Abstract
Phosphorus-efficient cultivars have an increased capacity to exploit the soil and/or to convert non-available forms of phosphorus (P) into available ones for root uptake. Preliminary field observations showed that nitrogen (N) inefficient maize cultivar ZD958 exhibited high tolerance to low P soil in the shoot performance than N-efficient cultivar XY335. However, it remains unknown whether ZD958 had a higher potential in acquiring sparsely soil P than XY335. In this study, three separate glasshouse experiments were carried out to explore the capacity of both cultivars in accessing soil P. The two cultivars grew for 40 days to evaluate functional root traits in soil columns (Expt.1) and for 20 days to examine root hair length in soil filled rhizoboxes (Expt.3) in a calcareous loamy soil amended with P (high P) or background soil (low P). The third experiment (Expt.2) cultured hydroponically the both cultivars for 15 days to determine the correlation between P uptake rate and P supply intensity. Results from Expt.1 showed that shoot P content of ZD958 was significantly higher than XY335. Higher capacity of the ZD958 to access soil P were not correlated with biomass allocation and root morphological traits, since ZD958 had a lower root mass ratio at two P supplies and a lower degree of total root length and root surface area at high P than XY335. Results from Expt.3 indicated that average root hair length was not associated with the improved P uptake by ZD958, since their root hair length remained the same under low P or high P supply. Therefore, changes in root morphological traits did not explain the improved P acquisition by ZD958 roots. Rhizosphere pH, malic acid concentration and acid phosphatase activity were similar between the two cultivars, while citric acid concentration was obviously higher in ZD958 than that in XY335 (Expt.1). These results suggested that the higher capacity of P acquisition by ZD958 might be attributed to the release more citric acids from roots. P uptake rate of ZD958 was significantly higher than XY335 with the solution P ranging from 12.5 to 250 μM (Expt. 2), indicating that the changes in P uptake rate largely explained the greater P acquisition by ZD958 than XY335. Taken together, ZD958 was identified as a P-efficient cultivar, with a better adaptation to low P environment by altering the exudation of citric acid and P uptake rate. The research findings highlight the importance of plant strategies in altering the root morphological and physiological traits for a better adaptation to the low P environment, and enhance our understanding of physiological mechanisms of plant P acquisition.
Highlights
Phosphorus (P) is the second most important nutrient element after nitrogen (N) and it is a significant factor limiting agricultural production in many regions of the world [1]
This study identified ZD958 as a P-efficient genotype, which better adapted to low P stress by altering root physiological traits, rather than root morphological traits
Treatments, respectively, on shoot dry weight (SDW), root dry weight (RDW), total dry weight (TDW) and root-shoot mass ratio (RMR), respectively, but there was no significant interaction between cultivar and P for these parameters except RDW (Table 1)
Summary
Phosphorus (P) is the second most important nutrient element after nitrogen (N) and it is a significant factor limiting agricultural production in many regions of the world [1]. Modifying carbon metabolism and alternative respiratory pathways by balancing metabolic costs and metabolic benefits for improved P acquisition; (iv) Enhancing physiological P-uptake capacity through activating expression of high-affinity phosphate transporters, (v) Extending the soil exploration space beyond the roots by establishing a symbiotic associations with arbuscular mycorrhizal (AM) fungi. Plant growth promoting rhizobacteria (PGPR) around the roots improve P acquisition by plants due to P solubilisation. The exploration of these strategies made crops more efficient in the acquisition of soil P and resulted in a reduction of requirements of P fertilizers [5,9,10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
