刚果12号桉对4种豆科植物的化感作用

采用室内生物检测的方法研究了刚果12号桉叶片自然释放的挥发性物质、叶片水抽提物、叶片经水蒸气蒸馏所得的桉油、含挥发性水溶性物质的冷凝水和含水溶性非挥发性物质的渣汁3个组分以及桉树根际土壤水浸液对绿豆、大豆、柱花草与大翼豆4种受体植物的化感活性。结果表明：刚果12号桉叶片释放的挥发性物质对4种受体植物种子的萌发有强烈的抑制作用：桉叶水抽提物与根际土壤水浸液对绿豆、大豆、柱花草与大翼豆4种受体植物种子萌发与幼苗生长不但有一定抑制作用，而且土壤水浸液对绿豆、大豆和柱花草幼苗的根生长还有不同程度的促进作用，处理分别比对照高出13％、2％、23％。从桉油、冷凝水与渣汁3个组分的化感活性来看，渣汁的最强，桉油次之，冷凝水最低，即单位叶片中水溶性物质的化感活性比挥发性的高。这表明水溶性化感活性物质可能是刚果12号桉的主要化感作用物质。     

巨尾桉挥发物化感作用初步研究

在实验室条件下进行巨尾桉(Eucalyptus grandis×E.urophylla)新鲜桉叶和桉油的挥发物对4种受试植物种子萌发和幼苗生长的影响试验.结果表明:巨尾桉挥发物对受试植物的种子萌发和幼苗生长均有抑制作用,且抑制作用强度,桉油挥发物均显著或极显著大于桉叶自然挥发物.桉油挥发物的作用强度有明显的浓度效应,浓度增大,抑制作用增强.不同受体植物对巨尾桉挥发物化感作用的敏感性差异明显,其中甜菜心和白萝卜敏感性较强,水稻和热研2号柱花草敏感性则较弱.     

磷胁迫对不同桉树品种酸性磷酸酶活性的影响

通过土培试验对磷胁迫条件下不同桉树品种酸性磷酸酶(APA)活性和桉树苗高、地径进行了比较研究.结果表明:1)在缺磷条件下桉树叶片和根际的APA活性明显高于正常供磷处理,而且随胁迫程度时间的延长,APA活性逐渐增大.不同桉树品种APA的变化规律不同,其中巨赤桉、尾赤桉、邓恩桉在磷胁迫条件下APA活性增加较快;巨桉和巨细桉增加缓慢;而缺磷环境对其根际和叶片APA活性不造成显著影响;尾细桉和尾巨桉介于以上二者之间,磷胁迫强度与不同桉树品种APA活性显著相关.2)磷胁迫对不同桉树品种苗高、地径影响表现为巨赤桉、尾赤桉、邓恩桉最大;尾细桉和尾巨桉次之;巨桉和巨细桉最小.这充分说明在磷胁迫条件下,桉树可通过叶片及根际APA活性的增强来适应缺乏磷环境,但不同桉树品种对磷缺乏的适应性存在明显差异.能否将APA活性作为评价桉树耐低磷特性的指标仍需结合大田试验进一步研究论证.     

假臭草水浸提液化感作用研究

以小白菜(Brassica campestris L.ssp.Pekinensis(Lour.)Olsson),萝卜(Raphanus sativus L.),水稻(Oryzasativa L.),热研2号柱花草(Stylosanthes guianensis cv.Reyan No.2)作为测试植物,研究新鲜假臭草(Praxelisclematidea(Griseb.)King and Robinson)水浸提液对种子发芽,新鲜假臭草和风干假臭草水浸提液对幼苗早期生长的化感效应以及不同生长环境下的假臭草浸提液对萝卜幼苗早期生长的化感作用。结果表明:新鲜假臭草浸提液对4种测试植物的种子发芽都有抑制作用。假臭草叶和完整植株水浸提液的化感作用明显大于其它器官水浸提液化感作用,叶可能是假臭草释放化感物质的主要器官。风干和新鲜假臭草水浸提液在低浓度时抑制所有测试植物幼苗根系生长。在逆境(如干旱和养分胁迫)中,假臭草会释放更多的化感物质,从而导致其化感作用增强。     

桉树叶水浸提液对香根草根系生长及部分生理指标的影响

为探讨香根草能否作为桉树人工林可选的林下经济植物,通过土培试验,研究桉树叶水浸提液对香根草根系生长及叶片部分生理指标的影响。结果表明:桉树叶水浸提液对香根草根系伸长和干重呈现出先促进后抑制的作用,但与对照相比差异不显著;香根草根系活力、叶绿素含量受桉树化感效应非常敏感,均随浓度的升高而呈现出先明显增加后显著下降的趋势;各浓度处理的香根草植株内丙二醛含量均高于对照,处理浓度≤40%时,差异不显著;高浓度≥60%,差异极显著。研究结果表明,香根草对桉树化感物质有较强的抗逆性,浓度≤40%桉树叶水浸提液促进了香根草的生长,仅在浓度≥60%时才表现为抑制作用。香根草有作为发展桉树人工林林下经济栽培植物的应用价值。     

植物促生菌对桉树幼苗生长及其氮素来源的影响

利用~(15)N稳定性同位素示踪法,研究施氮水平对接种或不接种植物促生菌的桉树幼苗生物量、N和P吸收量及其吸收氮素来源的影响。结果表明:随着施氮量的增加,桉树幼苗植株生物量、N和P吸收量均显著增加。接种PGPR SZ7-1植物促生菌能显著促进桉树幼苗生物量的增加和养分量的吸收。未接种植物促生菌的桉树幼苗,其植株吸收氮素主要来源于土壤,其次是肥料;而接种PGPR SZ7-1植物促生菌的桉树幼苗,其植株吸收的氮素则主要来源于生物固氮。PGPR SZ7-1植物促生菌具有较好的固氮能力,固氮率达40%以上。结果还显示,随着施氮量的增加,接种植物促生菌的桉树幼苗生物固氮能力下降,植株氮素主要来源于土壤氮,其次为生物固氮和肥料氮。在较低的氮素水平下,接种植物促生菌能有效促进桉树植株的生长发育和养分吸收,是一种减少肥料施用、保护生态环境的农业措施之一。     

不同品种桉树人工林生长特征及持水性能研究

以广西10年生的4种桉树人工林为研究对象,对比分析了不同林分的生长特征、林下凋落物和土壤持水特征的变化规律。结果表明:在林分生长特征方面,4种桉树林分平均胸径在13.9~15.5 cm之间变化,柳桉最小,大花序桉最大;树高和冠幅均达到极显著差异(p0.01),粗皮桉最小,大花序桉最大。在凋落物贮量及持水特征上,林下总的凋落物贮量范围是18.7~20.1 t/hm2,排序为:大花序桉(20.1 t/hm2)邓恩桉(19.6 t/hm2)粗皮桉(19.1 t/hm2)柳桉(18.7 t/hm2);最大持水量在25.9~40.7 t/hm2之间变化,排序为:邓恩桉(40.7 t/hm2)大花序桉(32.9 t/hm2)柳桉(27.2 t/hm2)粗皮桉(25.9 t/hm2)。在土壤持水特性方面,4种桉树人工林地的土壤总孔隙度、毛管孔隙度、饱和持水量、毛管持水量和田间持水量均为粗皮桉林地最小,柳桉林地最大。     

干旱胁迫对入侵植物假臭草幼苗生长和生理生态指标的影响

在控水条件下,研究干旱胁迫对入侵植物假臭草幼苗生长和生理生态指标的影响.结果表明,假臭草在干旱胁迫下,幼苗生长受到抑制;幼苗叶片的净光合速率、蒸腾速率均随着土壤含水量的减少而降低;体内的丙二醛(MDA)、脯氨酸(Pro)、叶绿素含量均发生了不同程度的变化.表明假臭草体内存有抗旱的机制,能够适应多种生境,这可能是其成为人侵植物的原因之一.     

桉树人工林间作豆科牧草适应性评价

桉树人工林单一种植引起植被多样性减少是普遍存在的问题,间作成为恢复与重建桉树林下植被多样性的重要途径。桉树人工林下间作豆科牧草综合评价结果表明GC1581、GC1517、热研10号和热研2号柱花草牧草产草量达296.54~852.08 kg/hm2,耐干旱,旱季牧草产量占年产草量的18.42%~23.95%,在极端干旱条件下仍保持一定的生长和生物量的积累,植株存活率达50.2%~61.9%,间作牧草在桉树行间形成良好的覆盖层,覆盖度达47.083%~79.252%,适应性强。间作可促进林下植被的恢复,进而促进植被多样性的形成,这对增加桉树人工林的群落组成、形成多层次片层结构有积极意义。     

猪屎豆提取物的化感作用研究

[目的]探究猪屎豆是否具有化感作用。[方法]采用种子萌发法(培养皿滤纸法),评价猪屎豆提取物对玉米、萝卜、莴苣和鬼针草的化感作用。[结果]猪屎豆乙醇提取物对鬼针草种子萌发、幼苗根长、苗高和萝卜根长具有化感抑制作用,对玉米、莴苣种子萌发、幼苗根长、苗高和萝卜种子萌发、苗高及莴苣幼苗根长表现为“低促高抑”现象。猪屎豆乙醇提取物的石油醚、正丁醇萃取物对玉米种子萌发、幼苗苗高具有化感抑制作用;而石油醚、乙酸乙酯、正丁醇和水相萃取物对玉米幼苗根长生长均具有促进作用,乙酸乙酯和水相萃取物对玉米幼苗苗高具有促进作用。[结论]猪屎豆提取物对不同植物的种子萌发和幼苗生长均有不同程度的影响,具有一定的化感作用。     

林草间作系统土壤微生物及其活性研究

试验对6年龄桉树人工林间作禾本科及豆科牧草后的土壤微生物进行研究,结果表明：间作牧草可显著提高林地土壤微生物的生物量、呼吸强度、硝化作用强度及纤维素分解作用强度,且均随着土层深度的加深而降低;其中以间作热研6号珊状臂形草、热研2号柱花草、GC1581柱花草和Mineirao柱花草的土壤微生物生物量最高;热研15号刚果臂形草、热研6号珊状臂形草、杂交臂形草、热研10号柱花草、Mineirao和GC1581的呼吸强度高于CK;热研11号黑籽雀稗、热研10号柱花草、GC1581和热研2号柱花草的硝化作用强度强于CK;热研9号坚尼草、杂交臂形草和热研6号珊状臂形草、热研10号柱花草和热研2号柱花草的土壤纤维素分解作用强度较强。     

The morphological and physiological responses of perennial ryegrass (Lolium perenne L.), cocksfoot (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.; syn. Schedonorus phoenix Scop.) to variable water availability

There is a growing interest in the use of deficit irrigation and perennial pasture species other than perennial ryegrass (Lolium perenne L.) in temperate agriculture, in response to the decreasing availability of irrigation water. Deficit irrigation requires an understanding of plant responses to drought stress to ensure maximum dry‐matter return on water applied. A glasshouse study was undertaken to investigate some of the morphological and physiological responses of perennial ryegrass, cocksfoot (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.; syn. Schedonorus phoenix Scop.) to varied moisture availability. One water treatment involved frequent applications of water to maintain a soil water potential of approximately ?10 kPa (100% treatment), and three other treatments involved applications at the same frequency, but using 33, 66 or 133% of the water applied in the 100% treatment. The water treatments continued over two plant regrowth cycles, followed by a ‘recovery’ phase of a single regrowth cycle during which all plants received the same water allocation as the 100% treatment. Depletion and replenishment of stubble water‐soluble carbohydrate (WSC) differed between the three species in response to soil moisture availability. By the second regrowth cycle, stubble WSC concentration and content in moisture‐stressed cocksfoot plants had increased, followed by a decrease during the subsequent recovery phase when the stored WSC reserves were utilized to support regrowth. The changes in stubble WSC reserves corresponded to the maintenance of relatively stable (i.e. the smallest reduction in leaf DM in response to moisture stress), but consistently lower DM production for cocksfoot compared with the other species. In contrast, moisture stress had no effect on the stubble WSC reserves of perennial ryegrass and tall fescue, with the exception of a significant decrease in WSC concentration under the 33% water treatment for perennial ryegrass. Perennial ryegrass achieved an intermediate DM yield and maintained positive growth rates throughout the study, even when watered at 33% of the requirement for optimal soil moisture levels. However, a more pronounced reduction in leaf DM in plants under moisture stress compared with the other species, combined with declining WSC reserves and the death of daughter tillers, highlighted the vulnerability of perennial ryegrass to poor persistence under prolonged drought conditions. Tall fescue appeared to have the greatest scope under moisture stress in terms of maintaining productivity and displaying attributes that contribute to persistence. Its leaf DM was consistently greater than that of the other species, displaying a smaller decline in growth under water stress compared to perennial ryegrass and an ability to recover faster upon re‐watering. This study has expanded the information available that compares and defines the potential of each species under moisture stress and emphasizes the importance of balancing short‐term DM production with long‐term persistence in choice of pasture species.     

混播比例对热研2号柱花草和飞机草早期生长竞争能力的影响

为明确热研2号柱花草(Stylosanthes guianensis cv.Reyan No.2)与飞机草(Chromolaena odorata(L.)R.M.KingH.Robinson)生长早期的竞争关系,探索飞机草替代控制的途径和管理策略。设置总株数固定(8株),5种柱花草和飞机草分株数混播比例(柱∶飞=8∶0、6∶2、4∶4、2∶6、0∶8)盆栽试验,就各混播比例下2种植物在浇水频率1次/2 d、生长30 d的生长情况和相对竞争能力进行定量分析。结果表明:随着柱花草混播株数的减少,柱花草和飞机草的相对株高、相对平均生长速度、相对单株总生物量和总生物量分配至根、茎和叶的相对生物量均逐渐降低;但飞机草的相对根长、相对根冠比和根生物量质量分数均逐渐减小、茎生物量质量分数无显著变化、叶生物量质量分数逐渐增大,而柱花草的各对应指标反之。柱花草比例较高时(柱∶飞为6∶2)2种植物的相对产量总和显著大于1,2种植物间无种间竞争现象,4∶4和2∶6时相对产量总和均与1相比无显著差异,2种植物间存在资源竞争;混播群落中柱花草的竞争平衡指数均显著小于0,说明生长早期柱花草的相对竞争能力比飞机草弱。下一步进行生长中期、晚期竞争试验和肥力、刈割等其他因素影响试验来确定柱花草替代控制飞机草的可能性。     

枯草芽孢杆菌T122F菌剂对香蕉的生物效应研究

采用室内与田间试验相结合的方法研究了枯草芽孢杆菌T122F菌剂对香蕉生物效应的影响。结果表明:菌剂能明显促进香蕉生长,主要表现为香蕉株高、假茎周长、叶片数以及叶绿素含量的增加。菌剂的施用还能显著提高香蕉内生细菌数量、叶片耐菌能力和根际土壤细菌数量。在300倍液处理下,从香蕉苗根部分离到的菌量为299.75×103 cfu/g FW,是对照的7.16倍,而从香蕉根际土壤中分离到的菌量则是对照的2.20倍。此外,经菌剂处理的香蕉根际土壤水浸液对香蕉枯萎病菌孢子萌发也表现出明显的抑制作用。     

水分胁迫对春小麦光合和渗透调节物质的影响

为进一步了解春小麦的抗旱生理机制,以春小麦品种陇春26号为材料,采用盆栽法研究了中度和重度水分胁迫下春小麦旗叶光合参数和渗透调节物质含量的变化.结果表明,随土壤水分的减少,春小麦旗叶的叶绿素含量、光合速率、气孔导度、胞间CO2浓度、蒸腾速率逐渐降低,可溶性糖和可溶性蛋白含量及酸性转化酶活性呈先增后减趋势,脯氨酸和丙二醛含量及过氧化物酶活性逐渐增强.中度水分胁迫的可溶性糖含量和酸性转化酶活性显著高于重度水分胁迫和正常供水对照;重度水分胁迫的可溶性蛋白含量显著低于中度水分胁迫和正常供水对照,而脯氨酸和丙二醛含量显著高于中度水分胁迫和正常供水对照.说明中度或重度干旱胁迫下春小麦旗叶光合速率降低是叶绿素含量降低和光合原料缺乏所致,脯氨酸含量和过氧化物酶活性升高有助于春小麦抵御干旱胁迫.     

Effects of Soil Moisture Conditions before Heading on Growth of Wheat Plants under Drought Conditions in the Ripening Stage: Insufficient Soil Moisture Conditions before Heading Render Wheat Plants More Resistant to Drought during Ripening

Abstract

Plants growing on soil with insufficient moisture need deep and dense roots to avoid water stress. In crop plants, the production of dry matter during ripening of grains is critically important for grain yield. We postulated that shoot growth would be suppressed but root growth would continue under an insufficient soil moisture condition before heading, while shoot growth would be more vigorous than root growth under a sufficient soil moisture condition. We anticipated that the plants growing under an insufficient soil moisture condition before heading would produce more dry matter and grain under an insufficient soil moisture condition during ripening. In order to examine our hypotheses and to determine the fundamental conditions for improving grain yield and efficient use of irrigated water under limited irrigation, we grew wheat plants (Triticum aestivum L., cv. Ayahikari) in pots (30 cm in diameter, 150 cm in height) with insufficient soil moisture (PD-D pots) or sufficient soil moisture (PW-D pots) for six weeks before heading followed by full irrigation, and then insufficient soil moisture condition during ripening. The growth of shoots was suppressed significantly but that of roots was not before heading in PD-D plants, with a higher resultant ratio of root to shoot than in PW-D plants. The former retained a high leaf water potential and, therefore, were able to produce more dry matter and grain during soil moisture depletion during ripening as compared with the latter plants. We also obtained similar results with field-grown plants.     

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.     

福州市长乐沿海木麻黄林下野生苗的根系形态特征

植物根系对环境的形态适应研究对准确揭示植物与环境的关系十分重要。为探索滨海恶劣环境条件下木麻黄林下植被天然更新特征,本研究以沿海木麻黄防护林林下野生苗为研究对象,比较不同高度级木麻黄野生苗根系的总根长、总根表面积、平均根系直径、总根体积和总根尖数,分析林下3种草本植物根系形态特征。结果表明：随着木麻黄野生苗高度级的增加,总根表面积、平均根系直径和总根体积显著增长（P<0.05）;高度级1的野生苗总根表面积随根系径级的增加显著减少,高度级2的野生苗总根表面积在0~2.0 mm随根系径级的增加而减少,但在>2.0 mm时显著增加（P<0.05）;与林下草本植物相比,木麻黄野生苗的根系生长不占优势,其平均根系直径是窃衣和一点红的2~3倍,但是总根尖数最少且显著少于天门冬（P<0.05）;此外,在根系径级>1.5 mm时,仅木麻黄有根尖存在,根尖数占总数的0.33%。研究结果为促进林下植被的更新和保持植物多样性提供参考。