ABSTRACT
Global climate changes have intensified water stress in arid and semi-arid regions, reducing plant growth and yield. In this scenario, the present study aimed to evaluate the mitigating action of salicylic acid and methionine in cowpea cultivars under water restriction conditions. An experiment was conducted in a completely randomized design with treatments set up in a 2 × 5 factorial arrangement corresponding to two cowpea cultivars (BRS Novaera and BRS Pajeú) and five treatments of water replenishment, salicylic acid, and methionine. After eight days, water stress decreased the Ψw, leaf area, and fresh mass and increased the total soluble sugars and catalase activity in the two cultivars. After sixteen days, water stress increased the activity of the superoxide dismutase and ascorbate peroxidase enzymes and decreased the total soluble sugars content and catalase activity of BRS Pajeú plants. This stress response was intensified in the BRS Pajeú plants sprayed with salicylic acid and the BRS Novaera plants with salicylic acid or methionine. BRS Pajeú is more tolerant to water stress than BRS Novaera; therefore, the regulations induced by the isolated application of salicylic acid and methionine were more intense in BRS Novaera, stimulating the tolerance mechanism of this cultivar to water stress.
ABSTRACT
The association between population increase and the exploitation of natural resources and climate change influences the demand for food, especially in semi-arid regions, highlighting the need for technologies that could provide cultivated species with better adaptation to agroecosystems. Additionally, developing cultivation technologies that employ waste materials is highly desirable for sustainable development. From this perspective, this study aimed to evaluate whether seed priming with glass waste microparticles used as a silicon source under red light irradiation mitigates the effects of thermal and water stress on seedlings of Moringa oleifera. The experimental design was set up in randomized blocks using a 2 × 2 × 2 factorial arrangement consisting of seed priming (NSP-no seed priming, and SPSi-seed priming with glass microparticles under red light irradiation), soil water replenishment (W50-50%, and W100-100% of crop evapotranspiration-ETc), and temperature change (TC30°-30 °C day/25 °C night and TC40°-40 °C day/35 °C night). Seed priming with glass microparticles under red light irradiation mitigated the effects of thermal and water stress on seedlings of Moringa oleifera seedlings through the homeostasis of gas exchange, leaf water status, osmotic adjustment, and the antioxidant mechanism.
ABSTRACT
Semiarid regions are characterised by water scarcity, a limiting factor on plant growth and development. The Sertão Canal was built in the semiarid region of Brazil, more specifically in the state of Alagoas, with the aim of making year-round irrigation possible. However, for the best water management, a physical and hydrological knowledge of the soils is necessary. As such, the aim of this study was to determine the physical and hydrological characteristics of three different types of soil (Argisol, Quartzarenic Neossol and Regolithic Neossol) under native vegetation (Caatinga) and agricultural systems in the semiarid region of Alagoas, as well as to adjust the soil water retention characteristic curves. Soil samples were collected at depths of 0-10, 10-20 and 20-30 cm in the municipalities of Inhapi, Delmiro Gouveia and Pariconha, in the state of Alagoas. The points of the moisture characteristic curve were determined by the Richards method, at pressures of 33, 100, 500, 1000 and 1500 kPa. Retention curves were modelled using the exponential decay equation and compared using the van Genuchten equation, modelled with the help of the RETC computer software. Particle size varied according to the textural classification of the different soils, from Sand to a Sandy Clay Loam. The retention curve fluctuated due to the particle size of the soil, with the Red-Yellow Argisol (Inhapi) having a greater capacity for water retention. Extremely sandy soils, such as those in the Delmiro Gouveia region, had a low capacity for retaining water. For each soil sample, the exponential decay equation gave the best fit, with values for R2adjust of greater than 0.93. When the measured soil moisture levels were compared with the levels estimated by the RETC model, some of the treatments were unable to estimate accurately the moisture levels obtained with the soil water retention curves.