBA DE CARVALHO2; MARA RÚBIA MENDES DE MELO3; fRANCIELLY GUIEIRO GOMES DE SOUSA4; luís roberto almeida gabriel filho5; antonio evaldo klar6 E hélio grassi filho7 1Trabalho originado da tese de doutorado do primeiro autor intitulada: “Cultivo de pimentão em sistema hidropônico com água de reúso em diferentes níveis de disponibilidade de água no substrato”. 2Doutora, Programa de Pós-graduação em Agronomia – Irrigação e Drenagem, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista (UNESP), Avenida Universitária, 3780, CEP 18610-034, Altos do Paraíso, Botucatu-SP, Brasil, [email protected]. 3 Doutoranda, Programa de Pós- graduação em Agronomia, Departamento de Produção e Melhoramento Vegetal. Faculdade de Ciências Agronômica, Universidade Estadual Paulista (UNESP), Rua José Barbosa de Barros, 1780. CEP: 18.610-307, Botucatu-SP - Brasil. E-mail: [email protected]. 4Doutora, Programa de Pós- graduação em Agronomia – Irrigação e Drenagem, Faculdade de Ciências Agronômica, Universidade Estadual Paulista (UNESP), Avenida Universitária, 3780, CEP 18610-034, Altos do Paraíso, Botucatu-SP, [email protected]. 5 Professor Associado do Departamento de Gestão, Desenvolvimento e Tecnologia da Faculdade de Ciências e Engenharia, Universidade Estadual Paulista (UNESP), Avenida Domingos da Costa Lopes,780, Jardim Itaipu, 17602-496, Tupã-SP, Brasil, [email protected]. 6 Professor Emérito do Departamento de Engenharia Rural da Faculdade de Ciências Agronômicas, Universidade Estadual Paulista (UNESP), Avenida Universitária, 3780, CEP 18610-034, Altos do Paraíso, Botucatu-SP, Brasil. E-mail: [email protected]. 7 Professor Titular do Departamento de Solos e Recursos Ambientais da Faculdade de Ciências Agronômicas, Universidade Estadual Paulista (UNESP), Avenida Universitária, 3780, CEP 18610-034, Altos do Paraíso, Botucatu-SP, Brasil, [email protected]. 1 RESUMO Este trabalho objetivou caracterizar a partir de análises físicas e químicas, o substrato de fibra de casca de coco antes e após o seu uso com a cultura do pimentão, cultivada em vasos com solução nutritiva preparada com água de reúso e água potável e diferentes lâminas de reposição dessa solução (100, 75 e 50% da evapotranspiração da cultura). O cultivo foi realizado em ambiente protegido ao longo de 175 dias, em vasos com capacidade volumétrica de 15 L, preenchidos com fibra de casca de coco. A cada 30 dias mediu-se o pH e a condutividade elétrica do substrato em laboratório. Após a colheita das plantas, foram coletadas amostras do substrato, com as quais avaliaram-se as características químicas e físicas: condutividade elétrica, pH, teores de NH4+, NO3-, P, K, Ca, Mg, S, Cl, B, Fe, Mn, Cu, Zn, capacidade de troca catiônica (CTC), capacidade de retenção de água (10kPA) e densidade volumétrica seca. A reposição de solução nutritiva no substrato através da evapotranspiração da cultura proporcionou aumento dos teores de nutrientes, condutividade elétrica, CTC do substrato e densidade. Os maiores valores desses parâmetros foram verificados para os tratamentos cultivados com solução nutritiva preparada com água de reúso. Palavras chave: salinização, nutrientes, água residuária, hidroponia, efluente. CARVALHO, R. S. C.; MELO, M. R. M.; GOMES, F. G.; GABRIEL FILHO, L. R. A.; KLAR, A. E.; GRASSI FILHO, H. PHYSICAL AND CHEMICAL CHARACTERIZATION OF IN COCONUT HUSK FIBER SUBSTRATE AFTER THE CULTIVATION OF PEPPER IN A HYDROPONIC SYSTEM WITH WATER REUSE AND DIFFERENT DEPHTS OF NUTRIENT SOLUTION 2 ABSTRACT This work aimed to characterize the physical and chemical characteristics of the coconut husk fiber substrate before and after its use with the pepper crop, cultivated in pots with a nutritive solution prepared with reuse and drinking water and different depths of this solution replenishment (100, 75 and 50% of crop evapotranspiration). Cultivation was conducted in pots greenhouse with a volumetric capacity of 15 L, filled with coconut husk fiber. The plants were grown for 175 days and every 30 days, the pH and electrical conductivity of the substrate were measured in the laboratory. After the plants were harvested, samples of the substrate were collected and the chemical and physical characteristics were evaluated: electrical conductivity, pH, NH4 +, NO3-, P, K, Ca, Mg, S, Cl, B, Fe, Mn, Cu, Zn, cation exchange capacity (CTC), water retention capacity (10kPA), and dry bulk density. The replacement of the nutrient solution in the substrate through crop evapotranspiration provided an increase in nutrient content, electrical conductivity, CTC of substrate and density. The highest values for theses parameters were verified ​​for the treatments cultivated with nutritive solution prepared with water reuse. Keywords: salinization, nutrients, wastewater, hydroponic, effluent.

Effect of Nutrient Solution Composition on Bio-Cemented Sand

Microbial-induced carbonate precipitation is an environmentally friendly foundation treatment technology that effectively improves soil engineering performance. The various nutrient components of liquid curing compounds significantly influence the curing effect. On the basis of penetration, dry density, water absorption, and unconfined compressive strength tests, this study showed the effect of nutrient solution composition, including urea, calcium chloride, sodium bicarbonate, ammonium chloride, and nutrient broth, on the physicomechanical properties of bio-cemented sand. The morphological differences of calcium carbonate precipitates under nutrient solution composition were compared through scanning electron microscopy (SEM). Results showed that the curing effect of compound nutrient solution was improved compared with the basic nutrient solution (urea and calcium chloride). Among the individual components added, ammonium chloride had the most remarkable effect, followed by sodium bicarbonate and nutrient broth. Among the paired components added, sodium bicarbonate + ammonium chloride had the most significant effect, followed by sodium bicarbonate + nutrient broth and ammonium chloride + nutrient broth. The strength of bio-cemented sand cured with compound nutrient solution containing five components could reach 3.43 MPa, which was 1.92 times higher than the strength of the basic nutrient solution. As shown by the SEM image, the calcium carbonate precipitation in the solidified sand was distributed in the clearance of sand particles, effectively bonding the sand particles. The calcium carbonate obtained by the composition of the compound nutrient solution precipitated the sand particles, and some of the sand particles were wrapped. Moreover, the amount of precipitation was evidently greater than that of the basic nutrient solution. Compared with the basic nutrient solution, the compound nutrient solution effectively reduced the apparent porosity and average pore size of the sand. Thus, the curing effect of the compound nutrient solution was better than that of the basic nutrient solution.

Effects of Nitric Oxide Application on Antioxidant Enzyme Activities of Pepper Plants under Drought Stress

The purpose of the study was to determine the relationship between the messenger molecule Nitric oxide (NO) and antioxidative enzyme (SOD: Superoxide Dismutase; CAT: Catalase; APX: Ascorbate Peroxidase) activities in some metabolic changes that occur under the effect of drought stress in plants, to determine the possible roles of Nitric Oxide and to obtain complementary information. The experiment conducted in a controlled environment, and plant were cultured in containers containing Hoagland nutrient solution. For drought stress application, 10% Polyethylene Glycol (PEG 6000) was added to the nutrient solution, which is equivalent to -0.40 MPa osmotic potential. Before the drought stress is applied, pepper seedlings of Demre cv were pre-treated with different doses of Sodium Nitroprusside (SNP) and Carboxy-PTIO (potassium salt) (cPTIO) (SNP 0.01, SNP 1, SNP 100 and SNP 0.01 + cPTIO, SNP + cPTIO, SNP 100+ cPTIO). On the 10th day of the drought application, the growth parameters of the plants; the plant fresh weights and their Antioxidative Enzyme Activities (SOD, CAT, APX) were determined. In terms of plant growth parameters, both plant growth and antioxidant anzyme activities of plants pretreated with 0.01 and 1 doses of SNP were lower than the high dose of SNP and the PEG application without pretreatment. The reason for the low enzyme activities in these applications can be attributed to factors such as the excess accumulation of organic acids such as proline in the cells of the plants and the decrease in H2O2 and O-2 levels in the presence of SNP.