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降低热岛效应和温室效应,实现2030年“碳达峰”与2060年“碳中和”目标,是城市绿地生态系统建设的首要任务。维持城市良好生态环境要求人均公共绿地面积达30~40 m2。草坪是城市绿地生态系统的重要组成部分,具有生态功能、娱乐功能和运动功能[1],通过本底、组成和衬托作用,对提升城市绿化容量、景观特征与精神文明水平具有重要作用。
草坪草依据适合的温度范围分为冷季型和暖季型两大类,温度是影响草坪生长发育及建植养护成本的关键因子[2]。四川盆地为典型的亚热带湿润季风气候,夏季≥30℃约120 d,且高于40℃的酷热天气频现[3],冷季型草坪分生再生能力差、夏眠期长、病害频发,管护疏忽极易使建成草坪1-3年退化殆尽[4]。研究暖季型草种对夏季高温的适应能力,是提升该区城市绿化水平的基本要求。
细叶结缕草(Zoysia tenuifolia)为禾本科结缕草属暖季型草种,具有低矮、纤细、节间短等生物学特征和耐贫瘠、耐践踏、抗干旱、耐盐土、耐低修剪[5]等生态学特性,竞争力、拓展力和分生再生能力强[6],在25-35℃的正常养护下,生长旺盛,极易形成低矮、致密草层[7]。根据亚热带季风气候区夏季超高温持续30 d左右的特点,设置5个高温梯度,对细叶结缕草幼苗进行30 d(2 h/d)的高温冲击处理后,通过测定形态指标、生理指标和生物量,分析细叶结缕草对高温的适应能力和应对策略。为亚热带湿润季风气候区的暖季型草坪建植、养护、管理提供依据。
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高温冲击对细叶结缕草地上形态指标均有显著影响(见表1) (P<0.05)。随冲击温度升高,株高和分蘖数逐步下降(P<0.05),叶片厚度增加,叶片数和总叶面积减少。细叶结缕草适温为25-35℃,36℃冲击对形态指标影响最小。38℃除分蘖数外,株高、叶厚、叶数、总叶面积均低于36℃。40℃冲击下分蘖数、叶片数和总叶面积比36℃分别下降49.01%、44.49%和52.48%。42℃的分蘖数和叶片数与40℃和44℃差异较小。44℃下株高、分蘖数、叶数、总叶面积仅为36℃的76.69%、34.73%、45.69%和27.13%。高温冲击对细叶结缕草形态指标影响大小为总叶面积>分蘖数>株高>叶数>叶厚。
温度
Temperature
(℃)株高
Vertical height
(cm)分蘖数
Tiller number
(number/plant)叶片厚度
Leaf thickness
(mm×10-2)叶片数
Leaf number
(number/plant)总叶面积
TotalLeafarea
(cm2/plant)36 17.25±0.05a 6.45±0.12a 10.22±0.02d 19.33±0.65a 32.36±0.25a 38 15.64±0.12b 5.69±0.35a 12.01±0.25c 16.24±0.24b 28.25±0.21b 40 14.16±0.08c 3.29±0.12b 12.35±0.32c 10.73±0.25c 15.38±0.25c 42 12.58±0.25d 2.97±0.08bc 12.85±0.05b 9.41±0.26cd 12.68±0.34d 44 13.23±0.03c 2.24±0.15c 13.88±0.08a 8.83±0.25d 8.78±0.08e F 15.241 33.513 8.847 14.181 55.463 P <0.001 <0.001 <0.001 <0.001 <0.001 注:同列不同小写字母表示温度间差异显著(P<0.05)。F值表示F检验的显著性,F越大表示越显著,P值表示概率值。下同。Note: Values in a same column with different lowercase letters indicate significant difference in temperatur (P<0.05). F value indicate the significance of the F test, with greater F value means the more significant, and P value indicates the probability value. The same mean on below tables. Table 1. Effects of high temperature shock on morphological characteristics of Z. tenuifolia seedlings
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高温冲击对结缕草总生物量和根冠比有显著影响(见表2) (P<0.05)。随冲击温度升高,总生物量和根冠比逐步下降。36℃和38℃的总生物量和根冠比差异较小(P>0.05),40℃总生物量和根冠比显著低于36~38℃,而大于42~44℃,42℃和44℃间几无差异。大于40℃高温显著影响生物量累积和分配,生物量优先向地上部分分配。
温度
Temperature
(℃)叶绿素
a CHL a (mg/g)叶绿素
b CHL b (mg/g)叶绿素
a/b CHL a/b总生物量
Total biomass (g)根冠比
Root to shoot ratio36 14.26±0.05a 4.12±0.04a 3.46±0.03a 3.45±0.04a 0.34±0.03a 38 13.21±1.01b 3.81±0.32ab 3.47±0.04a 3.42±0.03a 0.33±0.02a 40 12.32±0.29d 3.76±0.09b 3.28±0.11b 2.56±0.01b 0.28±0.01b 42 12.72±1.07cd 3.78±0.12b 3.37±0.09b 2.18±0.08c 0.22±0.01c 44 13.17±0.54c 3.96±0.12a 3.33±0.04b 2.12±0.11c 0.22±0.02c F 5.612 4.124 4.223 9.321 8.354 P 0.015 0.028 0.034 <0.001 <0.001 Table 2. Effects of high temperature shock on chlorophyll content and biomass of Z. tenuifolia
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高温冲击对叶绿素含量产生显著影响(见表2)。随冲击温度升高,叶片中的叶绿素a和叶绿素b含量先减少后增加(P<0.05)。38~44℃下叶绿素a和叶绿素b含量均低于36℃,≥38℃叶绿素a和≥40℃叶绿素b显著低于36℃。40℃叶绿素a和叶绿素b含量最低,44℃下叶绿素a和叶绿素b均有增加。温度显著影响叶绿素a/b,但≥40℃后叶绿素a/b无差异。高温冲击对叶绿素a的影响大于叶绿素b。
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高温冲击对抗性物质含量均产生显著影响(见表3) (P<0.05)。随冲击温度升高,SOD、POD活性和MDA、Pro含量均呈增加趋势,CAT活性则先降低后增加。36℃下SOD、POD活性和MDA、Pro含量显著低于其他温度,≥38℃冲击几种生理抗性物质含量的变化幅度不同,38~42℃下SOD活性差异较小(P>0.05),38℃和40℃的CAT活性和MDA含量差异较小。44℃时3种酶活性和MDA、Pro含量达最大值。高温冲击对抗性物质影响大小为MDA>POD>SOD>Pro>CAT。
温度
Temperature
(℃)超氧化物歧化酶
SOD Activity
(U/min∙g)过氧化物酶
POD activity
(U/min∙g)过氧化氢酶
CAT activity
(U/min∙g)丙二醛
Soluble MDA
(μmol/g)游离脯氨酸
Free Proline content
(ug/g)36 163.57c 167.55e 42.12a 20.14c 16.52d 38 182.64b 182.11d 39.02ab 20.68c 20.42c 40 187.62b 198.47c 36.58b 21.47c 22.15b 42 184.16b 273.29b 32.85c 29.41b 22.68b 44 213.23a 321.23a 43.88a 38.83a 28.38a F 24.827 39.324 11.267 40.616 13.651 P <0.001 <0.001 <0.001 <0.001 <0.001 Table 3. Effects of high temperature shcok on resistant substance of Z. tenuifolia
Effects of high temperature shock on growth and physiological response of Zoysia tenuifolia seedlings
doi: 10.12172/202310220001
- Received Date: 2023-10-22
- Available Online: 2023-11-30
- Publish Date: 2024-04-25
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Key words:
- Zoysia tenuifolia /
- high temperature /
- turfgrass /
- physiology /
- growth strategy
Abstract: Based on the climate characteristics of subtropical regions, five high temperature gradients (36℃, 38℃, 40℃, 42℃, 44℃) were set up to shock Zoysia tenuifolia seedlings for 30 days (2 h/d). The effects of the shocks on growth and physiological response of Z. tenuifolia seedlings were studied by measuring plant height, tiller number, leaf area, biomass, chlorophyll and physiological active substance content. The results showed that: (1) High temperature shock significantly affected the morphological indicators, with plant height, leaf number, and total leaf area decreased at ≥38℃, but tiller number decreased at ≥40℃. The impact on morphological indicators was as follows: total leaf area>tiller number>plant height>leaf number>leaf thickness. (2) High temperature shock significantly affected biomass accumulation and distribution, when ≥40℃ total biomass and root to shoot ratio decreased, with biomass preferentially distributed to the aboveground portion. (3) High temperature shock significantly affected chlorophyll content, with a decrease in chlorophyll a content at ≥ 38℃ and a decrease in chlorophyll b at ≥40℃,but chlorophyll a/b was less affected. (4) High temperature shock significantly affected physiological substances. The higher the temperature was, the greater the activity of SOD and POD was, as well as the content of MDA and Pro. The magnitude of the impact was MDA>POD>SOD>Pro>CAT. The response of resistant substance content to different high temperatures varies greatly. In summary, high temperature shock affected the growth, meristem, and photosynthetic capacity of Z. tenuifolia. By regulating resistant substances to resist high temperature damage, it can withstand 44℃ high temperature shock and safely survive the summer.