Field Studies on the Genetic Diversity for Black and Brown Rust Resistance in Wheat Crosses

Crosses of all the three resistant parents TzPP, MJI and E 8643 with susceptible varieties Pissi Local and NP4 indicated operation of a pair of dominant complementary factors for black rust. Crosses between resistant X resistant varieties revealed the diversity of genes. Crosses of TzPP indicated operation of two dominant independent factors indicating one common gene complementary with the other two resistant varieties. The two parents MJI and E 8643 seemed to have common factors or very close linkage.

For brown rust all the three R parents with susceptible varieties indicated the operation of one recessive factor and one additional gene in the cross TzPP X NP4 and one dominant additional gene in E 8643 x NP4. Presence of susceptible segregates in the crosses of R X R showed the diversity of genes. The factors in MJI and E 8643 were independent for brown rust resistance.

Related studies for black and brown rust revealed that crosses of TzPP with Pissi Local and NP4 indicated linkage of one or more genes for the two rusts while in other varieties inheritance was for independent factors.