Search results for "shoot"
showing 10 items of 298 documents
Isolation, culture and plant regeneration from protoplasts of Sideritis angustifolia
1998
Summary Factors promoting high yields of viable protoplasts from leaves of Sideritis angustifolia are reported. Isolated protoplasts divided and gave rise to callus when plated in modified liquid MS medium with growth regulators. Best plating efficiency was obtained when protoplast were cultured in the presence of 6 μM BA and 2 μM NAA. Calli were then transferred onto solidified regeneration media. Adventitious bud differentiation was only observed in calli grown on medium containing 8 μM BA and 2 μM NAA. These buds proliferated quickly when placed on hormone-free medium and subsequendy regenerated new buds and shoots. Once developed shoots were excised, the remaining tissues maintained thi…
Morphogenesis in leaf and single-cell cultures of mature Juniperus oxycedrus
1996
Single cells were mechanically isolated from leaf-derived callus of mature Juniperus oxycedrus L. These cells divided and gave rise to callus when plated on medium containing growth regulators. Best plating efficiency was obtained on a modified Schenk and Hildebrandt medium supplemented with 0.6 micro M 2,4-dichlorophenoxyacetic acid and 100 mg l(-1) casein hydrolyzate. Although single-cell-derived callus showed poor morphogenic potential, both adventitious shoots and embryogenic tissues differentiated from the callus. We also achieved induction of somatic embryogenesis in leaf explants of mature J. oxycedrus trees cultured in the presence of 6.0 or 10.0 micro M 2,4-dichlorophenoxyacetic ac…
Developmental morphology of Apinagia multibranchiata (Podostemaceae) from the Venezuelan Guyanas
2000
Abstract Apinagia ( c. 50 spp.) is the largest genus of American Podostemaceae. Apinagia multibranchiata (Matth.) Royen is a haptophyte endemic to the Venezuelan Guyanas. It fits well with the Podostemoideae bauplan known from other New World genera, such as Marathrum and Mourera . Shoots arise in pairs from filamentous creeping adhesive roots. During the rainy season submerged vegetative shoots grow up to more than a metre long. They are normally unbranched and provided with distichously arranged leaves which are laterally flattened into one plane. The lanceolate leaves may show a fimbriate tip. Tufts of threads are found on the upper leaf surface which faces the sky. When the water recede…
Shoot age as a confounding factor on detecting the effect of human-induced disturbance on Posidonia oceanica growth performance
2007
Abstract The response of orthotropic rhizome elongation and primary production of Posidonia oceanica to anthropogenic perturbations and potential confounding effects of shoot age were assessed using a Linear Multilevel Model (LMM). This model examined the confounding effect of age by comparing the estimates of impact and variance components obtained by excluding and including Age as an explanatory variable. Age had a negative effect on rhizome elongation and primary production with an annual decrease of 0.6 mm y − 1 and 7 mg dw y − 1 respectively. According to the LMM when age effect was omitted, the differences between disturbed and control locations in rhizome elongation and primary produ…
Thermally unstable throughflow of a power–law fluid in a vertical porous cylinder with arbitrary cross–section
2021
Abstract The present paper investigates how the cross–sectional shape of a vertical porous cylinder affects the onset of thermoconvective instability of the Rayleigh–Benard type. The fluid saturating the porous medium is assumed to be a non–Newtonian power–law fluid. A linear stability analysis of the vertical thorughflow is carried out. Three special shapes of the cylinder cross–section are analysed: square, circular and elliptical. The effect of changing the power–law index is investigated. The stability of a steady base state with vertical throughflow is analysed. The resulting stability problem is a differential eigenvalue problem that is solved numerically through the shooting method. …
Planting density, above-ground dry-matter partitioning and fruit quality in greenhouse-grown 'Flordaprince' peach (Prunus persica L. Batsch) trees tr…
1999
SummaryThe effect of planting density on yield, fruit quality and above-ground dry-matter partitioning into vegetative and reproductive organs of six year old peach trees was investigated in Sicily on the very early-ripening cv Flordaprince in greenhouse. Increasing the number of trees per hectare from 1500 to 5000 significantly reduced total above-ground dry matter, trunk cross-sectional area and total leaf area. Differences in growth did not result in substantial modifications in the source-sink relationships between the vegetative and the reproductive organs of the above-ground part of the tree, as shown by the lack of statistical differences in dry-matter partitioning into fruit, leaves…
Invasive and native populations of common ragweed exhibit strong tolerance to foliar damage.
2013
8 pages; International audience; Tolerance and resistance are defence strategies evolved by plants to cope with damage due to herbivores. The introduction of exotic species to a new biogeographical range may alter the plant herbivore interactions and induce selection pressures for new plant defence strategies with a modified resource allocation. To detect evolution in tolerance to herbivory in common ragweed, we compared 3 native (North America) and 3 introduced (France) populations, grown in a common garden environment. We explored the effect of leaf herbivory on plant vegetative and reproductive traits. Plants were defoliated by hand, simulating different degrees of insect grazing by remo…
In vitro Shoot Regeneration from Flower and Leaf Explants in Rhododendron
2003
Rhododendron shoot regeneration was accomplished using either flower explants (each consisting of ovary with pedicel) of Rhododendron cvs. Nova Zembla and Irina or leaves isolated from in vitro grown Rhododendron catawbiense Michx. Multiple shoot tip clumps were obtained on Anderson's medium containing 0.5 to 1.5 mg dm−3 thidiazuron (TDZ) in combination with 12 to 15 mg dm−3 N6-[2-isopentenyl]adenine (2iP) and 1 to 3 mg dm−3 indole-3-butyric acid (IBA). After 16 weeks on the regeneration media, explants with shoot tip clumps were transferred for shoot elongation to Anderson's medium with 3 mg dm−3 2iP. Two months later, the shoots have reached 5 to 40 mm in length and were fit for subcultiv…
Foreed flushing of branch segments as a method for obtaining reactive explants of mature Quercus robur trees for micropropagation
1994
The aim of this study was to micropropagate mature Quercus robur L. trees when material retaining physiologically juvenile characteristics (stump sprouts, epicormic shoots) is not available. Branch segments from 70–300 year-old trees were force-flushed and the flushed, partially rejuvenated or reinvigorated shoots were used as a source of explants for establishment of cultures. In vitro establishment and multiplication was achieved with seven of the eight selected trees. The proliferation capacity of cultures of vertically placed explants declined after several subcultures, but efficient shoot multiplication was achieved by culturing decapitated shoots placed horizontally on GD medium suppl…
Influence of arbuscular mycorrhizal colonisation on cadmium induced Medicago truncatula root isoflavonoid accumulation.
2012
Cadmium is a serious environmental pollution threats to the planet. Its accumulation in plants affects many cellular functions, resulting in growth and development inhibition, whose mechanisms are not fully understood. However, some fungi forming arbuscular mycorrhizal symbiosis with the majority of plant species have the capacity to buffer the deleterious effect of this heavy metal. In the present work we investigated the capacity of Rhizophagus irregularis (syn. Glomus irregularis) to alleviate cadmium stress in Medicago truncatula. In spite of a reduction in all mycorrhizal parameters, plants colonized for 21 days by R. irregularis and treated by 2 mg kg(-1) cadmium displayed less growth…