First report of partial dominance of photo-insensitivity in pigeonpea (Cajanus cajan L. Millsp.)

The time taken from sowing to flowering in pigeonpea is positively associated to its photoperiod responses; and it is expressed in terms of delay in flowering when exposed to long photoperiods. The late maturing genotypes, without exception, are photo-sensitive with critical daylength of around 11 h. The early flowering types, on the other hand, are invariably photo-insensitive. The past research on this subject has shown that the photo-insensitivity in pigeonpea was controlled by 2-3 simply inherited recessive genes. The present study was designed to understand dominance relationships among photo-sensitive and photo-insensitive alleles in six diverse crosses. It involved two photoinsensitive (Prabhat and Pant A3) and three photo-sensitive (Code 14, ICP 7065, T17) genotypes. Under long photoperiods, the three Prabhat hybrids, on average, flowered in 190.8 days, while the Pant A3 hybrids took only 82.1 days to flower. It was concluded that the two photo-insensitive genotypes carried different sets of genes for this trait. In Prabhat the photo-insensitivity was recessive in nature, while in Pant A3 it was controlled by partial dominant genes. This is the first report in pigeonpea where a photo-insensitive genotype with partial dominant genes has been identified.