*Central Rice Research Institute, Cuttack, 753 006.
Department of Botany, Osmania University, Hyderabad-500 007
Nature of sustenance and recovery from drought in deep and shallow rooted rice was examined under water deficit conditions. Studies with root boxes showed that the recovery of shoot system from wilting conditions took a shorter time (55 min.) when water was applied at the surface or at 25 cm depth (57.5 min.) than when the water was added at 50 to 75 cm depths (192.5 and 555 min. respectively), implying mat a deep rooting system does not have say additional advantage for recovery from drought Addition of water at deeper zones like 50 and 75 cm depths, did not help in relieving the moisture tension adequetely in plant tissues, although there was apparent visual recovery. The ability of a root system to utilize water at depths beyonds 50 cm did not differ with soil and root type as reflected in leaf water potential and relative water content (RWC). When adequate moisture was available at deeper layers, rice plants could not utilize that, when the soil moisture at upper layers was around wilting stage. The findings show that the nature and magnitude of water deficit occuringupto 30–40 cm depth is critical, and the depth of the root system does not determine the nature of drought tolerance of rice.
