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 entil is the most important pulse in Bangladesh. It is the most popular pulse in both urban and rural areas, and rice with lentil soup (known as dhal) is often eaten in the villages; most people try to include it in their daily diet. So it is not surprising that Bangladesh is the world's fourth largest lentil producer, exceeded only by India, Turkey and Canada--all of which have a far greater land area. The sown area of lentil in Bangladesh is about 210,000 ha, giving a production of 160,000 tonnes at an average yield of 769 t/ha.
Even so, this is not enough. In 1994, according to FAO, Bangladesh imported 75,000 tonnes of pulses with a value of around US $19.8 million. This was high; the figure fluctuates, but there is an obvious need to improve production. This can not be done by increasing the sown area. In an intensive cropping pattern, lentil faces tough competition from cereals and oilseeds and from other winter pulses. Indeed, lentil is grown as a sole crop in Bangladesh but also as a mix or intercropped with cereals, oilseeds and sugarcane. Intercropping and mix-cropping are age-old practices, particularly in the north and north-western parts of the country. In this situation, an increase in production can come only from better yield.
About 25-30% of the lentil area is grown in the transplanted autumn rice/lentil cropping pattern, being sown from the last week in November to the first week of December. The late-sown local cultivars perform badly, not only from the short growing period but also due to disease. Lentil is also grown as a relay crop in rice fields under zero tillage. The overriding problem is disease--in particular, two diseases: Stemphylium blight and rust. Incorporating resistance to these would clearly be the key to greater productivity.
Lentil rust, one of the major diseases in Bangladesh, was first reported in 1974. The disease causes variable degrees of damage depending upon the time of its onset, and it varies from year to year according to environmental fluctuations. High humidity, cloudy weather, and 20-22oC temperature are congenial for disease development. Disease often emerges in areas with a dense canopy and luxuriant vegetative growth. In severe infection, the leaves are shed and the plants dry up prematurely. Disease attack starts from late flowering and continues up to early/mid podding stage. The fungus is autoecious--that is, it completes its life cycle on lentil plants only. Yield loss up to 70% has been noticed in farmers field.
Stemphylium blight, another serious disease of lentil, was first noticed in 1981. Since then the prevalence of the disease has been monitored in farmer's fields. Preliminary studies have indicated that the disease can cause up to 62% yield reduction. The disease emerges with the appearance of small pin-headed light brown to tan colour spots on the leaflets. The spots enlarge rapidly, covering the entire leaf surface within 2-3 days. The foliage and twigs gradually turn dull yellow, giving a blighted appearance to the affected crop. The infected leaves shed severely, leaving only the terminal leaves on the twigs. The twigs bend down, dry up and gradually turn ashy white, but pods remain green. The disease attacks the crop in early pod setting stage. Even the early pods fail to fill with seeds. The pathogen initiates its infection when the ambient night temperature remains above 8oC, the mean day temperature goes above 22oC and the relative humidity inside the canopy goes up to 94%.
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