Cucurbit Genetics Cooperative Report 20:9-10 (article 5) 1997
Dang Yonghua ¹ , Cheng Zhihui ² , Du Junzhi ¹ and Wang Nong ¹
¹ Vegetable Institute, Shaanxi Academy of Agriculture, YangLing, Shaanxi, 712100, P.R. China
² Department of Horticulture, Northwestern Agricultural University, YangLing, Shaanxi, 712100, P.R.
Introduction. Cucumber is one of the most important temperature fruit vegetables worldwide. Recently in China, more attention has been placed on anti-season cultivation of cucumber. Thus, research on cold tolerance in cucumber related to this type of cultivation has increased (1-5). However, there have been no reports dealing with the reaction of leaves at different plant positions to low temperature exposure. Therefore, we report herein the effect of low temperatures on leaf position in cucumber.
Material and Methods. Tow cultivars, Jing Za No. 3 (spring season cultivation) and Autumn Chief (autumn season cultivation), were used in this experiment. Seedlings and plants were grown under polyethylene plastic film tent cultivation in the spring-summer season in China. Sample leaves were taken from plants when they reached maturity, cleaned and rinsed, and leaf discs (1.0 cm diameter) were prepared. Then, these discs were exposed to different temperatures (-4, -2, 0, 2, 4, 6 C) for 3 hours. The leakage (%) of electrolytes from leaf discs was measured by a conductivity gauge.
Results and Discussion. The results are provided in Table 1. (1) As the treatment temperature decreased, the electrolytes leakage percentage increased. This indicates that the destruction (degree) of cell membrane increases. There was only a slight difference between the temperature treatments of 6 C and 4 C, but electrolyte leakage sharply increased when temperature was decreased to 2 C or lower. Generally, the leakage rose to ~50% when the temperature was decreased to 0, -2 C or lower. (2) The electrolyte leakage from the leaf discs increased as the leaf position from the base of the plant increased. This indicates that the higher the leaf position, the more sensitive they are to low temperatures. This finding may be explained by the fact that the higher position leaves are growing in the higher temperature condition than lower leaves, and thus lack adaptability to the low temperatures. (3) The differences in cultivar tolerance to low temperature shows that electrolyte leakage from leaf discs of ‘Jing Za No. 3’ is lower. This means that ‘Jing Za No. 3’ is more tolerant to lower temperatures than the cultivar Autumn Chief.
Table 1. Electrolyte leakage (%) from cucumber leaves at different positions and when exposed to different temperatures.
Cultivar |
Leaf position |
Temperature (°C) |
|||||
6 |
4 |
2 |
0 |
-2 |
-4 |
||
| Jing Za No. 3 | 5 | 21.3 ± 1.4 | 22.8 ± 0.7 | 28.8 ± 1.5 | 32.0 ± 3.0 | 47.3 ± 4.7 | 67.8 ± 3.2 |
| 10 | 25.4 ± 3.3 | 26.2 ± 1.0 | 31.8 ± 3.0 | 36.3 ± 3.0 | 51.0 ± 2.6 | 57.2 ± 2.9 | |
| 15 | 28.3 ± 3.8 | 34.2 ± 6.6 | 34.4 ± 7.9 | 38.4 ± 2.3 | 46.4 ± 8.1 | 59.7 ± 3.3 | |
| 20 | 27.4 ± 2.5 | 30.2 ± 2.7 | 29.6 ± 1.2 | 33.9 ± 3.9 | 42.5 ± 8.4 | – | |
| 25 | 34.2 ± 2.3 | 35.0 ± 3.8 | 36.0 ± 1.9 | 37.1 ± 2.3 | 42.5 ± 0.9 | 40.7 ± 4.9 | |
| Autumn Chief | 5 | 24.5 ± 2.3 | 24.7 ± 1.9 | 33.5 ± 2.5 | 35.3 ± 2.6 | 44.2 ± 9.8 | 63.6 ± 3.8 |
| 10 | 28.4 ± 4.7 | 28.8 ± 2.6 | 33.6 ± 0.6 | 39.1 ± 3.8 | 47.0 ± 7.0 | 54.0 ± 1.3 | |
| 15 | 29.0 ± 2.7 | 32.8 ± 3.9 | 37.8 ± 2.9 | 43.7 ± 3.5 | 52.1 ± 2.6 | 57.4 ± 3.7 | |
| 20 | 34.2 ± 2.9 | 34.2 ± 2.0 | 37.2 ± 2.8 | 39.9 ± 6.2 | 51.4 ± 5.5 | 54.0 ± 0.9 | |
| 25 | 42.6 ± 9.0 | 46.8 ± 2.5 | 46.5 ± 4.5 | 53.1 ± 8.2 | 60.1 ± 3.4 | 57.6 ± 8.2 | |
Literature Cited
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