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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 тАФ 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
4тАУ5 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 тАФ particularly the form that infects the flower directly and sterilises it тАФ 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 тАФ 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 rate4тАУ5 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 тАФ 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 тАФ 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.