Interspecific cross- compatibility in the genus Abelmoschus

Abstract

Interspecific cross – compatibility in the genus Abelmoschus was undertaken with the objective of probing into the reasons of low fruit and seed set in the interspecifc hybrids of Abelmoschus which may pave the way for the development of yellow vein mosaic resistant varieties through recombination breeding. Crossing was done between the local cultivar Abelmoschus esculentus var. Anacomban and two semi wild species (A. manihot and A. manihot ssp. Tetraphyllus). The fruit set in direct crosses of A. esculentus var. Anacomban x A. manihot and A. esculentus var. Anacomban x A. manihot ssp. Tetraphyllus was very low compared to the reciprocal crosses, exhibiting partial incompatibility consequent on the slow pollen tube growth of A. manihot and A. manihot ssp. tetraphyllus. The seed set was low in crossed fruits and there was recovery of shriveled seeds which may be attributed to the poor endosperm development. The crossed seeds exhibited good viability. All the hybrids exhibited field tolerance to yellow vein mosaic disease. The four hybrids recorded pollen sterility which may be attributed to meiotic abnormalities, due to difference in chromosome number between the species. The seed set in the hybrids was very low. The seed set was inversely proportional to pollen sterility. The lower the pollen sterility higher was the seed set. The F2 seeds showed reduction in seed weight which may be due to high seed sterility exhibited by the hybrids. The recovery of empty seeds which appeared normal may be ascribed to endosperm degeneration. The seed viability of F2 seeds was very low. The result leads to the conclusion that the reason for low fruit and seed set in interspecific hybridization in Abelmoschus may be due to partial incompatibility. The interspecific hybrids displayed hybrid sterility which may be attributed to the meiotic abnormalities consequent on the difference in the chromosome number between the parents. However, all the hybrids were not completely sterile. The hybrids exhibited field tolerance to yellow vein mosaic disease which is an added advantage. Back crossing the F1 as the seed parent to the A. esculentus var. Anacomban may overcome the hybrid sterility and pave way for the development of varieties with yellow vein mosaic resistance coupled with economic attributes of the popular cultivar Anacomban.