Genetic variation in osmoregulation in bread and durum wheats and its relationship to grain yield in a range of field environments

Abstract

The association between osmoregulation and grain yield was examined using measurements of osmoregulation made on wheat plants grown in pots in a glasshouse and measurements of grain yields made in a wide range of field environments. Osmoregulation was determined from measurements of relative water contents and osmotic potentials made on the flag leaves of plants droughted near anthesis. The genotypes were advanced lines from two distinct breeding programs - one for bread wheats and one for durum wheats. All the genotypes in each program (27 bread and 14 durum) were closely related in having a common parent. The grain yields of the bread wheats were evaluated in 56 field trials covering a period of 4 years, and those of the durum wheats were evaluated in seven field trials in one year. Both droughted and irrigated sites were represented. Four field environments were also included for F4 segregating lines reported previously. Considerable variation in osmoregulation occurred which was positively associated with grain yield over the full range of environments sampled for each genotype group. The yields of genotypes which were high in osmoregulation were 11-17% higher in bread wheats and 7% higher in durum wheats than those which were low in osmoregulation, when class differences were based on rnaximising the average yield differences between osmoregulation groups. These results add further evidence favouring the use of glasshouse measurements of osrnoregulation as a selection criterion in wheat breeding.