Effect of kinetin spray on growth and productivity of black cumin plants

In field experiments, the test black cumin plants were sprayed with either deionized water (control test) or 10⁻⁵ M kinetin (KIN) at 40 (vegetative stage) or 60 (flowering) days after sowing (DAS). Spraying with KIN at 40 DAS brought about maximum stimulation of all parameters, whereas spraying at 60 DAS was not much effective. All characteristics recorded at 80 DAS (shoot length, leaf number, leaf area, branch number and dry weight per plant, net photosynthetic rate, stomatal conductance and leaf chlorophyll content), were significantly enhanced by KIN application. Further, at harvest (130 DAS), capsule number per plant, seed yield per plot, and biomass yield per plot, showed a significant increase over the control traits. However, number of seeds per capsule, 1000-seed weight and harvest index remained unaffected. Published in Russian in Fiziologiya Rastenii, 2007, Vol. 54, No. 5, pp. 790–793. The text was submitted by the author in English.     

Genetic variability of photosynthesis and water use in Balearic grapevine cultivars

A comparison of photosynthetic characteristics of 20 cultivars of grapevine ( Vitis vinifera L. ) from Mallorca (Balearic Islands, Spain) and two widespread cultivars, Cabernet Sauvignon and Chardonnay, was made under irrigation as well as in response to drought. Although these cultivars share a common origin, a high variability was found for several photosynthetic characters under irrigation. Interestingly, these variations were significant for gas-exchange parameters (net CO₂ assimilation, stomatal conductance and intrinsic water use efficiency) but not for chlorophyll fluorescence parameters (maximum photochemical efficiency, electron transport rate and non-photochemical quenching). Since water stress is the most limiting factor for plant production under the Mediterranean climate, it is presumable that these findings reflect specific selection pressures over physiological characteristics related to a balance between net carbon gain and water use. Some cultivars presented high carbon assimilation at the expense of a high water loss, whereas others were water savers, accompanied by low CO₂ assimilation even under irrigation. Escursach was found to be an interesting cultivar, presenting low water consumption at the same time as reasonably high carbon assimilation. These cultivars also showed different responses to drought, which allowed their classification in two main groups: alarmist cultivars, which showed strong reductions of stomatal conductance in response to relatively low decreases of leaf water potential, and luxurious cultivars, showing low reductions of stomatal conductance under water stress.     

Effect of Water Stress on Photosynthesis in Two Mulberry Genotypes with Different drought Tolerance

Three-month-old mulberry (Morus alba L.) cultivars (drought tolerant S13 and drought sensitive S54) were subjected to water stress for 15 d. Water stress decreased the leaf water potential, net photosynthetic rate (PN), and stomatal conductance (gs) in both the cultivars. However, the magnitude of decline was comparatively greater in the sensitive cultivar (S54). Intercellular CO2 concentration (Ci) was unaltered during mild stress, but significantly increased at severe stress in both cultivars. The photosystem 2 activity significantly declined only at a severe stress in both cultivars. The Ci/gs ratio representing the mesophyll efficiency was greater in the tolerant cultivar S13. Involvement of stomatal and/or non-stomatal components in declining PN depended on the severity and duration of stress. However, the degree of non-stomatal limitations was relatively less in the drought tolerant cultivar.     

Growth and gas exchange response to water shortage of a maize crop on different soil types

The effect of water shortage on growth and gas exchange of maize grown on sandy soil (SS) and clay soil was studied. The lower soil water content in the SS during vegetative growth stages did not affect plant height, above-ground biomass, and leaf area index (LAI). LAI reduction was observed on the SS during the reproductive stage due to early leaf senescence. Canopy and leaf gas exchanges, measured by eddy correlation technique and by a portable photosynthetic system, respectively, were affected by water stress and a greater reduction in net photosynthetic rate (A _N) and stomatal conductance (g _s) was observed on SS. Chlorophyll and carotenoids content was not affected by water shortage in either condition. Results support two main conclusions: (1) leaf photosynthetic capacity was unaffected by water stress, and (2) maize effectively endured water shortage during the vegetative growth stage.     

Response of the photosynthetic apparatus to a flowering-inductive period by water stress in <Emphasis Type="Italic">Citrus</Emphasis>

The photosynthetic responses to a flowering-inductive water-stress period and recovery were studied and compared in two Citrus species. Under greenhouse conditions, Fino lemon and Owari satsuma trees were subjected to moderate (−2 MPa at predawn) and severe (−3 MPa) water stress levels and were re-watered after 60 days. Vegetative growth was inhibited during the stress assays, and strong defoliation levels were reported, especially in Fino lemon. In both species, bud sprouting was induced after re-watering. Flowers and vegetative shoots developed in Owari satsuma after a drought period, and the development was independent of the stress level. In Fino lemon, vegetative shoots and flowers were primarily formed after moderate and severe stress, respectively. The photosynthetic rate and stomatal conductance were reduced by water stress, and a marked increase in water-use efficiency at the moderate water deficit level was observed. Nevertheless, the photosynthetic apparatus was not damaged, since the maximum quantum yield, photosynthetic pigment concentrations and Rubisco level and activity did not change. Furthermore, the measured malonyldialdehyde (MDA) and peroxidase activity indicated that oxidative stress was not specifically triggered by water stress in our study. Therefore, the gas exchange, fluorescence and biochemical parameters suggested that diffusional limitations to photosynthesis predominated in both of the studied Citrus species, and explained the rapid recovery of the photosynthetic parameters after rehydration. The net CO₂ fixation rate and stomatal conductance were recovered within 24 h in Fino lemon, whereas 3 days were required in Owari satsuma. This suggests the presence of some metabolic limitations in the latter species. Furthermore, the sensibility of the defoliation rates, the accumulation of proline and the stomatal behaviour in response to water stress indicated a higher drought tolerance of Fino lemon, according to its better acclimation to hot climates.     

Stomatal limitation of photosynthesis as affected by water stress and CO2 concentration

A water stress effect on photosynthesis and transpiration of wheat seedlings at 50-500 µmol(CO2) mol-1 was measured in an open gas exchange system. The limitation of photosynthesis by stomatal conductance was quantified by a stomatal control coefficient of the net photosynthetic rate. The stomatal control coefficient increased linearly as the water potential of root media decreased to -1 MPa, and it decreased with increasing CO2 concentration.     

干旱胁迫对降香黄檀幼苗光合生理特性的影响

采用温室盆栽方法,设置对照(CK)、轻度(LS)、中度(MS)和重度(HS)干旱胁迫4个水分条件,研究不同水分条件对降香黄檀幼苗光合和生理特性的影响。结果表明:(1)随着干旱胁迫程度增加,降香黄檀幼苗叶片叶绿素总含量总体呈现出下降趋势。(2)降香黄檀幼苗叶片净光合速率、气孔导度、胞间CO2浓度和蒸腾速率随着干旱胁迫强度增加均呈现出先增加后降低趋势,且MS和HS处理下的气孔导度和胞间CO2浓度同时降低,此时幼苗光合能力的下降主要受气孔因素限制。(3)随着干旱胁迫强度的增加,降香黄檀幼苗叶片细胞膜相对透性、丙二醛含量、游离脯氨酸含量和POD活性均呈现出增加趋势,而同期SOD和CAT活性呈现出先升高后降低趋势。可见,降香黄檀幼苗在轻度干旱胁迫下可通过增加叶片保护酶活性来清除活性氧对其组织造成的伤害,但胁迫超过一定程度后保护酶活性下降,表明降香黄檀幼苗的耐旱能力有限。     

Effects of foliar application of nitrogen on the photosynthetic performance and growth of two fescue cultivars under heat stress

The effects of nitrogen fertilization on the growth, photosynthetic pigment contents, gas exchange, and chlorophyll (Chl) fluorescence parameters in two tall fescue cultivars (Festuca arundinacea cv. Barlexas and Crossfire II) were investigated under heat stress at 38/30 °C (day/night) for two weeks. Shoot growth rate of two tall fescue cultivars declined significantly under heat stress, and N supply can improved the growth rates, especially for the Barlexas. Chl content, leaf net photosynthetic rate, stomatal conductance, water use efficiency, and the maximal efficiency of photosystem 2 photochemistry (F_v/F_m) also decreased less under heat stress by N supply, especially in Crossfire II. Moreover, cultivar variations in photosynthetic performance were associated with their different response to heat stress and nitrogen fertilization, which were evidenced by shoot growth rate and photosynthetic pigment contents.     

长期施肥对水稻光合特性及水分利用效率的影响

在实施了27年的长期田间定位试验区,研究了长期不同施肥对红壤区水稻光合特性及水分利用效率的影响.结果表明:在不施肥(CK)、无机肥(N、NP、NPK)、有机肥(猪粪+紫云英绿肥,M)和无机肥与有机肥配施(NPKM)处理中,长期施用肥料,特别是有机肥与无机肥配施提高水稻各生育期剑叶叶绿素含量、净光合作用速率、气孔导度、蒸腾速率、水分利用效率和水稻产量,降低水稻剑叶胞间CO_2浓度;水稻剑叶叶绿素含量、净光合作用速率、气孔导度、蒸腾速率随发育阶段演进而减小,孕穗期>齐穗期>乳熟期,而胞间CO_2浓度相反;水分利用效率以齐穗期为最大;水稻发育阶段叶绿素含量、净光合速率和水稻产量之间均呈显著正相关;长期施用肥料,特别是有机肥与无机肥配施更有利于红壤区水稻的生长发育、产量和水分利用效率的提高.

Abstract：

A field experiment has being conducted for 27 years in Jinxian County, Institute of Red Soil in Jiangxi Province (116°20'24" E, 28°15'30" N) to study the effects of fertilization on the rice photosynthetic traits and water use efficiency. Four treatments were installed,i. e., no fertilization (CK), chemical fertilization (N, NP, NPK), organic fertilization (M), and chemi-cal and organic fertilization (NPKM). Long-term fertilization, especially treatment NPKM, in- creased the flag leaf chlorophyll content, net photosynthetic rate, stomatal conductance, transpi-ration rate, and water use efficiency of rice at its all growth stages and the rice yield, and de-creased the flag leaf intercellular CO_2 concentration. With the growth of rice, the chlorophyll content, net photosynthetic rate, stomatal conductance, and transpiration rate decreased, but the intercellular CO_2 concentration increased. The water use efficiency was the greatest at full-head-ing stage. There were significant positive correlations between the chlorophyll content and net photosynthetic rate at various growth stages and the rice yield, Long-term fertilization, especially the combined chemical and organic fertilization, was favorable to the rice growth and develop-ment, water use efficiency, and yield production in red soil region.     

土壤水分与短期遮光对棉花光合及其气孔响应的影响

以陆地棉（Ｇｏｓｓｙｐｉｕｍ ｈｉｒｓｕｔｕｍ Ｌ．Ｚｈｏｎｇｍａｉｎ,Ｎｏ２３）为供试材料,探讨了在充分供水－水分胁迫－复水的处理过程中,短期不同遮光水平对棉花光合特性及其气孔响应的影响。结果表明,在水分处理过程中,所有不同遮光水平的棉花叶片对短期遮光具有相似的基本响应规律;短期遮光使净光合速率迅速降低,气孔导度减少,但减少速率缓慢;遮阳网去掉后,叶片气 重新开放速率和光合恢复被延迟,水分胁迫期     

Effects of root flooding and stage of development on the growth and photosynthesis of field bean (Vicia faba L. minor)

Field bean plants were subjected to flooding stress for 7 days, during two stages of development: at the vegetative phase (4-week-old seedlings) and at the generative phase (8-week-old plants). The height of plants, total area of leaves, the number of undamaged leaves, dry plant matter, chlorophyll content, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) activity, the maximum quantum yield of PS2 photochemistry (Fv/Fm ratio), the photosynthesis rate (P _N) and stomatal conductance (g _s) were determined. A strong reduction in stem elongation and leaf area as well as in dry matter production was observed as a result of flooding. The responses from vegetative plants were greater than in generative plants. Waterlogging decreased chlorophyll a and b in leaves, notably at the vegetative stage, and persisted after cessation of flooding. After flooding, photosynthesis was strongly reduced and positively correlated with decreased stomatal conductance. Damage to the photosynthetic apparatus resulted in a lower Fv/Fm especially in young seedlings. In vegetative plants Fv/Fm quickly returned to the control levels after the soil was drained. The results show that an excess of water in the soil limits growth and injures the photosynthetic apparatus in field beans, but that the extent of the injury is strongly age dependent.     

Photosynthetic performance of two coffee species under drought

Coffea arabica cv. Red Catuaí and C. canephora cv. Kouillou were grown in pots beneath a plastic shelter. When they were 14 months old, irrigation was withheld until the leaf pre-dawn water potential was about -1.5 and -2.7 MPa (designated mild and severe water stress, respectively). Under mild stress, net photosynthetic rate (PN) decreased mainly as a consequence of stomatal limitations in Kouillou, whereas such decreases were dominated by non-stomatal limitations in Catuaí. Under severe drought, further decreases in PN and apparent quantum yield were not associated to any changes in stomatal conductance in either cultivar. Decreases were much more pronounced in Catuaí than in Kouillou, the latter maintained carbon gain at the expense of water conservation. In both cultivars the initial chlorophyll (Chl) fluorescence slightly increased with no changes in the quantum efficiency of photosystem 2. In response to rapidly imposed drought, the Chl content did not change while saccharide content increased and starch content decreased. Photoinhibition and recovery of photosynthesis, as evaluated by the ratio of variable to maximum fluorescence and by the photosynthetic O2 evolution, were unaffected by mild drought stress. Photoinhibition was enhanced under severe water deficit, especially in Catuaí. In this cultivar the O2 evolution did not resume upon reversal from photoinhibition, in contrast to the complete recovery in Kouillou.     

干旱胁迫下杨树无性系苗期光合与气孔形态变异研究

为了解不同干旱胁迫处理下,杨树叶片光合特性和气孔形态的变化规律,本研究以4个杨树无性系为材料,对其干旱胁迫下光合指标与气孔形态指标进行测定分析,方差分析结果表明：除气孔器长在处理间差异不显著外,其他性状在无性系间、处理间和无性系与处理交互作用间均达极显著差异水平。随着土壤相对含水量的逐渐降低,无性系净光合速率、蒸腾速率和气孔导度都呈现出不同程度的下降;而胞间二氧化碳浓度呈现为先降后升趋势,表明当土壤相对含水量大于40%时,光合作用的主要限制因子是气孔因素,当土壤相对含水量低于40%时,光合作用的主要限制因子转换为非气孔因素。气孔形态研究结果表明,各指标均随土壤相对含水量的持续降低呈现出持续下降趋势。利用隶属函数法对不同干旱胁迫下4个杨树无性系的抗旱性进行综合评价,结果表明：白城小青黑杨的抗旱性优于其他三个无性系。     

西双版纳热带雨林中两种生态型蕨类植物的光合特性比较研究

通过比较分布于西双版纳热带雨林林下生境中的附生鸟巢蕨(Neottopteris nidus)和地生网脉铁角蕨(Asplenium finlaysonianum)的光合特征和光合诱导特性, 来研究不同生态型蕨类植物的光斑利用策略。研究结果表明, 2种蕨类植物的最大净光合速率、暗呼吸速率、表观量子效率、光饱和点和光补偿点没有显著差异, 但网脉铁角蕨的最大气孔导度远远高于鸟巢蕨, 表明后者具有更强的光合水分利用效率。在暗处理3小时接着光照(光强为20 mmol .m-2.s-1)30分钟后, 网脉铁角蕨的初始气孔导度显著高于鸟巢蕨。连续照射饱和强光后, 网脉铁角蕨达到最大净光合速率50%(T50%)和90%的时间(T90%)比鸟巢蕨短: 网脉铁角蕨和鸟巢蕨的T50%分别为0.57和5.31分钟, T90%分别为5.85和26.33分钟。诱导过程中, 气孔导度对强光的响应明显滞后于净光合速率。鸟巢蕨达到最大气孔导度的时间明显比网脉铁角蕨慢, 但在光合诱导消失过程中2种蕨类植物的 光合诱导维持能力却没有显著差异。上述结果表明, 与大多数地生林下植物(如网脉铁角蕨)相比, 附生鸟巢蕨的水分保护比碳获得更重要, 但却限制了附生蕨对光斑的利用。     

羊草叶片气体交换参数对温度和土壤水分的响应

 采用生长箱控制的方法研究了羊草(Leymus chinensis)幼苗叶片光合参数对5个温度和5个水分梯度的响应和适应。结果表明：轻度、中度土壤干旱并没有限制羊草叶片的生长,对气体交换参数亦无显著影响,反映了羊草幼苗对土壤水分胁迫的较高耐性。叶片生物量以26 ℃时最大,其它依次为23 ℃、20 ℃、29 ℃和32 ℃。温度升高使气孔导度和蒸腾速率增加, 却使光合速率和水分利用效率降低。水分和温度对叶片生物量、光合速率、气孔导度和蒸腾速率存在显著的交互作用,表明高温加强了干旱对叶片生长和气体交换的影响, 降低了羊草对土壤干旱的适应能力。高温和干旱的交互作用将显著减少我国半干旱地区草原的羊草生产力。     

Photosynthetic performance of two coffee species under drought

Coffea arabica cv. Red Catuaí and C. canephora cv. Kouillou were grown in pots beneath a plastic shelter. When they were 14 months old, irrigation was withheld until the leaf pre-dawn water potential was about -1.5 and -2.7 MPa (designated mild and severe water stress, respectively). Under mild stress, net photosynthetic rate (PN) decreased mainly as a consequence of stomatal limitations in Kouillou, whereas such decreases were dominated by non-stomatal limitations in Catuaí. Under severe drought, further decreases in PN and apparent quantum yield were not associated to any changes in stomatal conductance in either cultivar. Decreases were much more pronounced in Catuaí than in Kouillou, the latter maintained carbon gain at the expense of water conservation. In both cultivars the initial chlorophyll (Chl) fluorescence slightly increased with no changes in the quantum efficiency of photosystem 2. In response to rapidly imposed drought, the Chl content did not change while saccharide content increased and starch content decreased. Photoinhibition and recovery of photosynthesis, as evaluated by the ratio of variable to maximum fluorescence and by the photosynthetic O2 evolution, were unaffected by mild drought stress. Photoinhibition was enhanced under severe water deficit, especially in Catuaí. In this cultivar the O2 evolution did not resume upon reversal from photoinhibition, in contrast to the complete recovery in Kouillou. This revised version was published online in June 2006 with corrections to the Cover Date.     

施氮量对小麦叶片硝酸还原酶活性、一氧化氮含量和气体交换的影响

研究了不同施氮量对冬小麦分蘖到抽穗期叶片硝酸还原酶(NR)活性、一氧化氮(NO)含量、气体交换参数和籽粒产量的影响.结果表明:叶片光合速率（P_n）、蒸腾速率（T_r）、瞬时水分利用效率（IWUE）和产量均随施氮量的增加呈先升高后降低的趋势,在180 kg·hm^-2氮处理时达到最高.随施氮量的增加,叶片NR活性提高; 在分蘖期和拔节期,叶片NR活性与NO含量呈显著线性相关（R²≥0.68,n=15）,NO含量和气孔导度（G_s）呈显著正二次相关（R²≥0.43,n=15）;低氮处理下,NR活性较低使叶片NO含量维持在较低水平,促进气孔开放,高氮处理下,NR活性较高使叶片NO含量增加,诱导气孔关闭;在抽穗期叶片NR活性和NO含量无显著相关关系,虽然NO含量和G_s也呈显著正二次相关（R²≥0.36,n=15）,但不能通过施氮提高NR活性来影响叶片NO含量,进而调节叶片气孔行为.合理施氮使小麦叶片NO含量维持在较低水平,可提高叶片G_s、T_r和IWUE,增强作物抗旱能力,促进光合作用,提高小麦产量.     

NaCl胁迫对两种番茄气孔特征、气体交换参数和生物量的影响

为探讨番茄叶片气孔特征、气体交换参数和生物量对盐胁迫的响应机理,以赛棚和阿拉姆番茄为试材,通过向水培营养液中添加NaCl(0.1 mol·L^-1),在人工气候箱条件下进行为期90 d的NaCl盐胁迫处理.结果表明: NaCl胁迫导致赛棚番茄叶片的气孔密度、气孔宽度、气孔面积和气孔面积指数显著降低,降幅分别为32%、45%、25%、49%,但没有改变阿拉姆番茄叶片的气孔特征参数.同时,NaCl胁迫还导致赛棚和阿拉姆叶片气孔规则分布的空间尺度分别减少30%和43%,且赛棚品种的单个气孔最小邻域距离在盐胁迫下增加20%.另外,赛棚和阿拉姆叶片的净光合速率(P_n)、气孔导度(g_s)和蒸腾速率(T_r)在盐胁迫下均显著下降,通过气孔限制值分析发现,盐胁迫导致赛棚番茄叶片光合速率下降主要是由气孔限制因素引起的,而阿拉姆叶片则以非气孔限制因素为主导作用.盐胁迫还导致赛棚和阿拉姆番茄生物量显著降低,且地下生物量的下降幅度大于地上生物量.综合分析表明,阿拉姆的抗盐能力高于赛棚.     

Effect of Brown Stem Rot on Water Relations of Soybean

To investigate the effects of brown stem rot, a vascular disease of soybean (Glycine max) induced by Phialophora gregata, on the water relations of diseased plants, stems of greenhouse-grown plants of susceptible (Pride B216) and resistant (BSR 201) cultivars were injected with the pathogen at vegetative growth stage VI. Plants of both cultivars developed internal stem browning, but those of Pride B216 developed more severe symptoms of water stress (reduced leaf water potential and stem conductance). Inoculated plants of both cultivars also had reduced stem conductance and increased stomatal conductance and transpiration. Disease-related water stress can be attributed to the combined effects of reduced stem conductance and increased water loss resulting from increased stomatal conductance.     

番茄叶片光合作用对快速水分胁迫的响应

采用聚乙二醇(PEG 6000)溶液控制番茄根际水势和叶片离体的方式设置了水分胁迫处理,测算了光合诱导过程中净光合速率、暗呼吸速率和CO₂补偿点等光合参数的变化.结果表明： 在1000 μmol·m^-2·s^-1光诱导下,水分胁迫处理的番茄叶片净光合速率(P_n)达到最大值所需时间缩短为对照的1/3,气孔导度(g_s)快速增大为对照的1.5倍.水分胁迫处理的番茄叶片光饱和点(LSP)比对照降低了65%～85%,而光补偿点(LCP)比对照增加了75%～100%,缩小了番茄叶片利用光能的有效范围.水分胁迫处理的番茄叶片最大光合能力(A_max)低于对照40%以上,暗呼吸速率(R_d)增大了约45%.可见,快速水分胁迫处理使番茄叶片气孔迅速开放,光合诱导初始阶段消失.水分胁迫导致植物利用光能的效率和潜力降低是植物生产力下降的重要原因,而气孔调节是番茄适应快速水分胁迫的重要生理机制.