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Cucurbit Genetics Cooperative Report 18:19-29 (article 9) 1995

Alteration of Catalase Activity and Ethylene Release during Germination in Newly-Harvested Cucumber Seeds

Mingan Yin and Hongwen Cui

Dept. of Horticulture, Northwestern Agricultural University Yangling, Shaanxi 712100, P.R. China

In cucumber (Cucumis sativus L.) breeding and seed production, we often want to utilize newly harvested seeds for multiplication. However, the vigor of these seeds is low and their regrowth is difficult. Therefore, an understanding of the vigor characteristics of newly-harvested cucumber seeds is important. Catalase activity can define a seed's vigor. Likewise, a seed's ability to producing ethylene can act as an index of its vigor (1). This experiment was designed to study catalase activity and ethylene release during germination in newly-harvested cucumber seeds.

Methods. Seeds of 'Jinyan 6' cucumber were taken from fruits and fermented on July 16. Seeds were washed and dried in the sun on July 18, and the experiment was started on the same day. Newly-harvested seeds and seeds stored for one year (as control) were soaked in water for 6 h, and then germinated at 30C. Catalase activity and ethylene release were assayed every 5 j after seeds had sprouted. Both treatment and control were replicated three times. Catalase activity and ethylene production were determined by iodometry (2) and gas chromatography, respectively. Thirty-five seeds (~1 g) were sealed in a 75 ml glass jar for 1.5 h, and then gas samples were taken.

Results. The catalase activity of newly-harvested seeds was lower than that of stored seeds, except for the initial 9 h and terminal 8 h of a 50 h period (Fig. 1). These data suggest that the metabolic level of oxidation and vigor of newly-harvested cucumber seeds is lower than that of stored seeds.

In the first 25 h of experimentation the ethylene production of newly-harvested seeds was lower than that of stored seeds. In contrast, in the later half of the experiment, ethylene production of newly-harvested seeds was higher than that of stored seeds. The peak ethylene value of stored and newly-harvested seeds appeared at the 20th hour and at the 35th hour, respectively. These ethylene peaks were just 8 to 10 h after the germination peak. The different ethylene-producing patterns of newly-harvested and stored cucumber seeds indicates a difference which is attributable to their vigor.

Figures 1, 2

Literature Cited

  1. Fu, Jarei. 1985. Seed Physiology. Science Press.
  2. Wang, Shaotang, et al. 1987. Experimental Direction in Plant Physiology. Shaanbxi Science and Technology Press.
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