低温胁迫对两个油茶品种开花结实及生理特性的影响

The effects of low temperature stress on the flowering, fruiting and physiological characteristics of two Camellia oleifera cultivars

以油茶(Camellia oleifera)‘华硕’和‘华鑫’四年生盆栽植株为材料,研究2个温度(低温6℃和常温25℃)对2个油茶品种叶片光合作用、叶绿素荧光参数、RuBP羧化酶活性、抗氧化酶活性、激素含量及开花座果的影响。结果表明:和常温25℃相比,在6℃低温处理下2个油茶品种的净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、RuBP羧化酶活性、电子传递速率(ETR)、最大光化学效率(Fv/Fm)、实际光化学量子效率(ФPSⅡ)和光化学淬灭系数(qP)随着胁迫时间的延长均降低,在冷驯化25 d时2个品种的Pn、Gs、Tr、Fv/Fm及qP均显著降低,在常温25℃恢复7 d后以上指标均增加;和常温25℃相比,在6℃低温处理下2个油茶品种超氧化物歧化酶(SOD)活性、蔗糖合成酶活性和吲哚乙酸(IAA)含量均升高;随着低温处理时间的延长,多酚氧化酶活性先降低后增加,而乙烯含量先增加后降低。2个油茶品种的花粉萌发率、座果率及气孔张开度在6℃低温处理下降低,同时花基部分泌一种粘状物质保护幼果不受冻害。综上所述, 2个油茶品种光合效率降低主要是由气孔因素引起;2个油茶品种均有一定的抗寒性,油茶‘华鑫’对低温的响应比‘华硕’更敏感。

This study selected 4-year-old potted plant Camellia oleifera cultivars ‘Huashuo’ and ‘Huaxin’ under two temperatures(6℃ and 25℃ as control) as material to study the influence of low temperature treatments on photosynthesis, chlorophyll fluorescence parameters, RuBP carboxylase and antioxidant enzyme activities, hormone content and flowering and fruit setting. The results showed that the net photosynthetic rate(Pn), stomatal conductance(Gs), transpiration rate(Tr), RuBP carboxylase activity, electron transfer rate(ETR), maximum photochemical efficiency(Fv/Fm), actual photochemical quantum efficiency(ФPSⅡ) and photochemical quenching coefficient(qP) of the two cultivars decreased under 6℃ low temperature treatment, and the above indexes increased after 7 days recovery at 25℃;superoxide dismutase(SOD) and sucrose synthetase activities and IAA content increased;the activity of PPO decreased first and then increased, while the ethylene content increased first and then decreased. The low temperature of 6℃ also reduced the pollen germination and fruit setting rates and stomatal opening two cultivars, and mucilaginous substance secreted from the flower base protected the young fruits from freezing damage. In conclusion, the decrease of photosynthetic efficiency of two cultivars was mainly caused by stomata. Two C. oleifera cultivars had certain cold resistance at low temperature, and the response of ‘Huaxin’ to low temperature was more sensitive than that of ‘Huashuo’.