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Isabgol (Psyllium)RabiOpen-pollinatedUpdated 2 September 2026

Rajasthan Isabgol-1 (RI-1)

The best-documented downy-mildew-tolerant isabgol variety available — bred by gamma-ray mutation of RI-89 at Jodhpur and proven in peer-reviewed multi-year trials, making it the safer default where the disease has struck before.

SeasonRabi
Maturity period115 days
Expected yieldPooled trial mean about 1,074 kg/ha across 14 site-years; up to 1,255 kg/ha in a farmer-field adaptive trial
Suitable soilLight, well-drained sandy loam of the arid western plain

Quick facts

Crop
Isabgol (Psyllium)
Type
Open-pollinated
Season
Rabi
Maturity period
115 days
Seed rate
4–5 kg/ha, mixed with sand or fine soil for even broadcasting
Expected yield
Pooled trial mean about 1,074 kg/ha across 14 site-years; up to 1,255 kg/ha in a farmer-field adaptive trial
Suitable soil
Light, well-drained sandy loam of the arid western plain
Release
Released 2006 · Agricultural Research Station, Jodhpur

About this variety

Rajasthan Isabgol-1 (RI-1) was released in 2006 by the Agricultural Research Station, Jodhpur, developed through gamma-ray mutation breeding of the earlier RI-89 line. It matures in 115 days and, in a pooled trial across 14 site-years, averaged about 1,074 kg/ha, reaching up to 1,255 kg/ha in a farmer-field adaptive trial. What makes RI-1 stand out is its downy mildew tolerance: in peer-reviewed field trials comparing it against the RI-89, GI-2 and HI-2 check varieties, RI-1 consistently showed the lowest disease severity of the group. Since downy mildew — particularly the form that infects the flower directly and sterilises it — is the disease that decides most isabgol seasons, this documented tolerance is a genuine, evidence-backed reason to prefer RI-1 over an older variety in any tract with a history of the disease, especially the humid-prone parts of Rajasthan and Gujarat's growing belt.

Key characteristics

    Plant typeOpen-pollinated
    Maturity115 days
    Yield potentialPooled trial mean about 1,074 kg/ha across 14 site-years; up to 1,255 kg/ha in a farmer-field adaptive trial
    Disease resistanceMarkedly better downy mildew tolerance than RI-89, GI-2 and HI-2 checks in peer-reviewed field trials — lowest disease severity of the four genotypes compared
    SoilLight, well-drained sandy loam of the arid western plain
    SeasonRabi

Sowing & cultivation

  • Sowing timeFirst half of November for best yield
  • Seed rate4–5 kg/ha, mixed with sand or fine soil for even broadcasting

Yield & maturity

Maturity period

115 days

Expected yield

Pooled trial mean about 1,074 kg/ha across 14 site-years; up to 1,255 kg/ha in a farmer-field adaptive trial

Actual yield depends on sowing time, soil, irrigation, weather, seed quality and crop management.

Pest & disease considerations

Advantages & considerations

Why farmers may choose it

  • Best-documented downy mildew tolerance of any named isabgol variety, confirmed in peer-reviewed multi-year trials against three check varieties.
  • Solid, well-documented yield performance (about 1,074 kg/ha pooled trial mean, up to 1,255 kg/ha on-farm).
  • A relatively short, well-defined 115-day duration.

Things to consider

  • Officially developed and recommended for Rajasthan; confirm local availability and any state-specific recommendation before sowing outside Rajasthan.

Suitable regions

States this variety is recommended for — check locally, since a state can have more than one recommended zone.

  • Rajasthan

Frequently asked questions

Why is RI-1 recommended over an older variety like GI-1 or GI-2?

Peer-reviewed field trials comparing RI-1 against older check varieties (including GI-2) found it consistently had the lowest downy mildew severity of the group — a real, evidence-backed advantage in a crop where this one disease decides most seasons.

Sourced from: Agricultural Research Station, Jodhpur (Agriculture University, Jodhpur). editorial policy.