Cucurbit Genetics Cooperative Report 21:8-10 (article 3) 1998
Meng Huanwen¹, Cui Hongwen¹, Cheng Zhihui, and He Danrao²
¹Horticultural Department, Northwestern Agricultural University, Yangling, Shaanxi, 712100, P.R. China
²Garden Afforestration Brigade, Muidanjiang City, Heilongjiang, 157000. P.R. China
Introduction. Copper, one of the trace elements in plants (1), is essential to the normal growth of vegetables. Cucumber is one of the vegetables which is very sensitive to copper (2). Some research has shown that soaking seeds in CuSo4 (copper sulfate) solution may enhance plant growth and development, and even improve fruit nutritive quality in cucumber
Disease has proven to be a major threat to vegetable production worldwide. Seeds and soil are the two major initial sources of disease causing pathogens in vegetable production. Research has shown that soaking seeds of pepper and tomato in Cu2+ solution can control some diseases (3,4).
Seed coat techniques have proven to be a convenient and effective way to improve seed quality and seedling growth, and to control seedling diseases (5,6,7). In China, we are now conducting a project entitled, “Seed Technology Industrialization.” Seed coat evaluation is a major part of that project. Our research was conducted to evaluate the effects of Cu2+ in seedcoat agents on seed germination, seed storage, seedling growth, and seedling disease control in cucumber.
Materials and Methods. Cucumber seeds of cultivar Jin 4-3-1 and chemically pure copper sulfate were used in the experiment. Copper was added to the cucumber seedcoat agent at the concentration of 1.0% or 40%, and a no-copper control was added to the seed coating mixture. The seedcoat agent was applied to cucumber seeds at 1:10 (w:w) proportion of seedcoat agent to seed.
Germination testing of the coated seeds was conducted at the constant temperature of 25 C. One hundred seeds for each test plot (treatment) were sowed on a plastic foam bed (1 cm thick) in a culture dish. There were three replications of each treatment. The germinated seeds were counted 8 times from 24 hours to 108 hours after sowing in an interval of 12 hours (when the root length of the seeds exceeded half of the seed length). The germinating percentage was calculated according to the total seeds (100 seeds) sowed and the total germinated seeds at the end of germination. The germination energy was calculated using the total seeds sowed and the total germinated seeds counted at the first three data collection intervals (i.e., 48 hours after sowing). The germinating index (GI) was calculated with the following formula:
GI = ∑ (G1/D1)
where G1 is the number of germinated seeds at the data collection interval and D1 is the corresponding count of the data collection interval.
The storage ability of coated seeds was examined by an artificial aging method. The seeds were artificially aged at an air-tight container with a relative humidity of ~99% and a temperature of 42 C for 4 days. Germination was examined after this treatment.
The effects of copper-coated seeds on seedling growth were investigated by observation of seedlings under field conditions. SEeds were sowed in a vermiculite medium in a container 8 cm in diameter. Four seed were sowed in each container and after emergence seedlings were thinned to one plant. There were 10 containers in each pot with 3 treatment replications. Twenty-five days after sowing, seedling height, stem diameter (2 cm above ground), leaf area and fresh weight of roots and tops were measured. Leaf area was calculated as the sum of the cross-products of the length width of each leaf. Seedling index (SI) was calculated by the following formula:
SI = (stem diam/seedling height) x seedling weight
The effects of copper-coated seeds on disease resistance of seedlings were tested by sowing the coated seeds in \infected vermiculite medium and nursing seedlings under outdoor, natural conditions for 25 days. The percentages of the sprout rot and the wilted seedlings (caused by diseases) were calculated.
Results. Seed coating with either 1.0% or 4.0% of Cu2+ improved seed germination. The germinating percentage, germinating energy, germinating index, and the root length of coated seeds were increased by 10.7%, 3.2%, 12.4% and 2.5%, respectively. The SSR test showed that the germinating percentage, germinating energy, and germinating index of 1% Cu2+ coated seeds were significantly higher than those of the control (Table 1).
In contrast, copper in the seedcoat agent was not an advantage to the storage ability of coated seeds, especially with the higher copper concentration. However, the differences in germinating percentage, germinating energy and germinating index between the 1,0%,Cu2+ treatment and the control were not significant (Table 2). These data suggest that the coating of cucumber seeds with 1.0% Cu2+ will not significantly affect seed storage ability.
With regard to seedling growth, the copper seedcoat treatment showed some advantages. However, the effects of the copper treatment were related to the concentration applied. The 4.0% of Cu2+ treatment increased seedling height, seedling fresh weight and leaf area by 14.4%, 14.5%, and 3.0%, respectively. the increase of seedling fresh weight was most significant. The 1.0% Cu2+ treatments decreased the ratio of root fresh weight to top fresh weight of seedlings (Table 3).
Copper in the seedcoat agent showed the most significant effect on seedling disease control. Both 1.0% Cu2+ treatment and 4.0% Cu2+ treatment had almost the same effect (Table 4). Because of disease infection, 91.7% of the control seeds (no copper in the seedcoat agent) failed to produce seedlings, and either rotted in the germination stage or in pre-emergence. Also, some of the seedlings produced from the control treatment seeds suffered from post-emergence disease and died early in their growth. Therefore, the total incidence of the disease in the control reached as high as 94.9%. For the copper treatments, only 11.1% of the seeds were rotted during pre-emergence, and the total incidence of post-emergence disease was only 2.8%.
In conclusion, different concentrations of copper in seedcoat agent may have different effects. Generally speaking, the 1,0% Cu2+ treatment not only improved germination but also had fewer detrimental effects on seed storage. Results indicate that the 4.0% Cu2+ treatment was best for seedling growth, and had no significant effect on seed storage ability. For disease control, the 1.0% Cu2+ treatment had almost the same effect as 4.0% Cu2+ treatment.
Table 1. Effects of copper in seedcoat agent on germination of cucumber seeds.
Cu2+concentration(%) |
Germinatingpercentage |
Germinatingenergy%) |
Germinatingindex |
Root length(cm) |
Root fw(g) |
| 0 (ck) | 68.0 bA | 66.7 bA | 13.86 b | 1.88 | 0.037 |
| 1.0 | 82.7 aA | 80.7 aA | 18.34 a | 2.05 | 0.029 |
| 4.0 | 75.3 avA | 68.7 sbS | 15.58 ab | 2.35 | 0.036 |
Table 2. Germination of artificually-aged copper coated cucumber seeds.
Cu2+ concentration (%) |
Germinating percentage (%) |
Germinating energy (%) |
Germinating index |
| 0 (ck) | 24.1 aA | 22.7 aA | 3.73 aA |
| 1.0 | 16.0 abA | 16.0 abA | 2.28 abA |
| 4.0 | 9.3 bA | 9.3 bA | 1.45 bA |
Table 3. Effects of copper in seedcoat agent on seedling growth of cucumber.
Cu2+concentration(%) |
Seedlingheight(cm) |
Stemdiameter(cm) |
Seedling fw(g) |
Roof/topratio |
Seedlingindex |
Leafarea (Cm2) |
| 0 (ck) | 10.0 a | 0.36 a | 3.91 bB | 0.43 aA | 1.848 a | 46.4 a |
| 1.0 | 9.3 a | 0.34 a | 4.18 abAB | 0.40 abB | 1.840 a | 46.4 a |
| 4.0 | 11.4 a | 0.35 a | 4.45 aA | 0.35 bA | 1.690 a | 47.8 a |
Table 4. Copperin seedcoat agent on seedling disease control of cucumber.
Cu2+concentration(%) |
Emergence(%) |
Rottenpre-emergence (%) |
Fallenseedling(%) |
Totalincidence(%) |
|
| Expt. I | 0 (ck)
1.0 4.0 |
8.3
97.2 100.0 |
91.7
2.8 0.0 |
2.7
0.0 2.8 |
94.4 aA
2.9 bB 2.8 bB |
| Expt. II | 0 (ck)
1.0 4.0 |
0.0
88.7 88.7 |
100.0
11.1 11.1 |
0.0
5.6 0.0 |
100.0 aA
16.7 bB 11.1 bB |
Literature Cited
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- Allowag, B.J. 1984. Study on trace element copper in Japan. Proceedings in Soil Science. Vol. 4.
- Lian Lizhe. 1987. research on seed bearing pathogenes and their influence on seedlings of pepper. Seed (1):60.
- Zhu Zhendong. 1992. Influence of seed bearing pathogenes on seed quality. Seed (2):49-52.
- Li Yuanfang. 1987. Pelting and coating seed to standardize seed quality. Seed World (10):5-6.
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- Lue Cangxue. 1989. Prospect of the application of seedcoat agent to vegetables. Seed World (6):7.