Photosynthetic Acclimation and Productivity of Mungbean Cultivars under Elevated CO2 Concentration

Mungbean [Vigna radiata (L.) Wilczek] cultivars (Pusa Baisakhi, PS 16 and P 105) were grown in field at atmospheric (360 ± 10 ppm, AC) and elevated CO₂ (650 ± 50 ppm, EC) concentrations inside open top chambers for entire period of growth and development till maturity. Leaf net photosynthesis rate (P_N) of AC and EC grown plants when compared at same CO₂ concentration showed no significant down‐regulation of P_N in EC plants. In cv. P 105, even up‐regulation of P_N was observed in EC plants. Mungbean cultivars accumulated assimilates in the leaves during the day mostly in the form of starch. Nodule number and weight were also higher in EC plants. The positive effect of elevated CO₂ on P_N, dry‐matter production and seed yield was better expressed in cv. P 105 having greater podding ability.     

Comparative Study on the Effect of Water Stress on the Photosynthesis and Water Relations of Triticale, Rye and Wheat

An attempt was made to investigate the effect of water stress treatment on the components of photosynthesis and water relations of triticale ( Triticale octoploide ), Russian rye ( Secale cereale ) and wheat, ( Triticum aestivum var. Sonalika ). The results revealed that there was no significant adverse effect of water stress on the photosynthesis of triticale compared to wheat and rye. The maintenance of photosynthetic productivity under water stress in triticale has been accomplished by (a) reduction in water loss by stomatal behaviour and (b) by maintenance of water uptake through continued transpirational flow. Both these mechanisms served to maintain high water potential as stress occures. This ameliorates the onset of stress and helps to maintain photosynthesis. The rye also consists of another type of adaptability to drought through significant recovery of photosynthesis and chlorophyll development on reirrigation particularly at post-anthesis stage, when other species failed to recover. However, in wheat Sonalika both these adaptive characteristics did not exist in such intensity.     

水分胁迫对棉花幼苗水分利用和光合特性的影响

以转基因棉花品种农大棉8号和鲁棉研28号为材料进行盆栽试验,设置正常处理(CK)、轻度胁迫(LS)、中度胁迫(MS)、重度胁迫(SS)和极度胁迫(ES)5个水分处理。结果表明:随着水分胁迫程度的加重,棉花幼苗的生长受到明显的抑制,2个品种的叶片相对含水率、叶水势、净光合速率(Pn)、光能利用率(LUE)、PSⅡ最大光化学效率(Fv/Fm)、PSⅡ光化学量子效率(φPSⅡ)、光化学猝灭系数(qP)呈下降趋势;气孔限制值(Ls)、水分利用率(WUE)和非光化学猝灭系数(NPQ)呈上升趋势。两品种的Pn和NPQ的MS、SS和ES与CK相比差异显著,不同测定时期各胁迫处理的平均Pn比CK分别下降了11.5%、18.1%、32.1%和38.1%;平均NPQ比CK上升了24.1%、50.9%、79.4%和145.1%。表明棉花幼苗期持续轻度水分胁迫对叶片光合能力无显著影响,但高于中度的持续水分胁迫会造成叶片光合能力下降和光抑制加重。     

Interactive Effects of Elevated CO2 and Moisture Stress on the Photosynthesis, Water Relation and Growth of Brassica Species

Interactive effects of elevated CO2 and moisture stress on photosynthesis, growth and water relation of Brassica species were studied using open top chamber technology. Brassica species responded to the elevated CO2 significantly under moisture stress condition. The adverse effect of moisture stress on the photosynthesis and plant water components were minimized by elevated levels of CO2. Drought susceptible species of B. campestris and B. nigra responded better to elevated CO2 compared to drought tolerant Brassica species such as B. carinata and B. juncea. The plant water potential significantly improved by elevated CO2 coupled with higher stomatal resistance and root growth.     

Effect of Rooting Pattern on Rice Productivity under Different Water Regimes

Three rice varieties, viz. ADT 31 (drought tolerant) CO 41 (upland) and IR 50 (drought susceptible), were employed to study their rooting patterns under different water regimes. ADT 31 had better root penetration and distribution under water stress situation compared to others. The values on root weight also established a similar trend. Isotopic studies with ³²P also provided evidence in this regard wherein the variety ADT 31 showed its adaptiveness to drought. Marginal reduction in plant height, less tiller production and leaf area reductions were noted in ADT 31 and CO 41 under decreasing soil moisture which showed its ability to cope with the water stress situation. Though IR 50 recorded higher grain yield at normal irrigation, a drastic reduction was noted under extreme water deficit. But ADT 31 recorded consistent values in all situations with slight marginal reduction which evidently proved the interdependent nature of rooting pattern and its influence on productivity.     

水分胁迫对西藏不同基因型春大麦发芽的影响

此文通过不同的水分胁迫处理对4个西藏春大麦品种进行发芽研究。结果表明：（1）水分胁迫下,所有品种的种子萌发均受到不同程度的抑制作用,四个品种在重度胁迫时萌发抑制率为16%~52%,轻度胁迫时萌发抑制率为4%~50%,其中对日喀则17号抑制作用最大;（2）水分胁迫下,所有品种的种子发芽率、发芽指数及活力指数均下降,对藏青320的发芽影响最大,随着水分胁迫加强其发芽速度明显减慢,麦芽长势明显差,其次依次是曲玛132、日喀则17号和藏青148;（3）水分胁迫抑制春大麦发芽期间芽和根的生长,且表现出随着水分胁迫加强芽受抑制敏感程度大于根,日喀则17号对根部抑制表现最敏感,藏青320对芽的抑制表现最敏感。不同基因型春大麦发芽过程对水分胁迫的反应不同,说明春大麦种子耐旱性存在基因型差异,4个西藏春大麦品种中,从种子发芽期间的综合表现看,藏青148种子生育前期耐旱性相对较好,曲玛132种子次之,藏青320和日喀则17号种子耐旱性相对较差。     

Effect of Elevated CO2 on the Photosynthesis, Growth and Water Relation of Brassica Species Under Moisture Stress

An attempt has been made to study the interactive effect of elevated CO₂ and moisture stress on photosynthesis, growth and water relations of Brassica species using open top chambers. It was observed that plants responded to elevated CO₂ significantly under moisture stress condition mitigating the adverse effects on photosynthesis and growth of Brassica species. Relatively drought susceptible species, viz. B. campestris and B. nigra , responded to elevated CC₂ markedly as compared to less sensitive B. carinata and B. juncea plants. The water status of plants significantly improved under elevated CO₂ concentration possibly by increasing stomatal resistance and/or by increased root growth.     

Genotypic Variation in Wheat in Response to Water Stress and Abscisic Acid-Induced Accumulation of Osmolytes in Developing Grains

Two wheat genotypes differing in water stress sensitivity (C306, relatively tolerant; HD2329, relatively susceptible) were water stressed during early grain filling by withholding water for 7 days at watery‐ripe (WR) stage and examined for water status, abscisic acid (ABA) and osmolytes in grains as well as in flag leaf (FL). Both the genotypes differed significantly from each other in endogenous levels of ABA, proline, glycine betaine, total soluble sugars, reducing sugars, sucrose and potassium. The tolerant genotype showed higher content of ABA, proline, glycine betaine, total sugars, reducing sugars and had higher water content in its FL and grains than the susceptible genotype, which contained more of glycine beatine and potassium but had lower ABA and water content in its FL and grains. Although carbohydrates constituted the major amount of all the solutes, proline and glycine betaine increased manifold during stress. Exogenous application of 2 μm ABA at 5 days after anthesis to FL of stressed plants increased the endogenous content of ABA, accelerated the accumulation of osmolytes, improved the water status of FL and grains that resulted in higher grain weight, especially in the susceptible genotype. Differential response of contrasting wheat genotypes to water stress may be governed by ABA‐dependent solute accumulation in grains and FL.     

水分胁迫下紫花苜蓿根系特征与ABA含量的变化

研究通过温室盆栽试验探讨了干旱胁迫对‘三得利’、‘敖汉’和‘中苜1 号’3 个紫花苜蓿品种根系ABA浓度和根系特征的影响。按照田间持水量的100%（对照）、85%（轻度干旱）、70%（中度干旱）和55%（重度干旱）设置4 个梯度的水分胁迫处理,分别对3 个紫花苜蓿品种进行处理,并对根系ABA含量和根系性状进行测量。结果显示：水分胁迫可以显著影响不同生长时期的紫花苜蓿根系ABA的含量。随着处理时间的延长,不同水分胁迫处理的紫花苜蓿根系ABA含量均呈先升高后下降再升高的趋势。在移栽后的第75 天,根系ABA含量达到首个峰值,然后开始下降,到第105 天的时候将至最低,然后开始回升直至处理结束。移栽105 天以后,4 个水分胁迫处理（W1、W2、W3 和W4）紫花苜蓿根系ABA含量分别为44、56.6、64.6、94.4 ng/g FW。同时,不同紫花苜蓿品种根系ABA含量存在差异。移栽105 天以后,‘敖汉’、‘三得利’和‘中苜1 号’根系ABA含量均达到最低,分别为83.2 ng/g FW、61.7 ng/g.FW 和49.9 ng/g FW;之后,根系ABA含量开始回升。与对照相比,重度水分胁迫使根系长度降低了20.92%,使侧根数降低了20.71%,使根鲜重降低了43.79%,使根干重降低了37.96%。重度水分胁迫下植株根冠比是对照的1.9倍,这说明水分胁迫对地上部茎叶的影响要大于地下部的根系。水分胁迫降低了紫花苜蓿根长、侧根数、根鲜重和根干重,增加了紫花苜蓿根冠比,促使根系ABA含量升高。不同紫花苜蓿品种根系ABA含量存在差异。     

不同甘蔗品种在无氮肥条件下的光合生理特性

巴西甘蔗固氮品种B1、B3、B5、B8与本地甘蔗品种桂糖11号、新台糖16号种植于光温大棚的塑料桶中,不施氮肥,研究无氮肥条件对参试品种的光合特性的影响。结果表明：四个巴西甘蔗品种具有较良好的光合特性,表现为高净光合速率,高ATP酶活性、叶片叶绿素含量较高。无氮肥条件给桂糖11号与新台糖16号的光合作用带来不良的影响。B8在无氮肥条件下表现最强的光合能力,而桂糖11号易受无氮肥条件的影响,光合生理特性表现较差。     

水分胁迫对花生种子萌发过程中贮藏物质降解的影响

为明确花生种子萌发过程中水分胁迫对种子主要储藏物质含量变化的影响,采用不同浓度的PEG渗透溶液,进行不同品种发芽出苗阶段的水分胁迫试验。结果表明,花生种子萌发出苗过程中,随萌发时间延长,可溶性蛋白质、可溶性糖、淀粉含量均表现逐渐降低的趋势,且随胁迫浓度的增加其含量逐渐提高,胁迫处理均高于无胁迫处理。脂肪虽是花生的主要储藏物质,但在水分胁迫条件下,其变幅很小甚至有的品种略有升高。花生萌发出苗过程中水分胁迫,致使种子中可溶性蛋白质、可溶性糖、淀粉和脂肪等主要贮藏物质降解速度和强度降低,影响萌发出苗。     

水分胁迫对不同抗旱型玉米自交系苗期生长的影响

通过水分胁迫处理对不同抗旱型玉米自交系苗期的影响研究,为抗旱育种选择自交系提供选择参考。采用人工控水的方法,研究干旱胁迫对夏玉米抗旱型和对敏感型自交系苗期株高、地上部和地下部分干重、叶面积、比叶重、叶绿素和净光合速等的影响。结果表明：不同抗旱型自交系苗期对水分胁迫的响应不同。抗旱玉米自交系从5叶期开始在干旱胁迫期间的株高、地上部和地下部分干重、叶面积、叶绿素和净光合速率等指标均高于对水分敏感的玉米自交系,且比叶重相对稳定。这表明干旱条件下,抗旱型自交系较普通自交系在苗期能够表现出更好的适应性,本研究对加强抗旱自交系的筛选和选育,进一步提高耐旱节水玉米新品种选择效率具有一定参考价值。     

Compensatory Growth Responses During Reproductive Phase of Cowpea after Relief of Water Stress

Unpredictable drought affects growth and yield of dryland cowpea ( Vigna unguiculata [L.] Walp.) during rainy season. With the objective of identifying compensatory growth responses after relief of water stress, pot-grown plants (cv. C-752) were water-stressed at flowering, and physiological responses, short term dry matter partitioning upon relief of water stress, and productivity at maturity were studied. Water stress decreased, to varying degrees, leaf water potential, stomatal conductance, photosynthesis rate and transpiration rate. Recovery in assimilation lagged behind that in water relations. Assimilate supply seemed to be limiting early pod growth upon relief of water stress due to low photosynthesis rate, reduced leaf area per pod, and increased partitioning to leaf expansion. However, later pod growth was not limited by assimilate supply and final dry matter per pod was similar in both non-stressed and stress-affected plant. Cowpea exhibited the following growth responses during pod-fill stage upon relief of water stress: 1. increase in leaf area, 2. shift in dry matter partitioning in favour of leaf expansion, 3. extended green leaf duration, and 4. increase in pod number. These partially compensating physiological responses probably ensure reasonable productivity of dryland cowpea during rainy season.     

Effect of aluminum toxicity on flowering time and grain yield on rice genotypes differing in Al-tolerance

Aluminum is a major phytotoxic mineral in the soil at low pH conditions. The effect of aluminum (Al) on root length, flowering time, dry matter production, and grain yield was examined using two tolerant, Pungsan (PS) and Geumgang (GG), and one susceptible, IR36, rice varieties to acid soil. Rice seedlings were subjected to two Al treatments (+Al, 150 μM of Al; −Al, 0 μM of Al) in solution culture, where pH was always adjusted at 3.5. PS and GG showed significantly larger root length than IR36 in +Al at 2 and 8 weeks after the treatment (WAT). Flowering time was delayed 9 days in +Al compared to −Al in GG and PS and 27 days in IR36. Dry matter weight and grain yield of GG and PS were also significantly higher than those of IR36 under +Al. The inhibition of such agronomic traits by Al toxicity was less in Al-tolerant varieties than in a susceptible variety.     

Effects of Limited Irrigation on Accumulation and Distribution of Dry Matter,Yield, and Water Use Efficiency of Different Cotton Varieties

[Objective]We aimed to prove the effects of limited irrigation on the regulation of soil moisture, growth, and yield in different mature cotton varieties in the Yellow River region. [Method] Using the early maturing cotton variety CCRI 50, earlier middle maturing variety Nongdamian 601 (ND 601), and medium maturing variety Jimian 958 (JM 958) as test materials, field tests were carried out using both conventional irrigation (W1) and limited irrigation (proper irrigation before sowing, no irrigation during growing period; W2). The traits of interest were measured, including leaf area index, water use efficiency, and yield. [Result] The dry matter quality of the three varieties was significantly lower with the W2 treatment, with the greatest reduction observed in CCRI 50 (P＜0.05). Compared with the W1 treatment, the yield of the three varieties under the W2 treatment decreased significantly, with the greatest reduction observed in the early maturing variety CCRI 50. The water use efficiency of CCRI 50 decreased significantly while that of ND 601 and JM 958 improved significantly during the two study years. [Conclusion] ND 601 and JM 958 have good adaptability to moderate drought stress and W2 treatment can improve the water use efficiency of these varieties to obtain the ideal output level. CCRI 50 is sensitive to moisture; it is difficult to form a high yield population for this variety under W2 treatment.     

土壤水分胁迫对不同肥水类型冬小麦品种花后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,以山东省6个不同肥水类型的冬小麦品种（‘青麦6号’、‘鲁麦21’、‘烟农21’、‘烟农24’、‘济麦22’、‘良星99’）为材料,研究了水分胁迫对冬小麦花后光合特性与产量的影响及品种间差异。结果表明,在水分胁迫条件下,各冬小麦品种花后叶面积指数、旗叶叶绿素含量、净光合速率、气孔导度、蒸腾速率和水分利用效率均有所降低,产量显著下降。品种间对水分胁迫反应差异显著,其中旱地品种‘青麦6号’在水分胁迫条件下,旗叶叶绿素含量、净光合速率、蒸腾速率、水分利用效率及气孔导度均高于其他品种,产量构成因素和产量降低幅度最小,产量最高,仅比同期水分处理下降了14%。     

水分胁迫对干热河谷乡土树种清香木的光合影响

为了研究水分胁迫对清香木光合特性的影响,根据土壤田间持水量设置不同的土壤水分含量梯度（W1~W6,土壤田间持水量分别为100%、80%、50%、30%、10%、5%）。以清香木为材料,利用Li-6400测量6个不同土壤水分含量梯度下清香木叶片的净光速率(Pn)、胞间CO₂浓度(Ci)、气孔导度(Gs)、蒸腾速率(Tr)和水分利用率(WUE)。了解清香木对水分过多或过少胁迫的响应,旨在为云南干热河谷地区的植被恢复、清香木的培育种植提供一定的理论指导和技术参考。结果表明：（1）不同土壤水分含量梯度下清香木净光合速率Pn值显著差异,总体Pn呈现“降—升—降”的态势,日变化曲线呈“双峰”型,具明显的午休现象。Pn下降主要受到气孔限制和非气孔限制因素的影响。W1、W2受到气孔的限制,W3~W6受非气孔限制的因素影响,随着土壤含水量的下降,气孔限制向非气孔限制转变。（2）18:00以后,除了W3以外,其他Pn出现负值,呼吸作用大于光合作用,植物的光合生产力下降,植物死亡;W3则为水分适度的最佳选择,其田间持水量和土壤含水量分别在50%和33.6%左右。（3）气孔导度随着土壤含水量的减小而下降,土壤含水量在W3~W6时,气孔导度Gs日变化曲线无明显,基本呈现平缓状态。W1~W6的Gs值在8:00时最大,主要是空气湿度引起。（4）水分利用率WUE随着土壤含水量的下降而增加,适当的干旱胁迫有利于提高清香木光合生产力和水分利用率。     

花前渍水锻炼调控花后小麦耐渍性的生理机制研究

采用对渍水胁迫和渍水锻炼响应差异的小麦品种为材料,在四叶一心期和六叶一心期分别进行渍水锻炼2 d;在开花后7d进行渍水胁迫5d,分析不同小麦品种对渍水胁迫响应的差异及其生理机制。结果表明,花后渍水胁迫显著降低旗叶叶绿素含量(SPAD)和实际光化学效率(Φ_PSⅡ),抑制花后光合同化物积累(PAA),导致籽粒千粒重和产量降低;与不耐渍型品种相比,耐渍型品种在渍水胁迫下可维持较高的SPAD、Φ_PSⅡ和PAA,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)以及谷胱甘肽还原酶(GR)酶活性提高,过氧化氢(H₂O₂)、超氧阴离子自由基(O₂-~)和丙二醛(MDA)含量较低。与花前未进行渍水锻炼和花后渍水处理(NW)相比,花前渍水锻炼和花后渍水处理(PW)下,渍水锻炼敏感型品种较渍水锻炼不敏感品种显著提高了花后渍水胁迫下小麦旗叶SPAD (8.8%)和Φ_PSⅡ(17.6%)、降低非调节性能量耗散Φ_NO (10.7%)和...     

Effects of inter-varietal diversity,biotic stresses and environmental productivity on grain yield of spring barley variety mixtures

Varietal seed mixtures tend to increase and stabilize crop yields, yet their application is sparse. Large-scale cultivation of variety mixtures may require a better understanding of how inter-varietal interactions and their interaction with the environment may influence the grain yield of variety mixtures relative to their component varieties. For this purpose, six variety mixtures of spring barley and 14 component varieties were grown in each of 17 trial environments. A total of 28 observed and a priori plant characteristics, including grain yield, disease severity and weed competitiveness, were derived for each component variety in each trial. The relationship between inter-varietal diversity of each characteristic and the mixing effect on grain yield was analysed. Additionally, various types of yield stability were estimated and compared among mixtures and component varieties. One mixture out-yielded all of its component varieties in almost half of the trial environments. Inter-varietal diversity in grain yield potential correlated significantly with mixing effect, as did straw length diversity when weighted with weed pressure. The grain yields of most mixtures were more stable across environments than their component varieties when accounting also for the general response to environmental productivity. Hence, most mixtures adapted slightly better to environmental productivity and were less sensitive to environmental stress than their component varieties. We conclude that the efficacy of variety mixtures may be enhanced by mixing relatively high-yielding varieties differing in responsiveness to environmental productivity.     

水分胁迫对不同根型小麦幼苗水分利用率和导水率的影响

以旱地小麦晋麦47和高水肥小麦石4185为试材,比较分析了充分供水和模拟干旱胁迫条件下小麦幼苗水分利用效率(WUE)和根系导水率(Lpr)的差异。结果表明:正常供水条件下,晋麦47单株耗水量、根系干质量和单株干质量皆低于石4185,但根系水分利用率(WUEr)、茎叶水分利用率(WUEs)、单株水分利用率(WUE)以及根系导水率均高于石4185。轻度干旱胁迫下,石4185根系干质量稍有增加,晋麦47变化不明显,两者单株干质量均降低;两品种根系、茎叶和单株水分利用效率均显著提高,石4185根系水分利用效率反而高于晋麦47;但两品种根系导水率呈显著下降趋势,晋麦47下降幅度大于石4185并最终低于石4185。以上说明:水分充足条件下,晋麦47表现出“奢侈”利用水分,干旱条件下,表现出以降低水分消耗而维持地上部生长的耐旱节水机制;石4185在水分充足条件下耗水量大,表现出水地品种特点,胁迫条件下,水分利用率均升高且根系水分利用率升高相对更大,体现出干旱胁迫下依赖根系进一步发展增大吸收水分表面积来适应缺水环境。两者相比较,体现了不同根型小麦品种根系在干旱胁迫调节中的重要性和差异性。