ABSTRACT The cultivation of okra [Abelmoschus esculentus (L.) Moench] has potential for expansion in Northeastern Brazil. However, irregular precipitation, associated with high evapotranspiration rates, is a limiting factor for agricultural development. In this context, the use of water-retaining polymers stands out as a promising alternative due to their capacity to retain water and ensure favorable conditions for plant growth. Thus, the present study aimed to evaluate the effects of a water-retaining polymer on the growth, production, and fruit quality of okra under different water replacement levels. The experiment was conducted in a greenhouse at CCTA/UFCG, Pombal Campus, PB, Brazil. The experimental design was a randomized block in a 5 x 4 factorial scheme, corresponding to five water replacement levels (40, 60, 80, 100, and 120% of the actual evapotranspiration - ETr) and four doses of a water-retaining polymer (0, 1.0, 2.0, and 3.0 g L-1), with three replications. A water replacement level of 80% ETr resulted in the greatest growth and production of okra cv. Carcará. Both deficit and excess water replacement caused growth inhibition and a decrease in the number of fruits. The application of the water-retaining polymer at a dose of 3.0 g L-1 had a beneficial effect on the growth, fresh mass, and mean diameter of the fruits, being indicated for okra cultivation in semiarid areas. Irrigation with 40% ETr combined with a 1.3 g L-1 of the water-retaining polymer increased the ascorbic acid content in the fruits of okra cv. Carcará.

ABSTRACT The environmental impacts of agriculture have attracted considerable attention in recent years. Management practices such as the no-tillage system (NTS) can mitigate these impacts by enhancing soil biological activity, resulting in greater yield and resilience. This study evaluated the agronomic performance of summer-sown maize and soil quality indices under NTS with different cover crops in a crop rotation system. The experiment was conducted on a Latossolo Vermelho Distroférrico tipico in Dourados, Mato Grosso do Sul, Brazil, under NTS during the 2021 fall-winter through the 2022/2023 summer seasons, totaling two summer and two fall-winter crop cycles. The experimental design was a randomized block with five treatments conducted during the second season: an intercropping system composed of Crotalaria ochroleuca + pearl millet (Pennisetum glaucum L.) + buckwheat (Fagopyrum esculentum Moench) + signal grass (Urochloa brizantha), and the sole cropping of niger (Guizotia abyssinica), Crotalaria spectabilis, common vetch (Vicia sativa L.), and forage radish (Raphanus sativus L.), with four replications. Plant height, first cob insertion height, stem diameter, cob diameter and length, number of grains per cob, 1000-grain weight, and grain yield were evaluated at maize harvest. The treatments did not influence maize yield components. However, the activities of the arylsulfatase and β-glucosidase enzymes were affected by the crop rotation model, indicating that the adopted management contributed to improving soil biological quality. It is concluded that, based on crop rotation, NTS enhances soil biological quality and promotes the long-term sustainability of maize production.

ABSTRACT The limited availability of low-salinity water in the northeastern semi-arid region of Brazil is one of the main constraints to the expansion of irrigated agriculture. In this context, the objective of this study was to evaluate the effects of irrigation with saline water on the salinity tolerance of guava during the rootstock formation phase. The experimental design was a randomized complete block in a 2 x 5 factorial scheme, consisting of two guava genotypes (Crioula and cv. Paluma) and five levels of irrigation water electrical conductivity (ECw: 0.3, 1.2, 2.1, 3.0, and 3.9 dS m-1), with six replicates. Stem diameter, plant height, fresh biomass of leaves, stems, and roots, and the accumulation of dry biomass in leaves, stems, roots, and total biomass were measured, along with Dickson quality index, transpiration rate, stomatal conductance, CO2 assimilation rate, and the absolute and relative growth rates in plant height. Irrigation using water with electrical conductivity above 0.3 dS m-1 inhibited stem diameter growth, root dry biomass, leaf transpiration, relative growth rate in height, and Dickson quality index in guava seedlings. Among the genotypes, Crioula showed greater growth, photosynthetic activity, and Dickson quality index under saline water irrigation, indicating its potential for use as a rootstock under semi-arid conditions.

ABSTRACT The consumption of cowpea in the population's diet is an option to complement the intake of various nutrients, mainly proteins, and its black grain has great potential in the preparation of feijoada, as a more economical alternative to common bean for the Northeastern consumer. The objective of this work was to evaluate the cooking quality and protein content in black class cowpea genotypes, before and after cooking. Fifteen genotypes were evaluated, being 12 lines and 3 commercial cultivars. Cooking quality was evaluated using the percentage of cooked grains (PCG) and the protein content in raw and cooked grains. Data were expressed as mean ± standard deviation, with means compared by Student's t-test and grouped by Scott-Knott test (p<0.05). With regard to the cooking quality, a variation of the PCG between 31% and 87% was observed, with an overall mean of 71.07%. Protein content ranged from 23.35 to 29.80 g 100 g-1 in raw grains and from 24.72 to 33.70 g 100 g-1 in cooked grains. The cowpea genotypes evaluated in the present study showed high culinary quality and high protein content in raw and cooked grains. Thermal processing increased the protein content in the grain. Among the evaluated genotypes, the lines MNC10-982B-3-7 and MNC10-998B-20-3 show better cooking quality and higher post-cooking protein content. These genotypes meet consumer needs in terms of practicality and economy in grain preparation, constituting excellent options for the black cowpea market.

ABSTRACT In the Brazilian semi-arid region, the occurrence of water sources with high levels of salts is a limiting factor for irrigated agriculture, requiring the use of salt stress-tolerant genotypes and fertilization strategies that enable their production. In this context, the objective was to evaluate the morphophysiology and quality of early dwarf cashew seedlings cultivated under irrigation water salinity levels and combinations of nitrogen and potassium fertilization. The experiment was conducted in a randomized block design, in a 2 × 4 × 3 factorial scheme, referring to two cashew genotypes (Faga 11 and CCP 76), four levels of electrical conductivity of irrigation water - ECw (0.3; 1.8; 3.3 and 4.8 dS m-1), and three combinations of nitrogen and potassium fertilizers (100:50; 50:100 and 100:100% of the recommended dose), with three replicates and two plants per plot. Relative water content, electrolyte leakage, number of leaves, leaf area, plant height, stem diameter, biomass accumulation and Dickson quality index were evaluated. Irrigation water salinity above 0.3 dS m-1 increased foliar electrolyte leakage and reduced seedling growth and quality index. CCP 76 stood out for presenting higher seedling quality under saline stress. The 50:100% combination of nitrogen and potassium fertilization in the Faga 11 genotype resulted in the lowest phytomass accumulation. Combined fertilization with 100:100% nitrogen-potassium provides the lowest foliar electrolyte leakage.

ABSTRACT The objective of this study was to evaluate the physiology and growth of guava cv. Paluma as a function of irrigation with saline water and foliar application of ascorbic acid. The study was conducted using a randomized block experimental design in a 5 × 4 factorial scheme, whose treatments were formed by combining five levels of electrical conductivity of irrigation water - ECw (0.3, 1.2, 1.9, 2.6, and 3.3 dS m-1), associated with four concentrations of ascorbic acid - AsA (0, 30, 60, and 90 mM), with three replicates and one plant per plot. Stem diameter, crown volume, vegetative vigor index, photosynthetic pigment contents, photochemical efficiency, electrolyte leakage, and relative water content were evaluated. Ascorbic acid at concentration of 60 mM increased electrolyte leakage and relative water content in plants under ECw of 3.2 and 2.9 dS m-1, respectively. AsA concentration of 90 mM stimulated the biosynthesis of chlorophyll a, chlorophyll b, and total chlorophyll of guava plants grown under water salinity of 3.3 dS m-1. Salinity above 0.3 dS m-1 reduced chlorophyll a fluorescence, crown volume, and vegetative vigor index of guava. Foliar application of 30 mM ascorbic acid increased the quantum efficiency of photosystem II up to ECw of 2.5 dS m-1. The beneficial effect of ascorbic acid was obtained under ECw of 0.3 dS m-1.

ABSTRACT The use of mulch combined with drip irrigation is a common crop management technique in orchards and contributes to increasing yields while saving water. This work aimed to evaluate the effects of using plastic film mulching as soil cover and as an underground percolation barrier on the growth, yield, fruit quality, and irrigation water productivity of pineapple. Crop development, yield, fruit quality and irrigation water productivity were evaluated. The experiment was set up in a randomized block design with six replications, with a 2 x 2 split-plot arrangement for the treatments studied: With (WC) and without (NC) soil surface cover in the plots and with (WPB) and without (NPB) percolation barrier in the subplots. A plastic film (biodegradable agricultural mulching) was used to cover the ground and to prevent percolation. Plastic film mulching as soil surface cover reduced about nine times the water used for irrigation along the crop cycle, increased plant growth, fruit size and yield, improved fruit quality, and enhanced irrigation water productivity. The plastic percolation barrier did not significantly affect plant growth and production, but significantly enhanced irrigation water productivity.

ABSTRACT The application of wood ash in agriculture emerges as a promising technique to enhance agricultural productivity. Its chemical composition can improve soil attributes, acting as a fertilizer, corrective agent, and assisting in water retention. However, studies recommend controlled adoption to avoid adverse impacts. The objective of this article is to evaluate the potential of wood ash as a fertilization strategy in peanut cultivation, with an emphasis on optimizing plant productivity and reducing water deficit. The experiment was carried out in a greenhouse in 5 dm3 pots; the experimental design applied was randomized blocks, forming a 5x5 factorial scheme, corresponding to five doses of wood ash (0; 8; 16; 24 and 32 g dm-3) and five levels of water availability (25; 50; 75; 100 and 125% of field capacity), with four repetitions. The cultivar used was IAC OL-3. The data were subjected to the normality test to check whether they followed the normal distribution and, subsequently, subjected to analysis of variance and, when significant, subjected to regression analysis, at a 5% probability of error. Wood ash, rich in nutrients, proved to be a viable alternative source of nutrients. Doses between 18.4 and 22.8 g dm-3 of wood ash led to the most satisfactory results. The water availability that responded best ranged from 96 to 111.3%. Wood ash, at doses of 22.8 and 19.64 g dm-3, contributed to water consumption and soil water efficiency.

ABSTRACT Excess salts in water used for irrigation in the semi-arid region cause losses in growth and yield of cucurbits, such as watermelon. However, the choice of salinity-tolerant varieties can reduce the impact of stress on crop yield. Thus, the objective of this study was to evaluate the tolerance of watermelon varieties to irrigation water salinity during initial development. The experiment was conducted in a protected environment located at the Federal Rural University of the Semi-arid Region, Mossoró, RN, Brazil, in a randomized block experimental design in a 7 x 3 factorial scheme with four replicates, consisting of seven cultivars (Rochedo F1, Crimson Select, Charleston Gray, Fairfax, Crimson Sweet, Sugar Baby, Preciosa) and three irrigation water salinity levels (0.5, 4.5, and 9.0 dS m-1). Increasing irrigation water salinity reduced emergence, growth, and dry mass accumulation in seedlings. There was a tendency for photosynthetic pigments of watermelon seedlings to increase with increasing salts in the irrigation water, indicating that the time of exposure to salt stress was not sufficient to significantly reduce the levels of chlorophyll a, chlorophyll b and total chlorophyll. The Rochedo F1, Crimson Select and Fairfax varieties showed greater tolerance to salinity, while Sugar Baby and Preciosa were classified as moderately sensitive to electrical conductivity levels of 4.5 and 9.0 dS m-1 in the irrigation water.

ABSTRACT Table cassava cultivars efficient in the use of phosphorus (P) and responsive to phosphate fertilization represent a crop option for regions with low availability of the nutrient and for crops using technological packages, such as investment in fertilization. The objective of the study was to classify table cassava cultivars regarding efficiency and responsiveness to P application in two agricultural crops. For this, four table cassava cultivars (Água Morna, BRS Gema de Ovo, Recife and Venâncio) were evaluated under conditions of low P availability (and without phosphate fertilization) and high availability (and fertilized with 240 kg ha-1 of P2O5). The Água Morna cultivar proved to be efficient and responsive in the two harvests evaluated. Only the Venâncio cultivar was classified as non-efficient. There was variation in the response of the Recife cultivar between the crops evaluated.