Effects of cadmium on growth and pharmacologically active constituents of the medicinal plant Coriandrum sativum L.

The effects of high levels of cadmium in soil and in the atmosphere on the plants of Coriandrum sativum L. (Umbellifereae) were investigated. Plants grown in contaminated soil (0, 10, 100 ppm of cadmium) showed a significant reduction in the length of the stems and roots and the number of the umbels, a yellowing and ultrastructural alterations of the leaves and a significant decrease in the essential oil composition. Similar effects were observed in the plants exposed to a simulated atmospheric pollution (plants were sprayed with CdCl₂ solutions containing Cd 0, 10, 100 mg/L). The effects are related to a degree of environmental contamination.     

Ethnobotanical investigation and diversity of Gbolo (Crassocephalum rubens (Juss. ex Jacq.) S. Moore and Crassocephalum crepidioides (Benth.) S. Moore), a traditional leafy vegetable under domestication in Benin

Thirty five villages randomly selected across ethnic and agro-ecological zones of Benin were surveyed to document the indigenous knowledge associated with the domestication (bringing into cultivation), production and utilization of vegetable Gbolo (Crassocephalum spp.). The study revealed the existence of different morphotypes (1–4 per village) corresponding to two botanical species (Crassocephalum rubens (Juss. ex Jacq.) S. Moore) and (Crassocephalum crepidioides (Benth.) S. Moore) found unequally distributed throughout the country. The domestication (bringing into cultivation from the wild) of Gbolo was started in many villages and with some tribes in southern Benin, the vegetable is already being produced in sole cropping for commercial purposes. Regular consumption (49.90 % of responses) and scarcity (20.30 % of responses) were the two main reasons attributed by the interviewees for domestication of the vegetable. The cultural practices recorded were of five categories. The commonest cropping system found was mixed or inter-row cropping (92.31 % of producers) with either vegetable crops (53.85 % of producers) or non-vegetable crops (38.46 % of users). Sauce prepared with either fresh or dried leaves was the main type of preparation of Gbolo and the vegetable was reported to possess special nutritional and medicinal values. For further promotion, important researches directions are suggested.     

Selection of hybrids and edible citrus species with a high content in the diosmin functional compound. Modulating effect of plant growth regulators on contents.

The purpose of this study is to identify species, hybrids, and cultivars of edible Citrus species with high contents of diosmin as a functional compound and also to identify the developmental progress of the fruit in which it reaches maximum levels; these findings would be useful for extraction purposes and for the modulating effect of plant growth regulators on diosmin content to increase the level of this flavone. The results obtained reveal that the highest contents of diosmin are present in immature fruits of certain varieties of citron (Buda's finger) and lemon (Meyer), whereas the contents in the edible parts of the fruits are irrelevant from a pharmacological point of view. Similarly, it is shown that it is possible to increase the content of this flavone using hormonal treatments (6-benzylaminopurine and 2,4-dichlorophenoxyacetic acid) during the early stages of fruit growth.     

The endophyte Enterobacter sp. FD17: a maize growth enhancer selected based on rigorous testing of plant beneficial traits and colonization characteristics

With the aim to select powerful microbial strains to be used for the enhancement of maize yield and resistance to abiotic and biotic stresses, we tested five endophytic bacterial strains previously isolated from maize roots. A range of different laboratory assays in regard to potential plant growth promotion was performed and strains were further evaluated for improving growth of five maize cultivars under axenic and natural soil conditions. Endophytic colonization was an additional component in our selection process as it is of high importance for an inoculant strain to efficiently colonize the plant environment. All strains had the potential to improve maize seedling growth under axenic conditions. Enterobacter sp. strain FD17 showed both the highest growth-promoting activity under axenic conditions as well as colonization capacity. FD17 was therefore selected for further plant tests in a net house, in which two different maize cultivars were grown in large pots until ripening and subjected to outdoor climatic conditions. Results showed that inoculation significantly increased plant biomass, number of leaves plant^?1, leaf area, and grain yield up to 39 %, 14 %, 20 %, and 42 %, respectively, as compared to the un-inoculated control. Similarly, inoculation also improved the photochemical efficiency of photosystem II (PSII) of maize plant and reduced the time needed for flowering. We also confirmed that strain FD17 is able to colonize the rhizosphere, roots and stems. Based on rigorous testing, Enterobacter sp. strain FD17 showed the highest potential to promote growth and health of maize grown under natural conditions. This study suggested that in vitro plant growth-promoting traits and potential of maize seedling growth promotion by bacterial endophytes could be used for the selection of potential inoculant strains subjected for further testing as bio-inoculant under field conditions.     

The beautiful hills: half a century of vanilla (Vanilla planifolia Jacks. ex Andrews) breeding in Madagascar

Genetic Resources and Crop Evolution - An ambitious vanilla (Vanilla planifolia Jacks. ex Andrews) breeding program was started in Madagascar in the early 1950s to control Fusariosis, a serious...     

Fresh-weight measurements of roots provide inaccurate estimates of the effects of plant growth-promoting bacteria on root growth: a critical examination

Four strains of plant growth-promoting bacteria (PGPB), including three strains of Azospirillum and Pseudomonas fluorescens 313 were used to inoculate seeds of wheat, tomato, pepper, and cotton. Inoculated seedlings were grown to the two or three-leaf stage. After harvest, seven different environmental and technical conditions were evaluated to determine the effect of these conditions on the reproducibility of fresh and dry root weight measurements. Dry root weight of each sample showed no significant variations (smaller than 1%), despite the variations in measurement conditions. Root fresh weights varied greatly (usually in the range of 4-10%, but up to 18%), and were significantly affected (P≤0.05) by air temperature and relative humidity, air currents, different light intensities during extraction of plants from the substrate, duration of the extraction from soil (depending on the size of the experiment and type of plant growth substrate), and the type of absorbing paper used to blot excess water from harvested roots. Measurements by different technicians did not influence fresh or dry weight values. We conclude that fresh weight determinations are altered by factors independent of the intended experimental variables and should not be used to evaluate the effect of PGPB on plants.     

Different behavioral patterns of the earthworms Octolasion tyrtaeum and Diplocardia spp. in tallgrass prairie soils: potential influences on plant growth

This study addressed differences between Diplocardia spp. (a native North American earthworm) and Octolasion tyrtaeum (an introduced European species), with respect to behavior, influence on soil microbial biomass, and plant uptake of N in tallgrass prairie soils. We manipulated earthworms in PVC-encased soil cores (20 cm diameter) over a 45-day period under field conditions. Treatments included: (1) control with no earthworms, (2) Diplocardia spp. only, and (3) O. tyrtaeum only. Prior to addition of earthworms, seedlings of Andropogon gerardii (a dominant tallgrass) were established in each core, and a dilute solution of ¹³C-labeled glucose and ¹⁵N-labeled (NH₄)₂SO₄ was added to the soil to facilitate examination of earthworm/microbe/plant interactions. We found that Diplocardia spp. were significantly more active than O. tyrtaeum, and quickly assimilated ¹³C and ¹⁵N from the tracer. Individuals of Diplocardia spp. were present at shallower soil depths than O. tyrtaeum throughout the study. Contrary to expectation, this greater activity of Diplocardia spp. did not result in increased plant productivity. Rather, the activity of Diplocardia spp. was associated with less plant growth and smaller amounts of N acquired by A. gerardii seedlings compared to controls or O. tyrtaeum treatments. We observed few significant influences of earthworm treatments on microbial biomass C or N pool sizes, but the microbial C/N ratio was consistently greater in the presence of Diplocardia spp. relative to O. tyrtaeum. Results of this study indicate that activity of earthworms may enhance competition for N between microbes and plants during the growing season in tallgrass prairie.     

Rapid assessment of the rate of nitrogen immobilisation in organic components of potting media: II. Nitrogen drawdown index and plant growth

Abstract

In several experiments, cabbage seedlings were grown in soilless potting media produced using a range of aged and composted pinebarks, peat and sawdusts. Their growth was compared with the Nitrogen Drawdown Indexes (NDI) of the media, measured by a standard method previously reported. Growth was highly correlated with NDI when N was applied via pre‐plant additions and/or liquid drenches.

Aged pinebarks and composted hardwood sawdusts, with high N immobilisation potential, have NDI values near zero and consume N at about 300 mg/L each week. Adequate plant growth is difficult to obtain in these media. Media with NDI values of around 0.5 consume about 40 mg/L N each week. Pre‐plant amendment with N equivalent to that in 0.5–1.0 g/L NH₄NO₃ is desirable and weekly feeding with a solution containing 200–400 mg/L N will give maximum growth rate. Weekly feeding with solutions containing 100–150 mg/L N provides sufficient N for excellent plant growth in peat‐based media, whose NDI values are 0.95–1.0.     

Fruit and seed characterization of wild populations of a traditional Andean crop: Solanum betaceum Cav. (Solanaceae) in the Argentinian Yungas

Genetic Resources and Crop Evolution - Chilto (Solanum betaceum Cav.) is a traditional Andean crop, appreciated for its high nutritional and commercial value. Despite it is cultivated in many...     

Conservation benefits of biological control: The recovery of a threatened plant subsequent to the introduction of a pathogen to contain an invasive tree species

Biological control using host-specific natural enemies is sometimes the only long-term and cost-effective option to contain dominant invasive alien species in natural ecosystems. To assess biocontrol success, most monitoring studies focus on the negative impacts of the released biocontrol agents on the target invasive species. Very few studies have shown the conservation benefits, i.e. their positive effects on the recovery of native species and habitats. A fungal pathogen (Colletotrichum gloeosporioides f. sp. miconiae) was successfully released on the island of Tahiti (South Pacific) to control the dominant invasive tree Miconia calvescens which forms dense monospecific stands in native rain- and cloud forests. The pathogen causes a leaf disease leading to partial (5–35%) defoliation of Miconia canopy trees. We studied the demographical parameters of the rare endemic sub-shrub Ophiorrhiza subumbellata, growing in the understory of montane cloud forests invaded by Miconia. We compared Ophiorrhiza populations in 13 plots set up in two sites located between 950 and 1000 m elevation, having the same Miconia invasion degree but different levels of leaf damage. Our results showed that, whereas the total population density of Ophiorrhiza is not affected, plants’ growth and fertility were significantly higher in more defoliated Miconia forests. A 3-year-long survey of Ophiorrhiza population at one study site indicated that the number of seedlings and juvenile plants increased, suggesting better recruitment and survival. This study demonstrates that biological control has contributed to the recovery of an endemic plant directly threatened by an invasive species, and may be considered as an important management tool for the partial restoration of native forests.     

Ability of the earthworms Aporrectodea rosea and Aporrectodea trapezoides to increase plant growth and the foliar concentration of elements in wheat (Triticum aestivum cv. spear) in a sandy loam soil

In a greenhouse study, the ability of the earthworms Aporrectodea rosea and A. trapezoides to influence the foliar concentration of elements and the growth of wheat plants was assessed 27 days after sowing in a sandy loam soil. The presence of A. rosea and A. trapezoides (at densities equivalent to 314 and 471 m^-2, respectively) caused a significant increase in the shoot dry weight of wheat. The presence of A. rosea and A. trapezoides (at densities equivalent to 314 and 157 m^-2, respectively) was also associated with a significant increase in the root dry weight of wheat. The presence of A. rosea caused a significant increase in the foliar concentration of Ca, Cu, K, Mn, N, Na, and P, but did not influence the foliar concentration of Al, B, Fe, Mo, Mg, S, and Zn. The presence of A. trapezoides was associated with a significant increase in the foliar concentration of Al, Ca, Fe, K, Mn, N, and Na, but did not influence the foliar concentration of B, Cu, Mo, Mg, P, S, and Zn. These results demonstrate the potential of A. rosea and A. trapezoides to increase the growth of wheat in a sandy loam soil and suggest that the mechanism by which they increased plant growth was, in part, through increasing the availability and uptake of nutrients from this soil.     

Evaluation of fly ash as a soil amendment for the Atlantic Coastal Plain: II. Soil chemical properties and crop growth

Crop yields in the Atlantic Coastal Plain of the U.S.A. are limited by the low moisture-holding capacities of the sandy soils common to the region. Corn was grown in a Hammonton loamy sand soil amended with fly ash (0, 5, 10, 20, 30, and 40%) to determine if the ash rates required to improve soil moisture holding capacity would adversely affect plant growth, or soil and plant levels of nutrients and heavy metals. Fly ash increased soil test levels of P, K, Ca, Mg, Mn, Cu, Zn, B, Cd, Cr, Ni, and Pb. Nutrient concentrations in plants grown in the ash-amended soils, except P, Mn, and B, remained within established sufficiency ranges. The 20 and 40% ash rates increased soil soluble salt (EC) levels from 0.2 to 1.1–1.5 and 1.7–2.1 mmho cm^?1, soil pH from 5.6 to 6.0–6.4 or 6.3–6.9, and extractable B from 0.2 to 2.2–5.9 and 2.2–9.0 mg kg^?1. Fly ash reduced corn germination, delayed seedling emergence, and reduced root and shoot dry weights. Plant B concentrations at the 40% ash rate were in the phytotoxic range (136–189 mg kg^?1). Management practices that allow for pre-leaching of B and soluble salts will likely be required to attain satisfactory corn growth in ash-amended soils.     

The effect of Mg: Ca ratio and osmotic potential of nutrient solutions on calcium transport into emergent leaves of the strawberry plant cv. Cambridge favourite

Strawberry plants, cv. Cambridge Favourite were grown at osmotic potentials of ‐0.2 and ‐0.8 bars in nutrient solutions with magnesium : calcium ratios ranging from 0.3 to 5.6: 1. When the OP was ‐0.8 bars, all plants showed leaf tipburn, guttated little, yielded small volumes of exudate overnight from cut stolons and had small calcium concentrations and contents in their emergent leaves, regardless of the Mg: Ca ratio of the nutrient. No symptoms were seen in plants grown at an OP of ‐0.2 bars, although the calcium concentration in the emergent leaves was smaller when the Mg: Ca ratio of the nutrient exceeded 0.8: 1. The overall salt concentration, which reduced the water potential gradient through the root and prevented development of root pressure at night, was more important than the magnesium to calcium balance of the nutrient solution in causing a local calcium deficiency in emergent leaves of the strawberry plant.     

Resurrection of Soil Surveys: a case study of the acid sulphate soils of The Gambia.

Abstract. Statistical techniques are used to test and re-interpret archival data from soil surveys of the tidal floodplain of the River Gambia. Key soil attributes include salinity, ripeness and the acid sulphate hazard. Soil taxonomic units derived by cluster analysis of all the validated data do not correspond with the intuitively-defined soil series of the original surveys. However they do correspond with practical soil mapping units, and distinguish areas of quite different geotechnical behaviour, kinds and degrees of salinity and acid sulphate hazard.     

The adverse effects of soil salinization on the growth of Trifolium alexandrinum L. and associated microbial and biochemical properties in a soil from Iran

The aim of this study was to determine the effects of increasing concentrations of salt solutions (including 0.12, 2, 6, and 10 dS m⁻¹) on the growth of berseem clover (Trifolium alexandrinum L.) and related soil microbial activity, biomass and enzyme activities. Results showed that the dry weights of root and shoot decreased with an increase in the concentrations of salt solutions. Soil salinization depressed the microbiological activities including soil respiration and enzyme activities. Substrate-induced respiration was consistently lower in salinized soils, whereas microbial biomass C did not vary among salinity levels. Higher metabolic quotients (qCO₂) and unaffected microbial biomass C at high EC values may indicate that salinity is a stressful factor, inducing either a shift in the microbial community with less catabolic activity or reduced efficiency of substrate utilization. Acid phosphatase and alkaline phosphatase activities decreased with increasing soil salinity. We found significant, positive correlations between the activities of phosphatase enzymes and plant's root mass, suggesting that any decrease in the activities of the two enzymes could be attributed to the reduced root biomass under saline conditions.     

Effects of conventional and organic (manure) fertilization on soil,plant tissue nutrients and berry yields in vineyards. The use of the original native soil as a control

The effects of conventional and organic (manure) fertilization on soils of vineyards were examined in the area of Nemea in southern Greece. The soil properties of the adjacent natural environment (maquis), which served as a control (considering the land use changes as treatments), were also examined and compared with those of the vineyards. The null hypothesis was that there was no difference among them. The results rejected the null hypothesis. It was found that the maquis top soil had the highest C concentration than both types of vineyards and the organic vineyard had significantly higher C concentration than the conventional one. The organic soil N followed the same pattern. The vine leaves (blades) in the conventional vineyards had significantly higher concentrations of Ca, Mg, Mn, and Zn. The average values of Mg and Zn concentrations in leaves in the organic vineyards were below the suggested ranges for nutrient sufficiency in vines and for this reason a foliar application of Mg and Zn is recommended for the organic vineyards. The average berry yield was significantly higher in the conventional vineyards.