Increase in lodging safety factor of thigmomorphogenically dwarfed shoots of mulberry tree

The lodging safety factor of mechanically stimulated shoots of mulberry tree ( Morus bombycis Koidz. cv. Kenmochi) was measured to test the hypothesis that thigmomorphogenic dwarfing increases mechanical stability of plants. The lodging safety factor, an indicator of mechanical stability of erect shoots, has been defined as the ratio of critical lodging load to leaf fresh weight. Two-year-old shoot cuttings of mulberry tree were rubbed, brushed, and shaken every day. During the experimental period, the lodging safety factor of the control shoots remained at about 5. while the safety factor of the thigmomorphogenically dwarfed ones was ca 1.6 times larger, which supports the hypothesis. The mechanical stimulation reduced the stem elongation rate, but did not greatly change the partitioning of dry matter between leaves and stem. Therefore, it is concluded that the reduction of stem elongation rate was the main cause of the increase in the lodging safety factor of the stimulated shoots.     

Inhibition of apple ripening by succinic Acid, 2,2-dimethyl hydrazide and its reversal by ethylene

Ripening of McIntosh apples (Malus sylvestris L.) was delayed by treatments of succinic acid 2,2-dimethyl hydrazide (B-9) applied 2 weeks after bloom. The extent of retardation was dependent on concentration to 7.4 × 10⁻² m, at which level complete inhibition of ripening occurred under the conditions applied. The onset of the respiratory climacteric and fruit firmness changes were factors used to assess ripening.     

Control of apple ripening by succinic Acid 2,2-dimethyl hydrazide, 2-chloroethyltrimethylammonium chloride, and ethylene

Ripening of `Tydeman's Early' apples (Malus sylvestris L.) assessed by the occurrence of the respiratory climacteric was delayed by succinic acid 2,2-dimethyl hydrazide (B-9) but not by 2-chloroethyltrimethylammonium chloride (CCC), each applied 14 days after bloom. B-9 also inhibited ethylene production by fruits exhibiting the climacteric rise. Inhibition of the climacteric by B-9 was overcome by exogenous ethylene, but the latter treatment failed to completely reverse the B-9 inhibition of endogenous ethylene production.     

Cytokinins in shoots of the chestnut tree

Five cytokinins, trans-zeatin, 9-β-d-ribosyl-trans-zeatin, O-β-d-glucosyl-trans-zeatin, N⁶-(3-methyl-but-2-enyl)adenine and N⁶-(3-methyl-but-2-enyl)adenosine were identified in shoots of the chestnut tree.     

Growth response of coffee tree shoots and roots to subsurface liming

In the greenhouse growth of two coffee-tree varieties, Catuaí (sensitive) and Icatu (tolerant) to aluminum, was evaluated in surface-fertilized and limed soil following subsurface treatment with seven lime levels (0.0; 0.49; 1.7; 2.9; 4.1; 6.6 and 9.3 t/ha). Plants were grown for 6.5 months in soils in PVC columns, subdivided into two horizons. In the lower 12 – 34 cm depth horizon, soil Al saturation varied between 93 and 0%. For both varieties evaluated, shoot dry weight and leaf area remained unchanged following limestone application. This fact shows that surface layer correction permitted normal shoot growth. High Al saturation resulted in decrease of root dry weight percent, root length percent and root surface percent in the 12–34 cm horizon, which were compensated by higher percentages of these properties in the upper 0–12 cm horizon. The ratio between root surface – root dry matter (cm²/g) of Catuaí variety was increased by limestone application to the lower soil horizons, indicating that roots turn longer and thinner, when Al soil saturation decreased. This also shows a great sensitivity to Al of the Catuaí variety. In contrast, in the Icatu variety, all root characteristics remained stable at all levels of Al tested.     

Production of succinic Acid from citric Acid and related acids by lactobacillus strains

A number of Lactobacillus strains produced succinic acid in de Man-Rogosa-Sharpe broth to various extents. Among 86 fresh isolates from fermented cane molasses in Thailand, 30 strains (35%) produced succinic acid; namely, 23 of 39 Lactobacillus reuteri strains, 6 of 18 L. cellobiosus strains, and 1 of 6 unidentified strains. All of 10 L. casei subsp. casei strains, 5 L. casei subsp. rhamnosus strains, 6 L. mali strains, and 2 L. buchneri strains did not produce succinic acid. Among 58 known strains including 48 type strains of different Lactobacillus species, the strains of L. acidophilus, L. crispatus, L. jensenii, and L. parvus produced succinic acid to the same extent as the most active fresh isolates, and those of L. alimentarius, L. collinoides, L. farciminis, L. fructivorans (1 of 2 strains tested), L. malefermentans, and L. reuteri were also positive, to lesser extents. Diammonium citrate in de Man-Rogosa-Sharpe broth was determined as a precursor of the succinic acid produced. Production rates were about 70% on a molar basis with two fresh strains tested. Succinic acid was also produced from fumaric and malic acids but not from dl-isocitric, alpha-ketoglutaric, and pyruvic acids. The present study is considered to provide the first evidence on the production of succinic acid, an important flavoring substance in dairy products and fermented beverages, from citrate by lactobacilli.     

Changes in the factor of safety within the superstructure of a dicot tree

The objective of this study was to determine whether the factor of safety for mechanical stability varied among stems differing in size and age within the superstructure of a large dicot tree. Two factors of safety were selected for study: the quotient of the critical buckling height and the actual length of stems, Hcrit/L, and the quotient of the modulus of rupture (the force per unit area required to break a stem) and the working stress (the force per unit area resulting from the biomass measured distal to a stem), M_R/σ_w. These two dimensionless safety factors were determined for a total of 420 shoot segments comprising much of the aboveground biomass of a Robinia pseudoacacia (Fabaceae) tree measuring 18.7 m in height and 1347 kg in mass, and 0.46 m in diameter (40 yr old) at 1.2 m from the ground. An S-shaped trend was observed when each of the two factors of safety was plotted as a function of stem age. Each factor decreased from a local maximum for the most distal (peripheral) stems in the canopy to a local minimum value for stems ∼10 yr old; each factor increased again to another local maximum for stems 11–18 yr old, and then decreased steadily toward the base of the trunk. This trend was the result of the allometric relationships among stem diameter, length, biomass, and material properties (stiffness and strength) with respect to stem age. Although they were disproportionately more slender than their older counterparts, peripheral stems were sufficiently stiff and strong to sustain the stresses resulting from their weight and that of foliage without deflecting under these loads, yet they were sufficiently flexible to easily bend and thereby presumably provide a mechanism to reduce the drag forces acting on the entire tree. In contrast, the internally imposed mechanical forces acting on progressively older stems increased at a greater rate than the observed rate of increase in stem stiffness, strength, or diameter. The probability of mechanical failure, which must be considered from a demographic perspective (i.e., an age-dependent phenomenon), thus increased from older branches to the base of the trunk. Reports of similar allometric trends based on interspecific comparisons among diverse dicot species comply with the allometry observed for the R. pseudoacacia tree and suggest that the S-shaped trend for the factor of safety holds for stems differing in age drawn from individual trees and for the trunks of conspecifics differing in age drawn from a dense population.     

圆果大赤螨对桑树害虫的捕食功能反应

在室内条件下研究了圆果大赤螨对桑树害虫朱砂叶螨、桑蓟马和桑粉虱的捕食作用。结果表明,圆果大赤螨对3种猎物的捕食功能反应均符合HollingⅡ功能反应模型,经χ2检验,理论值与观测值差异不显著。捕食功能反应参数表明圆果大赤螨对桑蓟马、朱砂叶螨和桑粉虱捕食量差异显著,其最大日捕食量理论值分别为:416.67、222.22、97.09头。圆果大赤螨对猎物的搜寻效应均随猎物密度的增加而呈线性下降,且取食桑蓟马的搜寻效应明显高于朱砂叶螨和桑粉虱。HollingⅢ型功能反应新模型拟合得出,1头圆果大赤螨对桑蓟马、朱砂叶螨、桑粉虱的最佳寻找密度分别为77.54头、70.49头和27.27头。研究表明,圆果大赤螨对桑树害虫捕食能力依次为桑蓟马朱砂叶螨桑粉虱,且对3种害虫均具有较强捕食能力,是桑园害虫的重要天敌资源。     

Indoleacetic Acid biosynthesis in Avena coleoptile tips and excised bean shoots

Avena coleoptiles did not elongate when incubated with tryptophan under sterile conditions. Indole, anthranilic acid, and tryptamine promoted elongation. Under the same conditions, the tissue converted tryptophan-¹⁴C to IAA-¹⁴C. More IAA-¹⁴C was produced from indole-¹⁴C than from tryptophan-¹⁴C; however, the free tryptophan content of the tissue was also greatly increased by the indole treatment. Tryptophan-¹⁴C was readily taken up by the tissue but was mainly incorporated into protein and did not increase the free tryptophan level. When bean shoots were labeled with tryptophan-¹⁴C or indole-¹⁴C, the label incorporation into IAA-¹⁴C was very nearly the same. In this tissue the free tryptophan level in the tryptophan-¹⁴C and indole-¹⁴C treatments was also about equal. These results suggest that failure of exogenously supplied tryptophan to promote the elongation of Avena coleoptiles is a result of its predominant incorporation into protein and consequent unavailability for conversion to IAA.     

Relative extents of preformation and neoformation in tree shoots: Analysis by a deconvolution method

BACKGROUND AND AIMS: Neoformation is the process by which organs not preformed in a bud are developed on a growing shoot, generally after preformation extension. The study of neoformation in trees has been hindered due to methodological reasons. The present report is aimed at assessing the relative importance of preformation and neoformation in the development of shoots of woody species. METHODS: A deconvolution method was applied to estimate the distribution of the number of neoformed organs for eight data sets corresponding to four Nothofagus species and a Juglans hybrid. KEY RESULTS: The number of preformed organs was higher and less variable than the number of neoformed organs. Neoformation contributed more than preformation to explain full-size differences between shoots developed in different positions within the architecture of each tree species. CONCLUSIONS: Differences between the distributions of the numbers of preformed and neoformed organs may be explained by alluding to the duration of differentiation and extension for each of these groups of organs. The deconvolution of distributions is a useful tool for the analysis of neoformation and shoot structure in trees.     

Effect of photoperiod on some stomatal characteristics of in vitro cultured fruit tree shoots

The effect of the photoperiod on some stomatal characteristics in various leaf lamina zones and in leaves of different age was studied on in vitro grown shoots of Prunus cerasifera clone Mr.S. 2/5, t Malus pumila Mill clone M9, and peach x almond hybrid clone GF 677. Stomatal density was highest in leaves exposed to continuous light and lowest with continuous dark. Photoperiod treatments supplying the same quantity of daily radiation but distributed over different cycles (4 h light and 2 h dark, 16 h light and 8 h dark) led to differing stomatal densities intermediate between those of the above light treatments. The light regime with the shortest light and dark periods was found to be most favorable to stomatal differentiation. Regardless of light treatment, stomatal density was found to be lower in the leaf lamina basal zone as compared to the median and apical zones, and decreasing from the 1st to 3rd to 5th leaf counting down from the apex. The photoperiod effect was also confirmed by a stomatal index. The stomatal axis ratio showed no interaction with the photoperiod but did highlight a tendency to rounder stomatal shape with increasing stomatal age. This revised version was published online in June 2006 with corrections to the Cover Date.     

Light-exposed shoots of seven coexisting deciduous species show common photosynthetic responses to tree height

Functional traits of light-exposed leaves have been reported to show tree height-dependent change. However, it remains unknown how plastic response of leaf traits to tree height is linked with shoot-level carbon gain. To answer this question, we examined the photosynthetic properties of fully lit current-year shoots in crown tops with various heights for seven deciduous broad-leaved species dominated in a cool–temperate forest in northern Japan. We measured leaf mass, stomatal conductance, nitrogen content, light-saturated net photosynthetic rate (all per leaf lamina area), foliar stable carbon isotope ratio, and shoot mass allocation to leaf laminae. We employed hierarchical Bayesian models to simultaneously quantify inter-trait relationships for all species. We found that leaf and shoot traits were co-varied in association with height, and that there was no quantitative inter-specific difference in leaf- and shoot-level plastic responses to height. Nitrogen content increased and stomatal conductance decreased with height. Reflecting these antagonistic responses to height, photosynthetic rate was almost unchanged with height. Photosynthetic rate divided by stomatal conductance as a proxy of photosynthetic water use efficiency sufficiently explained the variation of foliar carbon isotope ratio. The increase in mass allocation to leaves in a shoot compensated for the height-dependent decline in photosynthetic rate per leaf lamina mass. Consequently, photosynthetic gain at the scale of current-year shoot mass was kept unchanged with tree height. We suggest that the convergent responses of shoot functional traits across species reflect common requirements for trees coexisting in a forest.     

Comparison of diurnal changes in nitrate and potassium contents in lucerne shoots

During 195-min light exposure following 5 d in dark, nitrate content was studied in different organs of lucerne plants in early bud stage. Nitrate content varied considerably especially in stems. Rapid diurnal variations in nitrate content were found in lower and upper halves of stems, in petioles and in leaf blades. The results reflected discontinuous nitrate movement in lucerne shoots. The positive correlation between the diurnal course of the nitrate and potassium contents in different plant organs showed that the K⁺ transport followed the NO₃ ^? transport. Similar diurnal changes were found also in Na⁺ and Ca²⁺ contents. Discontinuous salt movements occurring in xylem sap flow were in contrary to continuous transpiration stream and could be a consequence of temporary adsorption or binding of salts in xylem vessels.     

小麦种质抗倒性的评价和抗倒性状的相关与通径分析

对９６份小麦种质资源的抗倒性进行了鉴定评价,筛选出高抗型材料９份,其中４份是丰源,表明抗倒性能够与丰产性状很好地协调结合。对抗倒性状的相关分析表明,在株高相差较大的情况下,株高和重心高度对抗倒性十分重要。但在对株高相差不大的情况下,茎秆的机械强度是主要决定因素,对于株高较高的材料,重心高度对抗倒性有较大影响;对于较矮的材料,基部第一节间长度则较为重要。通径分析结果进一步表明,茎秆机械强度对抗倒性的     

Comparison of endogenous gibberellins in roots and shoots of elongating Salix pentandra seedlings

Gibberellins GA₁, GA₈. GA₁₉. GA₂₉. GA₂₀ and GA₅₆ (2-epi-GA₈). were identified by combined gas chromatography-mass spectrometry in root extracts of elongating Salix pentandra L. seedlings. The presence of GA₈ was also demonstrated for the first time in S. pentandra shoots. The levels of GA₁, GA₈, GA₁₉, GA₂₀ in shoot tissue and in roots were estimated by selected ion monitoring. While the amounts of GA₈ and GA₁₉ were similar in both plant parts. the levels of the biologically active GA₁ and its immediate precursor GA₂₀. were found to be much lower in roots than in shoots.     

Effect of Trichoderma species fungi on soil micromycetes, causing infectious conifer seedling lodging in Siberian tree nurseries

Soils in the tree nurseries studied were characterized by a lower species diversity of fungi than adjacent virgin soils. In particular, the relative abundances of representatives of the genera Mucor, Chaetomium, and Trichoderma in the nursery soil were two times lower than in adjacent virgin soils. On the other hand, the nursery soil exhibited greater abundances of fungi of the genus Fusarium, which are causative agents of many diseases of conifer seedlings. To appreciate the efficiency of biocontrol of the infectious diseases of conifer seedlings, we introduced several indigenous Trichoderma strains into the nursery soil and found that this affected the species composition of soil microflora considerably. Changes in the species composition of mycobiota beneficially influenced the phytosanitary state of soils and reduced the infectious lodging of conifer seedlings.     

Increase in volatile oil and chemical composition in the seeds of caraway and fennel plants induced by succinic acid 2,2-dimethylhydrazide

Spraying the growth retardant (B-9) ranging from 500 to 4000 ppm, on caraway and fennel plants reduced stem height, whereas increased the umbel number per plant. There was a slight increase in seed-yield as well as weight of 1000 seeds of the two umbelliferae plants, induced by B-9. The largest values of volatile oil, crude fat, and carbohydrate in the seeds of the two plants resulted from 4000 ppm B-9. Whereas, the crude protein was not affected by B-9 treatments in both plants.     

Comparison of carbon metabolism between chloramphenicol-treated and untreated cultures of Clostridium acetobutylicum

Summary Carbon distribution from substrates to products in Clostridium acetobutylicum ATCC 824 was investigated by adding ¹⁴C-labeled substrates as tracers. Comparison of carbon conversion between chloramphenicol (CAP)-treated and untreated cultures was also studied. The percentage of ¹⁴C recovery in butanol, acetone and ethanol from uniformly labeled [¹⁴C]glucose was increased by 17, 25 and 30%, respectively, after CAP addition. The incorporation of ¹⁴C in solvents from ¹⁴C-labeled acetate and butyrate was also increased by the antibiotic treatment. A total ¹⁴C recovery of 12% in all the products from added [¹⁴C]Na₂CO₃ indicates significant heterotrophic CO₂ fixation in this microorganism. The ratio of carbon in butanol derived from glucose, acetate and butyrate was about 71:6:18, and this ratio was unchanged by CAP treatment.This paper represents contribution No. 2685 of the Rhode Island Agricultural Experimental StationCorrespondence to: R. W. Traxler