Four recently developed moth bean varieties of the ICAR–Central Arid Zone Research Institute (CAZRI), Jodhpur, have demonstrated remarkable resilience to prolonged moisture stress in western Rajasthan, maintaining growth and pod development despite a rainless period of about 35 days during Kharif 2026.
Moth bean is one of the most important pulse crops grown in the hot and arid regions of western Rajasthan, covering nearly 10 lakh hectares. However, its productivity remains low at around 350 kg per hectare, largely because of low and erratic rainfall of 150–250 mm, prolonged dry spells and limited soil moisture availability.
To address these challenges, CAZRI has undertaken long-term breeding and genetic improvement programmes focused on developing moth bean varieties with greater stress tolerance, developmental plasticity and high yield potential under harsh arid conditions.
Over the past three years, four varieties, CAZRI Moth-4, CAZRI Moth-5, CAZRI Moth-6 and CAZRI Moth-7, have been released. Their performance during the current El Niño year has provided encouraging evidence of their ability to withstand severe moisture stress under field conditions.
Strong performance during 35-day dry spell
During the crop growth period from July 10 to September 2, cumulative pan evaporation was about 317 mm. After rainfall on August 3, there was no substantial rainfall during the subsequent crop growth and reproductive stages.
The resulting dry spell lasted approximately 35 days, from August 3 to September 7, during which cumulative pan evaporation reached around 180 mm. Rainfall during this period was limited to three or four scattered events of less than 2.5 mm each.
The crop had received adequate moisture during its early establishment and growth stages. The development of an early canopy, soil binding and moisture retention in the rhizosphere helped the plants establish successfully and withstand the prolonged dry period.
Surface soil moisture at the 0–10 cm depth was around 15–16 per cent (v/v) until August 2, following the last significant rainfall of 86 mm. It subsequently declined to about 5–6 per cent. At the 10–40 cm subsurface layer, moisture declined from approximately 23 per cent to 16 per cent, continuing to provide water to the crop.
Despite the prolonged moisture deficit, the four CAZRI varieties retained their green appearance, showed good growth and developed profuse pods at around 55 days after sowing. Significantly, the moisture stress coincided with flowering, pod formation and reproductive development.
Developmental plasticity offers adaptation advantage
According to CAZRI, an important adaptation characteristic of the varieties is developmental plasticity. They begin flowering at around 30 days after sowing and can adjust their growth and maturity according to the availability of soil moisture.
This trait is particularly valuable in western Rajasthan, where rainfall can vary substantially in amount, timing and distribution. The ability to move rapidly towards reproductive development while efficiently utilizing available soil moisture gives the varieties an important advantage under rainfed arid conditions.
The varieties were developed through more than a decade of systematic moth bean breeding and genetic improvement at CAZRI, with emphasis on adaptation to the region's harsh and unpredictable environment.
Crop management crucial for realizing genetic potential
The strong field performance was supported by appropriate crop management practices, including timely sowing with the onset of the monsoon in July, optimum plant geometry of 45 × 10 cm, mechanical interculture at 20 days after sowing for moisture conservation, mechanical and manual weed management, and effective canopy development.
The experimental fields were characterized by poor soil fertility, with organic carbon of only 0.13–0.18 per cent, pH of 7.9–8.1, available nitrogen of 90–100 kg per hectare, phosphorus of 10–15 kg per hectare and potassium of 250–260 kg per hectare.
Seed multiplication underway
Seed multiplication of all four varieties is also underway to facilitate wider adoption. Seed production is currently being carried out over seven hectares at the CAZRI Research Farm to meet the Saathi Portal-indented requirement of 23.32 quintals for 2026.
In 2025, the combined seed requirement for the four varieties through the Saathi Portal was 63.2 quintals.
CAZRI said one quintal of breeder seed can potentially produce around 1,000–1,400 quintals of certified seed. When properly multiplied and marketed as certified seed, this quantity could support cultivation over approximately 10,000 hectares. Even at 50 per cent of this potential, wider adoption in Rajasthan could cover around 25 per cent of the state's total moth bean area.
Seed multiplication is being undertaken by the Rajasthan State Seeds Corporation, National Seeds Corporation and selected private players.
Genetic improvement key to climate-resilient agriculture
Dr. M. L. Jat, Secretary, Department of Agricultural Research and Education (DARE) and Director General, ICAR, described moth bean as a unique crop of the Thar Desert and said CAZRI's climate-resilient varieties could contribute to making the region more prosperous. He said the varieties could create new income opportunities for farmers while contributing to India's goal of self-reliance in pulses.
Dr. Jat noted that the varieties' ability to maintain growth and pod development during a prolonged period without rainfall demonstrates the potential of genetic improvement as an important component of climate-resilient agriculture. However, he emphasized that varieties alone are not sufficient and that best management practices, including optimal plant population, timely sowing, weed management, and moisture-conservation measures, are essential to enabling them to realize their genetic potential under stress conditions.