羊草(Leymus chinensis)叶片光合参数对干旱与复水的响应机理与模拟

利用典型草原优势植物羊草（Leymus chinensis）对不同水分胁迫与复水响应的植物光合生理生态模拟实验与野外观测资料,分析研究了羊草叶片光合参数Kcmax（Rubisco的最大羧化速率）、Jmax（最大光合电子传递速率）和TPU（磷酸丙糖利用率）对干旱与复水的响应机理。结果表明,无论是模拟实验还是野外观测均显示羊草叶片的光合参数随着土壤水分的增加呈抛物线曲线变化,但各光合参数最大值对土壤水分的响应不同。温室模拟下的羊草光合参数Vcmax,Jmax和TPU在土壤含水量分别在15．56％,15．89％和16．23％时达到最大,而野外观测羊草的光合参数Vcmax,Jmax和TPU在土壤含水量分别为16．89％,17％和16．79％时达到最大。复水后羊草植株叶片光合参数的变化取决于前期干旱的影响,土壤含水量18％～19％和15％～16％处理的羊草复水后光合参数能够恢复正常,前者甚至超过正常水平,说明适宜的水分胁迫在复水后能够提高羊草叶片的光合能力,促进光合作用;土壤含水量10％～12％和7％～9％处理下的羊草复水后光合参数则不能恢复到正常水平。土壤含水量15％～16％可能是羊草光合能力在水分胁迫后能否恢复的阈值。     

不同油松种源光合和荧光参数对水分胁迫的响应特征

采用盆栽控水试验方法,设置正常水分(T1,田间持水量的70％-80％)、轻度胁迫(T2,田间持水量的50％-60％)和严重胁迫(T3,田间持水量的30％-40％)3个水分梯度,对6个油松(Pinus tabulaeformis Carr.)种源(陕西洛南LN,陕西桥山 QO,山西灵空山LK,辽宁千山QN,河北雾灵山WL和山西芦芽山LY)的光合参数和叶绿素荧光参数进行比较,探讨种源间光合和水分利用特征的差异及其与气孔导度和荧光参数的关系.结果表明,3个水分梯度下6个种源的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、水分利用效率(WUE)、原初光能转换效率(Fv/Fm)和PSⅡ潜在活性(Fv/Fo)差异均极显著(P＜0.01),在T1和T3下,各种源的实际光量子效率φPSⅡ和电子传递速率ETR差异显著(P＜0.05).在T2下,LK和WL的Pn达到最大,具有轻度胁迫下提高光合生产力的倾向.在T3下,QN种源的Pn和WUE较高(除LK的WUE最高外),而WL的Pn和WUE较低(除LK的Pn最低外);6个种源中QN的Pn、φPSⅡ和ETR最大,LY和QO的光合生产力仅次于QN,而LN、LK和WL的Pn、Gs、φPSⅡ和ETR比较低,其光合生产力及光量子产量受干旱胁迫影响较大.LK的WUE在各个水分梯度下均显著高于其它种源(P＜0.05).在T3下,各种源通过降低Tr提高WUE.在T1下,气孔限制是影响油松Pn的主要因素;在T2和T3下,Pn和WUE均与气孔导度、PSⅡ反应中心的光量子产量和电子传递速率密切相关.     

不同生育期玉米叶片光合特性及水分利用效率对水分胁迫的响应

利用大型移动防雨棚开展了玉米水分胁迫及复水试验,通过分析玉米叶片光合数据,揭示了不同生育期水分胁迫及复水对玉米光合特性及水分利用效率的影响。结果表明:水分胁迫导致玉米叶片整体光合速率、蒸腾速率和气孔导度下降以及光合速率日变化的峰值提前;水分胁迫后的玉米叶片蒸腾速率、光合速率和气孔导度为适应干旱缺水均较对照显著下降,从而提高了水分利用效率,缩小了与水分充足条件下玉米叶片的水分利用效率差值;在中度和重度水分胁迫条件下,玉米叶片的水分利用效率降幅低于光合速率、蒸腾速率和气孔导度的降幅, 有时甚至高于正常供水条件下的水分利用效率;适度的水分胁迫能提高玉米叶片的水分利用效率,从而增强叶片对水分的利用能力,抵御干旱的逆境;水分亏缺对玉米光合速率、蒸腾速率及水分利用效率的影响具有较明显滞后效应,干旱后复水,光合作用受抑制仍然持续;水分胁迫时间越长、胁迫程度越重,叶片的光合作用越呈不可逆性;拔节-吐丝期水分胁迫对玉米叶片光合作用的逆制比三叶-拔节期更难恢复。     

大豆光合速率和气孔导度对水分胁迫的响应

土壤水分胁迫使两个供试大豆品种(系)光合速率和气孔导度降低,“鲁豆四号”降低的幅度大于小粒大豆品系“7605”。在相同的叶水势下,“7605”的光合速率和气孔导度均高于“鲁豆四号”,但“7605”气孔随水势下降而关闭的速率大于“鲁豆四号”。水分胁迫使叶片温度升高,“7605”比“鲁豆四号”升温较快,但在同一水分处理中,“鲁豆四号”的叶温高于“7605”。水分胁迫降低了大豆的水分利用效率,且“鲁豆四号”降低的速率大于“7605”。结果表明,“7605”对水分胁迫具有较好的适应能力。     

NaCl胁迫对菠菜叶片中水分和光合气体交换的影响(简报)

NaCl胁迫下,菠菜幼苗叶片的净光合速率（Pn）、气孔导度（Gs）和蒸腾速率（Tr）下降。短期处理的叶片中CO2浓度（Ci）降低,气孔限制值（Is）升高,水分利用效率（WUE）增大,而长期处理的叶片中Ci升高,Is下降,WUE降低。NaCl短期处理下,菠菜光合降低以气孔限制为主,而在长期处理下光合的非气孔限制因素增大。     

不同产地披针叶茴香光合特性对水分胁迫和复水的响应

为了探讨披针叶茴香(Illicium lanceolatum)对水分胁迫的响应,选用4个不同产地的披针叶茴香(浙江临安产地(LA)、浙江开化产地(KH)、江西武宁产地(WN)和福建南平产地(NP))盆栽幼苗为试验材料,采用Li-6400便携式光合作用测定仪对不同水分胁迫下幼苗光合特性进行测定.结果表明:随着水分胁迫强度增加,不同产地幼苗光饱和点(LSP)和光补偿点(LCP)值表现出不同程度的降低,最大净光合速率(Pmax)的变化趋势存在产地差异,基本为先升后降;而表观光量子效率(AQY)呈增加的趋势.在水分胁迫复水后,4个产地幼苗LSP、LCP、AQY和Pmax值与正常供水时存在显著差异(P＜0.05),WN、KH和LA幼苗LSP值大于正常供水;除NP幼苗外,其余产地幼苗LCP值均不同程度快速回升;KH和WN幼苗Pmax值高于正常供水,LA和NP幼苗Pmax低于正常供水;WN、KH和LA幼苗的AQY值均明显高于正常供水.表明披针叶茴香不同产地植株光合特性对光强和水分敏感性不同,WN产地植株对水分和光照的需求较广、适应能力较强,其次为NP产地,而浙江产地(KH、LA)植株对于水分的要求较高.水分胁迫下,披针叶茴香幼苗光合响应曲线亦存在差异,在低光范围(≤200 μmol· m-2·s-1)时,其净光合速率(Pn)光响应值主要受土壤水分影响,当光强增大时,光照负面影响大于水分影响.表明披针叶茴香生长需要适宜水分,但最需要适宜光照,土壤水分条件较低时需实施弱光栽培措施来缓和逆境胁迫.     

舟山新木姜子(Neolitsea sericea)幼苗对不同盐胁迫的光合生理响应

为评价舟山新木姜子(Neolitsea sericea)的耐盐性, 对其在不同盐胁迫下的光合生理特性进行实验研究。以舟山新木姜子 2 年实生幼苗为试验材料进行盆栽实验, 通过添加不同浓度的 NaCl 溶液, 设置 4 个不同土壤盐分处理(土壤含盐量分别为 0、0.3%、0.6% 和 0.9%)。分别在第 10 d、20 d、30 d、40 d, 测定舟山新木姜子幼苗在不同处理条件下的叶片叶绿素含量(Chl)、净光合速率(P_n)和最大光化学效率(Fv/Fm)等指标。结果表明：在不同处理之间, 在相同的胁迫阶段, 叶片 Chl 无显著性差异(P>0.05);在各胁迫阶段, 随着土壤含盐量的增大,叶片 P_n、最大光合速率(P_nmax)和光饱和点(LSP)都呈现下降趋势。在轻度盐胁迫(0.3%)舟山新木姜子幼苗叶片 Fv/Fm 介于 0.74—0.78 之间, 与对照无显著性差异(P<0.05), 中度(0.6%)和重度盐胁迫(0.9%)最终都显著降低了叶片 Fv/Fm; 在胁迫初期, 0....     

差巴嘎蒿灌丛土壤和根系含水量对降雨的响应

以科尔沁沙地半固定沙丘灌木差巴嘎蒿(Artemisia halodendron)为对象,用土钻取样法和壕沟法研究了2006年生长季降雨后差巴嘎蒿周围土壤和根系含水量的时空分布特征及其相互关系,并计算了该灌丛的水量平衡.结果表明:该灌丛在降雨后对水分有暂时存储作用;降雨结束后,灌丛主干的茎流作用使得灌丛中心位置的土壤含水量高于灌丛丛幅垂直投影1/4和3/4处的土壤含水量;雨后6 h灌丛根系含水量与灌丛中心位置的土壤含水量呈极显著的负相关(r=-0.89,P＜0.01);灌丛根系含水量在雨后126 h内出现胁迫脉冲间歇反应.水量平衡计算表明,灌丛边缘外1 m处土壤蒸散量高于灌丛覆盖区的蒸散量,灌丛覆盖可降低土壤水分蒸散速率.     

Responses of photosynthetic parameters of Quercus mongolica to soil moisture stresses

The effect of drought on plant photosynthetic parameters has not been quantitatively described in the models of plant photosynthetic mechanism, so the seedlings of Quercus mongolica from Northeast China were used to study the responses of the photosynthetic parameters to soil water stresses. The results showed that the relationship between the maximum net leaf photosynthetic rate (P_max) of Quercus mongolica and soil moisture could be expressed as a quadratic curve (P < 0.01), and P_max reached the maximum when soil volume moisture was close to 35.45% of the field water holding capacity. The maximum rate of carboxylation (V_cmax), the maximum potential rate of electron transport (J_max) and triose phosphate utilization (TPU) rate of Quercus mongolica also had quadratic relationships with soil water content (P < 0.01). Namely, V_cmax, J_max and TPU had similar response curves to soil water, but had different optimal soil water contents. Based on the temperature and responses of plant photosynthetic parameters to water, this function provides researchers with the parameters and methodology for understanding and simulating the responses of plant photosynthetic parameters to drought stress.     

Responses of photosynthetic parameters of Quercus mongolica to soil moisture stresses

The effect of drought on plant photosynthetic parameters has not been quantitatively described in the models of plant photosynthetic mechanism, so the seedlings of Quercus mongolica from Northeast China were used to study the responses of the photosynthetic parameters to soil water stresses. The results showed that the relationship between the maximum net leaf photosynthetic rate (P_max) of Quercus mongolica and soil moisture could be expressed as a quadratic curve (P < 0.01), and P_max reached the maximum when soil volume moisture was close to 35.45% of the field water holding capacity. The maximum rate of carboxylation (V_cmax), the maximum potential rate of electron transport (J_max) and triose phosphate utilization (TPU) rate of Quercus mongolica also had quadratic relationships with soil water content (P < 0.01). Namely, V_cmax, J_max and TPU had similar response curves to soil water, but had different optimal soil water contents. Based on the temperature and responses of plant photosynthetic parameters to water, this function provides researchers with the parameters and methodology for understanding and simulating the responses of plant photosynthetic parameters to drought stress.     

羊草和紫花苜蓿生长特征及光合特性对不同土壤水分的响应

采用人工控制实验,对12%(T1)、16%(T2)和20%(T3)3种土壤水分条件下羊草和紫花苜蓿的净光合速率Pn、实际光化学量子效率ФPSⅡ、光化学淬灭q P、非光化学淬灭q N、水分利用效率WUE、株高、分枝分蘖数、生物量等参数进行测定。结果表明,在实验范围内,(1)ФPSⅡ和q P共同影响净光合速率,羊草和紫花苜蓿净光合速率对土壤水分的响应不同,紫花苜蓿的土壤水分生态幅要比羊草窄,羊草生长的最适土壤含水量为20%,随着土壤含水量的降低,净光合速率呈单调递减趋势;紫花苜蓿的最适土壤含水量为16%,其净光合速率与土壤含水量之间呈非线性关系,存在明显阈值。(2)适宜土壤含水量有助于羊草和紫花苜蓿株高和分枝分蘖的生长。(3)在土壤水分低于适宜土壤含水量范围时,羊草和紫花苜蓿有相似的响应机制,都通过增加根系生物量来适应环境胁迫。     

山杏叶片光合生理参数对土壤水分和光照强度的阈值效应

以半干旱黄土丘陵区主要灌木树种山杏(Prunus sibirica)为试验材料, 应用CIRAS-2型光合作用仪测定不同土壤质量含水量(W_m)下山杏叶片净光合速率(P_n)、蒸腾速率(T_r)及水分利用效率(WUE)的光响应过程, 探讨山杏光合特性对土壤水分和光照条件的适应性。结果表明: P_n、T_r及WUE对W_m和光照强度的变化有明显的阈值响应。随着W_m (6.5%-18.6%)的递增, 光补偿点降低, 光饱和点、表观量子效率和最大净光合速率均升高; 在W_m为18.6%时, 山杏利用弱光和强光的能力最强, 光照生态幅最宽。随着W_m (9.2%-18.6%)的递增, P_n、T_r有明显升高的趋势, 水分过高或过低, 两者均呈现下降趋势; 山杏对光照环境的适应性较强, 在光合有效辐射为800-1 200 µmol∙m^-2∙s^-1时, P_n和WUE都具有较高水平, 饱和光强在983-1 365 µmol∙m ^-2∙s^-1之间。以光合生理参数为指标对山杏土壤水分有效性及生产力进行分级与评价, 确定W_m < 9.2%或W_m > 22.3%时为“低产中效水”; W_m在20.5%-22.3%和9.2%-12.9%时, 分别为“中产低效水”和“中产中效水”; W_m在12.9%-20.5%时为“高产高效水”。其中W_m为18.6%时为“最佳产效水”, 对应光强为1 365 µmol∙m^-2∙s^-1。     

Acclimation to irradiance of leaf photosynthesis and associated nitrogen reallocation in photosynthetic apparatus in the year following thinning of a young stand of Chamaecyparis obtusa

In order to quantify the effects of thinning on photosynthetic parameters and associated change in leaf nitrogen (N) contents, half of the trees in a 10-year-old Chamaecyparis obtusa (Sieb. et Zucc.) Endl. stand (36° 3′N, 140°7′E) were removed, giving a final density of 1 500 trees ha⁻¹, in May 2004. Photosynthetic photon flux density (PPFD) and leaf N and carbon (C) contents in the lower (L), middle (M), and upper (U) crowns were monitored one, three, and five months after thinning in both the thinned stand and a non-thinned control stand. In addition, leaves’ photosynthetic responses to CO₂ concentration were simultaneously measured in situ to estimate the maximum rates of carboxylation (V_cmax) and electron transport (J_max). Thinning increased PPFD in the L and M crowns but not in the U crown. V_cmax in both the L and M crowns of the thinned stand increased significantly in comparison with the same crown position of the control stand in the three and five months following thinning. In addition, the thinned stand exhibited an increase in N partitioned to ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) in the L and M crowns relative to the control stand three and five months after thinning, indicating that N had been redistributed within the photosynthetic machinery. Thinning did not affect N per unit area at any of the crown positions, but significantly increased the content of N as a fraction of the total leaf dry mass in the L and M crowns three and five months after thinning. This was a consequence of a decrease in leaf dry mass due to rapid shoot growth. Thus thinning did not cause a redistribution of N between leaves. Thinning improved irradiance in the L and M crowns of C. obtusa, leading to photosynthetic acclimation. Photosynthetic acclimation in the first year mainly occurred via redistribution of N within but not between leaves.     

Changes in total leaf nitrogen and partitioning of leaf nitrogen drive photosynthetic acclimation to light in fully developed walnut leaves

Comprehensive studies on the processes involved in photosynthetic acclimation after a sudden change in light regime are scarce, particularly for trees. We tested (i) the ability of photosynthetic acclimation in the foliage of walnut trees growing outdoors after low‐to‐high and high‐to‐low light transfers made early or late in the vegetation cycle, and (ii) the relative importance of changes in total leaf nitrogen versus changes in the partitioning of leaf nitrogen between the different photosynthetic functions during a 2 month period after transfer. Changes in maximum carboxylation rate, light‐saturated electron transport rate, respiration rate, total leaf nitrogen, ribulose 1·5‐bisphosphate carboxylase/oxygenase (Rubisco) and total chlorophylls were surveyed before and after the change in light regime. Respiration rate acclimated fully within 1 week of transfer, and full acclimation was observed 1 month after transfer for the amount of Rubisco. In contrast, total nitrogen and photosynthetic capacity acclimated only partially during the 2 month period. Changes in photosynthetic capacity were driven by changes in both total leaf nitrogen and leaf nitrogen partitioning. The extent of acclimation also depended strongly on leaf age at the time of the change in light regime.     

Physiological differences of five Holm oak (Quercus ilex L.) ecotypes growing under common growth conditions were related to native local climate

An increase in the frequency and intensity of extreme climatic conditions is expected for the Mediterranean area as a response to climate change. As a consequence, the ability of Mediterranean plant species to adapt to complex and stressful environmental conditions plays an important role in driving their future distribution. The adaption of plant species may be expressed by ecotypes already adapted to local climate. Our goal was to analyse the seasonal physiological behaviour of five Quercus ilex ecotypes coming from different Italian geographical areas (from the north to the south) in order to test if ecotypes maintained their physiological traits when grown in the same environmental conditions. Measurements of gas exchange, biochemistry and chlorophyll fluorescence carried out during winter, spring and summer underlined that the response of the considered ecotypes reflected the climate of the original provenances, particularly under suboptimal conditions. The ecotypes from the northernmost and the southernmost limits were the most sensitive to high and low temperatures, respectively. Our results can be used to advance hypotheses about the respone of Q. ilex to climate change.     

不同土壤水分条件下紫藤叶片生理参数的光响应

测定了不同土壤湿度下2年生紫藤叶片光合速率（P_n）、蒸腾速率（T_r）及水分利用效率（WUE）等生理参数的光响应过程,探讨了紫藤正常生长发育所需的土壤水分和光照条件.结果表明:紫藤叶片的P_n、T_r及WUE对土壤湿度和光照强度的变化具有明显的阈值响应.维持紫藤正常生长（同时具有较高P_n和WUE）的土壤湿度范围为:体积含水量（W_v）15.3%～26.5%、相对含水量（W_r）46.4%～80.3%,最佳土壤湿度约为W_v 23.3%、W_r 70.6%.紫藤叶片对光照环境的适应性较强,在光合有效辐射强度（PAR）为600～1 600 μmol·m^-2·s^-1时,P_n和WUE具有较高水平,饱和光强在PAR为800～1 000 μmol·m^-2·s^-1.紫藤叶片光合作用非气孔限制的发生与土壤湿度与光照强度密切相关,W_v为18.4%～26.5%、W_r为55.8%～80.3%时,光合作用主要受气孔限制,光照强度的影响较小;超出此范围后,其受光照强度的影响较大,出现由气孔限制转变为非气孔限制的PAR临界值.紫藤正常生长允许的最低土壤湿度约为W_v 11.9%、W_r 36.1%,允许最高PAR约为1 000 μmol·m^-2·s^-1,是紫藤叶片光合机构受到破坏的临界点.     

西南旱地油菜田土壤水分和作物光合特征对覆盖材料和垄沟比的响应

为了应对西南地区频发的季节性干旱,提高旱作农田水分利用效率和作物光能利用效率,设置大田试验,研究不同覆盖材料(普通白膜、普通黑膜、生物降解膜和不覆膜)和不同垄沟比(40 cm∶40 cm和40 cm∶80 cm)对土壤贮水量和油菜光合特性、荧光参数、叶绿素相对含量(SPAD)的影响。结果表明:油菜生育期不同覆盖材料下的土壤贮水量为:普通黑膜垄作(BR)≈普通白膜垄作(WR)≈生物降解膜垄作(BDR)>不覆膜垄作(NR)>平作(FP);在同一覆盖材料下,垄沟比对土壤贮水量无显著影响。与平作相比,垄沟集雨处理的净光合速率、气孔导度、最大荧光、可变荧光、PSⅡ最大光化学量子产量、PSⅡ潜在活性、光化学猝灭系数和非光化学猝灭系数均有所提高;与平作相比,WR、BR、BDR和NR处理的SPAD值分别提高6.1%、8.6%、8.5%和3.6%,瞬时水分利用效率分别提高18.3%、11.4%、16.3%和10.4%。相比于平作,BR、WR和BDR处理可显著增加油菜产量,NR处理增产不显著,普通黑膜垄作+垄沟比40 cm∶40 cm处理的经济效益最高。可见,垄沟集雨种植可以改善西南旱地油菜田...     

基于东北温带落叶阔叶林通量数据的BEPS 模型参数优化

控制其他参数为经验常数,利用迭代方法对主要光合作用参数最大羧化速率(V_{c max}) 及最大电子传递速率(J_max)进行不同数值组合,将得到的多组模拟结果的逐日总初级生产力(GPP)分别与东北帽儿山落叶阔叶林的通量观测数据进行比较,实现对小时步长BEPSHourly模型V_{c max}和J_max的参数优化.结果表明: 对于东北温带落叶阔叶林,当V_{c max}为41.1 μmol·m^-2·s^-1、J_max 为82.8 μmol·m^-2·s^-1时,模拟的2011年逐日GPP与观测数据比较的均方根误差(RMSE)最小,为1.10 g C·m^-2·d^-1,R²最高,为0.95.经过光合作用参数V_{c max}和J_max优化后,BEPSHourly模型能更好地模拟GPP的季节变化.