AGRONOMIC PERFORMANCE OF CHROMOSOMES 1B AND T1BL.1RS NEAR-ISOLINES INTHE SPRING BREAD WHEAT SERI M82

The T1BL.1RS wheat (Triticum aestivum L.) - rye (Secale cereale L.) tr anslocations have been of particular interest and are widely used in b read wheat breeding programs. The objective of this study was to deter mine the effect of the T1BL.1RS chromosome on grain yield and its comp onents using 20 near-isolines of spring bread wheat cultivar 'Seri M82 ' (10 homozygous for chromosome 1B substitution and 10 homozygous for T1BL.1RS). The test lines have been produced by substituting the 1B ch romosome in Seri M82 (T1BL.1RS, T1BL.1RS) through backrossing. Two fie ld experiments were evaluated under optimum (five irrigations) and red uced (one irrigation) moisture conditions for two consecutive producti on cycles at the Mexican National Agricultural Research Institute, Ciu dad Obregon, Sonora, Mexico. The presence of T1BL.1RS had a significan t effect on grain yield, harvest index, grains/m(2), grains/spike, 100 0-grain weight, test weight, flowering date and physiological maturity in both moisture conditions. The agronomic advantage of the 1B substi tution lines on above-ground biomass yield at maturity, spikes/m(2) an d grain-filling duration was expressed only under the optimum moisture condition. The presence of T1BL.1RS increased grain yield 1.6% and 11 .3% for optimum and reduced moisture conditions, respectively. These r esults encourage further use of T1BL.1RS wheats in improving agronomic traits, especially for reduced irrigation or rainfed environments.