The use of saline water is one of the major challenges of agriculture, as it can cause nutritional imbalances and thus reduce crop yield. This study proposes to examine the efficiency of potassium nutrition as a salt stress-mitigating agent in melon grown in a protected environment. The experiment was laid out in a randomized-block design with ten treatments in a 2 × 4 factorial arrangement represented by two melon cultivars (McLaren and SV1044MF) and four nutrient solutions (S1 - standard nutrient solution, 2.5 dS m-1; S2 - nutrient solution salinized with NaCl, 5.0 dS m-1; S3 - nutrient solution salinized with NaCl + 50% K, 6.5 dS m-1; and S4 - nutrient solution salinized with NaCl + 100% K, 7.5 dS m-1). Yield (average fruit weight, production, fruit diameter, internal cavity, and pulp thickness), quality (pulp firmness, total sugars, soluble solids [SS], vitamin C, pH, titratable acidity [TA] and SS/TA ratio) and nutritional (K, Na and K/Na ratio) variables were evaluated. Plants fertigated with standard nutrient solution showed the highest values for fruit weight (1,190.6 g), production (2,381.3 g per plant), fruit diameter (13.6 cm) and pulp thickness (2.6 cm). Cultivar McLaren produced heavier fruits (931.4 g) with larger diameter (12.4 cm) and pulp thickness (2.4 cm). The addition of NaCl to nutrient solution induced a reduction in the yield variables but did not influence fruit quality. The addition of extra K to salinized nutrient solution did not mitigate the deleterious effect of salinity on the yield of melon.

This study aimed to evaluate lettuce production in different pot volumes and different irrigation frequency under saline stress. The experiment was carried out at the Department of Environmental and Technological Sciences of the Federal Rural University of the Semi-Arid, in Mossoró, RN, Brazil. Randomized block experimental design was used in factorial scheme of 2 × 3 × 3, with 3 replicates. Treatments were consisted of 2 water’s salinity levels (0.5 and 2.0 dS m-1), 3 frequencies of irrigation (6, 9, and 12 daily events), and 3 different pots (0.5, 1.0, and 3.0 L). Data from parameters evaluated at harvest were submitted to variance analysis and means were compared. We verified that when the lower saline water (0.5 dS m-1) was used lettuce production increased when cultivated in pots of 3.0 L and submitted to 6 daily events of irrigation. When 3.0 dS m-1 water was used the best results were obtained in 0.5 L and nine daily events of irrigation. The combination of 0.5 L pot and six or nine daily events of irrigation better inhibited the damaging effects of salinity.

Soybean stands out among the crops with the greatest application of transgenics, mainly for tolerance to herbicides, pests, and diseases; however, studies on salt stress in genetically modified plants are scarce. This study aimed to evaluate the tolerance of both traditional and genetically modified soybean genotypes to saline stress during the germination and seedling phases. Seeds of 13 soybean genotypes were selected (five traditional (BRS Carnaúba, BRS Pérola, BRS Tracajá, BRS Sambaíba, and FTR-4389) and eight transgenic (BRS Sambaíba RR, BRS-333-RR, BRS-9820- RR, PAS-13565-74-RR, PAS-11711-007-RR, BRS-918-IPRO, AS-3810-IPRO, and M-8210-IPRO)), subjected to four osmotic potentials (0.0, 0.1, -0.2, and -0.3 MPa). The seed quality was evaluated using the following variables: the germination percentage, germination speed index, shoot length, root length, dry mass accumulation, and salinity tolerance index. All variables were found to be affected by salt stress. However, the conventional genotypes, BRS Carnaúba, BRS Pérola, BRS Tracajá, and BRS Sambaíba, and the RR group PAS-13565-74-RR, and PAS-11711-007-RR were tolerant to salinity, whereas the genotypes FTR-4389 (conventional) and BRS Sambaíba RR (RR) were less tolerant to salt stress, and all genotypes in the IPRO group were moderately tolerant to salt stress.

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RESUMO:O objetivo desse trabalho foi avaliar a absorção de nutrientes pelo mamoeiro em função das épocas de cultivo. As plantas foram coletas em pomares comerciais localizados no município de Baraúna-RN. O delineamento experimental foi o inteiramente casualizado (DIC) com cinco tratamentos que corresponderam a dias após o transplantio (87, 145, 176, 236, 285 DAT) e quatro repetições. As variáveis avaliadas foram: fitomassa seca total da planta e do fruto, e absorção de nutrientes total da planta e frutos. Os frutos passaram a acumular maior quantidade de matéria seca a partir dos 200 dias, atingindo aos 236 dias 41% da fitomassa seca total da planta. O teor de potássio na planta ao final do ciclo foi cerca de quatro vezes superior ao conteúdo de nitrogênio, seguido do fósforo. PALAVAS-CHAVE:Carica papaya L; Macronutrientes; Composição mineral. ABSORPTION OF NUTRIENTS ACCORDING TO PAPAYA CULTIVATION STAGES SUMMARY:The objective of this work was to evaluate the nutrient absorption by papaya as a function of the growing seasons. The plants were collected in commercial orchards located in the municipality of Baraúna-RN. The experimental design was a completely randomized design with five treatments that corresponded to days after transplanting (87, 145, 176, 236, 285) and four replications. The evaluated variables were: total dry plant biomass of the plant and fruit, and total nutrient absorption of the plant and fruits. The fruits accumulated a greater amount of dry matter from the 200 days, reaching to 236 days 41% of the total dry plant biomass of the plant.The potassium content in the plant at the end of the cycle was about four times higher than the nitrogen content, followed by phosphorus.