SATrends Issue 16 
March 2002

NEWS FROM THE DRY TROPICS:

1. On the Wild Side

Many species from which modern crops are derived still thrive in the wild. Faced with such adversities as droughts, floods, heat, cold, pests and diseases, they have found ways to survive without the husbandry provided to domesticated species by farmers. The genes responsible for these strengths are what make wild relatives invaluable to agriculture today. Plant breeders, in their efforts to make these wild genes accessible, first “prebreed” them to decrease their undesirable traits, then cross them with domesticated cultivars.

In their search for useful genes, scientists have serendipitously brought to light various chapters of groundnut ancestry.

Krapovickas and Gregory (1994) divided Arachis hypogaea L., cultivated groundnut (or peanut), into nine sections. The 42 wild groundnut species held in the ICRISAT genebank represent eight of these sections. Also, of the 27 known wild species, 20 are available at ICRISAT.

While Arachis hypogaea has a tetraploid chromosome number, its wild relatives are diploid. The domestic groundnut came about when two wild relatives came together and doubled their chromosome number. One of the wild relatives, A. duranensis , is known, but its partner is still unidentified.

glabrata copy.jpg (11651 bytes) Two other wild relatives gave rise to yet another tetraploid, A. glabrata (right), also a wild species. It is presumed that one of those wild parents is from the species Rhizometous, which do not produce seeds but are propagated through their rhizomes.

At ICRISAT-Patancheru it was possible to cross both A. duranensis and A. hypogaea with A. glabrata. The success of this cross combined with common traits in their cytology indicate a common ancestor.

One ICRISAT success story concerns the transfer of resistance to Spodoptera litura (fall army worm) from the wild Arachis kempf-mercadoi. Spodoptera is a formidable pest in southern India. According to Dr Phil Stevenson of the Natural Resource Management Institute, UK, factors conferring resistance in A. kempf-mercadoi may be a group of chemicals called bioflavonoids. A. kempf-mercadoi has larger quantities of the bioflavonoids than the susceptible cultivars. 

Derivatives were obtained between cultivated groundnut and A. kempf-mercadoi through in vitro techniques. When tested against Spodoptera, some derivatives showed a high level of resistance. Resistant and susceptible derivatives were screened for the presence of the bioflavonoids, and these were present in far greater quantities in the resistant derivatives than in the cultivated species. These results showed the biochemical basis of resistance to Spodoptera litura, and more importantly the successful transfer of resistant genes.

Embryo copy.jpg (11894 bytes) There are many reports of producing hybrids between A. hypogaea and section Arachis members, but reports on intersectional hybrids are few. Also, this is the first report of crossing wild species from section Arachis with A. glabrata. (The picture shows an embryo rescue technique used to obtain hybrids from the cross A. hypogaea x A. glabrata). This and other intrasectional hybrids were screened for three foliar diseases: rust, late leaf spot, and early leaf spot. All showed the disease-resistant characteristics of A. glabrata.

Besides contributing genes against an array of constraints, crosses between wild and cultivated groundnut have been helpful in deciphering family relationships and origins. Two decades of research at ICRISAT has made it possible to cross A. hypogaea with species from other sections of Arachis such as Procumbentae, Heteranthae, Erectoides and Rhizomatosae.

For more information, contact n.mallikarjuna@cgiar.org

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2. A Handful of Seed

Photo_3 copy.jpg (13917 bytes)Sheaves of sorghum and millet heads hanging from thatched roofs and fences: this is the scene that greets you in village after village in Mali, Burkina Faso, and Niger. Ask a farmer the reason for such displays and she will tell you this is how all the households store seed for sowing.

Sorghum and millet are key food staples in West Africa. Most farmers grow traditional varieties using seed saved from their own harvests. Although improved varieties are available, farmers have little access to their seed since the formal seed sector is unable to meet their needs. The private sector, in its turn, is little interested in these crops.

Farmers are content using a traditional system that has thrived for centuries in the region: farmer-saved seed supplied through barter or gifts. But until now researchers knew little about this system.

Realizing the importance of understanding the dynamics of this system for creating an effective seed supply and distribution program, the IFAD-funded partnership-based ICRISAT project in West Africa conducted surveys in 2001.  The surveys covered about 1000 rural households randomly chosen from 46 villages in Mali, Niger, and Burkina Faso.

A preliminary analysis of these surveys showed up some interesting results:

Supply Source. The main source is farmers’ own stock. In Mali and Burkina Faso, over 90% of respondents said they used seed from their own stocks. When stocks are insufficient, farmers ask relatives, friends, and neighbors for seed.

Seed Transactions. Most transactions are made in the form of barter or exchange of varieties.

Reasons for Buying Seed. About 24% of respondents in Mali, 10% in Burkina Faso, and 22% in Niger said that they had bought sorghum seed at least once. The reasons mentioned in Mali were insufficient seed stocks and the farmers’ urge to experiment.

Farmers on an average buy sorghum seeds every 8 years and millet seeds every 9 years.

Adoption of New Varieties. Information on improved varieties, access to their seed, and the urge to experiment are the main factors for adopting new varieties.

For instance, over 25% of respondents in Mali stated they weren’t aware of improved millet varieties; 37% of those who were aware tested the improved varieties and 60% of those who tested continue to grow them.

“In West Africa, the informal seed sector forms the backbone of the sorghum and millet seed supply system,” said Dr J Ndjeunga, ICRISAT Economist who is actively involved in the project. “Such surveys will help us create sustainable and farmer-appropriate seed systems.”

For more information, contact n.jupiter@cgiar.org

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3. Here's to fungus - hic!

Since time immemorial, sorghum farmers faced with grain mold disease have not been able to sell or eat their crops. Until now, that is.

Grain mold copy.jpg (14073 bytes)ICRISAT scientists are working with collaborators in India’s Maharashtra state to find ways to use sorghum to make high-quality ethanol. Why Maharashtra? Because it is India’s most important sorghum-producing area, and because grain mold is a serious problem, destroying thousands of tons of grain each year. In a bad mold year, sorghum prices crash, farmers lose money, and questions are raised in the state legislative assembly. Worldwide, about 40% of grain is damaged by molds. (Left, sorghum attacked by grain mold).

In India, most ethanol is made from molasses. Elsewhere, it is mostly made from grain, which gives liquor of better quality and causes less environmental pollution than distillation from molasses.

Breweries and distilleries normally seek good quality grain as their raw material. But recent research has shown that grain mold-infected sorghum is almost as good. This is because the mold-derived compounds in the grain are removed, or converted to harmless metabolites, during the manufacturing process. In fact, several wines savored by connoisseurs worldwide, such as Sauterne and Tokay, deliberately use mold-infected grains to achieve their unique taste.

Enter the multinational giant Seagrams, which has set up a research station at Pune in Maharashtra. If India’s alcohol manufacturers switched from molasses to sorghum, utilization would increase by 280,000 tons per year. Equally important, a large proportion of damaged grain would suddenly become valuable. Smallholder farmers reeling from crop losses would be able to salvage a good part of their harvest, and with luck, convert a loss-making season into a profitable one!

This work targets rainy-season (kharif) sorghum. Nearly half the sorghum in India is produced during kharif by smallholder farmers without access to irrigation. Yields of kharif sorghum are generally poor, grain mold and other fungal diseases are common, and prices are low. The bottom line: better prospects for the poorest farmers and huge pay-offs at the national level.

Drought-tolerant sorghum is a major crop in SAT farming systems worldwide. But because there is a limited market for the crop, many smallholders are unwilling to invest cash and labor in productivity-enhancing technologies. If this work helps expand the market, farmers will benefit. So will drinkers looking for something new.

Cheers!

For more information, contact b.reddy@cgiar.org

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Highlights of Previous Issues:

February 2002:36 Percent -- and Rising • Of Stalk and Livestock • Stalking the Enemy •Sorghum Scoop from Mali

January 2002: Back to the Drawing Board • Weed Better, Weed Faster • With Minds of their Own! • Closing Ranks against the Pod Borer

December 2001: It's a bird! It's a plane! No, it's a Super scientist! • Viva Sorgo! • Small is Big! • Abortion Leads to Rebirth

November 2001: Sorghum Products: Poised to Take Off Cash from Cattle FoodEmpowerment Through Technology • Outwitting an Unfair Bug

October 2001: Backing a Winner • More than a Thousand Words • Sowing a New Future for Eritrea • A Casting Coup: Farmers' Day 2001

September 2001: Don’t Get Left on the Shelf • Nigeria Targets ‘Groundnut Leprosy’ • Two Heads Are Better than One • Desperately Seeking Seeds

August 2001: Finding Chinks in the Armour •   Brazilian Farmers get a Boost from the Sahel • Sahelian Partners Smash the Ivory Tower • What You See is What You Get - Simulation Modeling for Successful Farming

July 2001: Balaji Makes IT Waves • A Hot Date in the Sahel • It All Adds Up • More from Less • That's the Way the Cookie Crumbles

June 2001: Space-Age Partnership in West Africa Bad Taste is Good • Out of Africa • Seed Priming: Rhapsody in Simplicity

May 2001: Dodging Drought in Kenya • Vietnam and ICRISAT Save Watersheds • Farmers Enrich Malawi's Soils • Groundnut Mystery Disease Identified

April 2001: Women Farmers Guide Scientists in Namibia •   Ashta Puts it Faith in IPM • Sahelian Farmers Place Their Bets • China and Pigeonpea: Love at Second Sight

March 2001: Agriculture: an Ally Against Global Warming? • Breaking the Spell of Witchweed • Groundnut Taking Root in Central Asia and the Caucasus • Zimbabwean Smallholders Drive the Research Agenda

February 2001: Somalia: Seeds Deliver Hope Amidst Chaos • The CGIAR Fights Desertification in Africa • Creating the World's First Molecular Marker Map of Chickpea • Aflatoxin and Cancer: Cracking a Hard Nut in Developing Countries

January 2001: Things Grow Better with Coke®: Micro-fertilizer System Sparks 50-100 Percent Millet Yield Increases in the Sahel • Groundnut (Peanut) Production Accelerates in Vietnam •   Pigeonpea Broadens Farmer's Options in Sudan •   Private Sector Invests in Public Plant Breeding Research at ICRISAT.

December 2000: International Symposium on SAT Futures • Centers Team Up to Help East Timor • Spatial Variability in Watersheds • World's First Cytoplasmic Male-Sterile Hybrid Pigeonpea • Groundnut (Peanut) Variety Boosts Malawian Agriculture • National Researchers Persevere in El Salvador • ICRISAT Celebrates India-ICRISAT Day • ICRISAT and World Vision International Work Together in Southern Africa.