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SATrends Issue 21 August 2002 |
- Breaking New Ground with Groundnuts
- A Custard Apple a Day....
- Gerrymandering the Gene Pool Part 4
- Mineral and Manure: A Winning Combination
- Highlights of Previous Issues
1. Breaking New Ground with Groundnuts
In India, groundnut
is grown on an estimated area of 8.1 million ha with a production of 7.45 million tons of
pods. Though average productivity is increasing, it is still considerably lower than the
world average. One of the reasons for low yield in the semi-arid tropics is the damage
caused by such abiotic stresses as drought and low soil fertility, as well as by a number
of diseases caused by fungi, bacteria, and viruses. Peanut clump virus is a serious
problem in India and several West African countries. Annual losses incurred through this
disease globally are nearly US$ 40 million.
A research
team led by Dr Kiran Sharma at ICRISAT’s Headquarters in India, after developing the
technology for genetically transforming groundnut, introduced resistant genes into the
IPCV. The strategy included transferring the coat protein and the polymerase gene of IPCV
through Agrobacterium tumefaciens-mediated genetic transformation. After extensive
molecular characterization of the transgenics and preliminary studies in the glasshouse,
permission to carry out a field trial under controlled conditions was obtained from the
Department of Biotechnology, Government of India.For more
information contact k.sharma@cgiar.org
Top The custard apple, hitherto used mainly in ice cream and milkshakes, has found an important new role for itself – as an inexpensive, environment-friendly method to control crop pests.
Custard apples (right) grow abundantly in
India and other parts of the world. The fruits are tasty, though a nuisance to eat. Almost
30% of the weight of the fruit consists of seeds. But these irksome seeds have proved a
bonus because they contain chemicals known as acetogenins, which are toxic to insects.
ICRISAT and the Indian Institute of Chemical Technology, Hyderabad, working together to
isolate the biologically active ingredients from the seeds, have succeeded in formulating
extracts that farmers can use to fight pests cheaply and effectively.
The seed extracts are fractionated to yield potions
that work against different insect species. For example, hexane-soluble components reduced
leaf disc feeding and larval massing of the armyworm (Mythimna separata), in
laboratory tests. In field tests, the extracts controlled both the armyworm and the stem
borer (Chilo partellus). Alcohol extracts were found to be nearly as toxic as
nicotine sulfate, a commonly used but expensive chemical. Another important finding: seed
extracts showed synergistic activity in combination with neem seed extract – ie, the
combination is far more effective than either one used alone. This combination works well
on several pests, including Callosobruchus chinensis, Rhizopertha dominica
and Musca domestica nebulo.
The secrets of custard
apple have long been known to farmers in India and elsewhere. Farmers in Vietnam, for
example, use the apple’s oil to control rice leaf hoppers and plant hoppers. The oil,
especially when used in combination with neem oil, reduces survival of the leafhopper (Nephotettix
virescens) in rice and also reduces the transmission of rice tungro virus. Surveys on
indigenous biocontrol methods have documented the use of extracts from Annona
reticulata and Annona squamosa – both of which contain acetogenins – to control a number of pests: the cabbage aphid (Brevicoryne brassicae), the
pulse beetle (Bruchus chinensis), the green scale (Coccus viridis),
the cotton stainer (Dysdercus keonigii), the hairy caterpillar (Euproctis
fraternal), the brown plant hopper (Nilaparvata lugens), the sawtoothed
grain beetle (Oryzeaphilus surinamensis), the diamond-back moth (Plutella
xylostella), the white-backed plant hopper (Sogatella furcifera) and the
tobacco caterpillar (Spodoptera litura).
Like they say, a custard apple a day keeps the plant doctor away!
For more information contact h.sharma@cgiar.org
3.Gerrymandering the Gene Pool
Part 4: Marker-Assisted Breeding
Continuing from
Part 3 of the subject (Molecular Mapping) published in last month’s SATrends,
we now bring you the concluding part of the series.
The application of
molecular markers and genetic maps can greatly improves the efficiency of the breeding
process is considered. First, molecular markers are environmentally neutral – a DNA
fragment from the seedling stage of sorghum ICSV 745 accession in India amplified by a
polymerase chain reaction, is identical to the fragment amplified from a fully-grown ICSV
745 accession plant in Mali. Second, the positions of the markers on the genetic linkage
map indicate that the gene for an associated trait is to be found nearby – they are linked.
To make this application of molecular markers successful, plant breeders, physiologists, pathologists, statisticians and molecular biologists need to work hand-in-hand. The inputs of all five disciplines are of equal importance when working towards a second green revolution.
For more information contact c.t.hash@cgiar.org or r.folkertsma@cgiar.org
4. Mineral and Manure: A Winning Combination
Poor soil fertility is, after drought, the
single most important constraint to smallholder farmers in Africa. Some scientists would
even reverse this order, assigning more importance to the latter constraint. Through
untold generations of cereal cropping, soil nutrients have been drastically depleted. How
to replenish these lost nutrients? Manure supplies are limited because livestock herds are
small, and few smallholders can afford expensive chemical fertilizer.
ICRISAT scientists therefore tried something
new – they focused on improving the efficiency with which farmers use mineral
fertilizer. For example, banded application, or concentrating fertilizer application in
the area close to plant roots, will provide almost the same benefit as broadcasting of
fertilizer, at a fraction of the cost.
The FAO Projet Intrants, hosted by the
Ministere Nigerian du Developpement Agricole, in partnership with various NGOs, recently
conducted an experiment in southwestern Niger comparing three alternative
fertilizer-efficient methods – DAP (di-ammonium phosphate), DAP+urea and NPK to a
crop of pearl millet. They also examined how to maximize yields (and profits) by combining
chemical fertilizer with manure. Two types of manure were compared, each combined with the
different types of fertilizer – manure transported from the field, and high-quality
manure from the family kraal, where livestock are corralled at night.
The results of the two-year study (2000-01)
showed clearly that even small quantities of fertilizer can make a big difference (left).
For example, a combination of DAP and kraal manure gave yields as high as 613
kg ha-1 – more than four times the yield from non-manured,
unfertilized fields.
Method of application is crucial: use the right
method, and small amounts of fertilizer can work wonders. The method used in this
experiment was hill placement. A small quantity of fertilizer (often carefully
hand-measured) was placed immediately around the seed at the time of sowing.
The study was able to evaluate the performance
(both yield and profitability) of hill-placed application of different formulations of
mineral fertilizer. At the same time, it estimated yield response under different
biophysical and management conditions.
In addition, the study is helping monitor the
adoption of hill-placed fertilizer application. Data from these and similar experiments
being conducted elsewhere in West Africa are helping to develop practical recommendations
for soil fertility management. These studies provide hard numbers that can be used to
compare yields and returns from alternative investment options, and suggest how best
farmers can maximize returns from their small investments.
These results are applicable not only to West Africa, but across the semi-arid tropics of the world.
For more information contact b.gerard@cgiar.org
Highlights of Previous Issues:
July 2002: Gerrymandering the Gene Pool• Peanut Paternity Suit?• The Winds of Change in West Africa• Insect Problems? Try a Little Wax and Hair
June 2002: Gerrymandering the Gene Pool• Tribal Treasure Troves• The Return of the Native• Poverty and the Perch
May 2002: Gerrymandering the Gene Pool• Snap, Crackle, and Pop• Checking Africa's Pulse• High Tech for an Old Problem
April 2002: Disaster Relief with a Difference• From Crop to Tabletop• Golden Millet, Naturally!• The "Green" to "Blue" Water Continuum
March 2002: On the Wild Side• A Handful of Seed• Here's to Fungus - hic!
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 Food • Empowerment 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 CokeŽ: 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.