• Horticultural Science & Technology
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• v.32 no.3
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• pp.318-329
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• 2014

In order to gain insight into the physiological responses of plants to high temperature stress, the effects of temperature on Chinese cabbage (Brassica campestris subsp. napus var. pekinensis cv. Detong) were investigated through analyses of photosynthesis and chlorophyll fluorescence under 3 different temperatures in the temperature gradient tunnel. Growth (leaf length and number of leaves) during the rosette stage was greater at ambient $+4^{\circ}C$ and ambient $+7^{\circ}C$ temperatures than at ambient temperature. Photosynthetic $CO_2$ fixation rates of Chinese cabbage grown under the different temperatures did not differ significantly. However, dark respiration rate was significantly higher in the cabbage that developed under ambient temperature relative to elevated temperature. Furthermore, elevated growth temperature increased transpiration rate and stomatal conductance resulting in an overall decrease of water use efficiency. The chlorophyll a fluorescence transient was also considerably affected by high temperature stress; the fluorescence yield $F_J$, $F_I$, and $F_P$ decreased considerably at ambient $+4^{\circ}C$ and ambient $+7^{\circ}C$ temperatures, with induction of $F_K$ and decrease of $F_V/F_O$. The values of RC/CS, ABS/CS, TRo/CS, and ETo/CS decreased considerably, while DIo/CS increased with increased growth temperature. The symptoms of soft-rot disease were observed in the inner part of the cabbage heads after 7, 9, and/or 10 weeks of cultivation at ambient $+4^{\circ}C$ and ambient $+7^{\circ}C$ temperatures, but not in the cabbage heads growing at ambient temperature. These results show that Chinese cabbage could be negatively affected by high temperature under a future climate change scenario. Therefore, to maintain the high productivity and quality of Chinese cabbage, it may be necessary to develop new high temperature tolerant cultivars or to markedly improve cropping systems. In addition, it would be possible to use the non-invasive fluorescence parameters $F_O$, $F_V/F_M$, and $F_V/F_O$, as well as $F_K$, $M_O$, $S_M$, RC/CS, ETo/CS, $PI_{abs}$, and $SFI_{abs}$ (which were selected in this study), to quantitatively determine the physiological status of plants in response to high temperature stresses.

• Food Science and Preservation
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• v.16 no.5
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• pp.612-617
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• 2009

Kimchi is a traditional pickled food using Korean Chinese cabbage(Brassica campestris var. pekinensis) and also containing phytochemicals, glucosinolates. This study was carried out to investigate the changes in the total glucosinolates levels of Kimchi using Korean Chinese cabbage of harvest time(June-July, August-September, October-November, December-April, May) according to storage temperature(4, 10, $15^{\circ}C$) and storage duration(0, 1, 3, 5, 7, 10, 14, 21 and 28 day). For determination of glucosinolates, 50g of Baechu kimchi was used for analytical sample preparation provided with an anion exchanges column and measured by UV-visible Spectrophotometer. The highest contents of water occurred at August-September during fermentation. At 15, 10, $4^{\circ}C$, the pH in all of seasonal variation of Baechu kimchi declined, especially from 0 to 3 days at $15^{\circ}C$, from 0 to 7 days at $10^{\circ}C$ and from 0 to 14 days at $4^{\circ}C$. At that storage, the total glucosinolates levels in all of seasonal variation of Kimchi declined in storage temperature. Baechu kimchi at August-September showed the highest total glucosinolates levels. Also total glucosinolates levels decreased as storage period increased. Baechu kimchi fermented at $15^{\circ}C$ for 7days decreased rapidly and reached to the lowest at the 1day(ranged from $10.3{\pm}0.70$ to $23.4{\pm}0.37{\mu}mol/g$ dry weight). At $10^{\circ}C$ for 14days were ranged from $12.9{\pm}0.29$ to $33.7{\pm}1.81{\mu}mol/g$ dry weight before fermentation and decreased rapidly at the 3day(ranged from $9.5{\pm}0.54$ to $20.5{\pm}0.61{\mu}mol/g$ dry weight). Total glucosinolates levels of Baechu kimchi fermented at $4^{\circ}C$ for 28days decreased rapidly during 7day(ranged from $9.9{\pm}0.78$ to $21.1{\pm}0.96{\mu}mol/g$ dry weight) and then slowly decreased. Therefore the total glucosinolates levels decreased during storage time and depended on harvest time and storage conditions of Kimchi.