Salinity tolerance of the tree legumes: Mesquite (Prosopis glandulosa var.torreyana,P. velutina andP. articulata) Algarrobo (P. chilensis), Kiawe (P. pallida) and Tamarugo (P. tamarugo) grown in sand culture on nitrogen-free media

Summary Sand culture pot experiments were carried out with Proposis seedlings in the greenhouse on a nitrogen free nutrient solution with increasing levels of sodium chloride. All species tolerated a 6,000 mg/l salinity with no reduction in growth.P. velutina was the only species that poorly tolerated the 12,000 mg/l salinity level.P. articulata, P. pallida, andP. tamarugo tolerated 18,000 mg/l NaCl with little reduction in growth and grew slightly in a salinity (36,000 mg/l NaCl) greater than seawater. This is the first legume known to grown in salinities equivalent to seawater.     

Anatomical Changes in Prosopis tamarugo Phil. Seedlings Growing at Different Levels of NaCl Salinity

Seedlings of Prosopis tamarugo were grown in artificial substrateswith additions, of 200, 400 and 600 mM NaCl, and without salttreatment. Salinity induced anatomical changes in the roots,stems and leaflets. The diameters of the roots of seedlingsgrown in the increasing salt concentrations (up to 400 mM) wereprogressively smaller and differentiation of the stelar tissueswas delayed. At an NaCl concentration of 600 mM, the root structurewas strongly altered. On the contrary, stem diameter increasedas salinity rose. In the stems of seedlings grown in a concentrationof 200 mM NaCl, secondary xylem differentiation appeared earlierthan in the controls. At a concentration of 400 mM NaCl, disorganizationof the vascular cylinder of the stem was evident. Leaflets ofseedlings grown in 200 mM NaCl showed a delay in structuraldifferentiation: no water-storage cells or ‘special cells’could be seen. The leaflets from plants grown in 400 mM NaCl,had larger numbers of intercellular air spaces; probably anindication of the beginning of tissue disorganization. A progressivedecrease in cell size of leaflets as salinity rose was alsodemonstrated. Prosopis tamarugo Phil., seedling, salinity, anatomical changes     

Effects of light, CO2 and humidity on carnation growth, hyperhydration and cuticular wax development in a mist reactor

Summary Plant survival ex vitro requires functioning stomata, adequate cuticular wax composition and deposition, and normal morphological development. Light intensity, CO₂ and relative humidity were altered inside an acoustic window mist reactor to study their effects on carnation (Dianthus caryophyllus) growth, stomata development, hyperhydration and epicuticular wax content. Increasing the light intensity from 65 to 145 μmol m⁻² s⁻¹ and enrichment of the gas phase with CO₂ (1350 ppm) reduced the number of hyperhydrated plants from 75 to 25% and increased the percentage dry weight of normal (healthy) plants from 17 to 25%. Lowering the relative humidity (≈70% RH) surrounding the plants during the mist-off phase for the last 2 wk of culture reduced the number of hyperhydrated plants from 70 to 9% and also increased the percentage of dry weight of normal plants from 16 to 25%. The stomata on plants grown in conditions of high light or low humidity had smaller apertures and appeared sunken when compared to stomata from plants grown in low light and high relative humidity. The epicuticular wax profiles of plants from the greenhouse or Magenta boxes showed a distinct shift in wax compounds with developmental age, plant type (hyperhydrated or normal), and type of box that was used (vented or not). In addition, very different wax profiles were observed from plants grown in reactors with altered CO₂ and light intensities.     

Osservazioni Anatomo-Fisiologiche Sulla Kleinia Articulata Haworth

Abstract

Ultrastructural modifications of plastids in leaflets of Larix decidua and Picea excelsa during sprouting of buds.—Ultrastructural modifications of plastids in leaflets of Larix decidua and Picea excelsa during sprouting of buds kept in different light conditions were observed.

While in quiescent buds of both species typical plastids with magnograna are present, fully expanded leaflets kept in the light have plastids with an organized lamellar apparatus.

When the buds are kept in darkness the cells of the fully expanded, etiolated leaflets have hardly differentiated plastids with prolamellar bodies partially modified into short tubules and vesicles.

Plastids of Picea and Larix buds, in their development, behave almost identically both in darkness and in the light.

The differences previously observed in dark grown seedlings of the two species are not to be found in buds.     

Temporal organization of chilling resistance in cotton seedlings: effects of low temperature and relative humidity

The effect of temperature and relative humidity (RH) on the time course of the rhythmic endogenous changes of chilling resistance was studied in cotton (Gossypium hirsutum L. cv. Deltapine 50) seedlings grown under light-dark cycles of 12:12 h. The resistant phase to 5° C, 85% RH lasted during most of the dark period while to 5° C, 100% RH it was longer and extended into the last half of the light period because a transient phase advance occurred when chilling started at the middle of the light period. Seedlings acclimated by low temperature were resistant throughout the light-dark cycle. A treatment with 100% RH before chilling to acclimated seedlings introduced a sensitive phase that corresponded to that of non-acclimated seedlings. In non-acclimated seedlings, this treatment decreased the resistance but the basic pattern of the rhythm was sustained. Changes in chilling resistance were analyzed under fluctuating temperatures and RHs, and explained taking into consideration the functioning of the circadian clock and environmental induction of resistance.Abbreviations CR chilling resistance - LDC light-dark cycle of 24 h - RH relative humidity     

Maintenance of 32P uptake and transport in Pinus serotina seedlings under hypoxic growth conditions

In the present study, we examined the effects of long- and short-term hypoxia on net uptake and transport of phosphorus to shoots of pond pine (Pinus serotina Michx.), a moderately flood-tolerant southern pine, and the influence aerenchyma formation might have in maintenance of P uptake and transport. Seedlings were grown under aerobic (250 μM O₂) or hypoxic (≤50 μM O₂) solution conditions for 5.3 weeks in continuously flowing solution culture containing 100 μM P. Intact seedlings were then labeled with ³²P for up to 24 h to determine how short- and long-term hypoxic solution conditions affected rates of unidirectional influx and the accumulation of ³²P in roots and shoots. Seedlings in the long-term hypoxic treatment were grown for 5.3 weeks in hypoxic solution and also labeled in hypoxic uptake solution. The short-term hypoxic treatments included a 24-h hypoxic pretreatment followed by time in labeled hypoxic uptake solution for seedlings grown under aerobic or hypoxic conditions; in the latter case, diffusion of atmospheric O₂ entry into stem and root collar lenticels was blocked, thus removing any influence that aerenchyma formation might have had on enhancing O₂ concentrations of root tissue. Although unidirectional influx rates of ³²P in roots of seedlings grown under long-term hypoxic conditions were 1.4 times those of aerobically grown seedlings, accumulation of ³²P in roots was similar after 24 h in labeled uptake solution. These results suggest that ³²P efflux was also higher under hypoxic conditions. Higher shoot/root fresh weight ratios and lower shoot P concentrations in seedlings grown under hypoxic solution conditions suggest that the “shoot P demand” per unit root should be high. Yet accumulation of ³²P in shoots was reduced by 50% after 24 h in hypoxic uptake solution. Both short-term hypoxic treatments decreased accumulation of ³²P in roots by more than 50%. Short-term hypoxia decreased shoot accumulation in seedlings grown under aerobic and hypoxic conditions by 84 and 50%. respectively. Short- and long-term hypoxic conditions increased the percentage of root ³²P in the nucleic acid and chelated-P pools, resulting in a significantly smaller percentage of ³²P in the soluble inorganic phosphate (p_i) pool, the pool available for transport to the shoot. However, a reduction in pool size or in labeling of the pool available for transport cannot fully account for the large reduction in accumulation of ³²P in shoots, particularly in the short-term hypoxic treatment of aerobically grown seedlings. Our results suggest that both influx and transport of ³²P to shoots of pond pine seedlings are O₂-dependent processes, and that the transport of ³²P to shoots may be more sensitive to hypoxic solution conditions than influx at the cortical and epidermal plasmalemma, with aerenchyma formation supporting a substantial amount of both ³²P uptake and transport.     

Lack of Influence of the Epidermis on Underlying Cell Development in Leaflets ofPisum sativumvar.argenteum(Fabaceae)

We explored whether epidermal pressure regulates cell and organgrowth in leaflets ofPisum sativumvar.argenteum,a mutant cultivarof the garden pea characterized by reduced adhesion betweenthe epidermis and subjacent mesophyll. Developing leaflets ofleaves arising at three positions on the seedling axis werepeeledin situand grown to maturity in humidity chambers. Themature anatomy and morphology could be accurately assessed becausewound responses normally associated with peeling were preventedby theArgmutation that permitted peeling without damage to themesophyll and by the humidity chambers that protected peeledareas from desiccation. The mesophyll cell size, state of differentiation,and layering pattern as well as the overall morphology of mature,peeled leaflets were indistinguishable from those of mature,intact leaflets grown under the same conditions. The epidermisexerted no detectable regulatory effect on the expansion ofthe leaflets as a whole or on the tissue layers and cells withinthe leaflets.Copyright 1999 Annals of Botany Company. Biomechanics, compression, epidermis, leaf development, mesophyll, pressure, wound response,Pisum sativumvar.argenteum.     

Potential allelopathic effect of neo-clerodane diterpenes from Teucrium chamaedrys (L.) on stenomediterranean and weed cosmopolitan species

The allelopathic effects of neo-clerodane diterpenes, isolated from Teucrium chamaedrys (L.), have been evaluated on the seed germination and seedling growth of four coexisting Mediterranean species (Dactylis hispanica, Petrorhagia velutina, Phleum subulatum and Petrorhagia saxifraga) and two cosmopolitan weeds (Amaranthus retroflexus and Avena fatua). All of the structures have been elucidated on the basis of their spectroscopic features. The bioassays data, analyzed by principal component analysis, showed more negative effects on weeds respect to coexisting species. Moreover D. hispanica, P. velutina, P. subulatum showed both stimulating or inhibiting effects depending on the type of metabolite and the concentration used in the test.     

Secondary leaf fall of Hevea brasiliensis: meteorological and other factors affecting infection by Colletotrichum gloeosporioides

The lower leaf surface of Hevea brasiliensis was more susceptible to infection by Colletotrichum gloeosporioides than the upper. Few lesions were produced if spore drops on susceptible leaves were allowed to dry. Lesion development after 72 h was quickest at 21 ^oC, slower at 26.5 ^oC and was stopped at 32 ^oC, probably because of bacteria in the inoculation drop. On leaflets aged 7 days from bud-burst, the effective spore dose for 50% of leaflets infected (ED₅₀) after 16 h incubation, was 260 spores and after 46 h, 120 spores/infection droplet; the minimum ED₅₀ for the upper leaf surface was about 4 spores/mm². Leaflets 15 days old, which are normally resistant, were rendered susceptible by abrading the surface with carborundum powder. Spores caught in a Hirst spore trap reached a daily maximum at 23 h, at rates of up to 440 spores/m³ air/h, but fell to low concentrations as the humidity dropped during the daytime, and also during rain. There was some correlation between disease severity and duration of 97–100% relative humidity, and moderate to severe defoliation of clone PB 86 occurred when this reached 13.5 h/day. Rainfall increases infection by prolonging the period of atmospheric saturation and leaf wetness.     

Further properties of peanut clump virus and studies on its natural transmission

Purified preparations of particles of peanut clump virus (PCV) had A₂₆₀/A₂₈₀ values (corrected for light scattering) of 1.00. They contained rod-shaped particles with sedimentation coefficients of 183 S and 224 S, and a density in CsCl of 1.32 g/ml. PCV infected 36 species in 8 plant families. No serological relationship was detected between PCV and barley stripe mosaic, beet necrotic yellow vein, Nicotiana velutina mosaic and tobacco mosaic viruses. PCV was seed-borne for two generations in groundnut (Arachis hypogaea) but was not seed-borne in great millet (Sorghum arundinaceum), Phaseolus mungo or Nicotiana benthamiana. Seedlings of groundnut, great millet and wheat (Triticum aestivum) became infected when grown in soil from groundnut fields with outbreaks of clump disease, and the infectivity of soil survived air-drying at 25°C for 3 months. Groundnut seedlings became infected when grown in sterilised soil contaminated with washed roots of naturally-infected S. arundinaceum but not in soil to which roots of naturally infected groundnut or shoots of infected groundnut were added, or in which mechanically inoculated groundnut seedlings were grown at the same time. The patchy distribution of PCV in a crop was related to the infectivity of the soil for groundnut and to the presence of Polymyxa graminis resting spores which could be detected in the roots of S. arundinaceum bait seedlings, but not in those of groundnut. The results indicate that PCV is transmitted by a vector that is resistant to air-drying and closely associated with S. arundinaceum roots. For these reasons P. graminis is thought to be the vector of PCV.     

EFFECTS OF RELATIVE HUMIDITY AND TYPE OF CONTAINER ON THE GROWTH OF F1 HYBRID ANNUALS IN CONTROLLED ENVIRONMENTS

The effects of three levels of relative humidity (40%, 65%, and 90%) and two types of containers (clay and plastic) on the seedling growth of three F₁ hybrid annuals were determined after 14 days of controlled-environment treatment. Forty percent relative humidity was severely limiting to the seedling growth of ‘Blue Blazer’ ageratum (Ageratum houstonianum Mill.), ‘Pink Cascade’ petunia (Petunia hybrida Vilm.), and ‘Double Eagle’ marigold (Tagetes erecta L.). Raising the relative humidity to 65% resulted in striking increases in fresh weight, dry weight, and leaf area, especially when clay containers were used. Height of the main shoot was increased significantly at 65% relative humidity but node number was influenced only slightly. Increasing the relative humidity further to 90% had no significant effect on fresh weight, dry weight, or percent dry weight for any of the three species, in either container. Leaf area was increased significantly at 90% only in ageratum seedlings grown in clay pots. Each species responded differently to the type of container used. The fresh weight and dry weight of petunia seedlings were significantly greater in plastic pots at every level of humidity while those of marigold seedlings were unaffected by the type of container used. Ageratum seedlings, on the other hand, had significantly greater fresh weights and dry weights in clay pots only at 90% relative humidity.     

Structural and functional relationships in developing Pinus silvestris chloroplasts

The light dependent chloroplast development of dark grown seedlings of Pinus silvestris L. was followed by analyses of chlorophyll content, chlorophyll a/b ratios, chlorophyll/P700 ratios, chlorophyll-protein complexes and structural changes. Low-temperature fluorescence emission spectra of isolated chloroplasts and separation of sodium dodecyl sulphate solubilized chlorophyll-protein complexes by gel electrophoresis showed that the chlorophyll-protein complexes of photosystem 1 (P700-CPa), photosystem II (PS II-CPa) and the light-harvesting complex LH–CPa/b were present in dark grown seedlings. The low-temperature fuoorescence emission maxima of isolated P700–CPa and PS II–CPa shifted towards longer wavelengths during greening in light, indicating a light induced change of the chlorophyll organisation in the two photosystems. Illumination caused LH–CPa/b to increase relative to P700–CPa, whereas the ratio between LH–CPa/b and PS II–CPa remained essentially constant. Analyses of low-temperature fluorescence spectra with or without 0.01 M Mg²⁺ showed that the Mg²⁺ controlled distribution of excitation energy into PS I was activated upon illumination of the seedlings. The photosynthetic unit size, as defined by the chlorophyll/P700 ratio, did not change over a 96 h illumination period, although the chlorophyll content increased about 6–fold during that time. This result and the constant electron transport rate per unit chlorophyll and time during chlorophyll accumulation provided evidence for a sequential development of the photosynthetic units when illuminating dark grown pine cotyledons. Electron micrographs showed that exposure of dark grown seedlings to light for 2 h caused the prolamellar body to disappear and grana to form. These changes occurred prior to substantial accumulation of chlorophyll or change in the ratio between LH–CPa/b and P700–CPa. However, both the water-splitting system of photosystem II and the Mg²⁺ controlled redistribution of excitation energy was activated during this period.     

Is Fe deficiency rather than P deficiency the cause of cluster root formation in Casuarina species?

When subjected, directly (through nutritional deficiencies) or indirectly (through alkaline constraints leading to such deficiencies) to nutrient deficiencies, certain plants respond by developing special root structures called cluster roots. This phenomenon can be considered as an ecophysiological response to a specific nutrient deficiency enabling plants to enhance nutrient uptake. Experiments conducted on an alkaline and an acid soil showed that Casuarina glauca (Sieber ex Spreng.) produced cluster roots only in the alkaline soil and not in the acid soil. In addition, iron (Fe) and phosphorus (P) deficiencies were examined separately or together to determine their effect on cluster root formation in C. glauca seedlings grown hydroponically. Results from experiments carried out on three Casuarina species (C. glauca, C. cunninghamiana Miq. and C. equisetifolia L.) indicated that Fe is involved in cluster root formation. In nutrient media lacking P but containing Fe, no cluster roots formed while seedlings receiving P and lacking Fe developed cluster roots. When incubated on chrome-azurol S-agar on blue plates (CAS assay), a technique used routinely to detect the production of siderophores by micro-organisms, the root system of Fe-deficient plants exhibited orange halos around cluster roots, indicating production of a ferric-chelating agent. It is concluded that the capacity of cluster roots of C. glauca to chelate Fe allows the plant to grow normally on alkaline soils.     

Phosphorus concentration in barley (Hordeum vulgare L.) seed: Influence on seedling growth and dry matter production

The effect of phosphorus (P) concentration in barley seed on seedling growth has not been much investigated. Consequently, two experiments were conducted in the greenhouse to determine the effect of P concentration in barley seed (Hordeum vulgare L., cv. Empress) on the seedlings grown in sand-filled boxes receiving a culture solution without P. Seeds were selected with three P concentrations: high-P (113.0 mmol P kg⁻¹), medium-P (80.7 mmol P kg⁻¹) and low-P (54.9 mmol P kg⁻¹). At 21 days after sowing, the shoot and root yield or shoot height was the least with seedlings from low-P seed. In the other experiment, high-P and low-P seeds were wetted with distilled water or with a solution of 25.8 cmol L⁻¹ of NaH₂PO₄ for 24 h, and then grown for 31 days. Solution P had been imbibed by seeds whether low or high in native P, but only the imbibed P held by low native P seed benefited seedling dry matter accumulation and shoot elongation. The lack of benefit from seed-imbibed P on seedlings grown from high-P barley seed was associated with low recovery of the imbibed P in those seedlings.     

Stomatal characteristics during micropropagation of Wrightia tomentosa

A deviation from usually found characteristics of stomata in Wrightia tomentosa was noted during in vitro propagation. Increase in stomatal frequency in leaves of plants grown in vitro was observed with 29.4 % malformed stomata. The stomata were spherical, wide open, did not close in detached leaves even after 3 h. The leaves exhibited 93.4 % total water loss during 3-h period. Stomatal frequency, percentage of malformed stomata and rate of water loss declined in subsequent rooting phase. Nevertheless, for high survival rate plantlets were hardened under gradually decreasing air humidity either in partially opened glass bottles containing Soilrite™ moistened with 1/4 Murashige and Skoog nutrients or in pots covered with polyethylene bags. The stomatal characteristics of hardened plants were comparable to seedlings. Survival rate was more than 95 %.     

Systemic activity of plant extracts in Cedrela odorata (Meliaceae) seedlings and their biological activity on Hypsipyla grandella (Lepidoptera: Pyralidae) larvae

1 Deterrent and toxic substances known to affect Hypsipyla grandella larvae were bioassayed to determine their possible systemic activity under laboratory conditions in Turrialba, Costa Rica. 2 Leaflets from Spanish cedar Cedrela odorata seedlings grown in vitro on culture media treated with different plant extracts were excised from the seedlings and exposed to H. grandella larvae. 3 Both Azatin EC (derived from neem, Azadirachta indica) and plant extracts (from Quassia amara wood, Ruta chalepensis leaves and Sechium pittieri fruits) were able to translocate within Spanish cedar seedlings and express their biological activity against H. grandella larvae. 4 Rates of leaflet consumption were nil for seedlings treated with the commercial standard (carbofuran) and Azatin EC, both causing larval death. 5 Intermediate levels of consumption were reached with the three plant extracts, all of them causing deterrence, because they precluded feeding activity by larvae when exposed to treated leaflets.     

Effect of air humidity on the development of functional stomatal apparatus

Phaseolus vulgaris L. seedlings were grown under different air humidities simulating conditions during micropropagation (very high humidity duringin vitro cultivation and low air humidity after transferex vitro). The functional stomatal apparatus developed after a short period of growth at low air humidity at the beginning of plant ontogeny or after transfer from high to low air humidity, but not in plants grown steadily under high air humidity. The ability of stomata to regulate gas exchange was not persistent and disappeared after transfer of plants from low to high humidity. The author thanks Mrs. L. Kolčabová for her skilled assistance. The paper is a part of the project supported by the grant No. 501/95/1303 of the Grant Agency of the Czech Republic.     

Effects of natural and artificial selection on survival of columnar cacti seedlings: the role of adaptation to xeric and mesic environments

Escontria chiotilla, Polaskia chichipe, and Stenocereus pruinosus are species of Mexican columnar cacti that are economically important because of their edible fruits. These species are managed by gathering fruits from the wild, silvicultural management in agroforestry systems, and cultivation in home gardens. Previous studies reported that artificial selection favored individuals that produced larger fruits, which indirectly led to the production of larger seeds and seedlings, with possible effects on survival. We hypothesized that seedlings from managed populations would be larger but more susceptible to xeric conditions than those from wild populations. We evaluated the effects of artificial and natural selection on seedling survival of the three species in wild and managed populations, which were managed with low and high intensity, respectively. We tested seedling performance in gradients of shade (0, 40, and 80%) and humidity (low and high). A GLM of seedling survival showed significant differences among species, shade, and humidity treatments, with each species having environmental requirements associated with their particular adaptations. High humidity decreased seedling survival of all species, and high solar radiation decreased survival of S. pruinosus and P. chichipe. The effect of management type was significant only in S. pruinosus. Significant differences in the initial growth of seedlings among species were detected with ANOVA. In optimal conditions, the hypocotyl and the cotyledons decreased in size and the epicotyl grew, whereas under stress, these structures remained unchanged. The optimum conditions of shade and humidity varied among species and management types. The seedlings of S. pruinosus were the largest and the most susceptible, but in all species, seedlings from managed populations were more susceptible to environmental conditions. Thus, artificial selection influenced the susceptibility of these cacti to xeric environments.     

Non-pesticide alternatives for reducing feeding damage caused by the large pine weevil (Hylobius abietis L.)

The large pine weevil (Hylobius abietis L.) is an important pest of young forest stands in Europe. Larvae develop under the bark of freshly cut pine and spruce stumps, but maturing weevils feed on the bark of coniferous seedlings. Such seedlings frequently die because of bark consumption near the root collar. We tested the effect of three treatments (the insecticide alpha cypermethrin, a wax coating and a glue coating) on the feeding damage caused by H. abietis on Douglas fir (Pseudotsuga menziesii) and Norway spruce (Picea abies) seedlings under semi-natural conditions. In two experiments (one in 2016 and another in 2017) seedlings in cages were subjected to pine weevil feeding for 16 weeks under shaded outdoor conditions. The experiment in 2016 compared insecticide and wax treatments and an untreated control on Douglas fir and Norway spruce, and the experiment in 2017 compared insecticide, wax and glue treatments and an untreated control on Norway spruce. In both experiments, all treatments significantly reduced H. abietis feeding damage at week 8 at the end of both experiments (week 16); the effect of treatments was significant only on spruce seedlings. The damages on Douglas fir seedlings was less on treated seedlings than on untreated control seedlings but differences were not significant. Coating stems with glue and especially with wax was generally effective at reducing weevil damage and in most cases provided control that was not significantly different from that provided by insecticide treatment. Our results suggest that a wax coating has the potential to replace the protection of seedlings provided by insecticides.