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 dm3 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.