Osmoregulation as a selection criterion for drought tolerance in wheat

Abstract

A method is described in which measurements of osmoregulation made on glasshouse-grown wheat plants may be used to select lines which yield higher under conditions of water deficit in the field. The procedure involved growing F4 breeding lines in pots in a semi-controlled glasshouse. When the plants reached booting stage, they were transferred to a controlled environment chamber and droughted by withholding water. During the water deficit cycle approximately 10 flag leaf samples from each line were taken, and measurements were made of relative water content, osmotic potential and water potential. The lines were evaluated using estimates of the relative water content at either osmotic or water potential values of -2.5 MPa, after relationships between these measurements and relative water content had been established. The distribution of data into two main groups with a smaller intermediate group indicated possible single gene control. Under drought conditions in the field, lines selected from the high osmoregulating group maintained turgor to lower water potentials and gave grain yields which were 1.6 and 1.5 times greater than those selected from the low group at the F4 and F6 stages respectively.