Calidad de semilla de genotipos isocitoplasmicos de sorgo (Sorghum bicolor L. Moench.)

The production of sorghum hybrids depends almost entirely on one genic-cytoplasmic sterility system (Milo-Kafir, A1 Cytoplasm), therefore its importance in increasing the diversity of the number of male-sterile sources, as the named A2 Cytoplasm. This system was introduced at the Rio Bravo Experiment Station (lNIFAP-CIRNE) in Tamaulipas, Mexico, where ge-netic material and seed production were developed. The objetive was to compare the seed quality ofthe isocytoplasmic genotypes (A1 and A2 cytoplasm). A Completely Radomized Experimental Design with Factorial Arrangement and two replications was used. The results show that there were no differences between the two types of cytoplasm (A1 and A2) for the following quality traits: volumetric weight of seeds, 1000 seeds' weight, germination(G) and seedling dry weight (SDW), through nine months of storage; whereas in vigor (G and SDW after fast aging) the A2 cytoplasm surpassed the Al cytoplasm and the same behavior was observed on the seed harvested at its physiological maturity, while at harvest maturity the Al was superior in G and SDW.

Fodder yield and quality in forage sorghum: scope for improvement through diverse male sterile cytoplasms

Cytoplasmic male sterility (CMS) has proved to be an effective and efficient genetic tool in sorghum (Sorghum bicolor (L.) Moench) hybrid breeding programs. The A1 (milo cytoplasm) CMS type has been widely exploited to produce both commercial grain and forage sorghum hybrids. To explore the possibility of using alternative CMS (non-milo cytoplasm) sources, we studied the effect of cytoplasm on forage yield and quality in sorghum. Nine female (CMS) lines (representing three each in A1, A2, and A3 cytoplasms) and five male lines were used to generate 45 hybrids, which were evaluated in three environments. Cytoplasm and its first-order interaction with location and male and female lines showed the presence of a cytoplasmic effect on the majority of fodder yield and quality traits examined. The CMS lines possessing A3 cytoplasm (A3N213 and A3N193) were good combiners for important fodder yield and quality traits. For hydrocyanic acid, the CMS lines possessing A1 cytoplasm were good combiners. Mean performance of hybrids and combining ability analysis of parents revealed that A3 cytoplasm can be used along with the widely used A1 cytoplasm, which helps in the diversification of the male sterile base of forage sorghum hybrids.