Root traits of different crops under rainfed conditions in the High Barind Tract of Bangladesh

Root traits of six different crops grown on residual soil moisture in the post–rainy season in the High Barind Tract (HBT) of Bangladesh were investigated to better understand their adaptation to this moisture‐limited environment. Deep‐rooting chickpea is the currently favored rainfed crop grown after rainy‐season rice in the HBT, but it is necessary to identify alternative crops to chickpea in order to avoid buildup of pests and diseases. Averaged over 2 y, barley (1.72 Mg ha^–1) produced significantly more grain than chickpea (1.4 Mg ha^–1) which, in turn, yielded better than linseed (1.0 Mg ha^–1), wheat (0.93 Mg ha^–1), and mustard (0.77 Mg ha^–1). Lentil did not produce any grain at all. Grain yield for all crops increased as total root length increased above a threshold value of 0.05 to 0.1 km m^–2. In general, grain yield increased as the proportion of total root produced below 60 cm depth increased, although barley also had thin roots that could more effectively extract soil moisture. Expression of root traits varied considerably between seasons, which was attributable to the different rainfall patterns and bulk‐density characteristics of the soil profile in the 2 years of the study. Although favorable root traits, particularly rooting ability below 60 cm, are a prerequisite for acceptable yield levels of crops grown on residual soil moisture in the HBT, it is recognized that farmers' choice of a post‐rice crop will depend on its economic return or food‐security value.