The root to shoot ratio of trees from open- and closed-canopy cerrado in south-eastern Brazil

Background: The Brazilian savanna, or Cerrado, has been described as an ‘upside-down forest’, with higher below-ground than above-ground biomass. The cerrado vegetation, ranging from open grasslands to forests, comprises a wide range of ecological conditions and plant biomass.

Aims: To determine if and how root:shoot ratio in 102 trees differed between open- (cerrado sensu stricto) and closed-canopy cerrado (cerradão) within the same region in south-eastern Brazil.

Methods: Differences in root:shoot ratios and environmental conditions between the two cerrado types were examined, by uprooting and weighing trees from different species and functional groups.

Results: Root:shoot ratio was higher in the open than in the closed cerrado, especially among deciduous species. Root:shoot ratio in the open cerrado was lower than reported for the same cerrado type in central Brazil. Soil fertility did not differ between cerrado types, but soil water was lower and light availability was higher in the open cerrado.

Conclusions: The lower root:shoot ratio in closed than in open cerrado is probably a response to lower light and higher soil water availability, and/or to less frequent fires. Estimates of above-ground carbon storage alone significantly underestimate the carbon stock in open relative to closed cerrado.     

In vitro allelopathic effects of extracts and amenthoflavone from Byrsonima crassa (Malpighiaceae)

Abstract

Extracts and pure amenthoflavone isolated from Byrsonima crassa (Malpighiaceae), a shrub growing in the semi-arid region of Brazil Cerrado, were evaluated in vitro, at different doses, for their effects on tomato seed germination and subsequent growth of seedlings. A hydromethanolic extract showed general stimulatory effects. The EtOAc extract stimulated root elongation and root weight of tomato; shoot elongation was inhibited, while shoot weight was not altered. The pure amenthoflavone isolated from the plant, stimulated shoot elongation at concentrations ranging between 10^?4 M and 10^?6 M.     

Zum Vorkommen von Tomatenrassen des Pilzes Phytophthora injestans im Gebiet der Deutschen Demokratischen Republik

Occurrence of a new disease, shoot blight was observed afflicting mulberry (Morus spp.) in the southern peninsula of India. The disease initiated as marginal burning or blackening of leaf lamina which later spread across the whole lamina and then to the stems of affected shoots, resulting in the drooping of the entire shoot and complete death of the affected plants. On isolation of the causal organism, a bacterial isolate was found to be associated with the disease symptoms, which was identified as Xanthomonas campestris pv. mori. Scanning electron microscopic (SEM) examination of cross sections of stems revealed the presence of rod-shaped bacteria inside xylem vessels of affected plants. This indicates the vascular translocation and colonization of X. campestris pv. mori which resulted in shoot blight in mulberry.     

The effect of cadmium on potato (Solanum tuberosum L.) shoot culture growth

The uptake of cadmium and its effect on the growth of potato shoot tips grownin vitro were followed in dependence on cadmium concentration in nutrient medium. Concentration of 10 ⁻⁶ M Cd ²⁺ did not substantially affect potato plantlet growth dynamics; but the concentration of 10⁻³ M Cd²⁺ showed a strong growth inhibitory effect accompanied with increased cadmium accumulation in both root and shoot tissues.     

Triacontanol modulates photosynthesis and osmoprotectants in canola (Brassica napus L.) under saline stress

Abstract

An experiment was conducted to assess the effect of pre-sowing seed treatment with triacontanol (TRIA) in canola (Brassica napus L.) cultivar (RBN-3060) under saline stress. Canola seeds were soaked in three levels of TRIA (0, 0.5, and 1 mg L^?1) for 12 hours. Three levels of salt stress (0, 100, and 150 mM NaCl) in full strength Hoagland's nutrient solution were applied to 56-days-old plants. Salt stress caused a significant reduction in growth, gas exchange, photochemical quenching (qP), and shoot and root K⁺ contents, while increased leaf glycine betaine, free proline, and shoot Na⁺ contents. Pre-sowing seed treatment with TRIA increased shoot fresh weight, number of seeds per plant, photosynthetic rate, transpiration rate, ratio of chlorophyll a/b, qP, electron transport rate, shoot and root K⁺ contents, and free proline and glycine betaine contents of canola plants at various TRIA levels under nonsaline or saline conditions.     

Phenology and carbohydrate content of heathers of southern origin grown in Scotland

Summary

Plants of Erica vagans, E. mackaiana and E. ciliaris from Spain or southern England were characterised by late flowering, tardy shoot extension, erect growth form and a susceptibility to winter damage when grown outdoors in Scotland. Although these characteristics are shared by plants of Calluna vulgaris, Erica cinerea and E. tetralix of similar provenance these latter species are known to be capable of producing forms suited to more severe climates. Differences in carbohydrate contents were not strongly related to origin although Erica ciliaris, E. vagans and E. erigena tended to accumulate relatively greater amounts of polysaccharides than the other species. Erica erigena combined early flowering with late and slow shoot extension and remained undamaged during winter.     

In vitro studies on Pea (Pisum sativum L.): I. Callus formation,regeneration and rooting

Abstract

Callus production, shoot formation via organogenesis and rooting of the regenerated shoots are reported in an Egyptian variety of Pisum sativum L. Calli were initiated from hypocotyl, leaf, root and mature embryo explants when cultured on MS medium containing B5 vitamins and supplemented with 2 mg/l 2,4-D+1 mg/l kin. Among the different types of explants, hypocotyl showed best potential for callus proliferation. Hypocotyl, leaf and immature cotyledon explants were used for shoot organogenesis. The best results of shoot formation were achieved when hypocotyl explants were cultured on MS-medium supplemented with 2 mg/l BA+1 mg/l NAA. However, immature cotyledon explants showed the highest frequency of shoot formation with 1 mg/l BA. Data of in vitro rooting showed that maximum root frequency occurred on culture medium containing half strength of MS salts, 40 g/l sucrose and 2 mg/l NAA.     

Impact of the TaMATE1B gene on above and below-ground growth of durum wheat grown on an acid and Al3+-toxic soil

Background and aims

Subsoil acidity with a high aluminium (Al³⁺) soil content inhibits root growth and proliferation of durum wheat (tetraploid AABB, Triticum turgidum) leading to poor nutrient and water uptake. This study evaluated the impact of Al³⁺-tolerantTaMATE1B allele on root and shoot traits of durum wheat grown in an acidic soil with a high Al³⁺concentration.

Methods

Two durum wheat lines, Jandaroi–TaMATE1B with the TaMATE1B gene introgressed from Al³⁺-tolerant bread wheat and Jandaroi–null (a sister line lacking the Al³⁺-tolerant TaMATE1B allele), were grown in rhizoboxes in a glasshouse. We mapped root growth and proliferation over time and measured shoot traits and grain yield.

Results

Introgression of the Al³⁺-tolerant TaMATE1B allele into durum wheat enabled root growth and proliferation below 0.25 m of the soil profile, where the soil pH was low (4.1, CaCl₂ extract) with high Al³⁺ content (16.5 mg kg⁻¹), and increased total root length and biomass at 42 days after sowing (DAS; Z₃₃) by 38.3 and 22%, respectively, relative to the Jandaroi–null. Differences in root growth between the two lines were apparent from tillering stage (Z₃₃) and by 50% anthesis (Z₆₄), respectively. Jandaroi–TaMATE1B had 69.2% greater root biomass, 76.2% greater root length, 5.89% greater leaf area and 18% greater shoot biomass than Jandaroi–null at 50% anthesis (Z₆₄). Time to anthesis and physiological maturity was delayed 6–7 days in Jandaroi–TaMATE1B, compared to Jandaroi–null. Jandaroi–TaMATE1B tended to have relatively greater, but not significantly different, shoot biomass, grain yield and yield components than Jandaroi–null.

Conclusions

Introgression of the Al³⁺-tolerant TaMATE1B allele into durum wheat enabled root growth and proliferation down an acidic soil profile with a high Al³⁺ concentration. We assume that in the field where plants need to acquire water at depth differences in above-ground parameters would be amplified.

     

African Hepatica XXI. Microlejeunea,Chaetolejeunea and Pleurolejeuna

Abstract

Zoopsis nitida is described as a new species endemic to New Zealand, at present only known from Northland, and appears to be most closely related to Z. setulosa. It differs from other species of the genus in its very reduced leaves which are usually only discernible near the shoot apex.     

Phytoremediative potential of salt-tolerant grass species for cadmium and lead under contaminated nutrient solution

Abstract

Phytoremediation of heavy metal contaminated soils represents a promising technique and salt-tolerant hyperaccumulators for multiple metals are the need of time. Therefore, phytoremediation potential of four salt-tolerant grass species [Dhab (Desmostachya bipinnata), Kallar (Leptochloa fusca), Para (Brachiaria mutica) and Sporobolus (Sporobolus arabicus Boiss)] was evaluated for cadmium (Cd) and lead (Pb) in a hydroponic study. The plants were harvested after a growth period of 3 months in a nutrient solution containing different levels of Cd (0, 5, and 25?mg?L^?1) and Pb (0, 25, and 125?mg L^?1). Results indicated that Dhab grass showed the highest root and shoot dry matter yield followed by Para, Kallar and Sporobolus grass irrespective of metal or its level under which they were grown. All the grass species showed considerable Cd-accumulating potential with an accumulation of >150?mg kg^?1of shoot dry matter at a higher level of Cd-contamination (25?mg?L^?1). While in case of shoot Pb-accumulation only Para grass performed well and accumulated Pb >1000?mg kg^?1 of shoot dry matter at the higher level of Pb-contamination (125?mg?L^?1). Moreover, Para and Dhab grasses performed better for shoot Cd-uptake, while only Para grass showed promising shoot Pb uptake potential. In conclusion, these grass species could be penitentially used for phytoremediation of salt-affected Cd and Pb contaminated soils.     

Effects of Bacterial Inoculation to Immobilize Nickel in Wheat Grown on Ni-Contaminated Soil

Abstract

Plant growth stimulating bacteria are very effective in immobilization of metals and reducing their translocation in plants through precipitation, and adsorption. A pot experiment was conducted to investigate the effectiveness of chitosan- and hematite-modified biochar and bacterial inoculations on the immobilization of nickel (Ni) in polluted soil under wheat cultivation. Application of modified biochars and inoculation with Pseudomonas putida significantly increased both wheat root and shoot dry matter yields but decreased Ni phytoextraction efficiency. The Ni concentration, translocation factor and uptake in wheat shoot and root significantly decreased the application of either modified or unmodified biochars. Bacterial inoculation significantly decreased mean translocation factor and also root and shoot concentration and the uptake Ni in the shoot. Chitosan-modified biochar was the most influential treatment in decreasing Ni uptake by wheat followed by P. putida inoculation treatment. The results demonstrated positive effects of chitosan modified biochar and inoculation with P. putida in increasing dry matter yield and decreasing Ni uptake in wheat grown on Ni-contaminated soil. According to the results of present study, modified biochars application and bacterial inoculation are influential treatments which prevent Ni toxicity probably.     

A new Middle Eastern Grimmia

Abstract

Photosynthesis, respiration, net assimilation, chlorophyll b concentration, and levels of potassium, calcium, magnesium and iron were measured in 2 cm shoot segments of Pleurozium schreberi in order to examine patterns of physiological decline with ageing in a continuously growing species. Photosynthesis and chlorophyll b levels declined rapidly after the apical shoot segment and were undetectable after a distance of 8 cm from the shoot apex. Respiration rate also fell rapidly at first but then declined more gradually and some respiration was detected in all shoot segment samples. Potassium and magnesium levels declined approximately linearly in relation to segment number. Calcium levels, expressed on a concentration per unit weight basis, became progressively higher in older segments but the calcium content per segment may actually decline with age. The disparity may be due to a decline in the proportion of cytoplasm compared with cell wall material in older segments.

No clear division could be made between living and dead shoot segments. Different physiological processes decline at different rates as ageing occurs and the importance of the age structure of shoot samples is discussed in relation to design of physiological experiments.     

Arabidopsis thaliana: protocol for plant regeneration from protoplasts

We report a protocol for plant regeneration from leaf protoplasts of Arabidopsis thaliana ecotype Zürich. The protocol has been established in 1988 and has since been in routine use in our laboratory. Whereas recovery of proliferating protoplast-derived clones is routine, the success in plant regeneration from protoplast-derived clones is highly variable. In the hands of one of us (H.K.) average shoot regeneration frequency (% of calli regenerating at least one shoot) was ca. 60% and average plant regeneration frequency (% of calli yielding fertile plants in soil) was ca. 40%.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indoleacetic acid - NAA naphthaleneacetic acid - BAP benzylaminopurine - 2-iP 2-isopentenylaminopurine     

Somatic embryogenesis and shoot regeneration from leaf derived callus of Hypericum perforatum var. angustifolium (sin. Fröhlich) Borkh

Abstract

The development of in vitro regeneration systems for Hypericum perforatum var. angustifolium (sin. Fröhlich) Borkh, a medicinal plant used for treating neurological disorders, is described. For the first time in this variety, somatic embryogenesis and shoot regeneration were induced from leaf-derived callus. Well-formed plantlets were obtained through both shoot regeneration and somatic embryogenesis, with separate morphogenetic programmes. Proembryogenic masses were obtained in liquid MS and B5 media supplemented with 5.8 μM 2,4-D, 1.34 μM NAA, and 1.16 μM Kin; after being transferred onto hormone-free medium, they formed whitish and spherical structures that subsequently developed into the heart and torpedo stages.

On MS agarized medium containing thidiazuron (TDZ) at different concentrations (3, 6, 9, 12 μM) combined with 2 μM IBA, only shoot regeneration, and not somatic embryogenesis, was obtained. The mean number of shoots increased significantly when the concentration of TDZ was 3 μM.     

Factors affecting in vitro shoot formation from vegetative shoot apices of apple and relationship between organogenic response and cytokinin localisation

ABSTRACT

The effects of macro- and micro-elements, benzyladenine (BA) concentration, and the period of auxin application on adventitious shoot formation from callus originating from vegetative shoot apices were tested on apple (Malus domestica Borkh) rootstock Jork 9. The putative relationship between organogenic response and cytokinin localisation was also studied by an immunolocalisation technique for in situ determination of free cytokinins. The use of MS (Murashige & Skoog, 1962) salts in the medium instead of those of LP (Quoirin & Lepoivre, 1977) had a strong positive effect both on shoot formation rate and on the number of shoots produced. The highest organogenic response from callus was induced using 17.8 μM BA in the presence of 2.7 μM NAA and by maintaining the explants for 20 days in darkness, then transferring them to fresh auxin-free medium and to the light. The in situ localisation studies, performed using antibodies with a marked specificity against zeatin and isopentenyladenine, revealed changes in the localisation of free zeatin in the tissues during the shoot-forming process, in particular during the active cell division phase leading to callus formation, and in the initial phase of bud formation. Changes in zeatin distribution in the tissues of the vegetative shoot apex during shoot formation may indicate a role for this cytokinin free base in cell differentiation and organogenesis.     

入侵植物薇甘菊新枝在海南的月生长动态

【背景】薇甘菊是入侵性和危害性极强的外来入侵植物,对生物多样性和农林业生产造成严重影响。观测薇甘菊新枝的月生长动态,了解薇甘菊快速生长扩散的原因,能够为薇甘菊的合理防治提供参考。【方法】采用定点定时观测法,历时2年对海南7个市县薇甘菊新枝的月生长量进行测定。【结果】薇甘菊在海南全年可生长,一新枝月平均生长66 cm,全年累计平均生长795 cm。薇甘菊生长高峰期在6月和8月,其中6月平均生长120 cm,8月平均生长106 cm。薇甘菊最小生长量在1月和12月,平均生长量均为21 cm。薇甘菊在6—10月生长较快,一新枝累计平均生长489 cm,占全年生长量的61.5%;在4—5月和11月生长次之,一新枝累计平均生长196 cm,占全年生长量的24.7%;在1—3月和12月生长缓慢,一新枝累计平均生长110 cm,占全年生长量的13.8%。薇甘菊的花果期在10月至次年3月,一些种群在1—3月再次开花或在3—5月开花。薇甘菊的生长量与温度呈极显著正相关,相关系数为0.91;与降雨量呈显著正相关,相关系数0.56。【结论与意义】薇甘菊是多分枝植物,一新枝年生长量可达795 cm,能迅速生长形成种群。温度是薇甘菊生长的主要因素,降雨在一定程度促进了薇甘菊的生长。     

Indirect effects mediated by compensatory shoot growth on subsequent generations of a willow spittlebug

 We investigated whether oviposition by the spittlebug Aphrophora pectoralis on Salix miyabeana and S. sachalinensis in fall 1998 affected shoot growth pattern and further oviposition by subsequent generations of the willow spittlebug in early September 1999 and 2000. Spittlebug oviposition enhanced the growth of current-year shoots on 1-year shoots with oviposition (O-shoots) compared to those without oviposition (N-shoots): the length of current-year shoots increased in 1999 and 2000, the number of current-year shoots increased in 2000 despite a decrease in 1999, and the shoot abscission rate decreased during the 1999 winter. The number of egg masses per current-year shoot was greater on O-shoots than on N-shoots in 1999, and this tendency was reinforced in 2000. The total number of egg masses was greater on O-shoots than on N-shoots in 2000, although there was no significant difference in 1999. There is thus a positive feedback system between spittlebug attack and compensatory growth on willow. Received: April 11, 2002 / Accepted: July 30, 2002 Present address: Center for Ecological Research, Kyoto University, Otsu, Japan Acknowledgments We thank Masanori J. Toda and Andrew Davis for valuable comments and critical reading on this paper. Financial support was provided by a Japanese Ministry of Education, Science, Sports, and Culture Grant-in-Aid for Creative Basic Research to Takayuki Ohgushi. Correspondence to:A. Nozawa     

Distribution,structure and phenology of Posidonia oceanica meadows along sicilian coasts

Abstract

Distribution, structure and phenology of Posidonia oceanica meadows along Sicilian coasts are reported. Posidonia beds are frequently found in Sicily, especially along the south-eastern, north-western and western coasts. Leaf surface per shoot is identified as the most important variable among the phenological parameters. The rhizomes annual mean primary production turned out to be among the highest values observed in the Mediterranean Sea. Flowering and fruiting of Posidonia oceanica are frequent and can occur every year.     

Effects of 3,4-dihydroxybenzoic acid on tobacco (Nicotiana tabacum L.) cultured in vitro. Growth regulation in callus and organ cultures

ABSTRACT

The influence of 3,4-dihydroxybenzoic acid (protocatechuic acid), a naturally occurring benzoic acid derivative, on tobacco (Nicotiana tabacum L.) cell and tissue cultures was examined. The response to 0.1, 10 and 1000 µM 3,4-dihydroxybenzoic acid was tested with regards to cell proliferation in leaf explants, callus growth and shoot formation. Effects on shoot and root growth in micropropagated plants were also analysed. The highest concentration of 3,4-dihydroxybenzoic acid strongly inhibited the proliferation of leaf tissues, callus growth, shoot regeneration and root growth in micropropagated plants. On the contrary, the lowest concentration (0.1 µM) showed auxin-like activity by stimulating cell dedifferentiation, callus induction and rooting of leaf tissues. The presence of auxins and cytokinins in the media contrasted 3,4-dihydroxybenzoic acid inhibition of callus growth at all tested concentrations.     

Nitrogen form influences the response of Deschampsia antarctica to dark septate root endophytes

Fungi with dematiaceous septate hyphae, termed dark septate endophytes (DSE), are common in plant roots, particularly in cold-stressed habitats, but their effects on their host plants remain obscure. Here, we report a study that assessed the effects of six DSE on the growth and nutrient balance of Deschampsia antarctica when plants were supplied with the same amount of nitrogen in organic (casein hydrolysate) or inorganic (ammonium sulphate) form under controlled conditions. After 60 days, the DSE, that had each been isolated from D. antarctica and which analyses of internal transcribed spacer and large subunit regions indicated were similar to members of the Helotiales (Oculimacula yallundae, Mollisia and Tapesia spp.) and unassigned anamorphic ascomycetes, typically had no effect on, or reduced by 33–71%, shoot and root dry weights relative to uninoculated controls when plants had been supplied with nitrogen in inorganic form. In contrast, the DSE usually enhanced shoot and root dry weights by 51–247% when plants had been supplied with organic nitrogen. In the presence of inorganic nitrogen, only sporadic effects of DSE were recorded on shoot and root nitrogen or phosphorus concentrations, whereas in the presence of organic nitrogen, three to six of the DSE isolates increased shoot and root nitrogen and phosphorus contents. Most of the isolates decreased the phosphorus concentrations of shoots and roots when plants had been supplied with nitrogen in organic form. Our data suggest that DSE are able to mineralise peptides and amino acids in the rhizosphere, making nitrogen more freely available to roots.