Micro‐dose placement of phosphorus induces deep rooting of upland rice

Abstract

Upland rice production is often constrained by phosphorus deficiency (P) and drought events. Methods are needed to maximize P use efficiency, while promoting deep root development to mitigate drought. This study evaluates micro-dose P placement as a technique to enhance drought resilience of upland rice, thereby hypothesizing that P placement enhances deep root development, stimulated by the local P supply in the planting hole, compared to broadcast P. MethodsTwo pot experiments were conducted using P deficient upland soil in Tanzania (Expt.1) and Madagascar (Expt.2), with factorial combinations of P doses (control and two P levels), application method (placement versus broadcast), rice varieties (DJ123 & NERICA4) and water regimes (field capacity and drying periods). ResultsMicro-dose P placement strongly boosted the establishment of upland rice and enhanced P recovery rates (4-to 5-fold) and fertilizer use efficiency (9-to 14-fold) compared to broadcast P. Micro-dose P placements significantly enhanced the fraction of roots found at largest depth (>30 cm, Expt. 1; >15 cm, Expt. 2) by 22-to 33%. Surprisingly, shoot P concentrations were markedly lower under P placement than under broadcast at equivalent P doses or equivalent biomass, indicating a Piper-Steenbjerg effect. ConclusionThis study is first in showing the enhanced deep rooting after P placement, and suggests replication at field scale where subsurface moisture may yield stronger benefits than in pots. The depleted shoot P concentrations induced by vigorous plant establishment under P placement may, however, counteract benefits at later growth stages and need further attention.

A comparative study of Chilli (Capsicum Annuum) on biomass production by phosphorus application through micro-dose placement, broadcast, and optimized seedling Root-dip in P-enriched slurry

“…Comparison between SRD, micro-dose and full dose P application It was evident from the outcome that the MDP or SRD, both of which have a principle of localized P placement, outperformed the FD broadcast approach almost across all parameters. Localized placement of P promotes root proliferation, expanding the root absorption surface area and capturing more soil nutrients, as supported by previous studies (De Bauw et al, 2021;Jing et al, 2010). This can explain the increase in dry biomass production and P uptake in our nding (Table 2), as root proliferation in nutrient-rich areas can compensate for uneven nutrient distribution across the root system (Robinson, 2001).…”

Localized phosphorus promotes nutrient productivity of Brassica chinensis genotype with strong root morphological plasticity

“…Phosphorus is usually heterogeneously distributed in natural and agroecological systems (Adediran et al, 2020;George et al, 2018;Wang et al, 2020). To access patchy P effectively, plants have evolved diverse below-ground strategies which include increasing photosynthesis partitioning to grow roots, stimulating ne-root proliferation, and enhancing exudation of P-mobilizing compounds in nutrient-rich zone (De Bauw et al, 2021;Hodge, 2004;Jing et al, 2010). For instance, crops could invest large ratio of photosynthesis into nutrient-rich zone, produce long roots with diameter lower than 0.5 mm, and increase the secretion of acid phosphatase (Gao et al, 2019;Jing et al, 2012Jing et al, , 2022.…”

“…For example, Trifolium subterraneum L. Losa proliferated long roots in the top soil containing abundant plant-available P compared with the genotype Napier (McLachlan et al, 2020a). Besides, the effect size of heterogeneous nutrient on root proliferation and crop yield productivity depends on levels of P fertilization (De Bauw et al, 2021;Ma et al, 2020). Previous studies have demonstrated that heterogeneous P supply stimulated root allocation in the P-rich soil volume, and elicited large P content in crops fertilizing with low-dose P compared with high-dose P application (Ma et al, 2020).…”

Localized phosphorus promotes nutrient productivity of Brassica chinensis genotype with strong root morphological plasticity

“…Phosphorus is usually heterogeneously distributed in natural and agroecological systems (George et al, 2018;Adediran et al, 2020;Wang et al, 2020). To access patchy P effectively, plants have evolved diverse belowground strategies, which include increasing photosynthesis partitioning to grow roots, stimulating local ne-root growth, and enhancing exudation of P-mobilizing compounds in nutrient-rich zones (Hodge, 2004;Jing et al, 2010;De Bauw et al, 2021). For instance, crops could invest a large ratio of photosynthesis into nutrient-rich zones, produce long and ne roots, and increase the secretion of acid phosphatase (Jing et al, 2012(Jing et al, , 2022Gao et al, 2019).…”

“…For example, Trifolium subterraneum L. Losa developed long roots in the topsoil containing abundant plant available P compared with the genotype Napier (McLachlan et al, 2020a). In addition, the effect size of localized nutrients on root growth and crop yield productivity depends on the levels of P fertilization (Ma et al, 2020;De Bauw et al, 2021). Previous studies have demonstrated that localized P supply stimulated root allocation in P-rich soil and elicited a large P uptake in crops fertilized with lowdose P compared with high-dose P application (Ma et al, 2020).…”