Salinity is an abiotic factor that impairs the growth and physiological, biochemical, and molecular mechanisms of plants. Among plants, soybeans are an important crop worldwide, so managing abiotic factors is essential to mitigate plant damage. However, biostimulants, such as melatonin, are being employed to alleviate the stress caused by these factors. Therefore, this study aimed to evaluate the growth, photosynthetic pigments, and water relations of soybean plants subjected to salinity levels and exogenous melatonin application. The research was conducted in experimental area belonging to the Federal Rural University of the Semi-Arid Region, Mossoró, RN, Brazil. The experimental design was randomized blocks, arranged in a 3 x 3 factorial scheme (three salinity levels in the irrigation water - 0.50, 3.00, and 5.00 dS m^-1 and three melatonin concentrations - 0, 0.5, and 1 mM) with three replications. At 47 days after planting, plant height, stem diameter, number of leaves, root length, chlorophyll content (a, b, and total), relative water content, leaf moisture, and electrolyte leakage were evaluated. Soybean plants tolerated the effects of salinity on growth aspects, photosynthetic pigments, and water relations up to 3.00 dS m^-1, regardless of melatonin concentration. Exogenous application of melatonin mitigated the effects of salt stress on chlorophyll b and relative water content at salinity level of 5.00 dS m^-1 and concentration of 1 mM.

Cowpea is a species considered sensitive to salt stress, with losses in growth and yield from the irrigation water electrical conductivity of 3.3 dS m⁻¹. Melatonin is a promising tool with an attenuating effect on abiotic stresses. Thus, this study aimed to evaluate the water status and growth of ‘BRS Tumucumaque’ cowpea as a function of irrigation water salinity and exogenous melatonin application. The experiment was conducted in a greenhouse, in a randomized block design, in a 3 × 3 factorial scheme, with three replicates and two plants in each experimental unit. The first factor consisted of three salinity levels in the irrigation water (0.5, 3.0, and 5.0 dS m⁻¹), and the second factor of three melatonin concentrations (0, 0.5, and 1 mM). At 41 days after sowing, plant height, stem diameter, number of leaves and leaflets, root length, leaf area, dry mass of leaves, petiole, stem and root, relative water content, electrolyte leakage, leaf mass per unit area and succulence were analyzed. Increasing salinity concentrations reduced most growth variables and increased electrolyte leakage. Exogenous application of melatonin did not have a significant effect on the attenuation of salt stress in cowpea.

Okra (Abelmoschus esculentus L. Moench) has been less studied compared to other crop species of the family Malvaceae, thus presenting high potential for research, mainly in genetic improvement. Morphological characterization is a pre-breeding step that can be conducted using quantitative and qualitative descriptors. Thus, the objective of this study was to morphologically characterize commercial okra accessions to provide a foundation for breeding programs in this crop species. The experiment was conducted in the experimental area of the Federal Institute of Alagoas, Piranhas, AL, Brazil, using a randomized block design with five treatments and five replications. Okra plants and fruits were characterized through qualitative descriptors, using a hierarchical clustering of accessions based on Unweighted Pair Group Method with Arithmetic Mean (UPGMA). The greatest genetic distance was found between the Santa Cruz-47 and Clemson Americano-80 accessions, whereas the lowest distance was found between the Cariri and Apuim accessions. The UPGMA analysis resulted in two accession groups: group I consisting of Clemson Americano-80 and Canindé accessions, and group II consisting of Cariri, Apuim, and Santa Cruz-47 accessions. Viable hybrids can be obtained from crossings between accessions of group I and group II.

Grafting is an effective method for pathogen control in various crops and improved several plant and fruit characteristics. This technique has been successfully adopted in melon cultivation, particularly using rootstocks resistant to multiple diseases. The objective of this study was to evaluate the compatibility of melon scions with rootstocks resistant to Stagonosporopsis cucurbitacearum, Meloidogyne incognita, M. javanica, and M. enterolobii, and to assess the effects of grafting on rootstock biometry, fruit yield, and fruit quality. The experiment was conducted in a randomized block design with four replications, 16 treatments, and seven plants per plot. Production, quality, and biometric parameters were assessed. Grafting increased epicarp and mesocarp firmness, fruit shape index, and vitamin C content, while reducing fruit length, fruit width, and locule length. Compatibility analysis revealed variability in the effects on measured traits, based on the general combining ability observed for scions JAB20-11 and 'Olimpic Express'. Grafting did not affect the total number of fruits or total fruit weight, while rootstock PI482398 exhibited the most favorable general combining ability for fruit length.

Purslane (Portulaca umbraticola Kunth) is used as a food, medicinal, and ornamental plant. Its ornamental use is associated with the wide genetic variability in phenotypic traits, which is fundamental in breeding programs. The objective of this study was to select parents of P. umbraticola Kunth, based on genetic divergence of ornamental purposes. Twenty-two accessions were collected in the states of Ceará, Rio Grande do Norte, and Paraíba, Brazil. The experiment was conducted in a completely randomized design, with twenty-two treatments and three replicates. Plants were evaluated 40 days after planting, at full bloom. The evaluated traits were: plant height, stem diameter, crown diameter, leaf length, leaf width, flower diameter, petal length, number of flowers per plant, chlorophyll a, and chlorophyll b, and flower color. Data were subjected to analysis of variance and Scott-Knott test (p ≤ 0.05). Heritability and the ratio between coefficient of genetic variation and coefficient of environmental variation were estimated. The genotypes were grouped by Tocher’s method, and the importance of traits by Singh’s method. The accessions were grouped into seven clusters, demonstrating genetic variability, with greater importance of the traits crown diameter, plant height, and number of flowers per plant. Eight phenotypic classes were found for flower color, demonstrating the potential of these accessions for use in breeding programs. Based on intergroup distance and considering the key traits for ornamental purposes, the accessions Ac2, Ac4, Ac6, Ac16, Ac18, and Ac19 should be selected as parents. The use of selection index should improve the choice of the parents.

Melon is one of the main vegetable crops grown in Brazil and is severely affected by root-knot nematodes of the genus Meloidogyne . The identification of resistance sources is therefore essential. Estimates of genetic parameters in breeding programs provide insight into the effects underlying the traits under evaluation. The objective of this study was to identify melon accessions resistant to Meloidogyne incognita and M. javanica and to estimate genetic parameters using the REML/BLUP procedure. Four independent trials were conducted, two for M. incognita and two for M. javanica . In the initial screening trials, 41 melon accessions were evaluated. Ten accessions (nine classified as resistant to both species and one resistant only to M. incognita ) were re-evaluated to confirm resistance. In the screening trials, 71 and 26.8% of the genotypes were classified as resistant to M. incognita and M. javanica , respectively. In the confirmation trials, five genotypes retained resistance to M. incognita , whereas only two maintained resistance to M. javanica . The Scott–Knott test identified distinct groups in all trials for both nematode species. Broad-sense heritability was low to moderate, and selection accuracy was moderate. Accession AC-18 exhibited resistance to both nematode species and is a promising genotype for melon breeding programs. Five accessions were resistant to M. incognita , whereas only two were resistant to M. javanica .