10份沿阶草族种质材料叶片光合特性对低温胁迫的响应及抗寒性评价

Responses of leaf photosynthetic characteristics to low temperature stress in 10 Ophiopogoneae germplasms and evaluation of cold resistance

摘要:

【目的】 研究不同低温胁迫对沿阶草族种质的光合参数、叶绿素荧光特性的影响，以期为沿阶草族种质在西北地区的合理栽培利用提供依据。【方法】 以10份沿阶草族（Ophiopogoneae）种质为试验材料，设4个低温处理水平（5、0、-5和-10 ℃），以20 ℃为对照（CK），综合比较了10份沿阶草族种质的抗寒性。【结果】 低温加重了光合作用的光抑制。随着胁迫加剧，10份沿阶草族种质净光合速率 （P_n ）呈先上升后降低趋势、蒸腾速率（Tr ）、气孔导度（G_s ）呈降低趋势，而胞间 CO₂ 浓度（C_i ）呈上升趋势。 10份沿阶草族种质变化趋势一致，但对低温胁迫的反应存在差异。金边麦冬的Pn 下降幅度最小，受低温影响相对较小，而短药沿阶草受到的影响最大。在叶绿素荧光参数方面，温度降至-10 ℃，初始荧光 （F_o ）呈上升趋势，最大光化学效率（F_v /F_m ）、实际光化学效率（ФPSⅡ）呈先上升后降低趋势、电子传递速率（ETR）、光化学淬灭系数（qP）呈降低趋势。10份沿阶草族种质净光合速率与胞间CO2 浓度呈显著正相关（P＜0.05），净光合速率与初始荧光呈显著负相关（P＜0.05），蒸腾速率与气孔导度呈极显著正相关（P＜0.01），最大光化学效率与气孔导度、胞间CO2 浓度呈显著负相关（P＜0.05），初始荧光与最大光化学效率呈显著正相关（P＜0.05），与电子传递速率呈显著负相关（P＜0.05）。隶属函数法综合分析显示，10份沿阶草族种质的抗寒性强弱依次为短药沿阶草＞沿阶草（康县）＞沿阶草（文县）＞沿阶草（武都）＞金边麦冬＞山麦冬＞玉龙草＞沿阶草（河南）＞禾叶山麦冬＞麦冬。【结论】 短药沿阶草、 沿阶草（康县）、沿阶草（文县）种质抗寒性较强，更适宜在北方地区推广。

Abstract:

【Objective】 Low temperature is one of the main factors limiting plant growth and development. The effects of different low temperature stress on the photosynthetic parameters and chlorophyll fluorescence characteristics of Ophiopogoneae germplasm were studied in order to provide the basis for the rational cultivation and utilization of grass germplasm along the stage in Northwest China.【Method】 In this study，the cold resistance of 10 Ophiopogo- neae germplasm was comprehensively compared at 4 low temperature treatment levels （5 ℃ ，0 ℃ ，-5 ℃ and -10 ℃） and 20 ℃ as control （CK）.【Result】 The results showed that low temperature increased photoinhibition of photosynthesis. With the intensification of stress，the net photosynthetic rate （P_n ） increased first and then decreased， the transpiration rate （T_r ） and stomatal conductance （G_s ） decreased，while the intercellular CO2 concentration （C_i ） increased，indicating that non-stomatal factors were the main factors leading to the decrease of photosynthesis. The trend of germplasm change was the same among the 10 Ophiopogoneae，but there were differences in their responses to low temperature stress. The Pn of Liriope muscari Phnom Penh decreased the least，indicating that the influence of low temperature was relatively small，while the influence of the Ophiopogon angustifoliatus was the greatest. In terms of chlorophyll fluorescence parameters，when the temperature droped to -10 ℃，the initial fluorescence （F_o ） showed an increasing trend，the maximum photochemical efficiency （F_v /F_m ） and the actual photochemical efficiency （PSⅡ） show an increasing trend and then a decreasing trend，the electron transfer rate （ETR） and photochemical quenching （qP） show a decreasing trend. The results showed that the lower the temperature was，the greater the variation range of Ophiopogoneae germplasm along the rank was，the more obvious the photosynthetic inhibition was， and the greater the photosynthetic organ damage was. There was a significant positive correlation between net photosynthesis and intercellular CO₂ concentration（P＜0. 05）. There was a significant negative correlation between net photosynthetic rate and initial fluorescence（P＜0. 05）. There was a significant positive correlation between transpiration rate and stomatal conductance（P＜0. 01）. There was a significant negative correlation between maximum photochemical efficiency and stomatal conductance and intercellular CO2 concentration（P＜0. 05）. The initial fluorescence was positively correlated with the maximum photochemical efficiency （P＜0. 05），and negatively correlated with the electron transport rate（P＜0. 05）. According to the comprehensive analysis by membership function method，the cold resistance of 10 Ophiopogoneae germplasm members of the grass family was in the order of O. angustifoliatus＞ O. bodinieri（Kangxian）＞Ophiopogon bodinieri（Wenxian）＞O. bodinieri（Wudu）＞L. muscari＞L. spicata ＞ O. japonicus＞O. reversus （Henan）＞L. graminifolia＞O. japonicus.【Conclusion】 The germplasms of O. angustifo- liatus，O. bodinieri（Kangxian） and O. bodinieri（Wenxian） were more suitable for promotion in northern China because of their strong cold resistance.