Rhizosphere dynamics under nitrogen‐induced root modification: The interaction of phosphorus and calcium |
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| Authors: | Mitalie Makhani Marney E Isaac |
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| Institution: | 1. Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada, M1C 1A4;2. Department of Geography, University of Toronto, 100 St. George Street, Toronto, Ontario, Canada,?M5S 3G3 |
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| Abstract: | Optimizing root phosphorus (P) acquisition to reduce intensive fertilizer use is a crucial pathway for sustainable agriculture, particularly as P is an important plant macronutrient, often limiting in a majority of soils worldwide. Although many studies have assessed plant growth and P acquisition, few studies have investigated the interactive effects of nitrogen (N)‐induced root modification on soil P processes or the understudied effects of soil calcium (Ca) dynamics on soil P bioavailability. In this study, we investigate soil P and Ca response in the rhizosphere of durum wheat (Triticum turgidum L. spp. durum). Wheat grown under controlled conditions preloaded for 20 d with two N treatments preloaded low N (1 mmol KNO3 plant?1) and preloaded high N (2 mmol KNO3 plant?1)] were transferred to rhizoboxes for 12 d days after transfer (DAT)]. Shoot and root biomass, P and Ca concentration, and plant‐available P and extractable Ca were determined every three days (0, 3, 6, 9, 12 DAT). Significantly higher root mass (P = 0.7%), root length (P = 1.8%) and total biomass (P = 2.2%) were found at the end of the experiment but exclusively for high N preloaded wheat. This greater root biomass was associated with lower root P concentration, suggesting a dilution response, while little difference was observed in shoot P concentration over the 12 d. However, Ca accumulated in both roots and shoots under both preloading N levels. Concurrently, soil‐extractable Ca declined, and plant‐available P increased (r = –0.62; P = 0.03%), presumably due to a promoting effect of Ca uptake on soil P availability; lower soil Ca in turn increased the repulsive forces between P ions and the negatively charged soil surface, resulting in an increased P availability in the soil solution. This study contributes to the understanding of the complex interplay between multi‐nutrient dynamics within the rhizosphere. |
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| Keywords: | nutrient availability plant‐soil relationships rhizobox soil fertility sustainable agriculture wheat (Triticum turigidum) |
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