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Growth, development and nutrient status of micropropagated Rubus idaeus cv. Glen Prosen in response to inoculation with nine species of arbuscular mycorrhizal (AM) fungi from three different genera was investigated. The nine species of AM fungi included, Glomus clarum, G. etunicatum, G. intraradices, Gigaspora rosea, Gi. gigantea, Gi. margarita, Scutellospora calospora, S. heterogama and S. persica. Plant responses to AM fungi varied from growth enhancement to growth depression. Depressive growth effects were specific to Gigaspora species. Furthermore, particular species of AM fungi had unique effects on the mineral status of the raspberry plants. Importance of isolate selection for inoculation of micropropagated raspberry plants is discussed.

This study assessed the suitability of two deciduous woody perennials (Salix spp. and Populus spp.) and two summer green herbaceous perennials (Phragmites australis and Urtica dioica) for purification of nutrient enriched wastewater. The main hypothesis tested was that species with a particular trait combination of high relative growth rate (RGR), low nutrient productivity (A) and high mean residence time (MRT) of nutrients would be most effective in accumulating nutrients. The nitrogen and phosphorus use efficiency at the whole plant level was analysed. Four treatments comprising two possible phytoremediation substrates (municipal wastewater and landfill leachate) and two control plant nutrition situations (balanced nutrient solution and pure water) were applied in four replications to the four plant species. Generally, all four species studied showed a high RGR and a low P productivity in the balanced nutrient solution treatment, while the opposite (low RGR and high P productivity) was seen in the phytoremediation substrate and pure water treatments. The general conclusion is that if P is present in marginal proportions in the wastewater, a vegetation filter with Phragmites would have an advantage since biomass and nutrient accumulation in Phragmites does not decrease as much during phytoremediation as that in deciduous woody perennials.

Nitrogen levels at harvest in hybrid corn and weeds were determined over a three year period. Nitrogen losses due to grain removal accounted for 45% of all assimilated-N in the milpa. Percent N and percent P levels in the hybrid and a local black corn were also determined. Uptake of nitrogen and phosphorus in roots and leaves of both varieties were sigmoid until reproductive growth was initiated, at which time the percentage of both nutrients in the leaves declined rapidly. Levels in the seed at maturity in the hybrid variety accounted for 78% N and 52% P; levels were 58% N and 50% P in the local corn. Hybrid corn was not considered suitable for local farmers because a high percentage of total-N was removed at harvest and the hybrid had a high susceptibility to weevil attack.

The efficacy of CaO2 as an oxygen-supplying seed coating on the emergence of rice seedlings from flooded soils was studied. Seedling response became increasingly dependent on coating rates of 0–40% (by weight of seed loading with 60% CaO2 material) as the depth of planting increased from 0–2.5 cm. No emergence occurred from 5 cm. The emergence response to 40% CaO2 at 1.5 cm depth of planting was inhibited by the presence of 0.25% finely ground rice straw but was stimulated by increasing pH levels. The organic substrate likely increased microbial competition for available O2 while increasing pH levels improved the rate of CaO2 dissolution during the day 2–8 period of germination. Soil type effects on seedling response were speculated to be due to differences in O2 consumption rates between soils. The addition of CaO to the CaO2 coating improved the emergence response on an unlimed acid soil.

Typha angustifolia is a heavy metal tolerant plant that grows in a uranium mine tailings highly contaminated with iron. In this study three iron oxidizing microbes (FeOBs) isolated from Typha rhizoplane were investigated for their role in plant growth promotion (PGP). Their effect on iron nutrition in Typha under iron replete and excess condition was also evaluated. The PGP activities of the FeOBs were studied by measuring their influence on plant growth. To investigate the mechanism of growth promotion their ability to solubilize phosphate, and to produce Indole acetic acid and siderophores were studied. The influence of the FeOBs on root to shoot partitioning of iron was tested by measuring total iron content in roots and shoots treated with microbes. The FeOBs were named as Paenibacillus cookii JGR8, (MTCC12002), Pseudomonas jaduguda JGR2 (LMG25820) and Bacillus megaterium JGR9 (MTCC12001). The siderophore producers, influenced iron accumulation in the plant root. Additionally P. pseudoalcaligenes JGR2 increased shoot iron content overcoming the root- shoot barrier that allows Typha to exclude metals from its shoot. Among the PGP mechanisms tested, ability to solubilize phosphate appeared to be most significant for increasing the plant biomass. FeOBs that produce siderophore increased iron content in plant and therefore can be of immense biotechnological importance. However Biomass increase was directly correlated with increased phosphate acquisition and not with enhanced iron accumulation in Typha.

Models describing plant and ecosystem N cycles require an accurate assessment of root physiological uptake capacity for NH 4 + and NO 3 - under field conditions. Traditionally, rates of ion uptake in field-grown plants are determined by using excised root segments incubated for a short period in an assay solution containing N either as a radioactive or stable isotope tracer (e.g., 36ClO3 as a NH 4 + analogue, 14CH3NH3 as an NO 3 - analogue or 15NH 4 + and 15NO 3 - ). Although reliable, this method has several drawbacks. For example, in addition to radioactive safety issues, purchase and analysis of radioactive and stable isotopes is relatively expensive and can be a major limitation. More importantly, because excision effectively interrupts exchange of compounds between root and shoot (e.g., carbohydrate supply to root and N transport to shoot), the assay must be conducted quickly to avoid such complications. Here we present a novel field method for simultaneous measurements of NH 4 + and NO 3 - uptake kinetics in intact root systems. The application of this method is demonstrated using two tree species; red maple (Acer rubrum) and sugar maple (Acer saccharum) and two crop species soybean (Glycine max) and sorghum (Sorghum bicolor). Plants were grown in open-top chambers at either ambient or elevated levels of atmospheric CO2 at two separate US national sites involved in CO2 research. Absolute values of net uptake rates and the kinetic parameters determined by our method were found to be in agreement with the literature reports. Roots of the crop species exhibited a greater uptake capacity for both N forms relative to tree species. Elevated CO2 did not significantly affect kinetics of N uptake in species tested except in red maple where it increased root uptake capacity, V, for NH 4 + . The application, reliability, advantages and disadvantages of the method are discussed in detail.

The usefulness of a tensiometer-potometer system in investigations of water flow in the, vicinity of a plant root has been demonstrated. Measurements were made of the root-soil interface water potential, xylem potential and the distribution of water fluxes and root resistance along the length of a maize root. For a root growing in sand, the rhizosphere resistance was 3.5 to 8 times the radial resistance of the root at average rhizosphere, potentials of −250 m bars. For a root growing in sandy loam such rhizosphere resistance was not achieved until the average rhizosphere potential is approximately −2 bars.

An experiment was conducted in the greenhouse at Assiut University (Assiut, Egypt) to study the status of manganese in both the soil and rice plants under different water and fertilizer treatments. Rice seeds were sown in pots containing a clay loam soil submerged with water for a period of 45 days after which treatments were initiated. Water treatments consisted of five systems: continuous submergence, field capacity, saturation percentage, and alternative submergence for either 4 or 6 days followed by one day of drainage. Fertilizer treatments included the application of ammonium sulphate and/or manganese sulphate at three rates. Both the soil and rice plants were sampled at three intervals: 4,8, and 12 weeks after treatment initiation. Samples were properly prepared and analyzed for manganese. Statistical analysis of the obtained data was carried out for both the separate as well as the combined effects of all treatments. Results showed that the concentration of Mn in both the soil and the rice shoots was significantly increased as the period of water submergence was extended. Continuous submergence proved to be superior to all other water systems tested. Due to the slightly acidic nature of ammonium sulphate, its application resulted in increasing the concentration of Mn in the soil and subsequently in the shoots. Addition of manganese sulphate did not materially affect the level of Mn in the soil except after enough time was allowed (about 3 months). However, plant uptake of Mn was increased appreciably under such addition.

High deposition of gaseous/particulate fluorides and other air pollutants has resulted in an acidification and probable formation of soluble AlFx complexes in the soil in the vicinity of the industrial complex of Cubatão, SE Brazil. With the present field study we aimed at determining the contribution of F and Al uptake from fluoride-contaminated soil, supposedly as AlFx complexes, to the increase of foliar F and Al contents in saplings of an Al-accumulator tree species (Tibouchina pulchra) which were concomitantly exposed to fluoride-contaminated air and also the proportional contribution of both air and soil contamination to the mentioned foliar accumulation of these elements. The seasonal variations in F and Al accumulation and possible metabolic changes in the plants due to F and Al accumulation were also investigated. The saplings were exposed during three consecutive periods of 16 weeks to: (a) air and soil from a reference site (PVnoF); (b) air or soil from two polluted sites (CM-high air pollution, low F and MV-high air pollution, high F); and (c) both air and soil from these polluted sites. After exposure, the changes in the foliar concentrations of F and Al, the relations between both element contents and their relationships with oxidative stress indicators were determined. The data were grouped in three matrices: PVnoF–CMlwF and PVnoF–MVhgF, taking in account the possible air/soil exposure combinations in each, and soil/air from all sites. The slight F accumulation in plants of PVnoF–CMlwF matrix was a result of higher uptake from soil than from air (54 and 46%, respectively). At PVnoF–MVhgF matrix, the extremely high F accumulation in leaves of T. pulchra could be attributed to the combination of both air and soil contamination (83 and 17%, respectively). T. pulchra always showed higher foliar Al concentrations than 1000 μg g−1 dry mass, mainly after exposure to air and soil of both polluted sites (CMlwF and MVhgF). A highly significant linear regression was estimated between molar Al and F contents, taking in account the data obtained for saplings of T. pulchra cultivated in the different soils and exposed to ambient air of PVnoF, suggesting that both elements were taken as Al–F complexes from soil. The uptake of fluorides from air and/or soil of MVhgF caused significant metabolic changes in T. pulchra, but visible injury supposedly induced by fluorides were observed only when the foliar F contents surpassed 700 μg g−1 dry mass. On the contrary, Al did not cause any metabolic stress to the plants.