|SPORE Bulletin of the CTA No. 14 (CTA Spore, 1988, 16 p.)|
Breeding plants for higher feed value
The importance of crop residues as livestock feed has largely been ignored in plant breeders' search for higher arain yields.
To many agriculturists the "ideal" plant is one that produces a large amount of grain or seed with as little residue as possible, indeed the dwarf high-yielding varieties of cereals have benefited from the plant's capacity to switch starch production from leaf and stem tissue to the seedhead. But for smallholder farmers, where crop residues provide up to 80% of the feed for ruminant livestock, the plant residue is an essential resource.
A workshop on "Plant Breeding and the Nutritive Value of Crop Residues" was jointly organised in December 1987 by the Overseas Development and Natural Resources Institute (ODNRI) of the U K and the International Livestock Centre for Africa (ILCA) and was held at ILCA headquarters near Addis Ababa, Ethiopia. It brought together for the first time plant breeders, economists and nutritionists to highlight the potential nutritive value of such residues and to map research plans for enhancing their palatability digestibility and nutrient content.
The point was made by Dr John Walsh, ILCA's Director-General when he said "In most African livestock systems crop residues are critical to animal production, and if the nutritive value of crop residues could be increased by breeding, the amount of feed available to animals would greatly increase".
Several speakers stressed the need to re-evaluate the concept of crop residues. Dr Tom Nordbloom, an agricultural economist at the International Centre for Agricultural Research in the Dry Areas (ICARDA), based in Syria said, "In much of North Africa and West Asia, when farmers sow their crops they expect to get feed for their livestock at harvest. This clearly influences their choice of crops and the way they manage them". He went on to say that the farmer's viewpoint needs to be recognized by agricultural scientists and development workers, to make them aware that straws and stovers are not just residues, but rather joint products.
According to Dr R E McDowell, former chairman of ILCA's board and visiting professor at North Carolina State University, up to two tonnes of dry matter as crop residue is available in developing countries to feed livestock for each 500 ka livestock unit Speaking as a plant breeder, Dr Gurdev Khush of the International Rice Research Institute (IRRI) in the Philippines commented: "Plant breeders are increasingly aware of the farmers's need to make use of as much of the plant as possible. And that means that we must consider the nutritional value of the straw in our selection programmes". A first step in this process is to define standardized techniques to screen breeding materials for straw nutritive value -ones that correlate with in vivo nutritive value.
Participants felt that elite materials and released varieties should be screened, but some plant breeders said that screening methods could also be applied to parental lines used in a breeding programme. In some crops characteristics such as plant height and leafiness could be used initially to screen large numbers of line.
The participants endorsed the need for collaboration between animal nutritionists and plant breeders and in addition the need to improve storage methods to preserve the nutritive value of crop residues. There was general agreement that research efforts should be concentrated on cereal crops, but that cowpea, groundnuts and pigeonpea should also be studied
There were more than 40 participants at the workshop among them four from ACi countries supported by CTA.
Forecasting the weather, pests and even harvests
Experience with the latest outbreak of locusts in the Sahel has shown that weather forecasting services -- if accurate and quickly available --can play an important role in not only predicting but even preventing the invasion of locusts. It is now possible for the optimum conditions for locust swarming to be identified and quantified with considerable accuracy.
Once a certain number of conditions are operative, the alert can be given
The same is true for other insects or diseases like the cassava whitefly, the sorghum gall midge, sweet potato weevil or tomato nematodes. Early and comprehensive analysis of weather data also enables the evaluation of such problems during the growing period of the plants. This means that accurate estimates of the harvests can be made in order to prepare for any food imports that may be needed in the case of deficits
Good knowledge of future weather conditions could also enable farmers to plan their activities accordingly and thus optimize their investments rather than lose considerable time not to mention harvests, because they could predict the weather. For typical climates, with well-defined seasons (particularly those that can involve sudden changes with disastrous results for local people, as in the Sahel), weather forecasting has begun to provide an extremely valuable service to farmers
Much remains to be done, however, particularly in other regions. That explains why the national meteorological service of Benin, the World Meteorological Service and the International Institute of Tropical Agriculture organized last July in Cotonou a series of workshops on agroclimatology and crop protection in humid and sub-humid tropical lowlands.
Jointly sponsored by the FAO, UNDP and CTA, this seminar was designed to promote the exploitation of agrometeorological knowledge and data to forecast and follow the development of crop pests, to provide such information to improve protection measures while reducing their cost, to establish a dialogue between crop protection and weather forecasting services in order to determine what kind of information is needed, and to identify the techniques that should be used for plant protection measures.
The seminar attracted 55 people from 17 countries who participated in six workshops that dealt with questions as diverse as access to information, improving everyday collaboration between governments, the impact of meteorology on the development and movement of major migrators, as well as weather and plant protection techniques for economically important crops such as groundnuts and cotton.
As far as information needs are concerned, the seminar underlined the importance of maintaining good communication with users and providing extension workers with good data.
Considerable progress has been made in the collection and processing of data, but the most important task that remains is to ensure that such information be made available in a way that local users can understand.
For further details. the proceedings of this seminar are available from CTA.