Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.
Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
Ethylene involvement in grain sorghum germination and early seedling growth
Abstract
Grain sorghum [Sorghum bicolor (L.) Moench] is a major feed grain in the U.S. and a major food grain in much of the world's and semi-arid regions. Colder or warmer than optimal soil temperatures often hinder germination end emergence of this crop. The gaseous plant hormone, ethylene is frequently produced in response to plant stress and has been correlated with germination and release from dormancy in many plant species. The objectives of this research were: (1) Identify heat and/or cold tolerant grain sorghum genotypes; (2) Quantify ethylene and 1-Aminocyclopropane 1-carboxylate oxidase (ACCO) production during the first week of growth; and (3) Determine if ethylene was necessary for normal germination or early growth. Thirty five grain sorghum genotypes were screened for percent germination and early seedling growth at 14, 19, 28, and 35°C. Nine selected genotypes were grown in the field at Lincoln, NE in 1996 and 1997 for laboratory analysis at 14, 23 and 35°C. Average ethylene production was 0.21, 0.22 and 0.27 pmol seed−1 hr−1 at 14, 23 and 35°C, while ACCO activity was 93, 213 and 431 pmol ethylene seed−1 hr−1. ACCO activity correlated negatively (R 2 = −0.78) to percent germination at 35°C. Genotypes, Naga white, CE 145-66 and PI 550590 had 19% higher germination, 80% better vigor rating, 14% less ACCO activity, and similar ethylene production as other genotypes and were classified as temperature stress resistant. San chi san had 28% less ACCO activity, produced 34% less ethylene, had 50% better vigor rating and similar germination than other genotypes and was classified as temperature stress tolerant. These four genotypes should be utilized in future breeding programs for improved temperature stress response. Ethylene action inhibitor bioassays using 2,5-Norbomadiene (NBD) in varying concentrations were conducted to examine ethylene's effect on sorghum seedling growth. Germination was not affected by NBD until the concentration became toxic at 11.8 to 23.7 ml L−1. Increasing NBD concentration from 0 to 6 ml L−1 decreased root and shoot growth, while increasing ethylene production. This bioassay should be a useful tool for screening genotypes for seedling vigor and temperature stress response.
Subject Area
Agronomy|Botany
Recommended Citation
Stockton, Roger Dean, "Ethylene involvement in grain sorghum germination and early seedling growth" (1999). ETD collection for University of Nebraska-Lincoln. AAI9929235.
https://digitalcommons.unl.edu/dissertations/AAI9929235