Effect of Methanol on Photosynthesis and Chlorophyll Fluorescence of Flag Leaves of Winter Wheat

Photosynthesis and chlorophyll a fluorescence parameters, photochemical efficiency of PS II （Fv/Fm）, photochemical quenching of PS II （qP）, nonphotochemical quenching of PS II （NPQ）, maximum activity of PS II （Fv/Fo） as well as electron transport rate （ETR）, and quantum yield of PS II （ФPS II） were measured on flag leaves of the winter wheat treated by methanol at different concentrations. The results revealed that photosynthesis was greatly improved by methanol, as indicated by higher photosynthetic rates and stomatal conductance. The enhancement effect of methanol on photosynthesis was maintained for 3-4 days. Different methanol concentration treatments also increased intercellular CO2 concentration and transpiration rates. No significant decline was found in Fv/Fm, Fv/Fo, and ФPS II, which revealed no photoinhibition during methanol application in different methanol concentrations. Methanol showing no apparent inhibitory effects indicated higher potential photosynthetic capacity of flag leaves of winter wheat. However, the increase in photosynthesis was not followed by an increase in the photosynthetic activity （Fv/Fm）, and fluorescence parameters did not indicate an improvement in intercellular CO2 concentration and PS II photochemical efficiency compared with the control, thereby encouraging us to propose that lower leaf temperatures caused by applied methanol would reduce both dark respiration and photorespiration （most importantly）, thus, increasing net CO2 uptake and photosynthetic rates.

Effect of Nitrogen Fertilization on Leaf Chlorophyll Fluorescence in Field-Grown Winter Wheat Under Rainfed Conditions

The effect of nitrogen fertilization on leaf chlorophyll fluorescence was studied in field-grown winter wheat during grain filling underrainfed conditions in Loess Plateau. Results showed that the actual photochemical efficiency of PSⅡ reaction center (F PSⅡ)decreased significantly as leaf water stress progressed, however, the F PS was increased by nitrogen fertilization. The F PSⅡ of 0, 90 and180 kg ha-1 nitrogen treatments at noon were 0.197, 0.279 and 0.283, respectively, which decreased by 57.7, 56.4 and 40.2% as comparedto those in the morning. In the afternoon, the F PSⅡ partialy or completely recovered to the levels in the morning. The values of F PS Ⅱin 0 and 90kgha-1 treatments recovered to 87.3 and 81.5% of those in the morning. In 180kgha-1 treatment, the F PSⅡ in the afternoonwas even higher than that in the morning. Application of nitrogen fertilizer significantly increased maximum photochemical efficiency(Fv/Fm), photochemical quenching coefficient (qP) and non-photochemical quenching coefficient (qNP). These results indicated thatapplication of nitrogen fertilizer could increase the light energy conversion efficiency, the potential activity of photosynthetic reactioncenter, and the non-photochemical dissipation of excess light energy, which can prevent leaf photosynthetic apparatus from damage ofenvironmental stress. However, there was no significant difference in the values of F PSⅡbetween 90 and 180kgha-1 nitrogentreatments, indicating that the excess nitrogen was unfavorable to photosynthesis.

Effect of Heat Stress on Photosynthetic Characteristics of Different Green Organs of Winter Wheat During Grain-filling Stage

Four winter wheat (Triticum aestivum L.) varieties ('JD 8', 'Jing 411','Centurk' and 'Tam 202') were used to study the effect of heat stress on photosynthetic characteristics of flag leaf blade, nag leaf sheath, peduncle, glume, lemma and awn during grain-filling stage. The results showed that heat acclimation during grain-filling stage increased thermotolerance of wheat with significant differences among different green organs. During heat stress, the decreases of the efficiency of primary light energy conversion (F-v/F-m) of PS II and pigment (chlorophyll and carotenoid) content were much slower in peduncle, flag leaf sheath and glume than in nag leaf blade, lemma and ann; and the percentage of decrease in net photosynthetic rate (P-n) of ear was lower than that of the nag leaf blade. The measured photosynthetic parameters (F-v/F-m, P-n and pigment content) of 'JD 8', a relatively heat tolerant variety, declined more slowly than those of the other three varieties during the whole heat stress period.

Effects of Water Stress on Leaf Water and Chlorophyll Fluorescence Parameters of Sugarcane Seedling

[Objective] The aim was to explore the effects of water stress on leaf water and chlorophyll fluorescence parameters of sugarcane seedling,as well as to provide basis for the study on sugarcane production and evaluation. [Method] Seven different sugarcane varieties were studied at the seedling stage under drought stress,and the changes of leaf water and chlorophyll fluorescence parameters under stress conditions were detected. [Result] leaf water potential,leaf relative water content and soil relative water content showed a certain amount of internal relationship,the sugarcane varieties that had more tolerant to drought had higher utilization rate of soil water; the correlation analysis and factor analysis suggested that the survival rate at seedling stage under drought stress,Fv/Fm,leaf water potential and relative water content could be used as drought resistance evaluation indicators. [Conclusion] As a relatively independent influencing factor,water potential had dominating effect on drought resistance,and the reliability of Fv/Fm as drought resistance evaluation indicator had been verified.

Effects of drought stress on photosynthesis and chlorophyll fluorescence images of soybean(Glycine max)seedlings

The main purpose of this research is to provide a theoretical foundation for the screening of drought-resistant soybean varieties and to establish an efficient method to detect the PSII actual photochemical quantum yields efficiently.Three soybean varieties were compared in this experiment after 15 d when they were planted in a greenhouse.These varieties were then exposed to light drought stress(LD)and serious drought stress(SD)conditions.With five times’measurement,chlorophyll fluorescence and soil-plant analysis development considered as the main basis for this study.Several parameters in SD conditions significantly reduced,such as net photosynthetic rates(Pn),stomatal conductance(Gs),PSII primary light energy conversion efficiency(Fv/FM),PSII actual photochemical quantum yields[Y(II)],photochemical quenching coefficient(qP)and non-photochemical quenching coefficient(qN).The soybeans in the seedling stage adapted to the inhibitory effect of drought stress on photosynthesis through stomatal limitation.Under serious drought stress,non-stomatal limitation damaged the plant photosynthetic system.The amplitudes of Pn and Y(II)of drought-resistant Qihuang 35 were lower than those of the two other varieties.Based on the data of this study,a new method had been developed to detect Y(II)which reflected the photosynthetic capacity of plant,R=0.85989,u=0.048803 when using multiple linear regression,and R=0.84285,u=0.054739 when using partial least square regression.

Effects of drought stress on the photosynthetic physiological parameters of Populus 3 euramericana ‘‘Neva''

Populus 9 euramericana ‘‘Neva'' is the main poplar species in China, where drought stress is becoming extremely urgent. We carried out this research to study the effects of drought stress on the photosynthesis of Populus 9 euramericana ‘‘Neva''. Drought stress was induced by 58–62%(light), 48–52%(moderate), and 38–42%(severe) relative soil moisture content(RSMC). The effects of drought stress on photosynthetic rate, chlorophyll fluorescence parameters, and other related physiological parameters were investigated during treatment. Net photosynthetic rate(PN), and stomatal conductance decreased significantly and intercellular CO_2 concentration initially increased and then declined, whereas the stomatal limitation factors showed opposite trends in the light under moderate drought stress. Photosystem II(PSII) maximum photochemical efficiency, actual photochemical efficiency,and photochemical quenching decreased gradually under drought stress, whereas nonphotochemical quenching initially increased and then declined. Superoxide dismutase,peroxidase, and catalase activities initially increased and then decreased as RSMC was reduced, whereas malondialdehyde(MDA) content and relative electric conductivity(REC) increased gradually. These results suggest that stomatal factors accounted for the decline in PNunder light and moderate drought stress, whereas leaf PNdecreased mainly due to non-stomatal factors under severe drought stress. PSII was damaged; thus, photosynthetic electron transfer was restricted, indicating that heat dissipation is important for the light protection mechanism of plants.Antioxidant enzymes increased at the beginning of treatment, and the increased MDA and REC led to cell membrane damage. These results suggest that poplar seedlings stabilized their photosynthetic apparatus by reducing the light trapping ability under light and moderate drought stress conditions. This helped dissipate heat and enhance antioxidant enzyme activity. Stomatal factors accounted for the decline in P_N, whereas damage to PSII and antioxidant enzymes under severe drought stress suggested that the decline in P_N was caused by non-stomatal restrictive factors.

Physiological Effect of New FA Antitranspirant Application on Winter Wheat at Ear Filling Stage

The physiological effect of new FA antitranspirant on winter wheat was studied by field trial. The new FA antitranspirant was sprayed at ear filling stage, using the following concentrations： 0.5, 1.0, 1.5 and 2.0 mL L^-1. The results indicated that new FA antitranspirant increased nitrate reductase activity （NRA）, free proline content, chlorophyll content and water content of leaf, thus drought stress can be mitigated. The new FA antitranspirant increased photosynthesis, enlarged stomatal conductance and reduced transpiration rate, thus led to growth stimulation and water loss reduction. New FA antitranspirant caused an increase of grain yield by 7.2%, under the optimal concentration 1.5 mL L^-1.

Interactive Effects of Drought Stresses and Elevated CO_2 Concentration on Photochemistry Efficiency of Cucumber Seedlings

To reveal and quantify the interactive effects of drought stresses and elevated CO2 concentration [CO2] on photochemistry efficiency of cucumber seedlings, the portable chlorophyll meter was used to measure the chlorophyll content, and the Imaging-PAM was used to image the chlorophyll fluorescence parameters and rapid light response curves （RLC） of leaves in two adjacent greenhouses. The results showed that chlorophyll content of leaves was reduced significantly with drought stress aggravated. Minimal fluorescence （Fo） was increased while maximal quantum yield of PSII （Fv/Fm） decreased significantly by severe drought stress. The significant decrease of effective quantum yield of PSII （Y（Ⅱ）） accompanied by the significant increase of quantum yield of regulated energy dissipation （Y（NPQ）） was observed under severe drought stress condition, but there was no change of quantum yield of nonregulated energy dissipation （Y（NO））. We detected that the coefficient of photochemical quenching （qP） decreased, and non-photochemical quenching （NPQ） increased significantly under severe drought stress. Furthermore, we found that maximum apparent electron transport rate （ETRmax） and saturating photosynthetically active radiation （PPFDsat） decreased significantly with drought stress aggravated. However, elevated [CO2] significantly increased FvlFm, qP and PPFDsat, and decreased NPQ under all water conditions, although there were no significant effects on chlorophyll content, Fo, Y（Ⅱ）, Y（NPQ）, Y（NO） and ETRmax. Therefore, it is concluded that CO2-fertilized greenhouses or elevated atmospheric [CO2] in the future could be favorable for cucumber growth and development, and beneficial to alleviate the negative effects of drought stresses to a certain extent.

Canopy Temperature Depression as a Potential Selection Criterion for Drought Resistance in Wheat

Field studies were conducted at Bushland, Texas, USA, in 2004 to examine usefulness of canopy temperature depression （CTD）, the difference of air-canopy temperature, in screening wheat （Triticum aestivum L.） genotypes for yield under dryland and irrigated. Forty winter wheat genotypes were grown under irrigation and dryland. CTDs were recorded after heading between 1 330 and 1 530 h on 6 clear days for dryland and 9 days for irrigation. Drought susceptible index （DSI） for each genotype was calculated using mean yield under dryland and irrigated conditions. Genotypes exhibited great differences in CTD under each environment. The dryland CTDs averaged 1.33℃ ranging from -0.67 to 2.57℃, and the average irrigation CTD were 4.59℃ ranging from 3.21 to 5.62℃. A low yield reduction was observed under dryland conditions relative to irrigated conditions for high-CTD genotypes. CTD values were highly negatively correlated with DSI under dryland, and genotypes of CTDs = 1.3℃ in dryland condition were identified as drought resistant. For 21 genotypes classified as drought resistant by DSI, their CTDs were 1.68℃ for dryland and 4.35℃ for irrigation on average; for 19 genotypes classified as drought susceptible by DSI, average CTD was 0.94℃ in dryland and 4.85℃ in irrigation. The high-yield genotypes consistently had high CTD values, and the low-yield ones had low CTD values for all measurements in dryland. After heading, genotypes maintained consistent ranking for CTD. Regression results for CTD and yield suggested that the best time for taking CTD measurement was 3-4 weeks after heading in irrigation but any time before senescence in dryland. Crop water stress index （CWSI） calculated from CTD data was highly correlated with CWSI calculated from yield, which suggesting traditional costly CWSI measurement may be improved by using portable infrared thermometers. Most importantly, grain yield was highly correlated with CTD under dryland （R^2 = 0.79-0.86） and irrigation （R^2 = 0.46-0.58） conditions. These results clearly indicated grain yield and water stress can be predicted by taking CTD values in field, which can be used by breeding programs as a potential selection criterion for grain yield and drought resistance in wheat, but a second study year is needed to confirm further.

干旱胁迫条件下朱槿叶绿素荧光特性

以朱槿为试验材料,研究了干旱胁迫及复水对朱槿叶片叶绿素荧光参数的影响。结果表明:朱槿在经受25 d自然干旱胁迫后,除Fv/Fm值显著降低外,Y(Ⅱ)、qP、NPQ、ETR等值均有所上升。复水1 d后,Fv/Fm值有止降回升的趋势,Y(Ⅱ)、qP、NPQ、ETR等参数则恢复到对照水平。利用直角双曲线修正模型拟合的快速光曲线结果表明,中度干旱胁迫提高了朱槿光化学反应的启动能力,在弱光条件下具有最高的光能利用效率。当光强超过190μmol/(m^(2)·s)时,CK和复水1 d的适应能力更强,具有最大适应光强变化的能力和光合活性。研究综合认为,朱槿在干旱胁迫下具有良好的自身调节能力,具有较强的光合系统损伤修复能力,表现出极强的抗干旱胁迫能力,可在较干旱地区栽培应用。

PEG6000模拟干旱胁迫对铁皮石斛幼苗生理和叶绿素荧光特性的影响

【目的】研究聚乙二醇6000(PEG 6000)模拟干旱对铁皮石斛Dendrobium candidum生理和叶绿素荧光特性的影响,为铁皮石斛的品种选育、产业化栽培和近野生栽培等提供参考。【方法】以铁皮石斛‘晶品1号’D.candidum‘Jingpin No.1’幼苗为实验材料,通过不同质量分数PEG 6000(5%、10%、20%、30%)模拟干旱胁迫处理铁皮石斛幼苗,观察铁皮石斛幼苗茎段和叶片细胞结构,并检测铁皮石斛叶片过氧化物酶(POD)、过氧化氢酶(CAT)活性及丙二醛(MDA)质量摩尔浓度、可溶性糖质量分数、可溶性蛋白质量分数、叶绿素质量分数及叶绿素荧光参数的动态变化。【结果】①高质量分数PEG 6000(20%-30%)处理后铁皮石斛茎段和叶片细胞内叶绿素质量分数减少。②PEG 6000模拟干旱胁迫处理对铁皮石斛幼苗可溶性糖和可溶性蛋白、MDA、POD和CAT有显著影响(P<0.05)。可溶性糖质量分数随着PEG 6000质量分数的增加和处理时间的延长均呈上升趋势,到第12天时达最高值;可溶性蛋白则呈下降趋势;MDA质量摩尔浓度、POD活性和CAT活性随着PEG 6000质量分数的增加呈先上升后下降的趋势,在PEG 6000为20%时达到峰值。③PEG 6000模拟干旱处理对铁皮石斛幼苗最大光化学效率(F_(v)/F_(m))、光合效率(α)、电子传递速度(ETR)、光化学猝灭系数(q_(P))和非化学猝灭系数(qNP)等叶绿素荧光参数有显著的影响(P<0.05)。随着PEG 6000胁迫处理时间的延长和PEG 6000质量分数的增加,α、ETR、F_(v)/F_(m)和q_(P)均呈显著下降趋势(P<0.05);而qNP则呈先上升后下降的趋势。【结论】20%PEG 6000处理12 d可用作铁皮石斛抗干旱品种的筛选,铁皮石斛幼苗可通过增加可溶性糖质量分数,减少可溶性蛋白质量分数,提高POD和CAT活性等防御酶活性抵抗和适应一定程度的干旱胁迫;铁皮石斛幼苗的最大光能转换效率降低,光合系统Ⅱ(PSⅡ)受到胁迫损伤,严重影响铁皮石斛幼苗的光合作用。同时,铁皮石斛幼苗通过启动qNP途径来消耗PSⅡ反应中心吸收的过剩光能,维持正常的光合作用。因此,可溶性糖和可溶性蛋白、POD和CAT以及叶绿体荧光参数均可作为铁皮石斛耐干旱的指标。

基于BA-SVM的冬小麦旱情表型分析与诊断

提升作物水分表型诊断精度和时效性是当前智慧灌溉领域研究的难点和热点之一。该研究针对以上难点提出了一种改进机器视觉算法的冬小麦旱情智能诊断方法。在测坑试验系统中设置了适宜水分处理(CK)、中度干旱处理(T1)、重度干旱处理(T2),通过数码相机获取冬小麦早期RGB高清图像,利用HSV色彩空间改进的K-means聚类算法对小麦图像分割敏感区域,提取图像颜色和纹理特征数据并开展主成分分析,辨别出累计贡献率达到97.2%的前3维主成分。采用蝙蝠算法优化支持向量机(bat algorithm-support vector machine,BA-SVM)惩罚因子(c=5)和核参数(σ=0.1),建立了基于蝙蝠算法优化的冬小麦旱情感知支持向量机模型,运用主成分分析降维后的识别精度优于其他特征组合,识别正确率为96.5%。明显高于GA-SVM(6.5%)和SVM(9.3%),运行时间分别缩短7、14 s。构建了冬小麦旱情智能诊断方法,可为实时诊断冬小麦旱情和智慧灌溉决策提供参考。

土壤逐渐干旱条件下玉米和构树光合特性的变化

在气候和喀斯特地形地貌的影响下,一些喀斯特地区依旧处在日益严重和频发的干旱情况中,这会对植物的光合特性和叶绿素荧光特性产生严重的影响。本文以喀斯特地区两种土壤(粉砂质壤土(Ld)和粉砂质粘壤土(Lc))和两种植物(玉米(Zea mays L.)和构树(Broussonetia Papyrifera(Linn.)L'Her.ex Ven.))为研究对象,研究了在逐渐干旱的条件下构树和玉米叶片的光合参数和叶绿素荧光变量的变化规律。研究结果表明,干旱胁迫期间,两种植物的净光合速率(A)、蒸腾速率(E)和气孔导度(gsw)均逐渐降低,胞间CO_(2)浓度(Ci)后期显著上升,水分利用效率(WUE)均表现为先上升后下降的趋势。在相同土壤中玉米的WUE高于构树,不同土壤中同种植物的最大WUE均为Ld高于Lc。玉米在两种土壤条件下的初始荧光(Fo)随时间的变化呈现前期先降低,中期稳定,后期再快速升高的趋势,最大光化学效率(Fv/Fm)的变化趋势与Fo相反。构树的Fo则只存在先下降后升高两个阶段,其Fv/Fm的变化趋势也与Fo相反。同时根据叶片A、gsw和Ci的变化趋势判别出气孔限制和非气孔限制分别是干旱前中期和后期影响玉米和构树光合特性的主要因素,且Lc和Ld中玉米的两种限制的交替时间节点分别为第10天和第9天,构树为第10天和第7天,当超过这个时间点,植物即使复水光合作用也无法回升,也可称此节点为调亏灌溉点。本研究可为了解喀斯特地区植物对干旱环境的适应性和用水特征以及田间水分管理提供科学依据。

不同水分条件下施磷对冬小麦穗花结实及光合特性的影响

为探究不同水分条件下施磷肥对冬小麦光合及结实特性的调控效应,明确施磷调控光合生产力促进穗花发育成粒的机制,于2020—2022年设置3种水分处理(W0:重度干旱;W1:中度干旱;W2:正常水分)和2种磷肥处理(P0:不施磷;P1:施磷)的盆栽试验,以大穗型品种周麦16(V1)和多穗型品种豫麦49-198(V2)为试验材料,通过测定不同穗位(基部、中部和顶部)的可孕小花数、结实数以及叶片净光合速率、叶绿素、叶绿素荧光参数、蔗糖含量等,分析不同水分条件下磷素对两类型品种冬小麦光合及结实特性的影响。结果表明,施磷肥可以有效增加冬小麦开花期(W10时期)可孕小花数,尤其对基部穗位的可孕小花数提升效果最显著(13.74%—27.01%),其次是顶部(9.57%—20.19%),再次是中部(6.97%—14.01%)。对成熟期的结实粒数而言,施磷肥可以提高干旱胁迫下每穗的小穗数以及各小穗的结实数,进而显著提高每穗的结实粒数。此外,施磷肥可以有效提高两类型品种叶片净光合速率、叶绿素含量、光系统Ⅱ最大光化学效率(F_(v)/F_(m))和实际光化学效率(Φ_(PSII));对蔗糖含量的影响因水分而异,干旱处理下增施磷肥降低了蔗糖含量,正常水分条件下则增加了蔗糖含量。将两类型品种光合指标分别与可孕小花数和穗粒数进行通径分析发现,5个光合指标与可孕小花数和穗粒数均呈正相关,其中净光合速率和蔗糖与可孕小花数的直接通径系数为1.001和0.435,与穗粒数的直接通径系数为0.996和0.626,远高于其他指标。最终,施磷通过增加穗数、穗粒数以及千粒重来显著增加产量,其中穗粒数在不同水分下均达到显著水平,穗数在W1和W2处理下显著,千粒重提升效果不显著。综上所述,在不同水分条件下施磷肥均可以通过调控冬小麦的光合性能提高其光合生产力,以维持正常的生理代谢功能,从而减少可孕小花的退化和败育以促进穗花成粒,最终达到缓解干旱胁迫危害以实现高产稳产的目的。研究结果为小麦生产中合理施用磷肥缓解干旱胁迫提供理论依据和技术支撑。

高温干旱复合胁迫下冬小麦叶片和冠层尺度SIF与光合作用的关联变化特征研究

为探究高温干旱复合胁迫下叶片和冠层尺度日光诱导叶绿素荧光(solar-induced chlorophyll fluorescence,SIF)与植物光合作用的关系,开展冬小麦高温干旱复合胁迫田间试验,共设置三种水分条件[严重干旱(50%~60%田间持水量)、轻度干旱(65%~75%田间持水量)和正常供水对照组(80%~90%田间持水量)]和三个温度水平(半包式增温、全包式增温和大田环境温度对照组),分析不同胁迫处理下冠层和叶片尺度SIF、冠层总初级生产力(gross primary productivity,GPP)和叶片净光合速率(net photosynthetic rate,P_(n))的日变化和季节变化特征,探讨小麦叶片SIF与P_(n)和冠层SIF与GPP之间的关联性。结果表明,高温干旱复合胁迫下日尺度和季节尺度叶片和冠层SIF总体均呈现出单峰型变化特征,季节尺度冠层SIF对干旱胁迫的响应比叶片SIF明显,且高温干旱复合胁迫对叶片和冠层SIF的影响均大于单一高温或干旱胁迫。P_(n)和GPP总体分别呈现出双峰型和单峰型变化特征。高温干旱复合胁迫下叶片SIF与P_(n)的相关性(R^(2)=0.42)小于冠层SIF与GPP的相关性(R^(2)=0.52),随着单一胁迫的增强,二者之间的相关性逐渐降低,且干旱胁迫对二者关系以及P_(n)和GPP的影响均大于高温胁迫。此外,环境变量中温度对SIF与P_(n)关系的影响最大,其次是饱和水汽压差(vapor pressure deficit,VPD),光合有效辐射(photosynthetic active radiation,PAR)影响最小,且SIF与P_(n)之间的相关性随温度的增加逐渐降低,随VPD的增大先降后升,随PAR的增加先升后降。高温干旱复合胁迫下冠层和叶片SIF大小与植物光合作用强弱有一定关联性,并受环境变量影响。

穗分化末期-灌浆初期干旱胁迫对优质食味粳稻根系形态和叶片光合特性的影响

【目的】研究穗分化末期至灌浆初期土壤干旱对优质食味粳稻根系形态生理与叶片光合特性的影响,为水稻抗旱栽培提供理论参考。【方法】以南粳9108和丰粳1606为供试材料,分别在穗分化末期至籽粒灌浆初期20 d(BAH)、穗分化末期10 d(BH)与灌浆初期10 d(AH)设置轻度干旱(LD,ψsoil=−20±5 kPa)、重度干旱(SD,ψsoil=−40±5 kPa)及常规水分(CK)处理。【结果】1)在处理结束当天、处理结束后10 d、穗后30 d与成熟期,根长、根表面积、根体积、根尖数、根干质量与根系活力均表现为SD<LD<CK,根冠比呈相反趋势。在处理结束时,BAH时段SD、LD均与CK差异显著,除根冠比外,BH、AH时段SD与CK差异显著,LD与CK无显著差异。处理结束后10 d、穗后30 d与成熟期,BAH时期SD与CK差异显著,除根尖数外LD与CK差异不显著,BH时期SD根系部分指标与CK差异显著,AH时期水分处理间无显著差异。2)在处理结束时、处理结束后10 d、穗后30 d与成熟期,剑叶净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、胞间CO_(2)浓度(Ci)、最大光化学效率(Fv/Fm)、光化学猝灭系数(qp)均表现为SD<LD<CK,非光化学猝灭系数(NPQ)呈相反趋势。在处理结束时,BAH时段SD、LD各指标均与CK差异显著,除Ci外SD、LD间差异也显著,BH、AH时段SD各指标均与CK差异显著,LD与CK差异不显著。在处理结束后10 d、穗后30 d与成熟期,BAH时段SD与CK差异显著,LD与CK差异多不显著,BH时段SD的Pn、Tr、Fv/Fm较CK差异显著,而AH时段各指标在水分处理间差异多数不显著。3)三处理时段下各胁迫处理间产量均表现为SD<LD<CK,BAH、BH时段不同水分处理间差异显著,AH时段LD、CK间无显著差异,但二者均与SD差异显著。【结论】BAH时期轻度干旱、重度干旱均会抑制根系生长与叶片光合能力,显著降低产量,其中轻度干旱影响较小。BH时期土壤重度干旱时,根、叶形态生理指标在处理结束后难以恢复至对照水平,AH时期轻度干旱、重度干旱处理各指标在处理结束后能较快恢复。可见,在穗分化末期至灌浆初期,水稻根系和叶片生长对穗分化末期干旱胁迫更为敏感。

4种毛茛科植物对干旱胁迫的光合生理响应及抗旱性评价

目的:研究干旱胁迫对4种毛茛科植物光合生理指标的影响,为其引种驯化提供重要依据。方法:以4种毛茛科植物为试验材料,试验分为对照(CK)、轻度干旱(D1)、中度干旱(D2)和重度干旱(D3)4个梯度处理,通过干旱胁迫对4种毛茛科植物光合特性的影响判断植物干旱耐受性。结果:随着干旱胁迫加剧,毛茛、猫爪草、天葵叶片叶绿素a(Chla)含量、叶绿素b(Chlb)含量、类胡萝卜素(Car)含量呈下降趋势,华东唐松草各叶绿素含量则先升后降;干旱处理下,4种毛茛科植物叶片净光合速率(P_n)、气孔导度(Gs)、蒸腾速率(Tr)与胁迫程度呈负相关,胞间CO_(2)浓度(Ci)与胁迫程度呈正相关;除初始荧光(F_o)外,4种毛茛科植物叶片最大荧光(Fm)、可变荧光(Fv)、PSⅡ最大光学效率(Fv/Fm)、PSⅡ潜在活性(Fv/F_o)均较对照出现显著下降。结论:4种毛茛科植物抗旱性由强到弱依次为天葵、华东唐松草、毛茛、猫爪草。

持续干旱对毛竹实生苗叶绿素荧光参数的影响

为探索毛竹实生苗叶绿素含量和荧光对持续干旱的响应,以6个月生毛竹实生苗为材料,采用盆栽控水法,以正常供水为对照,分析持续干旱胁迫下实生苗叶片SPAD值和叶绿素荧光参数的变化。结果表明:毛竹实生苗叶片的SPAD值随着干旱胁迫时间的推进,呈现先上升后逐渐下降的变化趋势,最大荧光(Fm)、PSⅡ最大光化学效率(Fv/Fm)、PSⅡ实际光合效率[Y(Ⅱ)]和光化学淬灭系数(qP)均呈现出整体下降的趋势,而非光化学淬灭系数(NPQ)则呈现先上升后下降的变化趋势。研究结果可为进一步研究毛竹的抗旱性提供基础参考。

冬小麦新品种陇麦671的选育及思考

为解决我国干旱半干旱地区小麦生产“旱、寒、多病”等问题,创制适应逆境环境的“抗旱节水、耐冻抗病、高产优质”兼容性的小麦品种,以平凉43号为母本、中41-42为父本杂交,经水旱交替胁迫、多点穿梭,选育出冬小麦品种陇麦671。在2018—2020年进行的甘肃省陇东片冬小麦区域试验中,该品种2 a 13点(次)平均折合产量为4981.5 kg/hm^(2),较统一对照品种陇育4号增产12.2%;在2020—2021年度进行的甘肃省陇东片冬小麦生产试验中,平均折合产量为6889.5 kg/hm^(2),较统一对照品种陇育4号增产22.4%。陇麦671具有高产优质、抗旱节水、抗病耐冻、矮秆抗倒等优良特性,该品种株高85.2 cm,穗粒数33.4粒,千粒重33.0 g,容重789~802 g/L,抗旱指数0.975;籽粒含粗蛋白(干基)162.0 g/kg、赖氨酸(干基)3.6 g/kg、湿面筋(14%水分基)374.0 g/kg,沉淀值(14%水分基)44.0 mL。适宜在甘肃省陇东地区旱塬地、川台地及周边同类地区种植。

开花期与块茎膨大期干旱胁迫及旱后复水对马铃薯影响的差异

2021年4-7月在沈阳农业大学大型水分控制试验场进行马铃薯的控水实验,选取马铃薯开花期和块茎膨大期,设置轻度干旱(开花期土壤相对湿度50%、块茎膨大期土壤相对湿度60%)、中度干旱(开花期土壤相对湿度40%、块茎膨大期土壤相对湿度50%)和重度干旱(开花期土壤相对湿度30%、块茎膨大期土壤相对湿度40%)以及对照(开花期土壤相对湿度70%、块茎膨大期土壤相对湿度80%)处理,在每一个生育阶段各级干旱处理5d后进行复水,复水水平控制到对照处理水平,研究干旱胁迫及旱后复水对马铃薯光合特性、叶绿素荧光、生长及产量的影响。结果表明:开花期与块茎膨大期遭遇干旱胁迫会使叶片气孔导度、净光合速率均显著低于对照处理,叶片光系统II的光化学淬灭系数、光能转换率显著降低,非光化学淬灭系数显著升高。开花期轻度干旱持续5d后复水,叶片净光合速率比干旱处理提高20%,但块茎膨大期中、重度干旱恢复的程度很小。各级干旱处理下叶面积指数较对照下降17.6%~50.3%,干物质重降低23.4%~51.4%;开花期各级干旱处理下的马铃薯产量,分别较对照处理减少1.0%~19.6%,而块茎膨大期各级干旱处理下的马铃薯产量,分别较对照减产8.6%~30.5%,说明块茎膨大期干旱造成的减产大于开花期。由此可见,干旱胁迫会导致马铃薯叶片生长过程产生抑制,光合产物降低,最终导致产量下降,及时复水可缓解干旱胁迫对马铃薯的影响,实现作物的稳产高产。