1. Cooperation, Public Relations
  2. Press Release
  3. 2026

研究成果

Development of a Rice Line with Enhanced Nitrogen Use Efficiency and Grain Yield through Early Heading
—Achieving Higher Productivity than the Original Variety Under Long-Day Conditions with Low to Standard Nitrogen Fertilization—

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2026-04-09
Japan International Research Center for Agricultural Sciences (JIRCAS)
Philippine Rice Research Institute (PhilRice)

Key Points

  • A new early-heading, high-yield rice line (NR160E) suitable for mid-latitude, long-day conditions was jointly developed by introducing an early-heading gene into a high-yielding indica variety.
  • Even with heading occurring about 8–10 days earlier, dry matter production and grain yield during grain filling were maintained, and grain yield exceeding that of the original variety was achieved even under 50% reduced nitrogen fertilizer conditions.
  • The line demonstrates high nitrogen use efficiency, producing more grains with the same nitrogen uptake, and is expected to contribute to reduced fertilizer use and environmental impact as a sustainable rice cultivation technology.

Overview

JIRCAS, in collaboration with PhilRice, developed a new rice line “NR160E” based on the high-yielding indica variety “NSIC Rc 160 (NR160).” This new line maintains and improves grain yield compared to the original variety, even though its heading date is advanced by approximately 8–10 days.

Rice cultivation in the Asian monsoon region relies heavily on nitrogen fertilizers, making it a challenge to balance environmental impact reduction with yield maintenance. Field experiments were conducted at the JIRCAS Hachimandai Experimental Field in Tsukuba, Ibaraki, Japan, which is located under mid-latitude, long-day conditions. The results showed that the early-heading1 NR160E produced higher grain yields than the original NR160 under both low and standard nitrogen fertilization.

Under nitrogen application rates of 0, 4.8, and 9.6 g N/m², NR160E headed about 8–10 days earlier than NR160 while achieving higher grain yield. Notably, even under a reduced nitrogen condition of 4.8 g N/m²—representing a 50% reduction from typical levels (about 9–14 g N/m²) in intensive rice farming in the Asian monsoon region—NR160E maintained higher grain yield than the original variety. This improved performance is attributed to smaller reductions in dry matter production around heading and sustained production during grain filling. Additionally, multiple yield components such as 1000-grain weight and seed fertility were improved. As a result, the harvest index (HI)2 and physiological nitrogen use efficiency (PNUE)3 were enhanced.

These findings suggest that NR160E is a promising breeding material for maintaining and improving grain yield while reducing nitrogen fertilizer input in intensive rice cultivation under long-day conditions. Future work will focus on optimizing the selection and combination of early-heading genes to maximize effectiveness under different latitudes and day-length conditions. In addition, by incorporating effective early-heading genetic regions into widely adopted high-yield varieties in each region, researchers aim to facilitate practical adoption by farmers and provide concrete solutions for reducing chemical fertilizer use in line with regional and policy goals.

This research was published as an open-access article in the international scientific journal Plant Direct (online version, March 27, 2026, Japan time).

Related Information

Funding
This study was supported by the Cross-ministerial Strategic Innovation Promotion Program (SIP) “Technologies for Smart Bio-industry and Agriculture” (PI: OBARA Mitsuhiro) and the Moonshot R&D Program “Achieving Zero Food Risks by Improving Crop Robustness Using Cyber-Physical Systems” (PI: OBARA Mitsuhiro) (JPJ009237), both promoted by the Bio-oriented Technology Research Advancement Institution (BRAIN).

Publication Details

Authors
Kazuhiro Sasaki, Hiroki Saito, Teodora E. Mananghaya, Jonathan M. Niones, and Mitsuhiro Obara
Title
Development and Evaluation of an Early Heading Rice Line from the Indica High‑Yielding Variety NSIC Rc 160
Journal
Plant Direct
DOI: https://doi.org/10.1002/pld3.70160

Contact

JIRCAS President: HASEGAWA Toshihiro

Program Director:
OMORI Keisuke
Research Staff:
OBARA Mitsuhiro (Project Leader, Biological Resources and Post- harvest Division)
SASAKI Kazuhiro (Senior Researcher, Biological Resources and Post-harvest Division)
SAITO Hiroki (Senior Researcher, Tropical Agriculture Research Front)　
Press Coordinator:
MARUI Junichiro (Head, Public Relations Partnership Unit)
Email : info-pr@jircas.go.jp

Glossary

1 Early heading
It refers to a trait in which crop growth stages progress more quickly, allowing earlier heading and harvest. As the heading stage (when ears emerge) and heading stage occur earlier, the overall growing period becomes shorter.
2 Harvest Index (HI)
This is an indicator showing the proportion of harvested grain weight (rice grains) relative to the total above-ground biomass at harvest time.
3 Physiological Nitrogen Use Efficiency (PNUE)
This is an indicator of how efficiently a plant can produce yield per unit of absorbed nitrogen. It represents the ability to convert absorbed nitrogen into yield.

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