M. Matiur Rahman
Regional Agricultural Research Station, Ishurdi, Pabna, Bangladesh
Progress, Prospects, Minor Pulses, Bangladesh
Resource Development and Management
Black Gram: Black gram is the fourth most important pulse crop of Bangladesh, grown on 33 600 ha, producing 24 000 t of grain with a mean yield of 714 kg ha-1, and contributing about 13% of the total pulses (Islam and Rahman 1990). It is generally sown in August/September in well-drained high or medium highlands after harvest-ing upland aus (rainfed) rice or jute in the aus rice/jute black gram-fallow/wheat cropping pattern. Some farmers grow this crop in October/November in the char (sandy) land after the flood water recedes or sometimes as a relay crop with flood-affected Aman (rainy-season) rice. It is also grown under zero-tillage conditions, on the roadside or by dams, mostly for fodder purposes. Most of the late-sown crop is affected by powdery mildew (PM) disease which may cause a yield loss of about 3 2 % ( BARI 1987). Local cultivars suffer damage by yellow mosaic virus (YMV). There is variation among local cultivars for growth pattern, duration, disease reaction, etc. Short-duration cultivars (70-75 days) are grown in the aus ricc/jute black gram-postrainy-season (rabi) cropping pattern. Long-duration cultivars (85-95 days) are grown in the aus rice-black gram-fallow cropping pattern. The latter pattern is being replaced by the aus rice-fallow-postrainy-season cropping pattern, and consequently, the area under black gram is shrinking.
Current status: About 300 local and 450 exotic germplasm lines have been collected from India and Pakistan and evaluated for earliness and high yield potential. The variation for yield and yield-contributing characters is very low although there is some variation in seed size (100 seed mass varies from 3.0-5.3 g), crop duration (65-85 days), pods plant-1, and pod pubescence ( BARI 1986). The local collections are daylength sensitive and exotic ones are mostly photosensitive. One day length insensitive line (MAK1) has been placed before the National Seed Board (NSB) for release. Currently, these germplasm lines are being screened against PM and YMV diseases to identify resistance sources. Some sources of resistance have been identified against YMV but none has been found against PM so far.
Prospects Black gram is a more hardy crop, more tolerant to waterlogging, and has fewer disease and insect problems compared to other pulses. It also produces more stable yields and can be grown with minimum care. If a high-yielding variety is used, the total production can be increased with the existing cropping pattern. A cropping pattern trial has been conducted with the black gram line MAK1 and it was found that it can be grown under minimum tillage. It was found to fit well into the aus rice-black gram-lentil wheat/mustard cropping pattern (BARI 1986). This pattern is suitable for light-textured soils in high or medium highlands with adequate drainage facilities. If this pattern could be extended, a large area would come under pulses without disturbing the existing cropping pattern. Damage by floods has become a regular phenomenon in Bangladesh, and a search is on for suitable alternate agricultural technology. Black gram can play an important role in this respect. High-yielding varieties with late-sowing potential (October-November), resistance to PM, and with potential to be sown as a relay crop with partially damaged Aman rice are required.
Future research Future breeding efforts should focus on developing short-duration (65-70 days), high-yielding, YMV - resistant varieties suitable for the aus rice-black gram postrainy season cropping pattern, and high-yielding, powdery mildew-resistant varieties for the postflood situation. In both situations varieties capable of growing under minimum-tillage conditions are desirable. Therefore, hybridization programs and selection involving the normal cultivated type and the fodder types (which are grown with minimum tillage) should be made under those conditions. As a general strategy, additional exotic germplasm should be collected, and an extensive crossing program initiated to create variability. The podding potential in black gram is greater (Lawn and Ahn 1985) hence the number of pods per plant may be used as a selection criterion. For pulses in general, emphasis should be laid on a slightly larger seed size during selection. In addition, an effort should be initiated to select pure lines from the landraces. Simultaneously further agronomic studies should continue on the cropping pattern involving black gram. It has been observed that black gram has a depressing effect on the subsequent postrainy-season crops. A similar result has been reported from Australia (Lawn and Ahn 1985). Detailed studies should be undertaken to overcome this problem.
Advances in Pulses Research in Bangladesh Proceedings of the Second National Workshop on Pulses 6-8 Jun 1989 Joydebpur, Bangladesh
Report/Proceedings