Deteriorative changes in soybean and cotton seeds

• Main Author: Turnipseed, Errol Brent
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-1993
• Subjects: Agronomy
• ISBN: 9798208954850

Studies were undertaken to identify and characterize deteriorative changes associated with aging in soybean and cotton seeds and to relate selected changes at the biochemical and physiological levels with losses in performance capability of the seeds, viz., germinability and vigor. High quality seeds of the Mack and Tracy M cultivars of soybean and the DES 119 cultivar of cotton were adjusted to 12-13% moisture content and aged in plastic containers at 35-40$\sp\circ$C for periods from 0 to 40 days to obtain batches of seeds with different levels of deterioration for various studies. Deteriorative changes associated with aging of the seeds were identified and characterized in terms of the results of twelve response-reactions of the seeds: standard germination, rate of seedling growth, accelerated aging response, cool germination (cotton only), hot water soak (cotton only), conductivity of seed leachates, pH of seed exudates, release of volatile aldehydes, free fat acidity, level of free amino acids, respiration, and dehydrogenase activity. Standard germination was not significantly reduced until the seeds had been subjected to rather long periods of aging, i.e., aging levels 3 and 4, but rate of seedling growth, accelerated aging responses and cool germination (cotton only) decreased significantly very early during aging prior to any decrease in standard germination. Increased seed permeability was also one of the earliest and most prominent deteriorative changes associated with aging. The conductivity of seed leachates increased as aging level increased for both seed kinds. Increases in volatile aldehydes and free fat acidity indicated that degradation of the lipid fraction in seeds was a substantative change during aging and probably a major factor in the increased seed permeability. Proteins were also degraded during aging as evidenced by a consistent increase in the level of free amino acids with increased aging. The volatile aldehydes and free amino acids assays appear to have good potential for monitoring and indexing seed quality for deterioration and vigor, while the pH of exudate assay seems to be particularly well suited for rapidly estimating the percent germination.