Influence of drought stress on phosphorus dynamics and maize growth in tropical ecosystems
Mohsin Mahmood, Jujie Wang, Sajid Mehmood, Waqas Ahmed, Anam Ayyoub, Mahmoud F. Seleiman, Ahmed S. Elrys, Ahmed S. M. Elnahal, Adnan Mustafa, Xiuwen Wei, Weidong Li
Abstract
Drought has a significant impact on ecosystem functions, especially on the biogeochemical cycling of phosphorus (P), which is a crucial nutrient for plant growth and productivity. Despite its importance, the effects of different drought scenarios on soil P cycling and availability remain poorly understood in previous studies. This study simulated drought conditions in tropical soils using maize as a test crop under varying field capacity (FC) levels (100%, 80%, 60%, 40%, and 20%) over a 60-day pot experiment. P uptake and plant biomass decreased significantly lower FC level. P uptake was highest at FC100 (5 g kg − ¹) and lowest at FC20 (3.5 g kg − ¹). Similarly, biomass was greatest at FC100 (70 g plant − ¹) and declined to 35 g plant − ¹ at FC20, underscoring the adverse effects of drought on P availability and growth. The results showed a substantial increase in calcium-associated P (HCl D -Pi), reaching 45% at FC20. Conversely, labile inorganic P fractions (NaHCO₃-Pi and NaOH-Pi) decreased significantly, from 14.73 to 6.2 mg kg − ¹ and 29.4 to 17.7 mg kg − ¹, respectively, in FC20 compared to FC100. Organic P fractions (NaHCO₃-Po, NaOH-Po) increased by 6 and 2.4 times, respectively, under lower FC treatments, while HClc-Po was also elevated under drier conditions. These transformations were attributed to changes in soil pH and calcium content, favoring the stabilization of P as HCl D -Pi. Drought disrupted the replenishment of inorganic P in the soil solution, reducing bioavailability, though phosphatase activity enhanced organic P release. Pearson’s correlation analysis revealed positive associations between labile and moderately labile P fractions (NaHCO₃-Pi, NaOH-Pi, HCl D -Pi) and soil elements (Ca, Al, Fe). RDA highlighted a positive link between phosphatase activity and reduced labile P, while P uptake and biomass were strongly associated with labile and moderately labile P fractions. These findings demonstrate drought’s significant impact on P bioavailability, soil P cycling, and nutrient dynamics.