Jerrel B. Powell

Pearl Millet Breeding and Cytogenetics1

Publisher Summary Pearl millet, Pennisetum typhoides , a robust annual bunchgrass, occupies more than 45 million acres of the earths surface and occurs in every continent of the world. Although best adapted to the tropics, pearl millet also does well in hot areas of the temperate zone. It has many characteristics that make it an excellent tool for cytogenetic and breeding research. Yet it has been used very little for such studies. This chapter brings together widely scattered bits of information pertaining to the breeding and cytogenetics of pearl millet. It also includes unpublished information to make the treatment as complete as possible. Pearl millet has great economic potential for forage and grain production. Its unusual diversity, flexibility, and responsiveness suggest that its improvement as a useful crop for man has only begun. Few organisms of economic worth are very well suited to basic cytogenetic and plant breeding research. The knowledge of the karyotype of lines within species can give some indication of chromosome diversity and possible barriers to recombination. In pearl millet, the reports on karyotype have been divergent, yet the experience of breeding this species has uncovered no significant barriers to recombination. The chapter explains the cytogenetics of pearl millets and discusses the genetics of qualitative characters, genetics of quantitative characters, and details of breeding associated with pearl millets.

Karyological Leaf Squashes in Grasses, Aided by Pectinase Digestion at 45 C

Longitudinal sections of rapidly growing leaf shoots were soaked for 2–4 hr in 0.002 M 8-hydroxyquinoline at 25 C, blotted, and fixed in 3:4:1 ethanol, chloroform, acetic acid. A 30 min maceration at 45 C in a pectinase solution (Pectinal 59–L; Rohm and Haas) softened the material for staining and squashing. Excess pectinase was removed and 1% aceto-carmine stain was applied. After locating and gently tapping the cover clip to disperse the cells, heavy pressure was applied with a No. 9 rubber stopper and the heel of the hand. By the use of this procedure, karyotypes could be constructed in several genera of forage grasses. The karyotype of Paspalum notatum Flugge is illustrated.

An induced mutant of coastcross 1 bermudagras with improved winterhardiness

Abstract Coastcross 1 bermudagrass, a sterile F 1 hybrid, (Coastal × PI 255445 from Kenya) establishes faster, yields as much dry matter, is 12% more digestible, and gives 30–35% better daily gains and liveweight gains per ha when fed to cattle than does the Coastal clone but fails to develop rhizomes and lacks the winterhardiness of Coastal. To create a winterhardy mutant, some 500,000 green stems (each containing several dormant buds) were exposed to 7000 rad of 60 -Co rays at Oak Ridge. TN June 21, 1971 and were immediately planted at Blairsville, GA where relatively severe winters occur frequently. One of 4 plants surviving the 1971–1972 winter was like Coastcross 1 in yield, in vitro dry matter digestibility and appearance in a 3-yr test during mild winters at Tifton, GA. In the growing season following the moderate winter of 1976–1977, Coastcross 1-M3 yielded more than Coastcross 1 but only about half as much as Coastal. The severe winter of 1977–1978 destroyed about 98% of the plants in the clipped plots of Coastcross 1 and Coastcross 1-M3 but reduced the stand of Coastal very little. The small gain in winterhardiness by Coastcross 1-M3 suggests that several genes control the winterhardiness of well-established Coastal bermudagrass.