Cytoplasmic Effect of Wheat for High Temperature Tolerance.

To study cytoplasmic effect on heat tolerance in wheat, ten different alloplasmic lines of wheat were backcrossed to four different wheat varieties; Karl 92, Ventnor, U1275 and Jagger. The nuclear genome of these alloplasmic lines were substituted by backcrossing six times using the recurrent parent’s males. During the sixth backcross, reciprocal backcrossing was done to develop NILs (Near Isogenic Lines) for cytoplasm. 68 combinations of BC₆ F₁ and their parents were evaluated in growth chambers for heat tolerance at post anthesis stage. Plants were grown in green house and taken under heat stress at 10 days after anthesis for 14 days. Growth chambers were maintained at 35°C/30°C for heat stress and the greenhouse was maintained at 20°C/15°C as the control temperature.  Effect of high temperature on chlorophyll content and Fv/Fm (a chlorophyll fluorescence measuring parameter) were found to be significantly affected in this experiment. These results indicated that cytoplasmic effects can contribute to stay green quality of wheat during high temperature stress. The role of cytoplasm should be considered in wheat breeding programs as they breed for high temperature tolerance.