Shin Yu Kyeong, Bhandari Shiva Ram, Lee Jun Gu
Department of Horticulture, College of Agriculture & Life Sciences, Jeonbuk National University, Jeonju, South Korea.
Core Research Institute of Intelligent Robots, Jeonbuk National University, Jeonju, South Korea.
Front Plant Sci. 2021 Dec 22;12:786309. doi: 10.3389/fpls.2021.786309. eCollection 2021.
Chlorophyll fluorescence () is used to measure the physiological status of plants affected by biotic and abiotic stresses. Therefore, we aimed to identify the changes in parameters in grafted watermelon seedlings exposed to salt, drought, and high and low temperatures. Grafted watermelon seedlings at the true three-leaf stage were subjected to salinity levels (0, 50, 100, 150, and 200 mM) and temperature [low (8°C), moderate (24°C), and high (40°C)] stresses for 12 days under controlled environmental conditions independently. Eight parameters were measured at 2-day intervals using the FluorCam machine quenching protocol of the FluorCam machine. The seedlings were also exposed to drought stress for 3 days independent of salinity and temperature stress; parameters were measured at 1-day intervals. In addition, growth parameters, proline, and chlorophyll content were evaluated in all three experiments. The parameters were differentially influenced depending on the type and extent of the stress conditions. The results showed a notable effect of salinity levels on parameters, predominantly in maximum quantum yield (Fv/Fm), non-photochemical quenching (NPQ), the ratio of the fluorescence decrease (Rfd), and quantum yield of non-regulated energy dissipation in PSII [Y(NO)]. High temperature had significant effects on Rfd and NPQ, whereas low temperature showed significant results in most parameters: Fv/Fm, Y(NO), NPQ, Rfd, the efficiency of excitation capture of open photosystem II (PSII) center (Fv'/Fm'), and effective quantum yield of photochemical energy conversion in PSII [Y(PSII)]. Only NPQ and Rfd were significantly influenced by severe drought stress. Approximately, all the growth parameters were significantly influenced by the stress level. Proline content increased with an increase in stress levels in all three experiments, whereas the chlorophyll (a and b) content either decreased or increased depending upon the stressor. The results provided here may be useful for understanding the effect of abiotic stresses on parameters and the selection of index parameters to detect abiotic stresses in grafted watermelon seedlings.
叶绿素荧光（）用于测量受生物和非生物胁迫影响的植物的生理状态。因此，我们旨在确定嫁接西瓜幼苗在盐、干旱以及高温和低温胁迫下参数的变化。处于真三叶期的嫁接西瓜幼苗在可控环境条件下分别经受盐度水平（0、50、100、150和200 mM）和温度[低温（8℃）、中度（24℃）和高温（40℃）]胁迫12天。使用FluorCam机器淬灭协议，每隔2天测量8个参数。幼苗还独立于盐度和温度胁迫经受3天干旱胁迫；每隔1天测量参数。此外，在所有三个实验中评估生长参数、脯氨酸和叶绿素含量。参数受胁迫条件的类型和程度的影响各不相同。结果表明盐度水平对参数有显著影响，主要体现在最大量子产率（Fv/Fm）、非光化学淬灭（NPQ）、荧光下降比率（Rfd）和PSII中非调节性能量耗散的量子产率[Y(NO)]上。高温对Rfd和NPQ有显著影响，而低温在大多数参数上显示出显著结果：Fv/Fm、Y(NO)、NPQ、Rfd、开放光系统II（PSII）中心的激发捕获效率（Fv'/Fm'）和PSII中光化学能量转换的有效量子产率[Y(PSII)]。只有NPQ和Rfd受严重干旱胁迫的显著影响。几乎所有生长参数都受胁迫水平的显著影响。在所有三个实验中，脯氨酸含量随胁迫水平的增加而增加，而叶绿素（a和b）含量根据胁迫因素的不同而降低或增加。此处提供的结果可能有助于理解非生物胁迫对参数的影响以及选择指标参数来检测嫁接西瓜幼苗中的非生物胁迫。
