Abstract

Sesame is one of the world's most important oil crops. The seeds produce oil which is used for many purposes. It can be grown without irrigation and is well used in crop rotations. One problem with sesame is its low yield caused by dehiscence (seed scattering) in which, when close to ripeness, the seed capsule bursts open and the seed is scattered. The objectives of this project are to induce indehiscence and/or strong placentation (mechanism holding seed in pod) by a mutation breeding program and to screen these mutants for disease resistance, plant height, and improved capsule size and numbers.

Post-Project Summary

To create sesame seed mutations which would delay shattering, researchers used three mutagens (substances to increase frequency or extent of mutation): gamma-rays; ethyl- methane-sulfonate (EMS); and ethidium bromide (EB). Treated species were No. 45 (an Israeli type) and Cola de Borrego (a Mexican variety). Field plots of second generation mutations (M2) of these species were established in two locations in Israel and one in Mexico. Sixty-eight No. 45 plants shattered seeds four to six weeks later than most other No. 45 plants; and 30 Cola plants lasted three weeks longer than most other Cola plants before shattering. But tests in the third year showed no significant delays. Previous shattering delays were attributed more to environmental factors than to mutagenic effect. Two other Mexican sesame lines treated with gamma-rays and EMS confirmed the high tolerance of sesame seeds to irradiation. It was concluded that sesame seeds were strongly resistant to irradiation, especially gamma-rays. However, the rate of mutations (5% or more) obtained from gamma-rays and EMS in about 75% of the M2 populations was considered high enough to justify continued use of mutagens to select for indehiscence.

Recipient Institution(s)