Response of Mungbean Cultivars to Irrigation Gradient : III. Root Growth

Abstract

Drought stress may have a differential influence on root growth of four mungbean cultivars differing in maturity. Field studies were conducted on sandy loam, using a line-source sprinkler irrigation system at Chaiang Mai Field Crops Research Center, from February to May in 1990. Root samples were taken on three growth stages, at R2 (beginning pod formation), R4 (full seed development) and R6 (50% pod mature) to the depth of 1.00 m using the core method. The results showed that root density in the soil surface decreased with the increased level of drought stress and also increased from R2, R4 and R6, resepctively. Medium duration cultivars (Kamphaeng Saen 2 and U-Thong 1) had resisted greater water stress than in the short (Chai Nat 60) and long duration cultivars (Local) due to higher root density and extracted greater amount of water from deeper soil profile.