Studies on root traits for drought tolerance in rice (Oryza sativa L.) under controlled (PVC pipes) condition

Rice (Oryza sativa L.) is the most important food crop of the world; but drought stress is a serious limiting factor to rice production and yield stability in rainfed areas. In order to design an efficient breeding program for synthesis of new varieties with virtues of drought tolerance and high yielding ability, it is necessary to identify potential parents that combine well for both yield and drought tolerance. Hence, the present investigation was undertaken to evaluate genetic potentiality of eight lines and five testers along with 40 hybrids were evaluated under PVC pipes (controlled) Condition for root traits in order to use them in drought resistance breeding programmes. The parents and hybrids were raised in PVC pipes, where the plants were subjected to drought for a period of 20 days during tillering stage starting on 60 days after sowing. Observations were recorded on seven important root traits viz., root length, root volume, root length density, total number of roots, root thickness, root dry weight and root:shoot ratio. Five genotypes viz., Norungan, CT 9993, Moroberekan, Nootripathu and MDU 5 showed significantly superior mean values than grand mean for most of the root traits included in the study. Therefore, these genotypes can be used as potential donors in drought resistance breeding programme. Among the hybrids, CT 9993 / ASD 18, Moroberekan / ASD 16, CT 9993 / IR 50, Moroberekan / Co 47, Noungan / ASD 16, Nootripathu / MDU and Nootripathu / CO 47 were identified as outstanding ones for improving drought tolerance as they registered significant higher mean value for majority of the root traits.