Salt stress results in physiological changes that inhibit plant growth and development. Ca-complex sources are used as a potential salt stress attenuator. This study was carried out with the aim of verifying the effects of Ca-complex sources in reducing the effects of saline water stress on the physiological aspects of sour passion fruit seedlings. The experiment was carried out in a randomized block design with a 2 × 2 × 3 factorial scheme, consisting of two cultivars of sour passion fruit (BRS GA1 and BRS SC1), two levels of water salinity (electrical conductivity of 0.5 and 4.0 dS m⁻¹) and three sources of Ca-complex (without, organic acids and amino acids). The traits measured at 60 days after sowing were gas exchange, chlorophyll indices, chlorophyll fluorescence, electrolyte leakage, and relative water content in the leaf limb. Under moderate water salinity, the application of Ca-complex in amino acids promoted increases of 49.84% and 43.71%, respectively, in the efficiency of water use and carboxylation. The application of complex sources increased the stability of cell membranes, reducing electrolyte leakage, providing higher relative water content in seedlings irrigated with moderately saline water. From the results, we conclude that Ca-complex sources have potential as modulators of moderately saline water stress in sour passion fruit seedlings.

O uso eficiente de fósforo (P) na agricultura tem sido o foco principal das pesquisas com este macronutriente. Os fosfitos, que têm sido considerados estimulantes de plantas, podem contribuir para aumentar a eficiência do uso de P pelo milho. Objetivou-se avaliar a influência do fosfito via foliar sobre o crescimento e acúmulo de fósforo de milho na fase inicial de crescimento sob doses de P. Um experimento foi instalado em delineamento inteiramente casualizado, em esquema fatorial 5 x 2 com quatro repetições. Aos 45 dias após o plantio foram avaliadas a altura de planta e diâmetro de caule, massa seca de parte aérea, caule e raízes, teores, acúmulo e P a eficiência de utilização de P (EUP). A adubação fosfatada do milho, cultivado em Luvissolo crômico no estádio inicial é fundamental para incrementar seu crescimento e a produção de massa seca e acúmulo de P. O fosfito aplicado via foliar não produziu benefício adicional no crescimento, produção de biomassa ou nutrição fosfata do milho, mas aumentou a EUP na dose intermediária (200 mg dm-3) deste nutriente.

The sorghum crop is considered one of the most important worldwide due to its versatility. However, water stress can be considered a significant threat to its yield. The search for products that mitigate water stress is a crucial area of research in agriculture and water resources management. Thus, the objective in this study was to evaluate the feasibility of using salicylic acid as a water stress attenuator in sorghum. The experiment was conducted in a screened environment in a randomized block design with a 4 × 2 factorial scheme, with four replicates. Four levels of water (40, 60, 80, and 100% of evapotranspiration) and two concentrations of salicylic acid (0 and 2.76 g L^-1) were evaluated. Plant height, stem diameter, number of leaves, gas exchange, photosynthetic pigments, and chlorophyll a fluorescence were analyzed. Application of deficit irrigation depths reduced plant height, stem diameter, number of leaves, and total chlorophyll in sorghum. However, when these depths were associated with salicylic acid, it was observed that the damage was attenuated, especially in chlorophyll a and b. Furthermore, salicylic acid reduced leaf temperature and increased water use efficiency when applied alone. Thus, salicylic acid can be used to mitigate the effects of salt stress on sorghum plants.

The search for better quality inputs with lower environmental impact has been highlighted in agricultural technology research. Microalgae can improve soil fertility and seedling development. This study aimed to evaluate the influence of suspensions as a biostimulant based on the microalgae Chlorella sp. applied via root on the production of ‘Cantaloupe’ melon seedlings. The experimental design used was completely randomized, with ten replications, in a scheme of split plots in time. The plots consisted of three concentrations (0.0, 0.8, and 1.6%) and the subplots consisted of five evaluation periods (15, 18, 21, 24, and 27 days after sowing). The treatments significantly influenced the number of leaves, total leaf area, aerial part fresh mass, root fresh mass, and total fresh mass and dry mass (p<0.01), as well as plant height and stem diameter at 5% probability level by the ‘F’ test. The concentration of 1.6% was the one that showed the best performance for the increase in leaves, plant height, total leaf area, stem diameter, and fresh and dry phytomass of melon seedlings. The most significant accumulation of fresh and dry mass in the seedlings was obtained at the concentration of 1.6% of Chlorella sp.