Water use and water-use efficiency of chickpea and lentil in a Mediterranean environment

Water supply is a major constraint to crop production for both chickpea and lentil in West Asia and North Africa, both of which have a Mediterranean climate. This study examined water use and water-use efficiency of chickpea and lentil from 3 experiments over 12 seasons, 1986-87 to 1997-98, in northern Syria. The strongest determinant of grain yield of chickpea and lentil and their water use under rainfed conditions is rainfall and its distribution. Large inter-seasonal fluctuations in weather resulted in larger inter-seasonal fluctuations in water use, and therefore in production of legumes. Seasonal evapotranspiration (ET) was significantly correlated with seasonal rainfall for both chickpea and lentil. Mean ET over 12 seasons was 268 mm for chickpea and 259 mm for lentil. The depth of extraction was, on average, 120 cm for chickpea and 80 cm for lentil. The average extractable soil water was 125 mm for chickpea and 90 mm for lentil over 12 seasons. For lentil, water-use efficiency for dry matter (WUEdm) and for seed yield (WUEgr) was 13.7 and 3.8 kg/ha.mm, respectively; for chickpea, WUEdm and WUEgr, 8.7 and 3.2 kg/ha. mm, respectively. Supplemental irrigation can significantly increase grain yield of both chickpea and lentil. However, there was less increase in grain yield in the wet seasons than in the dry seasons. Estimated soil evaporation was 80 mm for lentil and 105 mm for chickpea. The average transpiration efficiency was 7.1 kg/ha.mm for lentil and 6.4 kg/ha.mm for chickpea. Estimated potential transpiration efficiency for seed yield was 11.8 kg/ha.mm for lentil and 12.2 kg/ha.mm for chickpea. Both the average water-use efficiency and potential transpiration efficiency for lentil and chickpea were lower than those for cereals. Despite this, the rotation benefits and higher economic return provide the potential for these legumes to replace fallow or to break continuous cereal cropping in the region's farming system.