Cucurbit Genetics Cooperative Report 20:3-6 (article 2) 1997
Meng Huanwen, Cheng Zhihui and Cui Hongwen
Department of Horticulture, Northwestern Agricultural University, Yangling, Shaanxi 712100 P.R. China
Introduction. It is very important to know what biochemical changes occur during seed germination. Such information is important for seed germination and seed physiology research, and for obtaining improved stand establishment of seedlings. Because information about germination of cucumber seeds is sparse, we report herein the concentration of several important biochemical constituents of cucumber seeds during germination.
Materials and Methods. The cultivar ‘C1-7-6 ‘ was supplied by our cucumber research group, and these seeds were used in our experiment (harvested in 1995), Each seed sample was weighed before sowing, and then they were put in germination dishes and held at 25 + 2 C. During germination, the ascorbic acid, free amino acid, soluble protein and soluble sugar content of the seeds was measured once every 12 hours until the experiment was terminated at 72 hours. The experiment had three replications. the content of ascorbic acid was determined using a method involving 2, 6-dichlorophenol indophenol titration, free amino acids were quantified by the ninhydrin reaction method, soluble protein were detected by colorimetric analysis using coomassie brilliant blue G-250, and soluble sugars were evaluated by colorimetric analysis using an anthrone reaction. The content of these selected seed constituents was calculated on a dry weight basis.
Results and Discussion. The results are shown in Table 1. (1) The content of ascorbic acid increased linearly during seed germination, except for a slight drop at 60 hours after sowing. (2) The total content of free amino acids in the seeds gradually increased during seed germination. Generally, the increase is less at the beginning (0-36 hr) of germination than at later stages of germination. (3) The content of soluble protein in seeds was low and constant from 0 to 24 hours during germination. However, protein content increases perceptively from 24 to 36 hours, and then rises dramatically from 48 to 72 hours. (4) Soluble sugar content decreased between 0 to 36hours after germination is initiated, and then increases dramatically.
In summary, the content of ascorbic acid and free amino acids in cucumber seeds increases during seed germination. However, the soluble protein and soluble sugar contents of the germinating seed increase slightly at the beginning of germination, and then increase dramatically.
Table 1. Biochemical changes in cucumber seeds during germination.
Stage of Germination (hr ) |
Seed constituent |
|||
Ascorbic acid (mg/100g) |
Free amino acids (mg/100g) |
Soluble protein (%) |
Soluble sugar (%) |
|
| 0 | 4.39 g F | 61.32 e E | 2.838 d D | 2.749 bc B |
| 12 | 11.11 f F | 64.67 de DE | 2.734 d D | 2.572 c BC |
| 24 | 31.25 e D | 74.05 de DE | 2.766 d D | 2.576 C BC |
| 36 | 115.85 d C | 92.38 d CD | 4.329 c C | 2.049 D bc |
| 48 | 169.68 b A | 117.86 c C | 4.345 c C | 2.459 cd BC |
| 60 | 125.58 c B | 158.25 b B | 6.227 b B | 3.093 b B |
| 72 | 177.55 a A | 224.54 a A | 7.935 a A | 3.758 a A |