Incompatibility studies in sugarcane (Saccharum spp.)

The study was undertaken during the period 2001-2004 to investigate the behaviour of the pollen tubes in the stigmatic tract of pistil parents utilized in intervarietal hybridization. Among the 173 breeding material screened for occurrence of incompatibility, 36 parents were identified self incompatible and among them nine incompatible parents were further studied for their cross compatibility. Pollen germination was normal in Co 86011, Co 91004 and Co 62198 and slightly inhibited in a cross with Co 99002. Fertilization was accomplished within 4 hr of pollination in crosses Co 8371 x Co 86011, Co 88028 x Co 86011. The presence of Co 86011 and Co 91004 pollen tubes in the ovary 8h after pollination indicated the possibility of normal fertilization, while in cross with Co 94008, restricted pollen tube growth was observed. Pollen tube in the clone 2000-147 did not penetrate the ovary even 10 h after pollination. Self pollen did not support the development of pollen tubes in Co 88028, Co 91004, Co 99002, Co 62198 and Co 86011. In the crosses of Co 88028 x Co 91004, Co 88032 x Co 99002 and Co 88028 x Co 86011 pollen germination and entry of pollen tube was normal. The study indicated that there is no hurdle at the pollen germination stage and delayed/restricted growth of pollen tubes indicated that the barrier operates in the stylar region of the parent. Thus, from our study it could be inferred that i) cross-incompatibility systems are responsible for the failure to produce successful crosses among Co 88028 x Co 91004, Co 88028 x Co 99002.ii) self incompatible parents could be used as safe pistil (Co 837, Co 8371, Co 88028, Co 88025) and pollen parents (Co 62198, Co 86011, Co 94008, Co 91004).