🧬 Sorghum — Breeding Objectives and Hybrid Development

Sorghum breeding in kharif regions must balance grain, fodder, and stress resilience under dryland pressure. This lesson explains objective setting and CMS-enabled hybrid strategy in Indian programmes.

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Origin and Importance

Sorghum (Sorghum bicolor (L.) Moench, 2n = 20) belongs to the family Poaceae. Its centre of origin is Northeast Africa (Ethiopia-Sudan region). Sorghum is the fifth most important cereal globally and is a critical kharif crop in the semi-arid tropics of India, particularly in Maharashtra, Karnataka, Rajasthan, and Madhya Pradesh. It serves as a dual-purpose crop, providing both grain for human consumption and stover for livestock feed.

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Breeding Objectives

1. High grain yield — compact panicle, bold grain, and high harvest index.
2. Dual-purpose types — combining good grain yield with high green fodder and stover quality (stem juiciness, digestibility).
3. Grain quality — bold, lustrous, white or yellow grain with high protein and micronutrient content. Low tannin and polyphenol content for better taste and digestibility.
4. Shoot fly resistance — the most destructive pest of kharif sorghum in India; resistant varieties exhibit seedling vigour, trichome density, and glossy leaf traits.
5. Grain mold resistance — a major post-flowering problem in kharif season; hard, corneous endosperm and tight glumes confer resistance.
6. Striga resistance — the parasitic weed Striga asiatica devastates sorghum in parts of Africa and Asia.
7. Drought tolerance — stay-green trait, deep root system, and osmotic adjustment for terminal drought.

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CMS-Based Hybrid Development

The discovery of cytoplasmic male sterility (CMS) in sorghum by Stephens and Holland (1954) using the milo cytoplasm revolutionized hybrid breeding. The three-line system (A line, B line, R line) is used to produce commercial hybrids.

• A line (CMS) — male sterile, serves as the female parent.
• B line (Maintainer) — identical to A line except for fertile cytoplasm; used to maintain the A line.
• R line (Restorer) — carries dominant Rf genes; crossed with the A line to produce fertile F1 hybrids.

India was the first country in the world to release a commercial grain sorghum hybrid — CSH 1 (1964), developed at the Indian Agricultural Research Institute. Subsequent hybrids include CSH 5, CSH 9, CSH 16, CSH 23, and the biofortified hybrid CSH 31. For fodder, multi-cut varieties like SSG 59-3 (sudangrass hybrid) are widely cultivated.

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Dual-Purpose Breeding

The challenge of dual-purpose sorghum is that tall, leafy plants with high fodder yield often have lower grain yield and vice versa. Modern breeding strategies use modified plant architecture — medium height, more leaves, and photoperiod insensitivity — to optimize both grain and stover production.

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Summary Cheat Sheet

Quick Recall Points\n- Sorghum is key for dual-purpose breeding: grain plus stover quality.\n- Major stress targets: shoot fly, grain mold, Striga, and terminal drought.\n- Hybrid seed production depends on the A-B-R CMS system.\n\n### Exam Traps\n- Tall biomass type alone is not ideal; grain-fodder balance is the breeding goal.\n- Stay-green is a drought adaptation trait, not simply delayed maturity.

References

2 sources • [1] [2]

[1]

ICAR eCourse: GPBR 213 Crop Improvement-I (Kharif Crops)

Book

[2]

ICAR Crop-specific research bulletins (IIRR, IIMR, IIMR Sorghum, ICRISAT, CICR, SBI, CRIJAF)

Website