NEWS FROM THE DRY TROPICS:
- Searching for the Fountain of Youth
- Topcross Hybrids, Topnotch Survivors
- LEADing from the Front
- Alfisols of the Semi-Arid Tropics: Problems and Potentials
- Highlights of Previous Issues
1. Searching for the Fountain of Youth
People around the world go to great lengths to look and stay young for the longest possible time. This idea has been extended to the plant kingdom as well. Humans use cosmetics, exercise, and change their diets, to preserve their appearances. With plants the “stay-green” benefits go beyond the individual.
Livestock contribute to improved livelihoods by providing food, manure, and draft power. Good livestock require good fodder from crop residues. Fodder quality depends on the greenness of the crop, which in turn depends upon the soil moisture.About half of India’s sorghum area is grown in rabi, the postrainy season, on residual soil moisture. Compared to kharif (the rainy season) rabi is typified by: (1) cooler average temperatures during the night, especially during the latter part of the season; (2) higher probability of moisture stress during the grain-filling stage; and (3) shorter days during flowering and grain development. Because all three of these conditions contribute to drought stress, the stay-green character in sorghum is associated with tolerance for drought.
About 30 years ago scientists used conventional hybridization methods to produce “stay-green” plants in which the aging factor was delayed. For sorghum the benefits are delay in senescence (which increases protein synthesis time in the leaves) and more accumulation of starch during the grain-filling stage. Also, fodder from stay-green plants is more nutritious.
(Left, compare the "stay-green" quality with the convential lines) ICRISAT scientists evaluated an array of 38 diverse lines collected from various sources (including the Indian national program), for stay-greenness, and identified 10 that scored high for stay-green characters.- Stay-green character and agronomic desirability, score 1 (scale 1 to 5 where 1= most green and 5= least green)
- Agronomic desirability score 2 (scale 1 to 5 where 1= most desirable and 5= least desirable)
- Withstanding lodging (broken stems), score 1 (where 1= < 10% lodged, and 5= > 75% lodged)
For more information contact b.reddy@cgiar.org
Top2.Topcross Hybrids, Topnotch Survivors
Successful new genetic materials for marginal, arid-zone environments must combine the stress-adaptive traits of farmers’ own landraces with improved grain and fodder yield, and the disease resistance that landraces often lack. Success in achieving these requirements by conventional breeding has been very rare, but collaborative research by ICRISAT and India’s Central Arid Zone Research Institute (CAZRI) in Rajasthan is exploring a new solution to farmers’ needs
The solution is the landrace-based topcross hybrid, which exploits heterosis between adapted, dual-purpose male-sterile lines and pollinators derived from local landraces. The difference between topcross hybrids in conventional single-cross hybrids is that the pollinator in the former case is a variable, open-pollinated variety, where in the latter case it is a uniform inbred line, a difference that has several important implications:
- Topcross hybrids are easier to breed, because experimental hybrids can be made directly from existing varieties without the need for extensive inbreeding before they can be evaluated.
- Topcross hybrids are genetically variable, providing better buffering against variable environments and better disease resistance than is possible in single-cross hybrids.
- The pollinators of good experimental topcross hybrids can be easily re-selected to improve specific traits in their hybrids.
Landrace-based topcross hybrids are unique in that they are based on pollinators derived from landrace cultivars, which preserves the benefits of generations of both farmer and natural selection. Successful examples of such hybrids have increased grain and biomass yields and improved disease resistance (from the seed parent), while retaining the all-important adaptation and preferred plant type of the landrace pollinator. Exploiting this concept requires the breeding of pollinators from widely grown landrace types and the identification of adapted, disease-resistant male-sterile lines. Adaptation in the male-sterile lines is measured by a positive general combining ability for total biomass in marginal, drought-stressed environments. The disease resistance of the resulting hybrids demonstrates the resistance of the male-sterile lines.
The first three of such experimental hybrids were entered into the Indian National trials in 2002. In preliminary trials conduced by ICRISAT/CAZRI, these hybrids produced a statistically similar grain yield (165 g m-2 vs 178 g m-2) as HHB 67 – the best conventional hybrid currently available for the arid zone – plus a statistically superior fodder yield (263 g m-2 vs 194 g m-2). In addition, all three male-sterile lines involved have adequate resistance to the current Rajasthan pathotypes of downy mildew, whereas the male-sterile line of HHB 67 does not. (Right, HHB 67)
For further information contact f.bidinger@cgiar.org
Last year, Zimbabwe suffered its worst drought since 1992. Smallholder farmers were the hardest hit. Many lost their seed stocks, leaving them unable to plant their fields the following season.A new partnership between ICRISAT, NGOs and the private sector is helping them rebuild. The USAID-funded LEAD Project aims to expand the production of drought-tolerant crops (sorghum, pearl millet, groundnut, cowpea). Seed Co, Zimbabwe’s largest seed company, will contract smallholder farmers to produce seed, which will then be sold to other farmers. In the first cropping year (beginning October 2003), the project will involve 1200 seed producers from five drought-prone districts. Another program, also funded by USAID and led by ICRISAT, will extend the same approach to Zambia, Mozambique and Tanzania – all affected by the 2002 drought.
The targets are ambitious. Specially selected and trained farmers will produce 1500-2000 tons of seed, enough to plant nearly half a million hectares. The seed will be purchased by Seed Co – cash on delivery – for sale to other farmers. ICRISAT will participate in crop grading and awareness programs to ensure that farmers understand the importance of seed quality, not simply in theory but in terms of the price difference between good and poor seed.
Work is in full swing in Zimbabwe. Seed production sites have been identified, and farmers organized into contiguous blocks to improve logistics and ensure genetic purity of the seed produced. Local supervisors have been recruited to monitor quality and provide technical advice.
Other features of the program:
- Improved varieties. Farmer feedback has clearly shown that lack of seed is the biggest reason for non-adoption of improved varieties. The program therefore focuses on producing seed of high-yielding, early-maturing varieties such as Macia sorghum and PMV 3 millet (both developed by ICRISAT).
- Soil fertility. ICRISAT has pioneered a new approach to soil fertility management. Farmers use small, affordable quantities of fertilizer in combination with manure. The program will use the same approach, not only improving seed yields and profitability but also promoting low-dosage fertilizer use in the target areas.
- Integrated pest management. Seed producers will use effective and environmentally friendly IPM techniques.
- Demonstration plots. Project farmers will use a suite of low-cost technologies especially developed for resource-poor smallholders. In parallel to the seed production effort, demonstration plots will be set up at each project site to promote these technologies among the local communities.
For more information contact r.jones@cgiar.org
4. Alfisols of the Semi-Arid Tropics: Problems and PotentialsAlfisols are the third most important soil order in the world, covering 13.1% of the world area. In the semi-arid tropics, Alfisols cover a much larger area of potentially arable and grazable lands than Vertisols, which have until now received far more attention from ICRISAT researchers. About 62% of the world’s Alfisols are located in West Africa and India.
Mixed farming is the rule when crops are produced for home consumption or local markets. Animal production for meat, milk and wool utilizes virtually all the rural land not used for crops. Overgrazing and over population of animals is common and often causes serious soil erosion and degradation.
Traditionally, Alfisols (right) are cropped during the rainy season. Because of the erratic rainfall patterns that typify the semi-arid tropics, crop yields on Alfisols are low and unstable. Experimental evidence, however, indicates that these soils are capable of producing more food with appropriate soil and water management.
Some of the serious constraints to crop production in Alfisols are:
- Low moisture storage capacity and the likelihood of moisture stress
- Greater runoff and loss of water
- Percolation, loss of water and nutrients
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Workability problems (Alfisols are easy to work when wet but harden on drying and require greater amounts of energy for tillage)
Crusting
Erosion
Low soil fertility
High yield increases of several crops were obtained under improved management practices over the traditional technology in trials undertaken at ICRISAT-Patancheru and elsewhere. The improved land treatments included graded bunds, contour farming and furrowing, and improved management (including high-yielding varieties, timely planting and fertilizer application).
Because the water-holding capacity of Alfisols is too low to allow postrainy season cropping, efforts are being made to extend the cropping season through the use of intercropping, relay planting or by shortening the growing season by using short-duration varieties. Efforts are also made to identify promising cropping patterns.
The scope for run-off farming from Alfisols is high. The tanks serve as percolation tanks and recharge the aquifers. The introduction of percolation tanks and wells impart economic viability and social cohesion to certain cropping patterns. Water from the wells can be pumped up to an elevated point and applied to crops even at the upper end of watersheds. With the use of appropriate technology, Alfisols can produce high yields.
For more information contact s.wani@cgiar.org or a.ramakrishan@cgiar.org or p.pathak@cgiar.org
5.Highlights of Previous Issues:
October 2002: King Baudouin Award - Yet Again!• Nibble a Needlefull• The "Earthworms" of the Sahel• Grow Pearl Millet, Fulfill Your Dreams
September 2002: "Donkey Work" for Peanuts• Wealth from Weeds• Andhra Pradesh Farmers go High-Tech
August 2002: Breaking New Ground with Groundnuts• A Custard Apple a Day...• Gerrymandering the Gene Pool Part 4• Mineral and Manure: A Winning Combination
July 2002: Gerrymandering the Gene Pool Part 3• Peanut Paternity Suit?• The Winds of Change in West Africa• Insect Problems? Try a Little Wax and Hair
June 2002: Gerrymandering the Gene Pool Part 2• 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 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.