Principles of Plant Genetics and Breeding

518 CHAPTER 30
disease that is common in humid production
regions. Sources of resistance include grain and
sweet sorghum types.
(c) Smuts. An important smut disease is the head
smut (caused by Sporisorium redianum).
(d) Rust. Puccinia purpurea is responsible for sorghum
rust, a disease that is not economically very
important in the US.
(e) Viral diseases. One of the most economically
important viral infections of sorghum is the maize
dwarf mosaic, a disease that is spread by the
greenbug and various species of aphids.
6 Insect resistance. Major insect pests of sorghum
include the following:
(a) Greenbug. The greenbug (Schizaphis grulninuln)
is a sucking insect pest with biological races.
Breeders, hence, have to continue to breed new
cultivars as new races evolve.
(b) Sorghum midge. The sorghum midge (Contarinia
sorghicola) is of economic importance
worldwide. Resistant germplasm has been identified
among accessions from Ethiopia and
Reference and suggested reading
Brazil. Resistance is quantitatively inherited.
Consequently, breeders should use resistant
A- and R-lines in developing resistant hybrids.
(c) Stalk borers. The European stalk borer
(Ostrinia nubilis) and the southwestern corn
borer (Diatraea grandiosella) are the most
economically important.
(d) Shoot fly. The shoot fly (Antherigona soccata) is
of economic importance primarily in the tropics.
7 Product quality. Sorghum is produced for grain
for food, especially in developing countries. For
food purposes, endosperm qualities are important
in breed-ing objectives. Sorghum endosperm may be
floury or corneous, the latter trait being important
in dry milling. The pericarp may by pigmented or
without pigment. To improve the nutritional quality
of sorghum for feed, one objective is to reduce the
tannin content. Sorghum is also grown for industrial
uses, including flour, syrup, and malt production. For
feed, an objective is to reduce the cynogenetic glucoside
content of the plant and improve its fodder,
forage, and silage qualities.
Acquaah, G. 2005. Principles of crop production. Theory, techniques and technology. Prentice Hall, Upper Saddle River, NJ.
Part A
Please answer the following questions true of false:
Outcomes assessment
1 Sorghum is a self-pollinated species.
2 Sorghum originated in Africa.
3 Sorghum bicolor is the most important species for crop production.
4 Most US sorghum cultivars are 2-dwarf.
Part B
Please answer the following questions:
1 Give the five major races of sorghum.
2 Give four examples of grain sorghum groups.
3 Give two of the top sorghum-producing states in the USA.
Part C
Please write a brief essay on each of the following topics:
1 Discuss the breeding of plant stature in sorghum.
2 Discuss the important diseases and insect pests of sorghum.
3 Discuss the pollination process in sorghum breeding.