Effects of phosphorus supply and salt stress on plant growth, organic acid concentration, and sodium, potassium, calcium, magnesium, and phosphorus utilization in wheat

Nutrient utilization efficiency in wheat could be affected by fertilizer supply and soil properties such as salinity. A greenhouse pot study involving two wheat genotypes (Shavano and AK58), two phosphorus (P) supply levels [imposed by adding 0.5 mM KH2PO4 (+ P), and 0 mM KH2PO4 (-P)], and two salt stress levels [imposed by adding 100 mM NaCl (+ S), and 0 mM NaCl (-S)] was undertaken to study the impact of P supply and salt stress on organic exudation, nutrient utilization, and plant growth in wheat. At the seedling stage in the -P-S treatment, the tall genotype (Shavano) had higher succinic, fumaric, malic, and malonic acid concentrations in roots than the dwarf genotype (AK58), suggesting genotypic differences in adapting to unfavorable conditions. Salt stress increased Na and decreased K in roots and shoots (straw). At maturity, the -P treatment increased the total root length (TRL) to aboveground biomass (ABG) ratio relative to the + P treatment, suggesting that -P wheat required more root length to sustain equivalent aboveground biomass than + P wheat. AK58 and Shavano required 8.6-13.8 mg and 31.9-36.1 mg P to achieve 1 g grain across all treatments, respectively. The increased P efficiency of AK58 relative to Shavano was probably due to the increased harvest index conferred by dwarf genes. Wheat coordinated adaptations in root architecture and aboveground plant biomass combined with changes in root exudation and nutrient uptake to deal with P deficiency and salt stress, consequently altering nutrient utilization.