Improvement of lentil and grasspea in Bangladesh

• Bangladesh Agricultural Research Institute, Bangladesh
• Victoria Institute of Dryland Agriculture, Australia

Bangladesh agriculture is predominantly rice based. To provide sustainability in the rice-based cropping system and to ensure protein supply to the vast majority of the population, the country's agriculture policy is currently to promote crop diversification with pulses. Lentil (Lens culinaris) and grasspea (Lathyrus sativus) are the two most important pulses in Bangladesh, comprising more than 60% of the total pulses grown in the country. Average national production of lentil in Bangladesh is 769 kg/ha, which is far below the world average (832 kg/ha). Major reasons behind the poor lentil yields in Bangladesh are low yield potential and susceptibility of local cultivars to disease.

Grasspea is a key legume in Bangladesh and occupies first position with respect to acreage. Although it is widely consumed as a dhal, it contains a neurotoxin, beta-N-oxaly1-L alpha-beta diaminopropionic acid (ODAP), which when eaten in large quantities may cause paralysis of lower limbs. This major consumption of grasspea typically occurs in drought years when other food grains are expensive and is confined to the poorest sector of the population. The International Centre for Agricultural Research in Dry Areas (ICARDA) has crossed Bangladesh land races of grass pea with low ODAP lines; this resulted in segregating populations suitable for testing in Bangladesh for adaptation and for ODAP content.

Project objectives were to: 1) develop high-yielding, disease-resistant lentil cultivars and verify their performance on farmers fields in Bangladesh; 2) develop high-yielding, low neurotoxin grasspea lines for verification in farmers field in Bangladesh; 3) upgrade the human resource capacity for lentil and grasspea improvement in relation to the above objectives; 4) transfer existing technology to the farmers (this component was added later).

Scientists gained access to material in breeding programs at ICARDA and elsewhere, and undertook trials of new lines in Bangladesh to select for high yield and disease resistance. Best performers were then tested on-farm. Selection tests were also scheduled for grasspea to identify lines with low content of the damaging neurotoxin ODAP.
ICARDA was the major source of improved genetic materials. The Bangladesh national program received 500 lines from core collections, 210 early-maturing and rust- resistant breeding lines, and segregating populations from targeted crosses specifically commissioned for Bangladesh. These materials were evaluated at various stages of testing cycles in three major testing sites. As well a small hybridization program was initiated with exotic materials, using the crossing techniques learnt at ICARDA by Bangladeshi scientists.
Experiments were conducted to develop a production package for farmers to maximise yield in lentil. At a later stage of the project, research on relay cropping of lentil in transplanted Aman rice was initiated.
Project pathologists screened for combined resistance to both rust (Uromyces fabae) and Stemphylium blight (Stemphylium botryosum), the major diseases of lentil, and initiated research on chemical control of these diseases. Studies were also undertaken to manipulate planting date to avoid cowpea aphid (Aphis craccivora).
Farmer adoption of new lentil varieties had been slow, so a joint technology transfer program was undertaken in 11 major lentil-producing districts to disseminate the technology to the farmers.
Grasspea research activities were restricted, mainly due to non-availability of low-toxin materials and lack of ODAP analysis facilities. However, research on outcrossing and genetic purification of the available lines was carried out.

The project made significant progress in lentil improvement, particularly in variety diffusion, adoption and impact at the farm level. Yield testing over years across many locations has led to the identification of promising lines for future release. However, disease screening through artificial means is yet to be developed and applied, and continuation of these activities has been suggested.
A significant number of village level extension workers and farmers were trained in improved production technology. Several block demonstrations were conducted in farmer's fields with the improved varieties. Seed multiplication was undertaken; farmer training, travelling workshops, farmer awards and field days were organized. Through these activities the farmers became aware of the modern varieties and learnt about production technology. About 20% of lentil areas (40,000 ha) are now planted to the improved varieties.
In grasspea, due to lack of laboratory facilities, ODAP analysis could not be carried out, however varietal dissemination and genetic purification were possible. Although grasspea is a self-pollinated crop, out-crossing by bees leads to genetic contamination. A study on out-crossing revealed that up to 27% cross-pollination can occur in grasspea. Genetic purification of advanced line, single plants was carried out based on a flower colour marker. A total of 1872 individual lines were purified for later agronomic and ODAP evaluation.