Sweet Sorghum: Breeding and Bioproducts - Industrial Crops: Breeding for BioEnergy and Bioproducts - page 4

subhumid regions through the reduction in the current LGPs in those zones. It
means sorghum could be grown in new areas of the currently humid tropics where
sorghum is not grown at present. Therefore, development of crop cultivars with a
maturity duration that suits the prevailing LGP will be one of the best options to
cope with changes in LGP. ICRISAT and Indian National Agricultural Research
System (NARS) have developed a wide variety of sweet sorghum female parental
lines and restorers besides varieties with altered LGP that can play pivotal role in
achieving the above said option.

Taxonomy

Sorghum was first described by Linnaeus in 1753 under the name Holcus . In 1974,
Moench distinguished the genus Sorghum from genus Holcus [ 14 , 15 ]. Subse-
quently, several authors have discussed the systematics, origin, and evolution of
sorghum since Linnaeus [ 16 - 19 ]. Sorghum is classified under the family Poaceae ,
tribe Andropogoneae , subtribe Sorghinae , and genus Sorghum. The genus was
further divided [ 20 ] into five subgenera: Sorghum , Chaetosorghum,
Heterosorghum, Parasorghum , and Stiposorghum . Variation within these five
subgenera except the subgenera Sorghum has been described [ 14 ]. Sorghum bicolor
subsp. bicolor contains all of the cultivated sorghums. Harlan and deWet [ 20 ] have
developed a simplified classification of cultivated sorghum which proved to be of
real practical utility for sorghum researchers. They classified Sorghum bicolor (L.)
Moench, subsp. bicolor into five basic and ten hybrid races as depicted in Table 1.1 .
The 15 races of cultivated sorghum can be identified by mature spikelets alone,
although head type is sometimes helpful. The Biodiversity International [formerly
International Plant Genetic Resources Institute (IPGRI)] advisory committee on
sorghum and millet germplasm has accepted and recommended this classification to
be used in describing sorghum accessions.

Table 1.1 Classification of
Sorghum bicolor (L.)
Moench. subsp. bicolor

Basic races Intermediate/hybrid races

(1) Race bicolor (B) (6) Race guinea-bicolor (GB)

(2) Race guinea (G) (7) Race caudatum-bicolor (CB)

(3) Race caudatum (C) (8) Race kafir-bicolor (KB)

(4) Race kafir (K) (9) Race durra-bicolor (DB)

(5) Race durra (D) (10) Race guinea-caudatum (GC)

(11) Race guinea-kafir (GK)
(12) Race guinea-durra (GD)
(13) Race kafir-caudatum (KC)
(14) Race durra-caudatum (DC)
(15) Race kafir-durra (KD)