Low-temp Tolerance of Coffea Seedlings Evaluated by Photosynthesis and Chlorophyll Fluorescence Indices
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摘要:
目的 探索低温逆境胁迫对咖啡幼苗光合及叶绿素荧光参数的影响,为咖啡抗寒育种、引种栽培提供科学依据。 方法 以3种咖啡幼苗为材料在8 ℃下分别持续0、24 、48 、72 h低温胁迫试验,观察叶片的叶绿素含量、气体交换参数及叶绿素荧光参数等指标的影响,利用隶属函数对咖啡的抗寒性进行综合评价。 结果 (1)大粒种和小粒种咖啡幼苗随着低温胁迫时间的延长,叶绿素含量先上升后下降,中粒种咖啡幼苗总体是下降趋势。(2)3种咖啡幼苗的净光合速率下降是由非气孔因素导致的, 净光合速率、蒸腾速率、气孔导度、水分利用效率和气孔限制值等光合参数在3种咖啡幼苗低温处理间差异不显著,处理和对照间差异显著。(3)在叶绿素荧光参数方面,3种咖啡幼苗的初始荧光总体水平上均有所上升,表明其PSII中心遭到低温胁迫的损伤程度较严重。非光化学猝灭系数呈先上升后下降趋势,PSII最大光化学效率、光化学猝灭系数、表观量子传递速率和实际光化学量子产量均下降,大粒种咖啡幼苗的下降幅度较中粒种和小粒种咖啡幼苗大,表明其叶片受低温胁迫损伤程度大。采用隶属函数法综合评判3种咖啡的抗寒能力,小粒种咖啡幼苗的平均隶属度最高,表明其抗寒能力较强,中粒种和大粒种咖啡幼苗的抗寒性则较弱。 结论 综合不同的光合及荧光指标,运用隶属函数法能较全面地评判咖啡幼苗的抗寒性,避免了单一指标评判的片面性,其鉴定结果准确可靠。 Abstract:Objective Tolerance to low-temperature stress of seedlings of 3 Coffea varieties was evaluated using photosynthetic as well as chlorophyll fluorescence indices for an improved prediction on cold-resistance of the plants for breeding and new cultivar introduction. Method Seedlings of 3 varieties of coffee cultivars were treated under 8 ℃ for 0, 24, 48 or 72 h. Effects of the low-temp stress on chlorophyll (Chl), gas exchange indices, and Chl fluorescence measurements of the leaves were monitored. Tolerance of the seedlings to low-temp treatments was evaluated using the membership function method. Result (1) The prolonged low-temp stress caused Chl to initially increase in Coffea liberica and C. arabica seedlings and declined later but decrease continuously in C. canephora. (2) The decreased Pn in seedlings was caused by non-stomatal factors. Pn, Tr, Gs, WUE, and Ls did not significantly differ among the treatments on 3 varieties under low-temp stress but did significantly between the treatments and control. (3) The total initial fluorescence (Fo) on the 3 varieties increased indicating the occurrence of significant damage to PSH. The non-photochemical quenching coefficient (qN) had a firstly-increase-then-decline pattern with the larger decreases on the maximum photochemical efficiency (Fv/Fm), photochemical quenching coefficient (qP), apparent quantum transfer rate (ETR), and actual photochemical quantum yield (ΦPSII) of PSII in C. liberica reflecting a greater damaging effect on its leaves than in the other two varieties. According to the analysis by the membership function method, C. arabica seedlings was most cold tolerant among the three varieties. Conclusion By using the photosynthetic and fluorescence indices on coffee seedlings in combination, the membership function method could accurately determine the low-temp tolerance of Coffea cultivars for breeding and/or new variety selection. -
表 1 低温胁迫对咖啡叶片叶绿素含量及光合参数的影响
Table 1. Effects of low-temp stress on Chl content and photosynthesis indices in Coffea leaves
品种 Cultivar 处理 Treaments Chl Pn Tr Ci WUE Ls Gs 大粒种 C. liberica CK 29.00±7.24 a 4.41±1.63 a 0.85±0.51 a 204.79±100.10 a 6.22±3.17 a 0.48±0.25 a 0.05±0.03 a 24 h 34.33±8.90 a 0.53±0.17 b 0.34±0.41 a 312.77±62.83 ab 4.41±4.34 a 0.22±0.16 ab 0.02±0.02 ab 48 h 31.77±8.90 a 0.28±0.13 b 0.35±0.24 a 330.61±59.10 b 1.50±1.73 a 0.17±0.15 ab 0.01±0.01 ab 72 h 30.33±5.54 a 0.29±0.06 b 0.25±0.04 a 348.87±4.73 b 1.14±0.11 a 0.12±0.01 b 0.01±0.002 b 中粒种 C. canephora CK 32.23±1.29 a 6.75±1.50 a 1.08±0.28 a 212.60±50.84 a 6.43±1.78 a 0.46±0.13 a 0.07±0.02 a 24 h 24.93±8.52 a 0.67±0.25 b 0.68±0.40 ab 350.14±34.51 b 1.29±1.04 b 0.12±0.08 b 0.04±0.02 a 48 h 26.70±6.46 a 0.13±0.09 b 0.44±0.47 ab 388.65±2.45 b 0.38±0.13 b 0.03±0.01 b 0.05±0.06 a 72 h 27.07±5.01 a 0.43±0.37 b 0.41±0.16 b 366.09±21.96 b 1.18±1.01 b 0.08±0.06 b 0.03±0.01 a 小粒种 C. arabica CK 45.54±3.72 c 7.73±1.22 a 2.16±0.39 a 255.61±35.96 a 3.72±1.27 a 0.35±0.09 a 0.12±0.031 a 24 h 55.15±4.34 b 1.71±0.38 b 0.69±0.36 b 311.13±70.85 ab 3.38±1.06 ab 0.40±0.50 a 0.05±0.03 b 48 h 63.89±1.42 a 1.20±0.33 bc 0.38±0.10 b 328.11±25.30 ab 3.28±1.06 ab 0.18±0.06 a 0.03±0.01 b 72 h 38.93±3.06 d 0.19±0.88 c 0.38±0.04 b 369.24±1.85 b 0.50±0.20 b 0.07±0.01 a 0.01±0.002 b 注:表中同一列中的不同品种不同小写字母表示差异显著(P<0.05)。表2同。
Note:different lowercase letters in the same column in the table represent significant differences(P<0.05).The same as table 2.表 2 低温胁迫对咖啡叶片叶绿素荧光参数的影响
Table 2. Effect of low-temp stress on fluorescence measurements of Coffea leaves
品种 Cultivar 处理 Treaments Fo Fv/Fm qP qN ETR ΦPSII 大粒种 C. liberica CK 746.59±95.79 a 0.74±0.04 a 0.53±0.08 a 1.49±0.09 a 46.11±12.17 a 0.18±0.05 a 24 h 784.93±19.72 a 0.71±0.02 ab 0.18±0.09 b 1.92±0.26 a 21.16±8.37 b 0.08±0.03 b 48 h 892.87±91.97 a 0.60±0.09 b 0.15±0.04 b 1.61±0.18 a 14.76±3.17 b 0.06±0.01 b 72 h 796.56±119.39 a 0.51±0.08 b 0.07±0.07 b 1.50±0.32 a 6.56±8.03 b 0.02±0.03 b 中粒种 C. canephora CK 651.71±104.64 a 0.72±0.02 a 0.52±0.06 a 1.53±0.09 a 47.32±5.95 a 0.18±0.02 a 24 h 722.48±66.001 a 0.65±0.05 ab 0.13±0.08 b 1.71±0.16 a 14.33±7.72 b 0.05±0.03 b 48 h 720.99±6.75 a 0.53±0.14 b 0.11±0.09 b 1.53±0.16 a 10.36±8.52 b 0.04±0.03 b 72 h 762.73±31.63 a 0.62±0.06 ab 0.11±0.02 b 1.74±0.21 a 12.19±0.48 b 0.05±0.002 b 小粒种 C. arabica CK 648.73±36.40 a 0.72±0.02 a 0.64±0.04 b 1.64±0.11 b 66.17±11.01 a 0.25±0.04 b 24 h 680.58±38.55 a 0.65±0.05 a 0.81±0.04 a 2.74±0.15 a 23.59±1.95 b 0.51±0.04 a 48 h 702.36±38.16 a 0.62±0.06 a 0.77±0.08 a 2.42±0.22 a 20.68±2.62 b 0.45±0.06 a 72 h 659.30±48.87 a 0.53±0.14 b 0.10±0.05 c 1.69±0.28 b 11.90±7.42 b 0.05±0.03 c 表 3 不同咖啡各单项指标的抗寒系数
Table 3. Cold tolerance coefficients on individual indices of Coffea varieties
品种 Cultivar Chl Pn Tr Ci WUE Ls Gs qP qN ETR Fo Fv/Fm ΦPSII 大粒种 C. liberica 104.59 6.58 29.41 170.35 17.76 25.00 20.00 11.32 100.67 14.23 106.69 68.92 11.76 中粒种 C. canephora 83.99 6.37 37.96 172.20 18.35 17.39 50.00 21.15 112.99 25.76 110.63 74.65 27.78 小粒种 C. arabica 85.49 2.46 17.67 144.46 13.40 20.00 16.67 15.63 103.05 17.98 101.63 72.73 16.00 表 4 各抗寒性指标间的相关性分析
Table 4. Correlation among cold tolerance indicators
相关性 Correlation Chl Pn Tr Ci WUE Ls Gs qP qN ETR Fo Fv/Fm ΦPSII Chl 1 Pn 0.119 1 Tr 0.101 0.827** 1 Ci −0.059 −0.666** −0.262 1 WUE 0.163 0.564** 0.153 −0.948** 1 Ls 0.125 0.531** 0.157 −0.905** 0.876** 1 Gs 0.111 0.717** 0.945** −0.164 0.088 0.073 1 qP 0.704** 0.559** 0.469** −0.438** 0.454** 0.487** 0.478** 1 qN 0.692** −0.141 −0.123 0.044 0.121 0.163 −0.035 0.572** 1 ETR 0.153 0.916** 0.822** −0.596** 0.511** 0.482** 0.710** 0.646** −0.058 1 Fo −0.265 −0.471** −0.422* 0.204 −0.206 −0.238 −0.378* −0.432** −0.227 −0.408* 1 Fv/Fm 0.331* 0.557** 0.516** −0.499** 0.539** 0.474** 0.521** 0.690** 0.390* 0.640** −0.297 1 ΦPSII 0.800** 0.314 0.263 −0.255 0.317 0.387* 0.314 0.943** 0.782** 0.391* −0.388* 0.600** 1 注:*在0.05级别(双尾),相关性显著;**在0.01级别(双尾),相关性极显著。
Note:*at level 0.05(double-tailed),the correlation is significant;**at level 0.01(double-tailed),the correlation is extremely significant表 5 各综合指标的系数及贡献率
Table 5. Coefficients and contribution rates of various indicators
特征向量
Eigen vectorChl Pn Tr Ci WUE Ls Gs qP qN ETR Fo Fv/Fm ΦPSII 特征值
Eigen value贡献率
Proportion
contribution
rate/%累积贡献率
Cumulative
contribution
rate%A1 0.46 0.85 0.69 −0.70 0.69 0.68 0.64 0.87 0.32 0.86 −0.53 0.80 0.72 6.27 48.23 48.23 A2 0.74 −0.46 −0.42 0.29 −0.12 −0.08 −0.32 0.40 0.87 −0.37 −0.05 0.09 0.66 2.648 20.37 68.60 A3 0.13 0.10 0.55 0.63 −0.67 −0.66 0.62 0.10 0.01 0.16 −0.25 0.01 0.09 2.11 16.23 84.83 表 6 3种咖啡幼苗抗寒指标的隶属函数值
Table 6. Subordinate function values of cold tolerance indicators of Coffea seedings
品种
CultivarChl Pn Tr Ci WUE Ls Gs qP qN ETR Fo Fv/Fm ΦPSII 平均隶属度
Average
Membership排序
Sort大粒种 C. liberica 0.14 0.02 0.00 0.22 0.13 0.20 0.00 0.00 0.01 0.00 0.61 0.00 0.00 0.10 3 中粒种 C. canephora 0.05 0.04 0.08 0.12 0.13 0.00 0.18 0.07 0.20 0.09 0.30 0.08 0.06 0.11 2 小粒种 C. arabica 0.36 0.01 0.07 0.11 0.02 0.79 0.09 0.05 0.16 0.09 0.04 0.19 0.04 0.16 1 -
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