Several technologies have been implemented to improve plant performance in irrigated crops, and one of them is the use of nanobiostimulants. Therefore, the aim of the present study was to explore the effects of applying different concentrations of a carbon-based biostimulant on the morphophysiology of cowpea plants subjected to varying electrical conductivities of irrigation water. The experiment was performed in a completely randomized design, in a 2 × 6 factorial scheme, with two electrical conductivities of irrigation water (ECw: 0.35 and 4.0 dS m^-1) and six concentrations of nanobiostimulant applied through the leaves (0, 80, 160, 240, 320, and 400 mg L^-1), with four replications. Growth and gas exchange variables were evaluated 31 days after sowing (V9 stage). Concentrations between 240 and 320 mg L^-1 of carbon-based nanobiostimulant promoted greater increases in growth and physiological variables, but they caused decreases in non-photochemical quenching. Water electrical conductivity of 4.0 dS m^-1 reduced the number of leaves (17.1%), stem diameter (10.0%), SPAD index (10.3%), net photosynthesis (10.9%), stomatal conductance (46.4%), transpiration (34.5%), instantaneous carboxylation efficiency (22.4%), and photochemical quenching (4.5%); in contrast, it increased the ratio between internal and ambient CO₂ concentration (18.0%), leaf temperature (2.9%), water use efficiency (32.5%), and non-photochemical quenching (12.4%). Concentrations of 240 to 320 mg L^-1 of the nanobiostimulant enhance the development and gas exchange of cowpea plants under non-stress conditions, whereas the concentration of 240 mg L^-1 promotes the maximum increase in plant height under salinity.

Soil salinization negatively affects the growth and yield of economically valuable crops such as soybeans. New technologies are being developed to minimize the damage caused by saline stress and improve crop performance. Therefore, the use of biostimulants in agriculture may offer an alternative method to mitigate the deleterious effects of salinity. Extracts of the seaweed, Ascophyllum nodosum and humic substances (fulvic acids) are commonly used. Therefore, this study aimed to evaluate the action of a biostimulant composed of A. nodosum seaweed extract and fulvic acid applied at different phenological stages on the biometric, biochemical, and physiological parameters of soybeans (Glycine max) subjected to irrigation with saline water. The experimental design used was completely randomized in a 3 × 2 + 2 factorial scheme, referring to three applications of the biostimulant at different soybean phenological stages: V3, V3R1, and V3R1R4, two levels of electrical conductivity of irrigation water (ECw): 0.5 (S0) and 5.0 dS m-1 (S1), two additional controls, one with a positive control (PC) and the other with a negative control (NC). The experiment had five replicates with one plant per plot. The results of this study suggest that the application of the biostimulant can mitigate the harmful effects of salt stress in soybeans. The results obtained with V3R1 application in the parameters stem diameter, leaf area, shoot dry mass, electrolyte leakage, and chlorophyll b represent greater efficiency in mitigating the harmful effects of salinity in soybean cultivation.

The production of seedlings by cutting is influenced by several factors, among them the type of substrate. In this context, the objective of this work was to evaluate the effect of different substrates on the vegetative propagation of lemon balm (Lippia alba). The experiment was carried out during the period from August to October 2014, in the municipality of Redenção, Ceará. The experimental design was in randomized blocks, with five treatments: T1 = soil, T2 = soil + bovine manure (2:1, v:v), T3 = soil + earthworm humus (2:1, v:v), T4 = soil + plant organic mat­ter (2:1, v:v), T5 = soil + bovine manure + earthworm humus + plant organic matter (2:1:1:1, v:v:v:v) and five repli­cates. Apical herbaceous branches were used to produce the cuttings, with the cutting being done in polystyrene trays. After a period of 35 days, the cuttings were removed from the trays and the number of leaves and shoots, length of root and shoot, fresh and dry mass of the cuttings were evaluated. The data obtained were submitted to analysis of variance and, subsequently, when significant by F test, to the Scott-Knott test at 5% probability for comparison of means. It was observed that all the evaluated variables had a significant influence of the types of substrates used, with emphasis on treatments soil + bovine manure + earthworm humus + plant organic matter and soil + bovine manure, in which the cuttings showed better responses. Since these substrates are efficient, they are indicated for the production of L. alba seedlings by cutting.

A fauna edáfica é de extrema importância para a manutenção dos ecossistemas como um todo, auxiliando na fragmentação de compostos orgânicos e na disponibilidade de nutrientes para as plantas. Nesse sentido, objetivou-se com o presente trabalho, verificar a influência do sistema de plantio convencional e em aleias na quantidade, na distribuição e na diversidade da fauna edáfica, em Acarape-CE, durante duas épocas de plantio. Para a realização das coletas foram utilizadas 15 armadilhas de tipo ‘’Pitfall’’ em dois sistemas de cultivo de abóbora, convencional e em aleias. Também foram instaladas armadilhas na mata nativa, próxima ao experimento, para fins de comparação de dados. As armadilhas foram instaladas entre os blocos 2 e 3 durante o início da floração de dois ciclos da cultura, sendo um no período chuvoso e outro no período seco. Os indivíduos coletados foram transferidos para recipientes com álcool 70%, triados e identificados em grandes grupos. Houve diferença significativa entre os períodos seco e chuvoso, sendo o chuvoso aquele que apresentou maior número de indivíduos. Por outro lado, não houve diferença significativa entre os sistemas de manejo, provavelmente devido ser o primeiro ano de cultivo na área utilizada.

This study aimed to evaluate the influence of salinity in the germination of four sorghum cultivars. The experimental design used was completely randomized, in a 4 × 5 factorial arrangement, with four sorghum cultivars (BRS-373, BRS-380, BRS-658, and BRS-716) and five NaCl concentrations (0, 50, 100, 150, and 200 mM). The variables investigated were final germination percentage, first count, mean germination time, germination speed index, and sodium and potassium contents (radicle and aerial part). The findings demonstrated that the salinity levels interfered negatively in the germination performance of all cultivars, showing an expressive reduction, mainly in the highest concentration of NaCl.

This study aimed to evaluate the influence of organic matter on the salt accumulation in three layers of soil cultivated with noni plants irrigated with brackish water, in open field and under partial shading conditions. The experimental design was in randomized blocks, arranged in a split-split-plot scheme with five replicates. The plots were constituted by the cultivation environments (open and shaded field), the subplots by the electrical conductivity of the irrigation water (0.3, 1.5, 3.0, 4.5, and 6.0 dS m-1), and the sub-subplots by the absence and presence of organic matter. At 110 days after application of the treatments, the electrical conductivity of the saturation extract and the potassium, sodium, calcium, and magnesium concentrations were determined in three soil layers (0-10, 10-20, and 20-30 cm). Partial shading reduced the total accumulation of salts and sodium in the soil compared to the open field. Increasing the electrical conductivity of irrigation water reduced potassium concentrations in the soil, but this effect is offset by the addition of organic matter, which releases potassium, calcium, and magnesium for plant nutrition. However, cattle manure increases sodium accumulation in the soil in treatments with the highest water salinity.