Sorghum (Sorghum bicolor) physiology and phytomass in saline-sodic soil treated with amendments and single superphosphate

Abstract

This study aimed to evaluate the physiology and phytomass accumulation of sorghum plants, in saline-sodic soil treated with amendments and doses of single superphosphate. The experiment was conducted in the period from January to June 2013, in a greenhouse in the municipality of Pombal, Paraíba, Brazil, using samples of a saline-sodic soil. The experimental design was randomized blocks, in a 2 x 5 factorial scheme, relative to two types of amendments of sodic soil and 5 levels of single superphosphate, with 3 replicates, totaling 30 experimental units. Each plot was represented by two pots with capacity for 2 dm 3 with one plant each. At 30 days after sowing, sorghum plants were evaluated for gas exchanges, chlorophyll a fluorescence and phytomass accumulation. Single superphosphate application positively stimulated the gas exchanges of sorghum plants at the doses of 97.9 mg dm -3 , for the soil treated with gypsum, and 88.1 mg dm -3 , for the soil treated with elemental sulfur. Soil treatment with agricultural gypsum promoted the highest levels of chlorophyll a fluorescence, in comparison to elemental sulfur treatment. Phytomass accumulation was favored by the single superphosphate, with highest accumulation when the dose of 75 mg dm -3 was applied.

Phosphorus doses alter the ionic homeostasis of cowpea irrigated with saline water

“…Larceda et al (2006), evaluating the interaction between salinity and phosphorus in forage sorghum plants, found that the optimum level of the nutrient for this species, in the absence of salt stress, can be toxic to it under salt stress conditions. However, some authors point out that increasing the doses of phosphorus (Sá et al, 2017) and potassium (Gurgel et al, 2010) brings benefits to the physiological responses and phytomass accumulation of species such as sweet sorghum and melon, respectively. This denotes that this characteristic can be variable depending on the species, variety and nutrient involved.…”

“…Irrigation in the semi-arid region is usually performed using saline water with high concentrations of sodium chloride salts (Medeiros et al, 2003;Sá et al, 2020). The use of saline water in agriculture poses high risks of salinization and environmental degradation of soils, since salinity is an environmental stress that limits crop yield, particularly in arid and semi-arid regions (Praxedes et al, 2010;Sá et al, 2017).…”

“…Irrigation with saline water reduces growth, photosynthesis and biomass accumulation of cowpea (Oliveira et al, 2017;Sá et al, 2018). Such reduction may be related to phosphorus deficiency, since the decrease in P cycling between the cytoplasm and stroma, caused by nutrient deficiency, can lead to decreases in the consumption and production of ATP and NADPH, reducing plant photosynthesis (Sá et al, 2017). Thus, an adequate dose of phosphorus can minimize the effects of salt stress on cowpea.…”