Água salina e biofertilizantes de esterco bovino e caprino na salinidade do solo, crescimento e fisiologia da fava - DOI:10.5039/agraria.v14i3a5672

The objective of this study was to evaluate the performance of three rice cultivars under saline water irrigation. The experiment was carried out in full sun at the Experimental Farm of the Unilab, in Redenção, Ceará, Brazil, in January 2016. The experimental design was completely randomized (CRD), in a 5 x 3 factorial scheme [irrigation water electrical conductivity (ECw: 0.5, 1.0, 2.0, 3.0 and 4.0 dS m^-1) versus three rice cultivars (C1 - Ligeirinho, C2 - Casado and C3 - Meruinho)], totaling 15 treatments, with 4 replicates of 30 seeds per cultivar. After 21 days, the following variables were evaluated: emergence percentage (EP), emergence speed index (ESI), mean time of emergence (MTE), mean speed of emergence (MSE), shoot dry matter (SDM), root dry matter (RDM) and total dry matter (TDM). The cultivar Ligeirinho showed higher tolerance to saline stress with respect to the emergence percentage, emergence speed index and mean speed of emergence. The cultivar Casado showed higher tolerance to saline stress for shoot dry matter, root dry matter and total dry matter in comparison to the other cultivars.

Vegetal mulching can mitigate the harmful effects of salts present in irrigation water. This study aimed to evaluate the effect of irrigation water salinity and mulching on the growth and yield of beet crops. The experiment was conducted in a greenhouse at Redenção, Ceará State. The experimental design was completely randomized in a 2 × 4 factorial scheme, with five replicates, composed of two levels of electrical conductivity of irrigation water - ECw: tap water - 0.3 dS m-1 and saline solution - 5.8 dS m-1; and four types of mulching (rice hulls, carnauba bagana, crop residues, and a control treatment without soil cover). The use of vegetal mulching, mitigated the effects of irrigation with saline water on the variables plant height, leaf area, stem diameter, and tuberous root. The increase of the salt concentration in irrigation water negatively affected the number of leaves, length of the tuberous root, and yield. But, it increased the soluble solids in the beet crop.

The study hypothesis proposes that the use of Trichoderma, associated with fertilization with 100% of the recommended phosphorus, may mitigate saline stress and maximize the productivity and quality of the tuberous root. This study aims to evaluate the mitigating effects of phosphate fertilization and Trichoderma harzianum in beet plants under salt stress, by measuring the initial growth, leaf gas exchange, productivity and quality of the beet. The experimental design used was entirely randomized, in a 3 × 2 × 2 factorial scheme, referring to three doses of phosphate fertilization (25%, 50% and 100%), with and without the use of Trichoderma-based inoculation, and two levels of electrical conductivity of the irrigation water (0.5 and 6.2 dS m⁻¹). Salt stress negatively affected the leaf area of the beet. The shoots’ dry mass was reduced as the electrical conductivity of the irrigation water increased, especially in the treatment with the 25% P₂O₅ dose. Salt stress reduced photosynthesis to a greater extent at the 25% P₂O₅ dose and in the absence of Trichoderma harzianum. Increasing the electrical conductivity of the irrigation water reduced transpiration and increased leaf temperature at the 25% P₂O₅ dose and in the presence of Trichoderma harzianum. The 25% P₂O₅ dose increased the stomatal conductance of the beet. The higher electrical conductivity of the irrigation water negatively affected water use efficiency, most significantly at the 25% P₂O₅ dose. Our data showed that the doses of 50% and 100% P₂O₅ were more efficient at increasing the productivity and quality of the beet, with the tuberous root diameter being higher under the lower electrical conductivity of the water and the absence of Trichoderma harzianum. The pH was high under the lowest electrical conductivity of the water, with a dose of 25% P₂O₅ and the absence of Trichoderma harzianum.

Salt stress affects the production of watermelon (Citrullus lanatus) seedlings. However, substrates with alternative materials in their composition can mitigate the harmful effects on the formation of watermelon seedlings. Thus, the objective of the present study was to evaluate the emergence and production of watermelon seedlings grown in different substrates under salt stress. The research was conducted in an agricultural greenhouse belonging to the Universidade da Integração Internacional da Lusofonia Afro-Brasileira, Redenção, Ceará, Brazil. The experimental design used was completely randomized in a split-plot scheme. The plots were five levels of electrical conductivity of irrigation water (ECw: 0.5, 1.5, 2.5, 3.5, and 4.5 dS m-1) and the subplots consisted of two formulations of substrates (SB1: sandy soil + sand + bovine manure; and SB2: sandy soil + sand + biochar; both in a 1:1:1 proportion on volume basis), with five repetitions of 25 seeds. The increase in the electrical conductivity of irrigation water from 1.5 dS m-1 reduces the percentage, speed index, and mean speed of emergence and increases the mean time of emergence of the watermelon crop. Substrate formulated with biochar reduces the time and increases the emergence indexes, besides enabling higher growth and biomass accumulation of watermelon seedlings. Salt stress reduces the growth, biomass, and quality of watermelon seedlings, but with less intensity with the addition of biochar.

Irrigation water salinity can cause serious problems in crop production, while organic fertilizer sources potentially mitigate saline stress. Thus, this study aimed to evaluate the productivity of maize crops under irrigation with saline water and organic fertilization. The study was conducted in the field from August to November 2020 at the experimental farm of the Universidade da Integração Internacional da Lusofonia Afro-Brasileira (UNILAB), Redenção-CE. A randomized block design was used, in subdivided plots, in which the plots consisted of two levels of irrigation water salinity (0.8 and 3.0 dS m-1). Four combinations of organic fertilizer sources were applied in the subplots, composed of 10 plants each, with four replications: C1, cattle manure + poultry biofertilizer + goat biofertilizer; C2, cattle manure + goat biofertilizer; C3, cattle manure + poultry biofertilizer; and C4, control treatment. The combination of organic fertilizer sources did not influence the accumulation of assimilates and productivity of maize crops under the irrigation water salinity of 3.0 dS m-1, except for C3, which attenuated the saline effect.