Major Constraints to Higher Productivity in Bangladesh
Biotic Stresses
Susceptibility to various diseases and Helicoverpa pod borer are major yield reducers. Fusarium wilt (Fusarium oxysporum f.sp. ciceri), dry root rot (Rhizoctonia bataticola), botrytis gray mold (Botrytis cineria), collar rot (Sclerotium rolfsii), and chickpea stunt (bean leaf roll virus) are the most important diseases in Bangladesh. Among insects, pod borer (Helicoverpa armigera) can reduce yields substantially in the field. Bruchids (Callosobruchus sp) can infest as much as 80 % of seeds in a lot within the first 3 months of storage in ambient conditions. Relatively high temperatures and more than 85 % relative humidity favor the growth of seed pathogens and bruchids. As many as 24 seed pathogens have been recorded on chick pea (Amiruzzaman and Shaha Chowdhury 1990). Under these conditions, seeds are liable to lose their viability and consumer acceptance. The loss of seed viability affects crop establishment adversely.
Abiotic Stresses A number of abiotic stresses can seriously affect chickpea productivity. These include moisture status of the soil, temperature regimes and humidity at sowing, flowering and podding, soil pH, texture, nutrient status, and reduced day length (cloudy days), especially at the reproductive stage.
Lack of Proper Management Poor plant stands in farmers' fields is probably the most important single factor limiting productivity in Bangladesh (Kumar 1984, 1985). Poor seed quality, too little or excess soil moisture at sowing, improper land preparation and methods of sowing, and damage by various seed and seedling pathogens can seriously reduce the plant stands, even when proper seeding rates are used. Farmers give the lowest preference to pulses in terms of land allocation, weed control, and inputs. Therefore, these crops are often grown in problem soils and outside their normal sowing time. For example, late sowing exposes the chickpea crop to early rains at maturity. Fields with poor soils, low in organic matter content and other macro and micronutrients and having low moisture-holding capacity or improper drainage are utilized for pulses. Irrigation, if at all available, is given to cereal and/or cash crops. Under these conditions, plant growth is often stunted and their full yield potential cannot be realized. However chickpeas, being indeterminate like other pulses, do not respond to high-input conditions. Rather, under such conditions they often produce excessive vegetative growth, which leads to lodging, development of diseases, and ultimately poor yields.
Chickpea Improvement at ICRISAT and its Role in Bangladesh
ICRISAT Center near Hyderabad (17.6°N) is almost at the fringes of the chickpea adaptation areas in India as the growing season is really too short for this crop. Here mainly short-duration materials (90-110 days) are bred. A major station at the Haryana Agricultural University, Hisar (29.4°N) for long-duration (150-180 days) and another one at the Jawaharlal Nehru Krishi Vishwa Vidyalaya (JNKVV), College of Agriculture, Gwalior (26.0°N) for medium-duration (120-140 days) chickpea have been established. Advanced breeding lines for short- and long-duration materials are also tested at Gwalior. We have facilities for the off-season advancement of important breeding materials. Short and medium-duration materials developed at ICRISAT Center and found promising at locations in central India generally suit Bangladesh environments because in this country the crop is cultivated in similar (22° to 25°N) latitudes.
Germplasm Collection, Supply, and Utilization
Bangladesh Agricultural Research Institute (BARI) and ICRISA jointly organized chickpea germplasm collections in Bangladesh in 1979 and 1985. A total of 201 accessions were collected and the seed of each was shared between the two organizations. These have been evaluated, characterized, cataloged, and maintained at ICRISAT. Their evaluation at BARI, RARS, Ishurdi, led to the selection of two promising lines RBH 121 and 135B. These have been crossed to sources of fusarium-wilt resistance. ICRISAT maintains over 15 000 germplasm lines of chickpea. We have supplied a large number of germplasm collections to local scientists on their request. These include sources of resistance to various biotic and abiotic stresses, genetic diversity, and high yield potential.
Breeding Materials, Nurseries, and Trials
Scientists at BARI , Bangladesh Institute of Nuclear Agriculture ( BINA ), and ICRISAT have cooperated in growing a number of international trials and nurseries at various locations in Bangladesh. International chickpea screening nurseries of short- and medium-duration, international chickpea cooperative trials of short- and medium-duration, F2 and F3 multilocation trials, promising parental lines, segregating populations, and disease and Helicoverpa pod borer nurseries have been grown here for over a decade. We at ICRISAT are very happy that BARI scientists have released a chickpea cultivar Nabin (S-1, ICCL 81248) recently (Rahman et al. 1990). They have also identified a number of other lines as promising in their multilocation trials. One or more of these may be released in the near future. Two kabuli lines, ICCL 83007 and 83008, with large attractive seeds have also done well in these trials (Islam et al. 1990). Hopefully the first kabuli cultivar in this country may be available soon.