Breeding for high yielding rice (Oryza sativa L.) varieties and hybrids adapted II. Evaluation of to aerobic (non-flooded, irrigated) conditions released varieties

Abstract

During wet season 2003, two hundred rice (Oryza saliva L.) varieties released for cultivation under various ecologies were screened in a puddled field (clay soil) under non-flooded, irrigated (aerobic) conditions, with Rasi and Vandana as check varieties. The checks known for their adaptation to water stress were planted at regular Intervals (after every ten entries) to serve as controls. Twenty seven varieties showed yield advantage over the check Rasi, The popular varieties grown under irrigated conditions such as Jaya, IR 8, IR 64 etc. were found unsuitable. Most of the varieties with high yield potential and adaptation to aerobic conditions were found among rainfed shallow lowland and hill rice upland varieties, while the frequency of such varieties was very low among rainfed upland group varieties. Most of the selected irrigated varieties showed better pertormance under favourable moisture conditions with a few exceptions like Vikas which combined high yield and adaptation to aerobic environments. However, the semi deep water and deep water varieties were found unsuitable under aerobic

conditions. Planting of checks at regular intervals as grids was very useful not only in dctecting varying levels of stress across Icngth and breadth of the field, but also in identifying suitable cultures for varying levels of stress