In cereal-based farming systems in dry areas, lentils, like other food legumes, make an important contribution to human and livestock nutrition, to crop diversification, and sustainable agricultural production, by adding nitrogen to the soil and breaking cereal monoculture. Although lentils are adapted well to dry areas, drought poses a serious challenge to lentil farmers, particularly in the context of global warming and climate change.

Lentil is among the most important cool-season food legumes in South Asia, West Asia, and North Africa. But in major lentil-growing areas, water is scarce and is expected to become scarcer. The key to success for the crop is greater water-use efficiency. The emphasis in lentil breeding programs must be on higher productivity in water-limited environments, so that lentil can continue to earn profit for farmers, and, thus, retain its place in rainfed cropping systems.
     Research at ICARDA has shown that total seasonal rainfall accounts for 80% of the variance in mean seed yield in lentil in a typical Mediterranean climate. Severity, timing and duration of drought, however, vary from year to year, which means that cultivars successful in a particular year might fail in the next. Making matters worse, drought seldom occurs in isolation, but rather interacts with other stresses, particularly high temperature. Such interactions add to the complexity of breeding for drought resistance.
     Despite these impediments, scientists at national and international research institutions remain committed to meeting the challenge. First, researchers tried to understand the mechanism of drought tolerance. They found that drought resistance can be achieved through various mechanisms: escape, dehydration avoidance, and dehydration tolerance. Escape is a particularly important strategy. It requires matching the crops development with the period of soil moisture availability to minimize the impact of drought stress. Early flowering and maturity with early and rapid biomass development are the important components of drought escape.
     Progress has been made by national agricultural research systems and ICARDA in developing early-maturing genotypes with good yield. Promising genotypes are added to the Center’s International Drought Tolerant Nursery (IDTN) and shared with national scientists. Breeding shorter-duration cultivars also mean that lentil can fit into more intensive cropping systems. Breeders also strive to develop genotypes that have a greater “phenological plasticity”—lines that can produce a reasonable yield under drought conditions, but continue to grow and produce more yield if moisture is abundant in the crop’s reproductive stage.
     In their search for drought-tolerant lentil, scientists have identified genotypes that have dehydration avoidance and tolerance traits and considerable variation in seedling stem length, taproot length, and lateral root number, traits directly related to yield performance. One line, ILL 8072, for example, stood up very well under severe water stress conditions, and is being used in breeding at ICARDA and elsewhere.

Research strategy

A key strategy employed by ICARDA involves selection of genetic material in target environments. ICARDA has a relatively drier testing site at Breda, in Syria, with annual average rainfall of 263 mm. In 1998/99, the site received just 195 mm, and under this severe condition, breeders were able to identify many promising lentil lines, some yielding up to 0.75 t/ha.
     Since no single character — morphological, physiological or biochemical – can impart drought resistance, breeders follow a strategy called pyramiding. Beneficial traits are added to the plants, as if one on top of the other, each contributing a bit to drought tolerance, depending on the prevailing growth conditions. The same strategy is followed in breeding for disease resistance. The so-called horizontal resistance is achieved by moving different genes carrying resistance to individual physiological disease races into one cultivar. ICARDA’s lentil breeding program works to combine useful traits, such as early seedling establishment, early growth vigor and canopy development, leaf area

Effects of intermittent drought on lentil in Nepal in 2001.

and early flowering and maturity, all of which contribute to escape, dehydration avoidance and tolerance.
     The researchers continue to search for sources of resistance among cultivated and wild species. They have identified wild accessions with high levels of drought tolerance, but these have so far been of limited value because of their meager biomass.

Marking success

The ICARDA lentil program has enjoyed notable success in developing drought-tolerant cultivars: Australia has released Cumra (ILL 590) and has identified ILL 7200 for future release; Syria has released Idlib-3 (ILL 6994); and several lines are in the pre-release stage, including ILL 7723 in Nepal, Masoor-93 in Pakistan, Bakria (ILL 4605) in Morocco, Sinai 1(selection from ILL 4605) in Egypt, and Dhamar 1 (ILL 4605) in Yemen. Many national programs are testing promising lines under farm conditions. For example, by widening the genetic base of lentil in South Asia, the national programs in the region have been able to develop early and extra-early genotypes to fit in different cropping system niches. ICARDA continues to supply promising material to national programs, which in turn select and adapt the material to local conditions. Through cooperation and sound science, the effects of drought can be reduced, for the good of farm families and national food security.

Dr A. Sarker (A.Sarker@cgiar.org) is Lentil Breeder at ICARDA; Dr R.K. Neupane is Agronomist at the National Agricultural Research Centre, Nepal; Dr B. Sakr is Grain Legume Breeder at the Institut National de la Recherche Agronomique, Morocco; Dr F. El Ashkar is Lentil Breeder, GCSAR, Douma, Syria; Dr A Lutf, is Legume Breeder, Dhamar, Yemen; and Dr W. Erskine, is Assistant Director General for Research, ICARDA.