香草醛和对羟基苯甲酸对杉木幼苗生理特性的影响

采用盆栽模拟实验 ,研究了不同浓度的香草醛和对羟基苯甲酸对杉木幼苗生理特性的影响 .结果表明 ,当浓度为 10mmol·L-1和 1mmol·L-1时显著抑制了杉木幼苗的叶绿素含量、光合作用、根系活力等生理指标 ,并且随着浓度的增加 ,对生理活性的抑制作用增大 .其中 ,用香草醛处理的杉木幼苗的净光合速率分别降低 37.0 %、2 5 .1% ;蒸腾速率分别降低 37.0 %、2 0 .3% ;气孔导度分别降低 4 6 .8%、33.7% ;根系活力分别降低 78.8%、5 1.6 % .连栽杉木林土壤中积累的香草醛、对羟基苯甲酸等酚类化合物能够对杉木幼苗产生化感作用 ,这是导致连栽杉木生产力降低的一个不可忽视的因素 .     

土壤湿度对香樟幼苗根系生长和构型的影响

以1年生香樟(Cinnamomum camphora)幼苗为试材,设置对照组(CK)、中度干旱处理(M)、重度干旱处理(S)三个处理,比较不同土壤湿度下香樟幼苗不同时期地上部分生长和根系构型,探究香樟幼苗根系对不同土壤湿度的适应性及其耐旱机制。结果表明,中度和重度干旱处理组的香樟根系及地上部分干物质积累、根系长度、根系表面积、根系直径和根尖数均显著小于对照组(P<0.05)。同时干旱显著增加香樟幼苗的根系拓扑指数,降低香樟根的分形维数和平均分枝角度(P<0.05)。可见土壤湿度程度及处理时间显著影响香樟根系的生长及在土壤中的布局。较低土壤湿度可显著抑制根长的延长、根表面积扩大和根的增殖,且随着土壤湿度的继续降低以及处理时间延长,香樟幼苗根系的生长受到水分亏缺的抑制作用加重,根系建成成本增高的同时,根系分枝的复杂性降低,根系必须通过朝着更陡、更深的方向生长伸长来提高水分吸收效率。建议在园林绿化工程养护过程中制定科学的水分管理策略,以满足香樟生长过程中对土壤水分的需要。     

旱涝胁迫对棉花根系生长的影响

为探究旱涝胁迫对棉花花铃期及吐絮期根系的影响,于2016年在武汉大学灌溉排水试验场开展了受旱、受涝及旱涝急转胁迫测坑试验,使用微根管系统对根系进行了原位生长过程监测,并用挖掘法对结果进行了验证。结果表明:通过微根管观测图片所获取的根系信息,代表了根管周围3.3 mm透视厚度土层的根系状况;从蕾期至吐絮期内,根系生长呈"S"型曲线,其中花铃期根系生长发育最快;0~30 cm是根系主要分布区域,约占根系总量的70%~80%;不同旱涝胁迫处理下总根长及总根表面积从大到小的顺序为受涝组旱转涝组正常组受旱组;涝渍导致表层根系大量繁殖,特别是根粗为0.2~0.4 mm的根系生长;干旱使得棉花根长密度变小,径变粗,深层根系生长加速、占比上升,根系重心下移;旱转涝后根系指标增速大于对照组,证明后期受涝对前期受旱在根系生长方面具有补偿效应。     

外源亚精胺对盐碱胁迫下番茄幼苗根系线粒体功能的影响

为探讨外源亚精胺(Spd)对盐碱胁迫下番茄根系线粒体功能的影响,采用水培法,以耐性不同的两个番茄品种‘金棚朝冠’(耐盐型)和‘中杂9号’(敏感型)为试材,通过模拟盐碱生态条件(Na Cl∶Na_2SO_4∶Na HCO3∶Na2CO3=1∶9∶9∶1),结合叶面喷施外源0.25mmol·L~(-1)Spd,研究盐碱胁迫8 d后Spd对番茄幼苗根系形态和根系线粒体功能的影响.结果表明:盐碱胁迫下,两个品种番茄根系线粒体内H_2O_2和丙二醛(MDA)含量增加,线粒体膜通透性明显增大,流动性降低,膜电位、线粒体内细胞色素c/a(Cyt c/a)吸光度比值、膜H~+-ATPase活性显著下降,使线粒体受到不同程度的损伤,从而抑制根系生长,且‘金棚朝冠’的上述指标变化幅度均小于‘中杂9号’.盐碱胁迫下,喷施外源Spd处理的两个品种根系线粒体H_2O_2和MDA含量显著降低,膜通透性减小、流动性增加,膜电位、线粒体内Cyt c/a吸光度比值、膜H~+-ATPase活性显著提高,可有效缓解盐碱胁迫对番茄幼苗根系线粒体的伤害作用,且这种缓解作用在‘中杂9号’上的表现效果更佳.     

部分根系供磷对黄瓜根系和幼苗生长及根系酸性磷酸酶活性影响

通过分根处理研究了部分根系供磷对黄瓜幼苗生长、植株体内的含磷量及根系酸性磷酸酶活性的影响。结果表明 ,2 0 %根系缺磷 (1条根缺磷 ,4条根供磷 )可以促进根系及植株地上部的生长 ,其根系及地上部的生物量分别是正常生长植株的 1.39倍和 1.2 1倍。2 0 %根系缺磷 ,还可以促进其它供磷根系对磷的吸收。分根处理后 ,2 0 %根系缺磷不影响植物对磷营养的需要 ,但却表现出了R/S比增大的典型缺磷反应 ,说明植物感应缺磷根系起着比地上部更为重要的作用。分根处理后不供磷根系的酸性磷酸酶活性显著高于供磷根系的酸性磷酸酶活性 ,并且根系的酸性磷酸酶活性只与根系的含磷量显著相关 ,与地上部的磷营养状况关系不明显。这说明 ,缺磷条件下 ,黄瓜植株根系分泌酸性磷酸酶活性的增高 ,是黄瓜根系对低磷胁迫的适应性机理 ,而不是地上部改善体内磷营养的调控机理。     

部分根系供磷对黄瓜根系和幼苗生长及根系酸性磷酸酶活性影响

通过分根处理研究了部分根系供磷结黄瓜幼苗生长、植株体内的含磷量及根系酸性磷酸酶活性的影响。结果表明,２０％根系缺磷（１条根所磷,４条根系地上部的生物量分别是正常生长植株的１．３９倍和１．２１倍。２０％根系缺磷,唯心论促进其它供磷系对磷的吸收。分根处理后,２０％根系缺磷不影响植物对磷营养的需要,但却表现出了Ｒ／Ｓ比增大的典型缺磷反应,说明植物感应缺磷根系起飞丰比地上部更为重要的作用。分根处理后不供磷     

外源亚精胺对盐碱胁迫下番茄幼苗根系线粒体功能的影响

为探讨外源亚精胺(Spd)对盐碱胁迫下番茄根系线粒体功能的影响,采用水培法,以耐性不同的两个番茄品种‘金棚朝冠’（耐盐型）和‘中杂9号’（敏感型）为试材,通过模拟盐碱生态条件(NaCl∶Na₂SO₄∶NaHCO₃∶Na₂CO₃=1∶9∶9∶1),结合叶面喷施外源0.25 mmol·L^-1Spd,研究盐碱胁迫8 d后Spd对番茄幼苗根系形态和根系线粒体功能的影响.结果表明： 盐碱胁迫下,两个品种番茄根系线粒体内H₂O₂和丙二醛（MDA）含量增加,线粒体膜通透性明显增大,流动性降低,膜电位、线粒体内细胞色素c/a(Cyt c/a)吸光度比值、膜H⁺-ATPase活性显著下降,使线粒体受到不同程度的损伤,从而抑制根系生长,且‘金棚朝冠’的上述指标变化幅度均小于‘中杂9号’.盐碱胁迫下,喷施外源Spd处理的两个品种根系线粒体H₂O₂和MDA含量显著降低,膜通透性减小、流动性增加,膜电位、线粒体内Cyt c/a吸光度比值、膜H⁺-ATPase活性显著提高,可有效缓解盐碱胁迫对番茄幼苗根系线粒体的伤害作用,且这种缓解作用在‘中杂9号’上的表现效果更佳.     

干旱胁迫对小麦幼苗根系生长和叶片光合作用的影响

采用水培试验方法,以2个耐旱性不同的小麦品种(敏感型望水白和耐旱型洛旱7号)为材料,研究了干旱胁迫对小麦幼苗根系形态、生理特性以及叶片光合作用的影响,以期揭示小麦幼苗对干旱胁迫的适应机制.结果表明： 干旱胁迫下,2个小麦品种幼苗的根系活力显著增大,而根数和根系表面积受到抑制;干旱胁迫降低了望水白的叶片相对含水量,提高了束缚水/自由水,而对洛旱7号无显著影响;干旱胁迫降低了2个小麦品种叶片的叶绿素含量、净光合速率、蒸腾速率、气孔导度和胞间CO2浓度,但随胁迫时间的延长,洛旱7号的叶绿素含量和净光合速率与对照差异不显著;干旱胁迫降低了2个小麦品种幼苗的单株叶面积,以及望水白的根系、地上部和植株生物量,而对洛旱7号无显著影响.水分胁迫下,耐旱型品种可以通过提高根系活力、保持较高的根系生长量来补偿根系吸收面积的下降,保持较高的根系吸水能力,进而维持较高的光合面积和光合速率,缓解干旱对生长的抑制.     

干旱胁迫对小麦幼苗根系生长和叶片光合作用的影响

采用水培试验方法,以2个耐旱性不同的小麦品种(敏感型望水白和耐旱型洛旱7号)为材料,研究了干旱胁迫对小麦幼苗根系形态、生理特性以及叶片光合作用的影响,以期揭示小麦幼苗对干旱胁迫的适应机制.结果表明： 干旱胁迫下,2个小麦品种幼苗的根系活力显著增大,而根数和根系表面积受到抑制;干旱胁迫降低了望水白的叶片相对含水量,提高了束缚水/自由水,而对洛旱7号无显著影响;干旱胁迫降低了2个小麦品种叶片的叶绿素含量、净光合速率、蒸腾速率、气孔导度和胞间CO2浓度,但随胁迫时间的延长,洛旱7号的叶绿素含量和净光合速率与对照差异不显著;干旱胁迫降低了2个小麦品种幼苗的单株叶面积,以及望水白的根系、地上部和植株生物量,而对洛旱7号无显著影响.水分胁迫下,耐旱型品种可以通过提高根系活力、保持较高的根系生长量来补偿根系吸收面积的下降,保持较高的根系吸水能力,进而维持较高的光合面积和光合速率,缓解干旱对生长的抑制.     

盐胁迫对黄瓜幼苗根系生长和水分利用的影响

采用营养液水培法,研究了NaCl胁迫对两个耐盐性不同的黄瓜品种幼苗根系生长、活力、质膜透性和叶片生长、蒸腾速率（T_r）、相对含水量（RWC）及水分利用率（WUE）的影响.结果表明,盐胁迫下黄瓜植株根系吸收面积下降,质膜透性升高,叶片数减少,叶片T_r和RWC在盐胁迫2 d后明显下降,根系活力和叶片WUE均先升后降,50、75和100 mmol·L^-1NaCl胁迫9 d时,耐盐性较弱的津春2号根系活力降低幅度分别比耐盐性较强的长春密刺高18.01%、12.17%和10.95%,胁迫8 d时WUE下降幅度分别比长春密刺高2.74%、5.27%和0.23%.短期盐胁迫下,黄瓜植株通过提高根系吸收能力来补偿根系吸收面积的下降,通过降低叶片T_r和提高WUE来减少水分散失,在一定程度上有利于缓解水分失衡,提高植株耐盐性;盐胁迫5 d后,根系活力和WUE的下降导致水分失衡加剧,表明根系吸收能力的下降是导致水分失衡的重要原因,叶片WUE的下降是水分失衡的反应,两者均与品种的耐盐性关系密切.     

In-ovulo embryo culture and seedling development of cotton (Gossypium hirsutum L.)

A convenient and reliable method for culturing cotton embryos is needed to obtain interspecific hybrids of this genus. C.A. Beasley and I.P. Ting (Amer. J. Bot. 60, 130, 1973) developed a phytohormone-supplemented medium (BTP) upon which the growth of ovules was similar that of in situ ovules. This medium was examined for in-ovulo embryo culture. Although good ovule growth occurred on BTP no embryos developed to maturity. However, when the medium was supplemented with NH ₄ ⁺ , more than 50% of the ovules produced mature embryos, and many of these germinated precociously after 8–10 weeks of culture. After germination seedlings were established on a separate medium designed to give balanced root and shoot growth. Subsequently young plants could be transferred to pots for greenhouse culture.     

Effects of fusicoccin on intact cotton plants (Gossypium hirsutum L.)

Fusicoccin (FC) was applied as a spray to shoots of intact field- and glasshouse-grown cotton plants. Distortions of shoot morphology resulted. Stems and petioles of FC-treated plants were irregular in diameter and twisted, whereas leaf laminae were curled and crinkled. Shoot elongation was inhibited by FC; the effect was dependent upon the concentration and timing of the applications.Abbreviation FC fusicoccin     

Chilling injury in cotton (Gossypium hirsutum L.) Prevention by abscisic acid

Cotton (Gossypium hirsutum L.) intact seedlings and isolatedcotyledonary discs were exposed to chilling (4?C) under humidconditions which prevented dehydration. The damage resultingfrom chilling was estimated by means of electrolyte leakageand survival in whole seedlings and by the electrolyte leakageand necrotic areas in isolated cotyledonary discs. Also, theeffect of chilling on membrane phospholipids and cellular reducedglutathione was determined. Within the first two and three daysof chilling, there was a marked reduction in the reduced glutathioneand membrane phospholipid levels without electrolyte loss andnecrosis. This reduction was completely prevented by pretreatmentwith abscisic acid. Prolonging the chilling period resultedin decreased survival in whole seedlings and in progressiveincrease in electrolyte leakage and necrosis in isolated cotyledonarydiscs. Pretreatment with abscisic acid prior to chilling almostcompletely prevented this chilling injury when exposure to 4?Cwas less than 5 days. Even with longer chilling periods, theabscisic acid pretreatment greatly reduced the damage. ³Incumbent of the Seagram Chair in Plant Science. (Received July 21, 1979; )     

Effects of ultraviolet-B radiation on cotton (Gossypium hirsutum L.) morphology and anatomy

Cotton (Gossypium hirsutum L.) crop, cultivated between 40 degrees N and 40 degrees S, is currently experiencing 2-11 kJ m-2 d-1 of UV-B radiation. This is predicted to increase in the near future. An experiment was conducted to study the effect of enhanced UV-B radiation on vegetative and reproductive morphology and leaf anatomy of cotton in sunlit, controlled environment chambers. From emergence to harvest, cotton plants were exposed to 0, 8 or 16 kJ m-2 d-1 of UV-B in a square wave approach for 8 h from 0800 to 1600 h. Changes in plant height, internode and branch length, mainstem node number, leaf area, length and area of petals and bracts, and anther number per flower were recorded. Epidermal cell and stomatal density, stomatal index, leaf thickness, and epidermal, palisade and mesophyll tissue thickness were also measured. Initial chlorotic symptoms on leaves turned into necrotic patches on continued exposure to enhanced UV-B. Exposure to high UV-B reduced both vegetative and reproductive parameters and resulted in a smaller canopy indicating sensitivity of cotton to UV-B radiation. Enhanced UV-B radiation increased epicuticular wax content on adaxial leaf surfaces, and stomatal index on both adaxial and abaxial leaf surfaces. Leaf thickness was reduced following exposure to UV-B owing to a decrease in thickness of both the palisade and mesophyll tissue, while the epidermal thickness remained unchanged. The vegetative parameters studied were affected only by high levels of UV-B (16 kJ m-2 d-1), whereas the reproductive parameters were reduced at both ambient (8 kJ m-2 d-1) and high UV-B levels. The study shows that cotton plants are sensitive to UV-B at both the whole plant and anatomical level.     

Chilling injury in cotton (Gossypium hirsutum L.) : Effects of antimicrotubular drugs

When exposed to 4°C for more than three days, intact cotton(Gossypium hirsutum L.) seedlings and isolated cotyledonarydiscs suffered chilling injury as shown by the leakage of electrolytesfrom the tissue and the development of necrotic areas. Applicationof antimicrotubular drugs such as colchicine, demecolcine orpodophyllotoxin during chilling significantly accelerated andenhanced tissue damage. Lumicolchicine, the stereoisomer ofcolchicine, was ineffective. Non-chilled tissues showed hardlyany damage when treated with the same levels of antimicrotubulardrugs. Prior treatment with 10^–5 M abscisic acid (ABA)prevented the appearance of symptoms of damage caused by chillingand the antimicrotubular drugs during the first 2 to 3 daysand greatly reduced it at later stages. Our present resultssuggest that chilling damage may be due at least in part, tothe cold-induced disassembly of microtubules. Furthermore, themode of action of ABA might be related to factors which influencethe physiological stability of the microtubule network. ¹Preliminary report of this work was presented at the 10th InternationalConference on Plant Growth Substances, Madison, Wisconsin, 1979. ³Incumbent of the Seagram Chair in Plant Sciences. (Received April 15, 1980; )     

Infraspecific DNA methylation polymorphism in cotton (Gossypium hirsutum L.)

Cytosine methylation is important in the epigenetic regulation of gene expression and development in plants and has been implicated in silencing duplicate genes after polyploid formation in several plant groups. Relatively little information exists, however, on levels and patterns of methylation polymorphism (MP) at homologous loci within species. Here we explored the levels and patterns of methylation-polymorphism diversity at CCGG sites within allotetraploid cotton, Gossypium hirsutum, using a methylation-sensitive amplified fragment length polymorphism screen and a selected set of 20 G. hirsutum accessions for which we have information on genetic polymorphism levels and relationships. Methylation and MP exist at high levels within G. hirsutum: of 150 HpaII/MspI sites surveyed, 48 were methylated at the inner cytosine (32%) and 32 of these were polymorphic (67%). Both these values are higher than comparable measures of genetic diversity using restriction fragment length polymorphisms. The high percentage of methylation-polymorphic sites and potential relationship to gene expression underscore the potential significance of MP within and among populations. We speculate that biased correlation of methylation-polymorphic sites and genes in cotton may be a consequence of polyploidy and the attendant doubling of all genes.     

Somatic embryogenesis and plant regeneration in cotton (Gossypium hirsutum L.)

Tissue culture methods for improvement of cotton has lagged seriously compared to other major crops. A method for regeneration of cotton which includes a morphogenetically competent cell suspension was needed to facilitate selection of stress-resistant variants and gene manipulation. Preliminary screening of eight strains of Gossypium hirsutum L. for embryogenic potential resulted in the production of somatic embryos in all strains. Coker 312 was selected for use in the development of a model regeneration system for G. hirsutum. Calli were initiated from hypocotyl tissues of 3-day-old-seedlings. Globular embryos were present after six weeks in culture. Calli were subcultured to liquid suspension in growth regulator-free medium. After three to four weeks, suspensions were sieved to collect globular and heart stage embryos. Collected embryos developed further when plated onto semi-solid medium. To induce germination and plantlet growth, mature embryos were placed on sterile vermiculite saturated with medium. Upon development of roots and two true leaves, plantlets were potted in peat and sand, and hardened. Mature plants and progeny have been obtained with this procedure. A high percentage of infertile plants was observed among the regenerants.Abbreviations NAA 1 naphthaleneacetic acid - IAA indole-3-acetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid - MS Murashige and Skoog - BA 6 benzylamino purine - 2i P N⁶-(²-isopentenyladenine     

Rapid in-vitro plant regeneration of cotton (Gossypium hirsutum L.)

A rapid, clonal propagation procedure has been developed to regenerate mature cotton (Gossypium hirsutum L.) plants from pre-existing meristems that were excised from in-vitro-grown tissues. This plant regeneration procedure was applicable to diverse cotton germplasms and required specific concentrations of 6-benzylaminopurine (BA) depending on the origin of the meristems. All shoots regenerated directly without a callus phase. Screening BA concentrations (0.0–10.0 μm) demonstrated that shoot meristems (apices), secondary leaf nodes, primary leaf nodes, and cotyledonary nodes derived from in-vitro-grown 28-day-old seedlings (Paymaster HS26) varied in their ability to form elongated shoots depending on the level of BA. Indicative of a germplasm-independent procedure, a BA concentration screen (0.0, 0.3, 1.0 μm) demonstrated that explants with pre-existing meristems, excised from diverse germlines, were also able to form elongated shoots at 0.3 μm BA. In most cases, elongated shoots derived from this procedure were rooted by a two-step process: an in-vitro maturation step (Murashige and Skoog medium-activated charcoal) followed by planting into soil after basal application of Rootone. This BA plant regeneration procedure was rapid, reproducible, and highly efficient for Stoneville 7A, Paymaster HS26, and other high-fiber-yielding germlines. Regenerated plants were phenotypically normal and all of the mature plants regenerated to date have initiated flowers and set viable R₁ seeds. Received: 15 March 1997 / Revision received: 28 August 1997 / Accepted: 5 September 1997     

NaCl胁迫对棉花种子萌发和幼苗生长的伤害

采用盐化土壤盆栽方法,选择耐盐性较强品种枝棉３号和耐盐性较弱品种泗棉２号,研究了盐分对棉花（Ｇｏｓｓｙｐｉｕｍ ｈｉｒｓｕｔｕｍ Ｌ．）种子萌发、出苗和幼苗生长的伤害。结果表明,在－０．５５和－１．１０ＭＰａ盐分胁迫下,对棉花伤害起决定性作用的因子是Ｎａ＾＋。２００ｍｍｏｌ／Ｌ ＮａＣｌ胁迫下,枝棉３号种子萌发时电导率上升幅度和子叶ＣＡＴ下降幅度均显著小于泗棉２号。１００和２００ｍｍｏｌ／Ｌ Ｎａ