摘要
为探究白及驯化苗在光温耦合作用下的生长发育变化,为白及夏季适应性锻炼提供科学依据,以2021年6月移栽大棚的白及组培苗为试验材料,在驯化90 d时,设置不同温度(25、30、35、38 ℃)和波动光[50 μmol/(
在自然条件下由于云层的运动,植物通常会经历光的突然增加,尤其是设施栽培环境下,温室骨架以及植物上部冠层的遮荫使温室植物冠层呈现大量且持续变化的光斑。当光强突然增加时,PSⅡ对光的吸收也会立刻增
兰科植物白及(Bletilla striata)是一种濒危药用植物,贵州野生白及生长于海拔950~1 600 m、土壤含腐殖质较丰富的林下、草丛、岩石缝
本研究以白及(Bletilla striata)种子培育的组培种苗为研究材料,炼苗后,移栽在泥炭混合基质(V泥炭∶V锯末∶V蛭石=3∶1∶1)的育苗穴盘中,在相对湿度为60%~70%的大棚中生长,使用遮阳网控制光照,夏季正午最大光强约为1 300 μmol /(
白及移栽30、60、90 d时随机选取10株白及,测量移栽苗株高、茎宽、叶片长、叶宽、块茎宽度及厚度、根长,称根、块茎、叶鲜质量。在105 ℃烘箱中杀青10 min,于80 ℃烘干至恒质量,称各部分干质量。烘干后的各部分样品粉碎,采用硫酸-苯酚比色法测定多糖含量。
参考Yang
测定期间,某时刻的光合诱导状态为此时的净光合速率占最大净光合速率的百分
植株首先在暗室中暗适应30 min,随后将待测叶片在6400-40荧光叶室中暗适应30 min左右,记录最小(Fo)和最大(Fm)荧光。暗适应结束后将Li-Cor 6400XT叶室内光强瞬时提高到1 000 mmol /(
测定结果显示,白及叶片经连续强光-弱光-强光转换,光合诱导状态对温度胁迫展现出不同的响应,高温胁迫显著降低了光合诱导状态,35和38 ℃处理下的光合诱导状态分别为55%~65%和30%~40%,25和30 ℃下的白及植株在经过一系列交替光的转换后光合诱导状态仍高达80%~90%和70%~80%(

图1 白及叶片经连续强光-弱光-强光转换下气体交换参数对瞬时温度胁迫的响应
Fig.1 Response of gas exchange parameters to transient temperature stress in Bletilla striata leaves
白色矩形条代表强光(1 000 mmol/(
under continuous strong-weak-strong light conversion
交替光转换下温度和Gs呈负相关,在25~35 ℃下降明显,峰值从0.17左右降到0.90左右(
在经历5 min的弱光后,强光来临时,各个温度达到稳态的时间t35 ℃<tCK<t38 ℃<t30 ℃(

图2 叶片经不同时间弱光处理后转移到强光下其光合速率变化过程对温度胁迫的响应
Fig.2 Response of photosynthetic rate change process of leaves to temperature stress
A:5 min 弱光;B:10 min弱光;横坐标0时刻表示再次光照的瞬间。A:5 min shade;B:10 min shade;The abscissa 0 moment represents the moment of relighting.
after different time of weak light treatment transferred to strong light
由
处理温度/℃ Temperature | Fo | Fv/Fm | NPQ | ETR | ΦPSⅡ | qP | Fv'/Fm' |
---|---|---|---|---|---|---|---|
25 | 529.31±12.53c | 0.84±0.12a | 1.56±0.15c | 202.25±24.07a | 0.48±0.11a | 0.72±0.16a | 0.67±0.16a |
30 | 537.82±11.03bc | 0.82±0.07ab | 1.63±0.18c | 194.30±15.12ab | 0.44±0.12a | 0.68±0.20ab | 0.64±0.12a |
35 | 554.67±8.69ab | 0.79±0.05bc | 1.83±0.24ab | 145.59±17.12c | 0.35±0.13b | 0.61±0.12bc | 0.58±0.12b |
38 | 565.20±10.41a | 0.78±0.10c | 1.97±0.12a | 108.20±18.13d | 0.26±0.16c | 0.47±0.14c | 0.54±0.14b |
由于白及组培苗抗逆性差、羸弱,不能直接进入大田栽培,需要移栽到人工大棚中进行适应性锻炼。驯化初期,30 与60 d的株高并没有表现出差异,但是在茎宽、根数、根长、块茎厚上表现出显著差异(P<0.05),随着驯化时间的延长,在90 d时,株高、叶片长、块茎宽和根长表现出显著差异(
处理时间/d Treatment time | 株高 Plant height | 茎宽 Stem width | 叶片长 Leaf length | 叶片宽 Leaf width | 块茎宽 Tuber width | 块茎厚 Tuber thick | 根长 Root length |
---|---|---|---|---|---|---|---|
30 | 14.01±1.08b | 0.12±0.04b | 10.48±1.39b | 1.01±0.34b | 0.74±0.09b | 0.64±0.05b | 3.55±0.88c |
60 | 13.81±0.77b | 0.21±0.02a | 10.67±0.83b | 1.56±0.18a | 0.80±0.10b | 0.85±0.16a | 9.34±1.95b |
90 | 16.51±1.07a | 0.20±0.03a | 12.82±1.16a | 1.47±0.45a | 1.08±0.29a | 0.82±0.09a | 11.56±1.70a |
白及移栽苗根冠比呈现先升后降的趋势,表明在移栽前期以地下部的生长为主,于90 d左右地上部的生长占主要部分。根的生物量占比和茎叶生物量占比均随驯化时间的延长而提高(

图3 移栽驯化时间对白及幼苗生物(A)和多糖含量(B)的影响
白及多糖含量是白及质量指标之一,由
净光合速率下降,胞间CO2浓度或气孔导度上升,说明净光合速率的下降是由非气孔限制因素造成
在本研究中,35 ℃与CK相比光合速率显著降低,而在前人的研究中34 ℃短期内对白及的光合速率不会产生太大的影
叶绿素荧光参数是植株响应热胁迫的重要指标,高温会使Fo升高,原因是类囊体结构遭到了破坏,因此,Fo也被作为植物耐热性相关的生理特
本研究探讨了夏季光温耦合对白及驯化苗生长发育及多糖含量的影响,结果表明:白及移栽苗的生长指标和驯化时间成正比,根冠比在90 d内先升后降,块茎多糖含量90 d较60 d增加了51%,夏季波动光和高温对白及生长发育产生严重危害。因此,在夏季应该加强对白及驯化苗的水肥管理,从而减轻高温和波动光带来的伤害。
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