Title page for ETD etd-06062008-154412

Type of Document Dissertation
Author Oluoch, Melkizedek O.
URN etd-06062008-154412
Title Effects of priming and stage of development on vigor and longevity of muskmelon (Cucumis melo L.) seeds
Degree PhD
Department Horticulture
Advisory Committee
Advisor Name Title
Welbaum, Gregory E. Committee Chair
Morse, R. D. Committee Member
Orcutt, David M. Committee Member
Parrish, David J. Committee Member
Veilleux, Richard E. Committee Member
  • muskmelon seeds
Date of Defense 1996-02-01
Availability unrestricted
Muskmelon seeds were harvested at eight stages of development to determine the

optimal harvest time for best seed quality and long-term storage. Several types of osmotic

and matric priming treatments were investigated to determine the optimal treatment for

maximal seed vigor and to test the effects of priming on seed storage life. The most

effective priming treatments for improved germination of muskmelon seeds occurred at

water potentials ('¥) between -1. 5 and -1. 8 MP a and at priming durations of 4 to 7 days.

Osmotic priming in KN03 and PEG 8000 solutions was more effective than matric

priming with calcium silicate, vermiculite~ and Hayter loam soil. Priming increased the

storage life of newly matured 40 and 45-days after anthesis (DAA) stored seeds but

decreased the storage life of 55 DAA seeds. Fifty, 55, and 60-DAA seeds showed the

greatest tolerance to adverse storage conditions and water stress and had the greatest

seedling vigor. The highest quality seeds were attained 50 to 60 DAA from fruit harvested

after edible maturity but before the onset of severe decomposition. After 6 years of

storage, seeds washed in water at harvest were more vigorous and resistant to accelerated

aging than unwashed seeds at most stages of development. Primed seeds retained some

beneficial effects after 9 years of storage at optimal conditions but lost viability, vigor, and uniformity of germination more rapidly than nonprimed seeds following controlled

deterioriation. lnstron analysis showed that priming weakened the perisperm envelope

tissue prior to radicle emergence. Less force was required to puncture primed seed pieces

than nonprimed. The penetration force and energy required to puncture the perisperm

envelope tissue decreased gradually during imbibition, increased steadily during seed

development and dry storage, and was negatively correlated with seed vigor. Priming

accelerates enzymatic breakdown of perisperm envelope during germination. Endo-f3-

mannanase-1ike activity declined steadily during imbibition and was higher in nonprimed

seeds than primed seeds, indicating that enzymatic activity in the perisperm peaked during

priming. Flow cytometry revealed that the beneficial effects of priming and seed maturity

do not correlate with DNA replication activity in muskmelon seeds. This study has shown

that seed maturation inside the fruit until just after edible maturity is necessary for highest

muskmelon seed vigor. Priming treatments should be performed as close to the planting

date as possible, because primed seeds exhibit reduced storage life compared to

nonprimed seeds.

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