1. Publication
  2. Research Highlights
  3. 2023

Localized phosphorus application via P-dipping is most effective in increasing lowland rice yields when combined with seedlings at 4.5~6.5 leaf age

Related Research Project
SATREPS Madagascar
Country
Africa Madagascar

Description

P-dipping refers to the placement of phosphorus (P) fertilizer at the root system during transplanting of rice by adhering P-enriched slurry to the seedling roots. This approach is beneficial for smallholder farmers in sub-Saharan Africa who apply small amounts of P to highly P-fixing soils. This study aimed to identify the optimum seedling age for maximizing the impact of P-dipping. Pot experiments revealed that the adhered amounts of slurry to the roots with P-dipping increased in a sigmoidal pattern against seedling age along with the increases in the root mass (Fig. 1). Correspondingly, the effect of P-dipping on the initial biomass was enlarged with older seedlings in a sigmoidal pattern, increasing slowly during the young seedling age (<4.5 leaves), sharply during the intermediate seedling age, and plateauing during the old seedling age (>6.5 leaves) (Fig. 2). Combining P-dipping with much older seedlings at 8 leaves resulted in severe transplanting shock and plant death. 

On-farm trials on 90 fields demonstrated a significant interaction between seedling age and P treatment on grain yield under a range of growing conditions in the central highlands of Madagascar. The highest yield gains over the control from P-dipping were observed in seedlings with intermediate age (4.5~6.5 leaves), followed by old (>6.5 leaves) and young (<4.5 leaves) seedlings at 1.0 t ha-1, 0.7 t ha-1, and 0.6 t ha-1, respectively (Table 1). These results suggested that vigorous and intermediate seedlings with higher slurry adherence than young seedlings and a lower risk of transplanting shock than old seedlings benefited most from P-dipping (Fig. 3). This finding provides smallholder farmers with practical knowledge on how to apply P-dipping more efficiently for achieving improved P management for sustainable rice production. It should be noted that the optimal seedling status and root development for  P-dipping can be affected not only by the leaf age but also by the growth conditions in the nursery bed, e.g., sowing density, temperature, water management, light intensity, soil fertility, fertilizer management, and varieties.

Figure, table

  1. Figs
Research project
Program name

Food

Term of research

FY2017-2023

Responsible researcher

Tsujimoto Yasuhiro ( Crop, Livestock and Environment Division )

KAKEN Researcher No.: 20588511

Aung Zaw Oo ( Crop, Livestock and Environment Division )

Rakotoarisoa Njato Mickaël ( Centre National de Recherche appliquée au Développement Rural, Madagascar )

Tashiro Toru ( Nagoya University )

KAKEN Researcher No.: 109315

Nakata Mana ( Nagoya University )

ORCID ID
0000-0003-1904-2596
KAKEN Researcher No.: 70623958

Ehara Hiroshi ( Nagoya University )

ORCID ID
0000-0001-5367-1332
KAKEN Researcher No.: 10232969

ほか
Publication, etc.

Rakotoarisoa et al. (2023) Crop and Environment 149: 126901. 
https://doi.org/10.1016/j.crope.2023. 10.002

Japanese PDF

2023_B11_ja.pdf537.76 KB

English PDF

2023_B11_en.pdf350.28 KB

＊ Affiliation at the time of implementation of the study.

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