Quantification of allelopathic potential of sorghum residues by novel indexing of richards' function fitted to cumulative cress seed germination curves

The inhibitory activity of aqueous extracts of field-grown sorghum (Sorghum bicolor cv. Bird-a-boo) herbage and roots was quantitatively indexed by three aspects of cumulative cress (Lepidium sativum cv. Curlycress) seed germination: the germination onset; weighted mean rate; and final germination percentage. Extract potency was greatest for herbage collected four weeks after planting but declined sharply thereafter as the plants matured. About 91% of the inhibitory activity obtained from four-week-old herbage was in a low molecular weight fraction. Differential effects of herbage and root extracts on cress seed germination suggest that the nature and/or proportion of biologically active substances extractable from these plant parts is dissimilar.     

Evaluation of genetic variability in choosen apple (<Emphasis Type="Italic">Malus</Emphasis> × <Emphasis Type="Italic">domestica</Emphasis> Borkh.) cultivars by ISSR-PCR analysis

The aim of the study was to determine the genetic variability in eight apple cultivars: Delikates, Cortland, James Grieve, Lired, Jonathan, Golden Delicious, Jonagold, and Idared from the collection of Fruit Growing Research Station in Rajkowo of the West Pomeranian University of Technology, Szczecin. The cultivar Delikates was obtained from the crossing of two cultivars: Cortland, and James Grieve, whereas cultivar Lired is a James Grieve’s sport. The second one cultivar—Jonagold was obtained from the crossing of Jonathan and Golden Delicious. The cultivar Idared is a hybrid obtained from the crossing of Jonathan and Wagener. Out of 40 primers, 17 were chosen for the final study. Those amplified a total of 183 loci (872 amplicons) out of which 34 (18.5%) were monomorphic, 128 (69.5%) were polymorphic and 22 (12%) cultivar-specific. Specific ISSR products were detected for each apple cultivar. A dendrogram was constructed using the UPGMA method which revealed two distinct clusters: I—Delikates, Cortland, James Grieve and Lired, II—Jonathan, Golden Delicious, Jonagold and Idared. Genetic similarity between Delikates, Cortland and James Grieve was 68.6, 70.8%, respectively and between cultivar Jonagold, Jonathan and Golden Delicous was 79.8, 85.2%, respectively.     

Impact of European red mite on Golden Delicious and Oregon Spur apples in Israel

To develop a damage threshold for the European red mite (ERM), Panonychus ulmi (Koch), the effect of ERM injury on fruit weight and return crop in the apple cultivars (CVs) Golden Delicious and Oregon Spur were studied in the Upper Galilee of Israel for two consecutive seasons. The ERM significantly affected the leaf colour, chlorophyll content, fruit weight and return harvest in both CVs. High population levels of 450 adult female cumulative mite days (ACMDs) reduced the fruit weight on Golden Delicious but not on Oregon Spur. Population levels above approximately 600 and 900 ACMDs in Golden Delicious and Oregon Spur, respectively, caused a substantial reduction in the return harvest. Because no damage was observed at low population levels, an action threshold of 150 ACMDs is recommended.     

Changes in Levels of Naturally Occurring Gibberellin-like Substances during Germination of Seed of Lycopersicon esculentum Mill.

Naturally occurring gibberellin-like substances possessing acidic,basic, and neutral properties were detected, by paper partitionchromatography, in ethanolic extracts of tomato seed and ofetiolated seedlings after 72 and 116 hours' growth. Dwarf maizemutants of the d-1 and d-5 types, ‘Meteor’ pea seedlingsand young ‘Potentate’ tomato plants were used asbioassay material. Hydrolysis of seed and seedling proteinsby ficin in phosphate buffer, pH 6.2, after removal of ethanol-solublesubstances, liberated more and different ‘bound’gibberellin-like substances. It is suggested that protein hydrolysisduring germination is an important means of liberating thesesubstances at different stages of seedling development. Acidic substances were present in all the extracts prepared,but in general two with Rfs 0.25 and 0.55 in iso-propanol: ammonia:water : : 10:1:1 v/v were differentiated on d-2 and d-5 maizerespectively. Neutral substances in dry seed extracts chromatographedin the same solvent, had Rfs of 0.05, 0.35, and 0.95 and thesewere found only in the ethanolic (‘free’) extracts.They were active on d-1 and d-2 maize and ‘Meteor’pea. Basic gibberellin-like substances with Rfs of 0.05 and0.35 were found in ‘free’ extracts of both dry seedand etiolated seedlings after 116 hours' growth which were activeon d-2 maize only. Two others with Rfs 0.45 and 0.95 were extractedfrom seedlings after 72 hours' growth and these were activeon young ‘Potentate’ tomato plants. It is suggested that certain gibberellin-like substances, capableof reversing dwarfism in test plants, may be responsible formorphogenetic or other responses not involving stem extensionin the parent species. Changes were found in the levels of gibberellin-likesubstances but there was no evidence of changes in levels ofseed inhibitors relative to seed growth substances.     

Pattern of growth regulating substances in the leaves of vernalized sugar-beet during flowering period

The changes in the levels of growth regulating substances using the wheat coleoptile straight growth test were determined in the leaves of vernalized (flowering) and non-vernalized (non-flowering) plants of sugar-beet, cv. Poly-AG-Poland at two stages; the end of vernalization treatment (210 days from planting) and full-flowering stage. IAA was detected only in the extracts of the leaves of non-vernalized plants after210 days from planting. No inhibitory activity was detected, except in the case of the concentrated extract of the leaves of non-vernalized plants. This growth promoting zone was found at R_f 0.5–0.8 in the leaves of flowering plants after cold treatment and at flowering time. This zone of growth promoting action was suggested to have a major role in the flowering of sugar-beet.     

Thermosensitive genetic dwarfs of apple

The role of environment on the dwarfing (short internode) phenomenon of apple (Malus domestisca Borkh.) was investi gated and defined in controlled environmental chambers. Orchard-grown very dwarf, dwarf and semi-dwarf trees obtained by natural sibcrossing of spur-type cv. Golden Delicious and cv. Delicious, as well as standard cv. Golden Delicious, were propagated via in vitro techniques. Growth was rapid and none of the 4 types exhibited dwarf-like characteristics when grown at constant 27°C with 12, 14 or 16 h daylengths. Standard and very dwarf plants grew at nearly the same rate at constant 30°C, whereas growth nearly ceased on both types at constant 35°C after 7 days. Dwarf and very dwarf plants responded differently from standard and semi-dwarf plants when grown under alternating (ramped) night/day temperatures (15 or 20°C night ramped up to a daytime maximum over 8 h of 23, 28, 33 or 38°C, held for 2 h and then ramped down over 5 h to the night temperature). As the night/maximum day temperature differentia) increased from 0 to 23° under the ramping environments, growth of dwarf plants decreased markedly as compared to standard plants. When the same night/maximum day temperature differential occurred, the effect on decreasing shoot length was greater at the higher (20°C) night temperature. Increasing maximum day temperatures under the ramped environment also reduced leaf area plant^?1 but did not markedly affect leaf number, resulting in short internodes. When a period of constant temperature was followed by ramped temperatures or vice versa, the sequence of constant vs ramped environments made little difference in the final growth of the 4 plant types. The data point to high temperature as the major factor for causing dwarfing of the sensitive plant types. Increasing the differential between night and maximum day temperature resulted in short internode. dwarf plants with small leaves similar to orchard-grown dwarf trees.     

A new method for the identification and isolation of genes essential forArabidopsis thaliana seed germination

Seed viability, dormancy and germination efficiency are very important aspects of the life cycle of plants and their potential to survive and spread in the environment. To characterize the genes controlling these processes, we have devised a technique for the selection of mutants impaired in seed germination. Selection for such a trait is complicated by physiological factors that interact with these processes and affect seed germination efficiency. The distinction between low seed germination potential due to physiological factors that interfere with seed maturation or germination and germination deficiency due to genetic factors was based on screening for tagged mutations.Arabidopsis thaliana T-DNA primary transformants obtained by an in planta transformation technique are all heterozygotes. We screened for lack of germination of 1/4 of the seeds in the progeny of independent transformants, and simultaneously for the abnormal segregation (2:1 instead of 3:1) of a kanamycin resistance marker carried by the T-DNA inserted into the genome of these primary transformants in the plants that germinate. This yielded several mutants affected in the germination processes. One of the mutants, designated ABC33, was further characterized. Once the viable embryos from non-germinating seeds were removed from their testa, they grew and displayed a dwarf phenotype which could be complemented by providing gibberellic acid. A genetic and molecular analysis, based on the characterization of the flanking genomic sequences of the T-DNA insert, showed that ABC33 is a new loss-of-function allele at theGA ₁ locus.     

A new method for the identification and isolation of genes essential forArabidopsis thaliana seed germination

Seed viability, dormancy and germination efficiency are very important aspects of the life cycle of plants and their potential to survive and spread in the environment. To characterize the genes controlling these processes, we have devised a technique for the selection of mutants impaired in seed germination. Selection for such a trait is complicated by physiological factors that interact with these processes and affect seed germination efficiency. The distinction between low seed germination potential due to physiological factors that interfere with seed maturation or germination and germination deficiency due to genetic factors was based on screening for tagged mutations.Arabidopsis thaliana T-DNA primary transformants obtained by an in planta transformation technique are all heterozygotes. We screened for lack of germination of 1/4 of the seeds in the progeny of independent transformants, and simultaneously for the abnormal segregation (2:1 instead of 3:1) of a kanamycin resistance marker carried by the T-DNA inserted into the genome of these primary transformants in the plants that germinate. This yielded several mutants affected in the germination processes. One of the mutants, designated ABC33, was further characterized. Once the viable embryos from non-germinating seeds were removed from their testa, they grew and displayed a dwarf phenotype which could be complemented by providing gibberellic acid. A genetic and molecular analysis, based on the characterization of the flanking genomic sequences of the T-DNA insert, showed that ABC33 is a new loss-of-function allele at theGA ₁ locus.     

Potential biological control of weeds in rice fields by allelopathy of dwarf lilyturf plants

Dwarf lilyturf (Ophiopogonjaponicus Ker-Gawl), a medicinal plant, hasbeen used for sore throat therapy andinhibition of physiological thirst sinceancient times. Experimental studies wereconducted to determine the allelopathic effectsof dwarf lilyturf plants on germination andgrowth of three main weed species, viz.,barnyardgrass (Echinochloa crusgalli L.),monchoria (Monocharia vaginalis P.) andsmallflower umbrella (Cyperus difformisL.), in rice production and on emergence andgrowth of weeds in rice fields in Japan. Theseresults showed that all aqueous extracts (1, 2,4, 8%, w/v) from the dried powders ofunderground parts of dwarf lilyturf containedwater-soluble substances that significantlyinhibited seed germination and seedling growthfor monchoria and smallflower umbrella. Withrespect to barnyardgrass, all aqueous extractshad less effect on germination, but lowconcentrations (<2%, w/v) had stimulatoryeffects on growth. However, higherconcentrations (>4%, w/v) had significantinhibitory effects. In a glasshouse experiment,all treatments (50, 100, 150 g m^–2) of thedried powders significantly inhibited theemergence and dry weights of weeds in ricepaddy fields and the inhibition became strongeras the concentration increased, except that50 g m^–2 concentration had slightstimulatory effects on the emergence ofbarnyardgrass. The 150 g m^–2 concentrationmarkedly inhibited emergence (77.6%) and dryweight (91.1%) of rice field weeds. Inaddition, all treatments had no inhibition oninitial rice plant growth. Dwarf lilyturfplants may have inhibitory potential on weedsas a natural rice field herbicide.     

Isolation, Crystallization, and Partial Identification of Potato Factor II from Potato Tubers

The isolation, crystallization, and partial identification of potato factor II, a stimulator from the chemically neutral fraction of potato extract, is described. The compound was originally found to stimulate elongation of dwarf peas grown under red light, a gibberellin bioassay. It melts between 137° and 139°. In paper chromatography it migrates to R_F 0.62 in isopropyl alcohol: ammonium hydroxide: H₂O (10:1:1, v/v). Based on infrared and NMR data, it does not contain a lactone ring and possibly possesses an amide radical and an OH⁻ group, as well as many methylene radicals. Potato factor II may be similar to certain of the fatty acid derivatives previously reported to stimulate growth of excised sections, but it is unique in that it stimulates growth of intact plants. This effect points to the need for completely separating neutral from acid gibberellin-like substances when the latter are assayed on dwarf peas.     

Demography and mass-rearing of Carposina sasakii Matsumura (Lepidoptera: Carposinidae) reared on Golden Delicious and Red Fuji apples in the laboratory

Carposina sasakii Matsumura (Lepidoptera: Carposinidae), is one of the most serious fruit-boring pests in over ten species of fruit trees, and is especially damaging apples in the northern of China. The application of new planting systems, i.e., high-density and dwarfing rootstock orchard systems with mixed apple varieties, makes it important to study the fitness of C. sasakii on these apple varieties to gain fundamental knowledge for use in pest management involving this insect. In this study, life table data of C. sasakii were collected using Golden Delicious and Red Fuji apples as hosts. The egg-larva duration of male C. sasakii reared on Golden Delicious apples (22.81 d) was significantly shorter than that reared on Red Fuji apples (24.27 d). The egg-larva mortality in Golden Delicious apples (59.00%) was lower than that in Red Fuji apples (72.49%). The mortality of the pupal stage, however, was higher in Golden Delicious (10.51%) than in Red Fuji (0%). The total oviposition period (TPOP) on Golden Delicious apples (32.94 d) was significantly shorter than in individuals reared on Red Fuji apples (34.19 d). The intrinsic rate of increase (r = 0.0581 d⁻¹), net reproductive rate (R₀ = 7.57 offspring), and finite rate of increase (λ = 1.0598 d⁻¹) were all higher on Golden Delicious than those on Red Fuji. When the net reproductive rate (R₀) was used, the harvest rate of pupae was higher (0.8678) when reared on Golden Delicious apples than when reared on Red Fuji apples (0.8398). When a large cohort size (n = 200) was used for effective bootstrap sample, the P_E values for C. sasakii reared on Golden Delicious apples and Red Fuji apples were both almost equal to 1. For C. sasakii culturing purposes, Golden Delicious apples would be more productive than Red Fuji.     

Seed dormancy in Acer: Endogenous germination inhibitors and dormancy in Acer pseudoplatanus L.

Summary Dormant seeds of Acer pseudoplatanus L. contain two zones of inhibition on paper chromatograms in 10:1:1 as detected by the lettuce and cress seed germination, and the wheat coleoptile bioassays. One zone at R_f 0.6–0.8 was partitioned into ethyl acetate at acid pH and was shown to contain ABA by its behaviour on GLC and isomerization under ultra-violet light. The other zone at R_f 0.9 was detected only in the germination bioassays and was partitioned into ethyl acetate over a range of pH indicating the presence of one or more neutral compounds.The inhibitors present in the embryo of dormant sycamore seeds inhibited the germination of non-dormant sycamore seeds at relatively low concentrations. A comparison with the effects of application of exogenous ABA indicated that endogenous ABA could not solely account for the inhibitory activity of seed extracts, which appeared to be due partly to the presence of ABA and partly to that of neutral compounds present in the embryo. Leaching treatments that removed dormancy led to a decrease in the level of inhibitors present mainly in the basic fraction. The exogenous application of kinetin to dormant sycamore seeds increased germination whereas gibberellic acid had no effect. Similar responses were obtained with lettuce seeds inhibited by the basic fraction of dormant sycamore seeds.It is suggested that an inhibitor-cytokinin interaction may be involved in the dormancy of sycamore seeds.     

The effect of ethylene, octanoic acid and a plant-derived smoke extract on the germination of light-sensitive lettuce seeds

The effects of an aqueous plant-derived smoke extract, octanoic acid and ethylene on germination of light-sensitive Grand Rapids lettuce seeds were investigated. The smoke extract brought about a concentration dependent increase in germination and a complete inhibition of germination at high concentrations. Octanoic acid could not induce germination. Ethylene at concentrations over 5 L L^–1 increased lettuce seed germination, but not to the same degree as smoke. Aqueous smoke in combination with ethylene showed a synergistic effect on germination at suboptimal smoke concentrations. At high smoke concentrations the effect of ethylene was almost completely inhibited. Octanoic acid in combination with ethylene brought about a higher level of germination than with ethylene alone, but only at the highest concentration of octanoic acid tested (1 mM). Standardized hexane and dichloromethane-partitioned smoke extracts and octanoic acid were subjected to TLC separation. The R _f -fractions in the smoke lanes showing activity in the lettuce seed bioassay did not correspond to the R _f -value of octanoic acid. As aqueous smoke can withstand autoclaving and can be separated by TLC and HPLC without loosing activity it is unlikely that the activity of aqueous smoke is linked to ethylene. It thus appears that the active compound in smoke is neither octanoic acid nor ethylene.Abbreviations TLC thin layer chromatography - HPLC High performance liquid chromatography     

Levels of gibberellin-like substances and their possible transport in developing dwarf and normal cultivars of pea (Pisum sativum L.)

The level of gibberellin-like substances was determined in the cotyledons and axis of developing seedlings of dwarf (Little Marvel) and normal (Tall Telephone) cultivars of pea (Pisum sativum L.). The effect of cotyledon removal with GA₃ application on growth was also examined. Greater levels of gibberellin-like substances were observed in the cotyledons of the normal cultivar than the dwarf. This was particularly evident in the cotyledons during the early stages of seedling growth. Subsequently there was a decline in GA levels in the cotyledons. This was coincidental with a rise in GA content in the axis with markedly greater levels in the normal than the dwarf cultivar. Decotyledonated dwarf and normal plants supplied with GA were much taller than the decotyledonated controls. This observation along with those of the gibberellin levels in the cotyledons and axis, provided circumstantial evidence that there may be translocation of gibberellins from the cotyledons to the axis.     

黄土丘陵区草本群落演替中先锋种群茵陈蒿浸提液的化感作用

为探索自然演替中植被群落结构与化感作用之间的关系,以黄土丘陵区自然演替中先锋种群茵陈蒿为研究对象,通过种子萌发试验,分析演替初期优势种群茵陈蒿浸提液(甲醇浸提液和水浸提液)对自身以及伴生种种子萌发以及幼苗生长的影响,从化学生态学角度解释演替初期群落结构形成的原因。结果表明,茵陈蒿浸提液对3种伴生种(铁杆蒿、白羊草和达乌里胡枝子)的种子萌发均有显著化感作用,低浓度(0.002g/m L)时表现为促进或轻微的抑制作用,高浓度(0.2g/m L)时为较强的抑制作用;不同部位茵陈蒿浸提液的化感作用不同,相比之下,地上部的抑制作用更为强烈,其浸提液均抑制铁杆蒿、白羊草和达乌里胡枝子的种子萌发,尤其在浓度为0.2 g/m L时,达到完全抑制;根系甲醇浸提液对铁杆蒿种子萌发的抑制作用要强于同浓度下的水浸提液,而地上部水浸提液对受体植物根芽的作用大于甲醇浸提液。茵陈蒿对于自身具有一定的抑制作用,表现为高浓度(0.2和0.02 g/m L)的水和甲醇浸提液抑制自身种子萌发和幼苗生长。研究结果说明化感作用可能是该地区在演替前期形成以茵陈蒿为优势种植被群落的重要原因之一。创新点:从化学生态学的角度解释了黄土丘陵区植被演替初期植物之间的关系以及群落结构形成的原因,为认识自然恢复的内在机理提供了新的视角。     

SEED GERMINATION OF AMERICAN POKEWEED (PHYTOLACCA AMERICANA). I. LABORATORY TECHNIQUES AND AUTOTOXICITY

Seeds of pokeweed (Phytolacca americana L.), an underinvestigated species, were studied to determine optimal conditions for laboratory germination. Soaking seeds in acid solutions prior to sowing increased rates of germination. Concentrated (conc) H₂SO₄ was more effective than conc NO₃ or conc HCl acids. Physiological evidence from seed germination studies suggests that autotoxicity, or intraspecific inhibition, exists in pokeweed, a species known to possess several biologically active compounds. Seed germination was investigated in the laboratory with aqueous extracts of vegetative and reproductive structures of the plant. The presence of extracts from most plant parts correlated with reduced or no germination by seeds of its own species, whereas the presence of distilled water correlated with high percentages of germination by control seeds. Whether diluted with water by 5-fold (20% v/v) or undiluted, juice of pokeweed fruits completely inhibited the laboratory germination of pokeweed seeds. Also, extracts of freshly harvested mature leaves, stems, and immature fruits inhibited seed germination. However, results with root extracts, obtained from a single individual, depended more on concentration, since the highest concentration (50% v/v) inhibited germination, and lower concentrations (10 and 20% v/v) increased germination percentages over control samples. Results with extracts of juvenile leaves correlated with neither inhibition nor promotion of germination. Thus, except for juvenile leaves and the root, most extracts of the pokeweed plant inhibited seed germination with more mature structures exerting more inhibition and less mature structures exerting less or no inhibition. The ecological implication of autotoxicity is that seeds are more dispersed through time and space. In regard to seed germination by other species, especially those taxa known to possess biologically active compounds, these and other results suggest that the phenomenon of autotoxicity might be more widespread than previously suspected.     

Effects of aqueous extract of rice plants (Oryza sativa L.) on seed germination and radicle elongation of Monochoria vaginalis var. plantaginea

Laboratory experiments were conducted to examine the allelopathic potentials of rice plants (Oryza sativa L.) on seed germination and radicle elongation of Monochoria vaginalis (Burm. f.) Presl var. plantaginea (Roxb.) Solms-Laubat. To compare the relative allelopathic potentials of rice plants at different growth stages, aqueous extracts of dried tissues were obtained from the seeds, husks, and seedlings harvested 10, 20, 40 and 120 days after seeding. When M. vaginalis seeds were incubated in solutions containing aqueous extracts, significant increases in the germination rate were observed for all the aqueous extracts except for the extract of 10 d-old shoots at higher dosages. When partitioned with ethyl acetate, the germination-promoter(s) in the aqueous extracts remained in the aqueous phase while some inhibitors were extracted with ethyl acetate. In contrast, aqueous shoot extracts added to the incubation media at the same dosage for promotion of seed germination inhibited radicle elongation of M. vaginalis, indicating that the sensitivity of the weed varies between these two growth stages.     

赤霉素的矮化作用及在草坪草育种中应用展望

赤霉素(GA)在植物的种子萌发、茎的伸长和花的发育等许多方面起着非常重要的作用。GA矮化突变体可分为两类,合成型突变体和非应答型突变体。合成型突变体在于抑制、阻碍了激素的生物合成和代谢步骤,使得内源GA缺乏或痕量存在。在GA的非应答突变体中,其突变体表现出GA合成缺陷型矮化,但体内含有大量有生物活性的GAs。在草坪草育种中,利用GA的矮化作用,通过基因克隆和转基因技术育成矮化的草坪草品种,以降低修剪费用。     

Effects of foliar apple trichomes on Galendromus occidentalis (Nesbitt) (Acari: Phytoseiidae): preferences,fecundity and prey consumption

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Effects of brassinosteroids on conditioning and germination of clover broomrape (Orobanche minor) seeds

Brassinolide [2, 3, 22R,23R-tetrahydroxy-24S-methyl-B-homo-7-oxa-5--cholestan-6-one] and its related compounds, brassinosteroids, applied at the early stages of conditioning shortened the conditioning period required before clover broomrape seeds would germinate after exposure to germination stimulants, such as dl-strigol and natural stimulants from red clover (Trifolium pratense L.) root exudate. Brassinosteroids applied after conditioning increased the rate of the seed germination induced by these stimulants. The inhibitory effect of light on seed germination when it was induced by dl-strigol could be overcome by brassinosteroids. Brassinosteroids also eliminated the inhibitory effects of light and dl-strigol applied at the early stages of conditioning. GA₃ was also effective in causing seed conditioning and increased the rate of the germination induced by these stimulants. There was a relationship between brassinosteroids and GA₃ in many of the experiments conducted. These findings may have practical implications in increasing the effectiveness of applying germination stimulants in the field to soils for suicidal germination of broomrape seeds.