Breeding wheat for salt tolerance and stem rust resistance

Abstract

Fast and effective hydroponics screening technique that could identify physiological variation in salinity tolerance of wheat was applied. A set of 442, previously unexplored wheat varieties/lines representing a wide range of genetic diversity was planted as control in 1/2 strength Hoagland's nutrient media, whereas two sets of the same material were exposed to salt (NaCl) application under two treatments i.e., 10 dS m-1 and 20 dS m-1 for the first 2 years (2003-04 and 2004-05). For the third year (2005-06), more intensive stress was applied with salinity levels of 12.5 dS m-1 and 25 dS m-1. Salinity tolerance was defined as differences in biomass (root-shoot ratio) production in saline versus non-saline conditions over prolonged periods, of 3-4 weeks (seedling to pre booting stage). For this purpose parameters like shoot length, root length, shoot weight and root weight alongwith their relative ratios were measured. As a result of 3 year study 11 common salt tolerant varieties/lines were identified including Pasban-90, LU 26S, V-01078 (Seher 06) and V-01180. Under saline field conditions some of these lines like Gamdow-6, BAV 92//SAP/MON and Lakata-1 produced higher grain yield, whereas, Uqab-2000 was the best yielding in saline field conditions, although it was found non tolerant in hydroponic studies. Line Ning 8319 showed good resistance for stem rust comparable to Parula and Pavon. These selected lines are being used in specific breeding programs for the development of high yielding wheat varieties having high degree of salt tolerance and stem rust resistance.