Leaf Temperature and Transpiration of Field Grown Cotton and Soybean under Arid and Humid Conditions

Abstract

Abstract : Cotton (Gossypium hirsutum L.) and soybean (Glycine max (L.) Merr.) cultivars were grown under arid (Urumqi, Xinjiang, China) and humid (Matsudo, Chiba, Japan) conditions to analyze their abilities to adapt to arid conditions in terms of transpiration, leaf movement and leaf temperature. Under the arid condition, the leaf temperature of the cotton cultivars was higher than that of the soybean cultivar and the air temperature. There was no significant difference in leaf temperature among the cotton and soybean cultivars under the humid condition. The flow rate of stem sap in the cotton cultivars under the arid condition was always higher than that in the soybean cultivar, and was largely affected by vapor pressure deficit (VPD). Under the humid condition, however, the flow rates of stem sap were lower in the cotton cultivars than in the soybean cultivars. These results indicate that cotton can avoid heat stress by the high transpiring ability possibly supported by well-developed root systems, which leads to higher drought resistance under the arid condition. Soybean would adapt to arid conditions by the combination of paraheliotropic leaf movement and reduced transpiration.     

旱涝急转对不同花生品种生理生化指标的影响

为探讨旱涝急转对花生生理生化的影响,以不同旱涝耐性的3个花生品种中花8号（抗旱）、豫花15（耐涝）和湘花2008（旱涝兼耐）为材料,进行不同梯度的先旱、后涝连续处理,比较不同花生品种的叶片相对含水量,过氧化物酶（POD）、过氧化氢酶（CAT）、超氧化物歧化酶（SOD）、谷胱甘肽还原酶（GR）活性,以及丙二醛（MDA）含量的变化情况。结果表明,在旱、涝急转的胁迫过程中,干旱对叶片相对含水量的影响甚于湿涝。一定强度的旱或涝胁迫总体上均可使花生叶片的4种抗氧化酶POD、SOD、CAT、GR活性提高,随着胁迫的加深活性降低,复水后活性回落至对照水平,且旱甚于涝。MDA含量总体变化趋势是干旱胁迫下各品种花生叶片中MDA含量有所升高,并于复水解除干旱胁迫后恢复至对照水平;而湿涝处理阶段,MDA含量呈直线上升趋势,在胁迫解除后有所降低。中花8号、豫花15、湘花2008等3个花生品种具有显著不同的水分适应性,中花8号抗旱性更强而耐涝性较弱,豫花15抗旱性较弱而耐涝性强,湘花2008抗旱性中等而耐涝性更强,为水分广适性品种。     

Leaf Growth,Gas Exchange and Chlorophyll Fluorescence Parameters in Response to Different Water Deficits in Wheat Cultivars

Abstract

We investigated responses of wet climate (CY17) and dry climate (XN889) Trititcum aestivum L cultivars under 85, 55 and 25% field water capacity (FC). Less decrease in grain yield, relative water content, growth, gas exchange and chlorophyll fluorescence parameters indicated that XN889 was more drought-tolerant than CY17. At 55%FC, CY17 showed a lower net photosynthetic rate (Pn) than XN889 mainly due to stomatal closure. Stomatal closure was also observed in XN889, but its Pn was higher at 55%FC than at 85%FC. The higher Pn in XN889 may be associated with a higher chlorophyll content and resulting increase in photochemical quenching (qP), apparent electron transport rate, and effective quantum yield of photosystem II (PSII). Both cultivars showed photodamage at 25%FC, but XN889 showed less photodamage in terms of maximal PSII photochemical efficiency. XN889 showed higher qP and non-photochemical quenching than CY17, further demonstrating its superior drought tolerance.     

Transpiration and Leaf Movement of Cotton Cultivars Grown in the Field under Arid Conditions

Abstract

Five cotton (Gossypium hirsutum L.) cultivars were grown in the field in Xinjiang, China to evaluate their adaptability to arid conditions in terms of leaf temperature, transpiration rate and leaf movement. Leaf temperature was higher in the morning and lower in the afternoon as compared with air temperature. There were large differences in the transpiration rate represented by the flow rates of stem sap per unit leaf area (FRSS) among the cotton cultivars. The transpiration rate in cotton generally depended on vapor pressure deficit (VPD). In the cultivars with a low transpiring ability, however, the influence of VPD was lower in the higher range of VPD. Cultivars with higher transpiring ability tended to have higher intercepted radiation per unit leaf area (IRL), i.e., to show active diaheliotropic leaf movement. The higher transpiring ability of cotton might be able to reduce heat stresses caused by diaheliotropic leaf movement and be profitable for yield under the arid conditions.     

不同嫁接方式下大豆对干旱胁迫的响应

为明确大豆地上和地下部分对干旱胁迫的响应及对产量的影响,以用于大豆抗旱改良,利用耐旱型品种 辽豆14与干旱敏感型品种辽豆21进行相互嫁接,采用盆栽试验,在结荚期进行水分胁迫处理（土壤含水量保持在 田间持水量的50%）13 d后,测定大豆叶片相关生理指标和各器官生物量。结果表明,水分胁迫使辽豆21自身嫁接 植株叶片的叶色值、叶面积、PSII 系统光化学量子产量Y（II）,调节性能量热耗散Y（NPQ）、最大电子传递速率 ETRmax、半饱和光强下最小饱和光强Ik显著降低,非调节性能量热耗散Y（NO）显著提高。无论以哪个品种为砧木, 与辽豆21相比,辽豆14作为接穗始终具有较高的叶色值、叶面积、Y（II）,Y（NPQ）、ETRmax和Ik,从而获得较高的植 株生物量。另外,干旱条件下,辽豆14作为砧木具有较高的根系活力,能使辽豆21接穗的叶面积、Y（II）,Y（NPQ）、 ETRmax和Ik显著提高,最终获得荚重的增加。由此说明,大豆PSII性能和物质生产能力主要由地上部叶片特性决 定,但干旱下大豆的生长也会受到根系生理活性的影响。     

水分胁迫对秋植花生结荚期同化物运输的影响

在秋播花生开花下针期至饱果成熟期给予不同程度的干旱处理,结果表明,无论是轻度、中度或严重干旱均影响果实的发育,使代谢源中的同化物向代谢库(荚果)中输出减少,植株叶片的含水量下降,蒸腾速率、光合速率及叶绿素含量降低,呼吸速率升高,同时花生经济产量降低。     

Effect of defoliation and drought stress on yield components and chlorophyll content of wheat

In order to examine the effects of source restriction and drought stress on yield components, flag leaf chlorophyll content and Relative Water Content (RWC) of wheat cultivars, a greenhouse experiment was carried out at Shiraz University, Shiraz, Iran, during 2009-2010. The wheat cultivars including Shiraz, Bahar, Pishtaz, Sistan and Yavaros were sown in 5 kg plastic pots. The source manipulation treatments including control (C), defoliation of all leaves (D1), defoliation of all leaves except the flag leaf (D2) and defoliation of all leaves except the flag leaf and penultimate leaf (D3), were imposed at anthesis. Results showed that source restriction decreased number of grain per spike significantly in Shiraz cultivar under drought stress condition. Maximum 100-grain weight was observed in C treatment of Yavaros and Shiraz under well-watered condition. Among the defoliation treatments under drought stress condition, D2 in Pishtaz and D1 in Shiraz had the highest (3.66 g) and lowest (2.71 g) 100 grain weight, respectively. In all cultivars drought stress decreased main shoot yield significantly but in Pishtaz and Sistan decreasing rate was less than the other cultivars. RWC in Shiraz decreased sharply from 92.1% in well-watered to 66.7% (27.5% reduction) under drought stress at 10 DAA. After anthesis, Pishtaz and Sistan maintained higher content of flag leaf chlorophyll (from 49.4 to 56.8 SPAD unit) under drought stress condition. Generally, selection and culture of cultivars that had small responses to defoliation might be a useful strategy in yield improvement of wheat in areas where the water availability is low.     

镉胁迫对花生叶片衰老的影响

试验在盆栽条件下研究了镉胁迫对花生叶片衰老的影响。结果表明,轻度镉胁迫（1．00mg／kg）对豫花15号和XB023叶片中叶绿素含量,光合速率及保护酶活性影响不大,叶片未表现明显衰老;中度镉胁迫（2．50mg／kg）降低了豫花15号叶片的叶绿素含量和光合速率,增加了SOD、POD、CAT含量,叶片出现衰老迹象,但对XB...     

不同土壤肥力下旱后复水对冬小麦光合特性及水分利用效率的影响

为给冬小麦节水高产栽培提供理论依据,采用盆栽试验,研究了不同土壤肥力下返青后干旱及拔节期复水对冬小麦光合特性和水分利用效率的影响。结果表明,同一土壤水分条件下,光合速率、蒸腾速率、气孔导度、胞间CO2浓度均随土壤肥力的降低而降低;同一土壤肥力下,光合速率、蒸腾速率、气孔导度、胞间CO2浓度均随干旱程度的增加而降低。干旱胁迫复水24 h后,光合速率、蒸腾速率、气孔导度、胞间CO2浓度均出现了补偿或超补偿效应,但中度干旱恢复度大于重度干旱。光合速率以HA处理（高肥力、最大田间持水量的85%）最高,单叶水分利用效率在干旱胁迫下和复水24 h后均以HB处理（高肥力、最大田间持水量的55%）最高。以上结果说明,冬小麦返青期中度干旱条件下,高肥力土壤有利于复水后光合系统恢复和单叶水分利用效率提高,而重度干旱下贫瘠土壤应减少基肥的施入量。     

Growth,stomatal resistance,and transpiration of Aloe vera under different soil water potentials

Aloe vera (Sábila) is used in folklore medicine and commercial cosmetology products in many countries. Little is known about the plant's physiological, growth, and yield responses under different irrigation regimes. The plant has a crassulacean acid metabolism (CAM) that allows water conservation within the tissue, and therefore, resistance to high water stress. A. vera plants were submitted to different irrigation regimes in a greenhouse experiment to evaluate the response of the physiologic processes such as stomatal resistance and transpiration as well as leaf growth and yield. The experiment consisted of three irrigation regimes under a completely randomized design. No initial effect on stomatal resistance or transpiration was exhibited, but as time elapsed changes in these variables were noted. We suggest that the high water content in the parenchyma maintains stomatal opening despite water stress. In a subsequent period, the leaves that were submitted to water stress at the beginning, showed stomatal opening reduction related to low soil water potential. The low soil water potential reduced leaf weight, plant growth rate, and leaf number, mainly in leaf growth during the experiment confirming the sensitivity of new leaves to water stress. The results suggest that the low leaf temperature increases stomatal resistance, decreases plant and leaf growth rates. This behavior is opposite to other CAM species in semiarid condition.     

干旱胁迫下冠菌素对花生幼苗叶片渗透调节物质及膜脂过氧化的影响

以鲁花11号花生（Arachis hypogaeaL．）种子为试验材料,在温室条件下研究不同浓度的冠菌素浸种,对干旱胁迫下花生幼苗叶片渗透调节物质及膜脂过氧化的影响。结果表明：干旱胁迫下,冠菌素可提高花生幼苗叶片主要渗透调节物质一可溶性糖、可溶性蛋白质和游离脯氨酸的含量,且随着胁迫时间的延长,增幅加大;花生幼苗叶片丙二醛（MDA）含量明显减少。冠菌素浸种浓度以0．01μmol／L的抗旱效果最好。研究表明冠菌素对提高花生幼苗的抗旱性具有积极作用。     

Effects of water stress on photosynthesis and chlorophyll fluorescence of five potato cultivars

Summary Reduction of leaf photosynthesis due to water stress has been analyzed into various components and genetic variation in these components has been evaluated. Five potato cultivars were grown on nutrient solution in a conditioned glasshouse. Water stress was imposed by adding polyethylene glycol to the nutrient solution. Photosynthesis, transpiration and chlorophyll fluorescence were measured on intact leaves during the stress period and after recovery from the stress. Water stress reduced photosynthesis, initially as a consequence of stomatal closure, but after 3 days increasingly by inhibiting directly the photosynthetic capacity (mesophyll limitation). Stomatal closure correlated with the reduction in photosynthesis, but it was not the sole cause of this reduction because the internal CO₂ concentration in the leaves was not affected by water stress, indicative of inhibitory factors other than stomatal ones. Chlorophyll fluorescence emission suggested that the Calvin cycle was inhibited, while quantum efficiency was not affected at 17°C. Increasing the temperature to 27°C reduced quantum efficiency but only in the stress environment. The recovery of young leaves after relief of the stress was associated with a lower stomatal conductance but a higher mesophyll conductance compared with the control, which caused a low internal CO₂ concentration and probably invoked photo-inhibition and leaf damage. Cultivar differences in photosynthetic rate were highly significant under both optimal and stress conditions, and corresponded with differences in mesophyll conductance.     

花生野生种及其在花生抗病中的利用

花生是世界上重要的油料作物之一。与栽培种相比,花生野生种具有较高的遗传多样性,能够适应一系列复杂环境,是抵抗生物胁迫和非生物胁迫的重要基因来源。多项研究表明,花生野生种对根结线虫病、晚斑病和锈病具有较高抗性。本文综述了野生花生的种类以及花生栽培种起源种相关研究进展,总结了野生花生对花生病害的抗性以及在育种中应用。结合花生基因组学最新研究,展望了花生野生资源的利用前景。     

低温胁迫下不同果蔗品种光合及荧光特性的变化及耐寒性评价

以6个果蔗品种幼苗为试材,研究低温（0℃）胁迫对各品种叶片的叶绿素含量、气体交换参数及叶绿素荧光参数等指标的影响,利用隶属函数对果蔗品种的抗寒性进行综合评价。结果表明,随着低温胁迫时间的延长,‘桂果蔗1号’和‘拔地拉’的叶绿素（Chl）含量先上升后下降,其余4个果蔗品种幼苗叶片Chl含量持续下降;低温胁迫下,6个果蔗品种的净光合速率（Pn）、气孔导度（Gs）和蒸腾速率（Tr）显著下降,但胞间CO2浓度（Ci）、水分利用效率（WUE）和气孔限制值（Ls）却显著增加,说明光合作用的下降主要由非气孔因素引起;在叶绿素荧光参数方面,低温胁迫下6个果蔗品种的初始荧光（Fo）和非光化学淬灭系数（NPQ）呈上升趋势,而PSⅡ最大光化学效率（Fv/Fm）、光化学淬灭系数（q P）和PSⅡ实际光化学量子产量(ΦPSⅡ)均显著下降,表明低温对PSⅡ反应中心的电子传递潜力产生明显的抑制。用隶属函数法综合评价抗寒性由强到弱依次为:‘桂果蔗1号’>‘拔地拉’>‘闽引黄皮果蔗’>‘白玉果蔗’>‘龙黑果蔗’>‘川蔗26号’。      

不同密度椰林间作荫蔽对花生光合特性的影响

花生是我国重要的经济和油料作物,海南岛独特的地理条件和气候优势适合花生生长,发展椰林下间作花生有利于提高海南省花生种植面积,促进花生种植业在海南的发展。花生为喜光作物,为揭示不同光照环境对花生光合特性和产量的影响,以‘本红1号’为材料,在单作人工荫蔽和椰林间作自然荫蔽条件下,分析不同荫蔽度与花生叶片叶绿素含量、光合参数、荧光参数和间作花生产量的关系。结果表明,人工荫蔽和自然荫蔽均对花生光合作用有显著影响,2种荫蔽处理均证明荫蔽能促进花生叶片叶绿素含量的增加。在人工荫蔽条件下,随荫蔽度增加至65%,花生叶绿素含量显著上升;在自然荫蔽条件下,25%~35%荫蔽处理下花生叶片的总叶绿素含量显著大于其他荫蔽处理组。在人工荫蔽条件下,25%荫蔽度下花生的净光合速率[P_n,23.06 µmol/(m²·s)]、蒸腾速率[T_r,6.61 mmol/(m²·s)]、气孔导度[G_s,606.21 mmol/(m²·s)]最高;在自然荫蔽条件下,15%~25%荫蔽度处理（4 m×6 m椰林）的花生P_n[18.27 µmol/(m²·s)]、T_r[7.66 mmol/(m²·s)]、G_s[618.10 mmol/(m²·s)]最大。在人工荫蔽条件下,花生可变荧光和最大荧光先显著增高后显著降低,在自然荫蔽条件下无显著差异。产量结果显示,与花生单作对照相比,不同密度椰林间作荫蔽均能够显著提高花生产量。本研究证明适度荫蔽能够促进花生光合作用,4 m×6 m（15%~25%荫蔽度）为间作花生推荐的椰林种植密度,可为构建高产高效的椰园花生间作模式提供科学参考。     

Cotton water-deficit stress,age, and cultivars as moderating factors of cotton fleahopper abundance and yield loss

Field experiments were conducted in 2012 and 2013 during drought conditions in South Texas and the Texas High Plains to test whether cotton water-deficit stress, age, and cultivars are moderating and interacting factors that affect cotton fleahopper, Pseudatomoscelis seriatus (Reuter) (Hemiptera: Miridae), abundance and yield loss. Irrigation and sequential plantings of several cultivars were used to simulate a range of water stress, plant ages, and cultivar variability. Cotton grown under these experimental conditions were exposed to cotton fleahopper using natural and artificial infestation. Cotton cultivars had a strong influence on cotton fleahopper abundance, with higher densities on Stoneville cultivar 5458 B2RF, which is relatively pubescent, than on the Phytogen cultivar 367 WRF, which is relatively glabrous, in South Texas (p < 0.04). But the strong cultivar effects on cotton fleahopper abundance did not correspond to yield reduction. No water stress effects on cotton fleahopper densities were observed in 2012 (p > 0.05), whereas cotton fleahopper densities increased on older cotton grown under no water stress in 2013 in South Texas (p < 0.05). In contrast, yield response was primarily sensitive to soil moisture conditions (up to 50% yield reduction when grown in dryland mimic conditions below 75% crop ET replacement, p < 0.0009). Water and cotton fleahopper stress synergies were detected but variable, with greatest lint yield loss attributable to cotton fleahopper seen in cotton grown in high water stress conditions in the High Plains (p < 0.05). Yield trends were consistent across cultivars (no interaction with cultivar), even though cotton fleahopper populations varied significantly across cultivars and exceeded regional economic thresholds beginning the second week of squaring (p < 0.05).     

小麦叶片蜡质含量与水分利用效率和产量的关系

为了进一步了解植物叶片蜡质含量与植物抗旱节水性的关系，本试验对6个小麦品种在灌浆后期的旗叶蜡质含量与抗早生理指标进行了相关分析，结果表明，干早条件下小麦灌浆后期叶片蜡质含量与光合速率、叶温、叶片水分利用效率和产量呈显著正相关．蜡质含量高的品种叶片温度高、蒸腾速率大，这与传统现点不同．分析认为蜡质含量高的品种在干早胁迫条件下可能叶片细胞膜稳定性强，气孔不容易发生关闭，因此其叶片水分利用效率和产量较高．蜡质含量除了受遗传因素决定外，还受环境因素影响．     

干旱胁迫对不同肥水类型小麦旗叶光合特性及产量的影响

为给小麦抗旱育种和节水高产栽培提供理论和技术支持,在防雨旱棚池栽条件下研究了干旱胁迫对6个不同肥水类型小麦品种旗叶光合特性和产量的影响。结果表明,干旱胁迫条件下,小麦开花后旗叶的净光合速率、气孔导度、蒸腾速率、气孔限制值和单叶水分利用效率均呈下降趋势,而胞间CO₂浓度有所升高。其中,水浇地品种烟农21、烟农24和济麦22净光合速率、气孔导度、蒸腾速率、气孔限制值和单叶水分利用效率较低且下降幅度大,而旱地品种青麦6号、济旱5034和鲁麦21的净光合速率、气孔导度、蒸腾速率、气孔限制值和单叶水分利用效率较高且下降较为缓慢,而胞间CO₂浓度较低。青麦6号具有较高的抗旱指数,在干旱胁迫条件下能够保持较好的叶片结构和功能状况,是其获得高产的重要原因。     

Physio-Biochemical Responses of Oil Palm (Elaeis guineensis Jacq.) Seedlings to Mannitol- and Polyethylene Glycol-Induced Iso-Osmotic Stresses

References

The aim of this investigation was to comparatively examine the physio-biochemical responses of oil palm seedlings to mannitol- and PEG-induced iso-osmotic stresses. The water content of osmotically stressed oil palm seedlings decreased, but the proline content and the electrolyte leakage of the seedlings increased with decreasing water potential (Ψ_w). However, the responses varied with the strength of osmotic stress and type of osmotic agent. Relative electrolyte leakage (REL) was negatively correlated to chlorophyll content in the osmotically stressed leaves. Chlorophyll a (Chl_a), chlorophyll b (Chl_b), total carotenoids (C_x+c) and total chlorophyll (TC) in the seedlings were significantly reduced by osmotic stress, subsequently reducing maximum quantum yield of PSII (F_v/F_m) and photon yield of PSII (Φ_psii), thereby lowering net-photosynthetic rate (P_n) and inhibiting growth. Physio-biochemical parameters, including REL, F_v/F_m, and Φ_psii in oil palm seedlings were reduced more greatly by PEG-induced osmotic stress than by mannitol-induced stress. A deterioration in morphological characters, including leaf chlorosis, leaf burn, and green leaf area reduction were demonstrated in oil palm seedlings under osmotic stress induced by either mannitol or PEG. However, the toxic symptoms in oil palm seedlings under PEG-induced stress were severer than in those under mannitol-induced iso-osmotic stress, especially under severe osmotic stress.     

Water relations of the potato (Solanum tuberosum L.) cultivars Raritan and Shepody

Physiological responses to drought stress were evaluated in the potato cultivars Raritan and Shepody. Under well-watered conditions, Raritan exhibited a higher transpiration rate than Shepody. This higher rate could be related to a lower calculated stomatal resistance on abaxial leaf surfaces. Under drought stress conditions, Raritan consistently demonstrated superior performance over Shepody in the following areas: leaf water retention, epicuticular wax levels, desiccation tolerance and root growth. The estimated relative water content at a leaf water potential of-1.0 MPa was higher for Raritan than Shepody regardless of leaf age and may indicate a greater drought resistance in the former cultivar.