Recessive, day length-insensitive earliness to synchronize flowering of pearl millet hybrid parents

The availability of recessive genes for early flowering-day length insensit ivity offers an opportunity to synchronize the flowering of late-flowering or day length-sensitive parents with that of early-flowering parents withou t necessarily affecting the flowering of their hybrids, provided that the e arlier parent does not carry the same recessive allele. This study evaluate d the hypothesis that incorporating the recessive e(1) allele for early flo wering-day length insensitivity into a late-flowering, photoperiod-sensitiv e pollinator in pearl millet [Pennisetum glaucum (L.) R. Br.] would synchro nize its flowering and improve seed production with earlier-flowering femal e parents, without affecting the time to flowering or the performance of th e resulting hybrids. An e(1)/e(1) isoline of the late-flowering pollinator ICMP 85410, produced by six backcrosses, flowered 16 d earlier under natura l day lengths at Patancheru, India, (17 degrees N) and 19 d earlier under e xtended day lengths (equivalent to 29 degrees N) than its near isogenic E-1 /E-1 counterpart. As a consequence, it successfully produced hybrid seed wh en sown simultaneously with early, male-sterile line 843A, whereas the late isoline failed under the same conditions. The E-1/e(1) versions of eight n ear-isogenic hybrids ton a range of eight E-1/E-1 male-steriles) flowered a n average of 3 d earlier than their E-1/E-1 counterparts in 2 yr of tests u nder both natural and extended day length conditions at the same location. This earlier flowering had small effects on hybrid yield components, consis tent with known effects of earliness in the crop, but did not affect grain yield. The results indicate that the e(1) allele is a powerful tool for exp loiting heterosis between early- and late-flowering parents in pearl millet , which is otherwise difficult to realize without complicated seed producti on practices.