Intergeneric somatic hybridization in Gramineae: somatic hybrid plants between tall fescue (Festuca arundinacea Schreb.) and Italian ryegrass (Lolium multiflorum Lam.)

Summary Tall fescue (Festuca arundinacea Schreb.) protoplasts, inactivated by iodoacetamide, and non-morphogenic Italian ryegrass (Lolium multiflorum Lam.) protoplasts, both derived from suspension cultures, were electrofused and putative somatic hybrid plants were recovered. Two different genotypic fusion combinations were carried out and several green plants were regenerated in one of them. With respect to plant habitus, leaf and inflorescence morphology, the regenerants had phenotypes intermediate between those of the parents. Southern hybridization analysis using a rice ribosomal DNA probe revealed that the regenerants contained both tall fescue- and Italian ryegrass-specific-DNA fragments. A cloned Italian ryegrass-specific interspersed DNA probe hybridized to total genomic DNA from Italian ryegrass and from the green regenerated somatic hybrid plants but not to tall fescue. Chromosome counts and zymograms of leaf esterases suggested nuclear genome instability of the somatic hybrid plants analyzed. Four mitochondrial probes and one chloroplast DNA probe were used in Southern hybridization experiments to analyze the organellar composition of the somatic hybrids obtained. The somatic hybrid plants analyzed showed tall fescue, additive or novel mtDNA patterns when hybridized with different mitochondrial gene-specific probes, while corresponding analysis using a chloroplast gene-specific probe revealed in all cases the tall fescue hybridization profile. Independently regenerated F. arundinacea (+) L. multiflorum somatic hybrid plants were successfully transferred to soil and grown to maturity, representing the first flowering intergeneric somatic hybrids recovered in Gramineae.     

Temporal and spatial patterns of soil water following wildfire-induced changes in plant communities in the Great Basin in Nevada,USA

Infection of tall fescue (Festuca arundinacea Schreb.) with its endemicNeotyphodium coenophialum-endophyte (Morgan-Jones and Gams) Glenn, Bacon and Hanlin appears to reduce copper (Cu) concentrations in forage and serum of grazing animals, contributing to a range of immune-related disorders. A greenhouse experiment was conducted to identify effects of novel endophyte strains on Cu acquisition by tall fescue (Festuca arundinacea Schreb.) varieties Grasslands Flecha and Jesup infected with a novel, non ergot producing endophyte strain AR542, and two perennial ryegrass (Lolium perenne L.) varieties Aries and Quartet infected with a novel, non lolitrem B producing strain AR1, and their noninfected (E−) forms. Individual endophyte/grass associations were cultivated in nutrient solutions at 1.0 (P+) and 0.0 mM (P−) phosphorus concentrations. The Cu²⁺-binding activity of extracellular root exudates, and concentrations of Cu and other heavy metals in roots and shoots were measured. Extracellular root exudates of AR542-infected vs. E− tall fescue had higher Cu²⁺-binding activity only in P− nutrient solution as shown by lower concentration of free Cu²⁺ (0.096 vs. 0.188 mmol Cu²⁺ g⁻¹ root DM, respectively). The Cu²⁺-binding activity by root exudates of perennial ryegrass was not affected by endophyte infection, but was higher (i.e., lower concentration of free Cu²⁺) in P− vs. P+ nutrient solution (0.068 vs. 0.114 mmol Cu²⁺ g⁻¹ root DM). In this hydroponic experiment, Cu concentrations in shoots of both grasses were not a function of Cu²⁺-binding activity and endophyte effects on heavy metal concentrations in shoots and roots were specific for each variety. The Cu²⁺-binding activity of extracellular root exudates may affect Cu accumulation by field-grown, endophyte-infected tall fescue under P-limiting growth conditions and warrants verification by more specific methods.     

A national survey of airborne pollen and grass flowering in New Zealand,with implications for respiratory disorder

Airborne pollen and spore levels were monitored at seven sites in New Zealand using the Intermittent Cycling Rotorod sampler during the summer of 1988/1989. Grasses formed the major component of atmospheric pollen levels during spring and summer at every locality. Peak levels of grass and total pollen occurred during December or late November, with a slight latitudinal lag apparent at the more southern sites. Highest levels were recorded at the smaller rural centres of Gore and Kaikohe and the lowest at the larger urban centres of Auckland, Christchurch and Wellington. We make a first approximation of the likely risk to hayfever and allergic asthma patients at each of the seven centres. For example, significantly higher grass pollen levels were experienced at Kaikohe on 44% and 65% of days during November and December, compared with just 15% and 8% at Auckland. By recording the flowering seasons of the principal allergenic grass species at each locality, we determined the potentially allergenic grasses contributing to peak pollen levels, the most ubiquitous being tall fescue (Festuca arundinacea Schreb.), ryegrass (Lolium perenne L.,L. multiflorum Lam.), cocksfoot (Dactylis glomerata L.), Yorkshire fog (Holcus lanatus L.) and sweet vernal (Anthoxanthum odoratum L.). Corresponding author. Deceased.     

Influence of dissimilarities in temporal and spatial N-uptake patterns on15N-based estimates of fixation and transfer of N in ryegrass-clover mixtures

The temporal N-uptake patterns of white clover (Trifolium repens L.) mixed with perennial ryegrass (Lolium perenne L.) and of red clover (Trifolium pratense L.) mixed with Italian ryegrass (Lolium multiflorum Lam.) were determined in successive harvests of herbage within the growth cycles of a ley established near Zürich (Switzerland). Rooting patterns were examined by injecting¹⁵N-fertilizer at soil depths ranging from 10 to 40 cm. The results were analyzed to determine the effect of variations in time and depth of N-uptake on the¹⁵N-based measurement of N from symbiosis (N_sym) and N from transfer (N_trans).Grasses in mixture appeared to have deeper rooting systems than grass monocultures, which led to an overestimation of N transfer from white clover to perennial ryegrass if¹⁵N was spread on the soil surface.White clover generally lagged behind grass in soil N- uptake. Soil N-uptake of red clover slowed down before that of the grass because % N_sym almost reached 100% during the second half of each growth cycle. However, the effect of these dissimilarities on the seasonal average of %N_sym did not exceed 2%.It is concluded that at the observed high levels of N₂ fixation, failure to account for the N-uptake patterns of the test and reference crops only slightly affected the estimates of % N_sym and % N_trans, and did not invalidate the observed differences between species.     

Assay of nitrogen supplying capacity of tropical rice soils

Summary The nitrogen supplying capacity of 39 wetland rice soils evaluated by two anaerobic incubation methods and six chemical methods was compared with N uptake of IR 26 rice grown on these soils under flooded conditions in a greenhouse pot study. The uptake of N by rice correlated highly with the N supplying capacity determined by anaerobic incubation methods involving incubation of soils at 30°C for 2 weeks (r=0.84^**) or at 40°C for 1 week (r=0.82^**) as well as with the organic carbon (r=0.82^**) and total N (r=0.84^**) contents of soils. Among the chemical indexes, available N determined by the oxidative release of soil N by alkaline permanganate, acid permanganate, acid dichromate and hydrogen peroxide also provided good index of soil N availability to rice. According to these results soil organic carbon and total N contents seem to be good indexes of available nitrogen in tropical wetland rice soils.     

Changes in Dry Matter, Carbohydrate and Seed Yield Resulting from Lodging in Three Temperate Grass Species

The adverse effect of lodging on grass seed yield may be attributed,in part, to assimilate limitation during the seed filling period.This investigation examined plant dry matter assimilate partitioningand seed yield as affected by lodging in three species thatare closely related but phenotypically different: tall fescue(Festuca arundinacea Schreber.), Italian ryegrass (Lolium multiflorumLam.), and perennial ryegrass (L. perenne L.). Studies wereperformed in field plots at Corvallis, Oregon, USA. Seed yieldcomponents (seed number per inflorescence, seed yield per inflorescence,and single seed mass) and leaf, stem (lower, middle, and peduncle)and seed inflorescence dry mass were measured just prior toanthesis to seed maturity. Dry mass and water soluble carbohydrates(WSC) were determined for shoot components. The reduction indry mass and WSC in leaves and stem components following anthesiswas often greater in lodged plants compared to upright plants.The relatively low seed yield depression in lodged tall fescuesuggested a higher compensation potential for partitioning reserveassimilate from leaves and stems to support seed growth anddevelopment. This potential does not appear to be present tothe same degree in Italian ryegrass and to an even lesser extentin perennial ryegrass. These findings suggest that the potentialto compensate for reduced assimilate supply during the periodof high assimilate demand by seeds may be attributed, in part,to the total assimilate reserve accumulated prior to photoassimilatereduction caused by the lodged condition. Copyright 2000 Annalsof Botany Company Tall fescue, Festuca arundinacea Schreber., Italian ryegrass, Lolium multiflorum Lam., perennial ryegrass, L. perenne L., assimilate partitioning, source–sink     

Symbiotically fixed nitrogen from field- grown white and red clover mixed with ryegrasses at low levels of15N-fertilization

A field study was carried out near Zürich (Switzerland) to determine the yield of symbiotically fixed nitrogen (¹⁵N dilution) from white clover (Trifolium repens L.) grown with perennial ryegrass (Lolium perenne L) and from red clover (Trifolium pratense L.) grown with Italian ryegrass (Lolium multiflorum Lam.). A zero N fertilizer treatment was compared to a 30 kg N/ha per cut regime (90 to 150 kg ha⁻¹ annually). The annual yield of clover N derived from symbiosis averaged 131 kg ha⁻¹ (49 to 227 kg) without N fertilization and 83 kg ha⁻¹ (21 to 173 kg) with 30 kg of fertilizer N ha⁻¹ per cut in the seeding year. Values for the first production year were 308 kg ha⁻¹ (268 to 373 kg) without N fertilization and 232 kg ha⁻¹ (165 to 305 kg) with 30 kg fertilizer N ha⁻¹ per cut. The variation between years was associated mainly with the proportion of clover in the mixtures. Apparent clover-to-grass transfer of fixed N contributed up to 52 kg N ha⁻¹ per year (17 kg N ha⁻¹ on average) to the N yield of the mixtures. Percentage N derived from symbiosis averaged 75% for white and 86% for red clover. These percentages were affected only slightly by supplemental nitrogen, but declined markedly during late summer for white clover. It is concluded that the annual yield of symbiotically fixed N from clover/grass mixtures can be very high, provided that the proportion of clover in the mixtures exceeds 50% of total dry mass yield.     

Molecular and cytogenetic characterization of repetitive DNA sequences from Lolium and Festuca: applications in the analysis of Festulolium hybrids

Summary A set of species-specific repetitive DNA sequences was isolated from Lolium multiflorum and Festuca arundinacea. The degree of their species specificity as well as possible homologies among them were determined by dot-blot hybridization analysis. In order to understand the genomic organization of representative Lolium and Festuca-specific repetitive DNA sequences, we performed Southern blot hybridization and in situ hybridization to metaphase chromosomes.Southern blot hybridization analysis of eight different repetitive DNA sequences of L. multiflorum and one of F. arundinacea indicated either tandem and clustered arrangements of partially dispersed localization in their respective genomes. Some of these sequences, e.g. LMB3, showed a similar genomic organization in F. arundinacea and F. pratensis, but a slightly different organization and degree of redundancy in L. multiflorum. Clones sequences varied in size between 100 bp and 1.2 kb. Estimated copy number in the corresponding haploid genomes varied between 300 and 2×10⁴. Sequence analysis of the highly species-specific sequences from plasmids pLMH2 and pLMB4 (L. multiflorum specific) and from pFAH1 (F. arundinacea specific) revealed some internal repeats without higher order. No homologies between the sequences or to other repetitive sequences were observed. In situ hybridization with these latter sequences to metaphase chromosomes from L. multiflorum, F. arundinacea and from symmetric sexual Festulolium hybrid revealed their relatively even distribution in the corresponding genomes. The in situ hybridization thus also allowed a clearcut simple identification of parental chromosomes in the Festulolium hybrid.The potential use of these species-specific clones as hybridization probes in quantitative dot-blot analysis of the genomic make-up of Festulolium (sexual and somatic) hybrids is also demonstrated.Abbreviations bp Base pair (s) - CMA chromomycin A₃ - DAPI 4,6-diamidino-2-phenylindole - IPTG isopropyl -D-thio-galactopyranoside - kb kilobase pair(s) - NBT nitroblue tetrazolium chloride - X-gal 5-bromo-4-chloro-3-inonyl -D-galactopyranoside     

Nitrogen transfer from arrowleaf clover to ryegrass in field plantings

Arrowleaf clover (Trifolium vesiculosum Savi) and annual ryegrass Lolium multiflorum Lam.) commonly are overseeded in dormant bermudagrass (Cynodon dactylon L. Pers.) sod on coastal plain soils in the southeastern United States. Two field experiments were conducted in consecutive years at different sites to estimate the amount of N transferred from the clover to the annual grass. Nitrogen treatments included 50 kg N ha^-1 as ¹⁵N depleted ammonium nitrate applied in either February or April, and a check (no N applied). Three clippings were made during the cool-season from March to June. In both experiments, less than 5 kg N ha^-1 were transferred from the clover to the grass. Ryegrass yields of dry matter and total N were not increased by growing with clover. Clover growth was typical for the region; average dry matter yield in pure stand was 2,615 kg ha^-1 over the two-year period. Clover in mixed stand fixed between 20 and 60 kg N/ha. Less than 13% of N contained in ryegrass was transferred from arrowleaf clover to ryegrass at any clipping while clover was actively growing. The quantity of N transferred over the entire season was not statistically significant.     

Phylogeny of tall fescue and related species using RFLPs

The wild species of tall fescue (Festuca arundinacea var.genuina Schreb.) represent a wide range of genetic variation and constitute potential germplasm for tall fescue improvement. Our objective was to evaluate genome specificity of the previously-identified DNA probes and to examine the phylogenetic relationship of tall fescue with six related species by using RFLP data. A total of 29 DNA probes from aPstI-genomic library of tall fescue were hybridized toEcoRI-orHindIII-digested DNA of 32 plants from sixFestuca species and fromLolium perenne L. Fifteen probes hybridized to all seven species. The remaining 14 probes showed differential hybridization patterns (i.e., ±), especially at the diploid and tetraploid levels. This hybridization pattern reflected genome divergence in these species. The DNA probes will be useful markers in breeding programs involving interspecific and intergeneric hybridization. Cluster analyses were performed using the average genetic distances calculated with the RFLP data from 53 probe-enzyme combinations. Generally, genotypes from the same species were grouped in the same cluster. These data indicated that tall fescue has a close relationship withF. pratensis Huds. (diploid),F. arundinacea var.glaucescens Boiss. (tetraploid), andL. perenne L. (diploid) and thatFestuca pratensis andL. perenne had the closest degree of relationship.This paper is a contribution of the Missouri Agricultural Experimental Station, Journal Series no. 11,798     

Effect of Ploidy on Quality of Tall Fescue, Italian Ryegrass x Tall Fescue and Tall Fescue x Giant Fescue Hybrids

Selected quality parameters were measured for forage leaf tissuefrom a spaced-plant nursery. The genotypes used were Ky 31 tallfescue and hybrids of Italian ryegrass (Lolium multiflorum Lam.)x tall fescue (Festuca arundinacea Schreb.) and tall fescuex giant fescue [Fescue gigantea (L ) Vill.]. Hybrid ploidy rangedfrom 2n = 28 to 84 chromosomes. Forage quality was characterizedby neutral detergent fibre (NDF), acid detergent fibre (ADF),total soluble carbohydrates (TSC) nutritive value index (NVI),hemicellulose, and in vitro dry matter disappearance (DMD). Quality of tall fescue, as measured by increased DMD, was improvedby hybridization with giant fescue. Improved DMD and NVI correlatedwith lower NDF and ADF in the hybrids. A few hybrids of Italianryegrass x tall fescue (2n = 28) were higher in some qualityparameters than Ky 31. Tall fescue x giant fescue hybrids (2n= 80 to 84), as a group, had significant quality improvementover Ky 31 in higher DMD and NVI and lower NDF and ADF. Whilesome individual hybrids within each group were significantlyhigher in quality, only the 2n = 80 to 84 chromosome group wasconsistently higher than Ky 31. Prediction equations for DMD,NDF, and ADF were established based on solvent extraction withnear-infrared reflectance spectroscopy (NIRS). Linear correlationcoefficients between chemical measurement and NIRS for eachquality parameter were 0–95 or higher. Acid detergent fibre, neutral detergent fibre, dry matter disappearance, hemicellulose, nutritive value index, Festuca arundinacea, Festuca gigantea, Lolium multiflorum     

The Effects of Nitrogen Fertilization and the Growing Season on Carbon Partitioning in a Sward of Tall Fescue (Festuca arundinacea Schreb)

The effect of N fertilization on the relative carbon partitioningto the roots of tall fescue (Festuca arundinacea Schreb ), grownunder field conditions, was studied with a ¹⁴C-labelling techniqueon three regrowths representing contrasting growing seasonsUnder non-limiting N growing conditions, the relative carbonpartitioning to the roots averaged 17.0, 15 8, and 11 1% inthe summer, autumn, and spring regrowths, respectively The relativecarbon partitioning to the roots increased during the summerand autumn regrowths but decreased during the spring regrowthIn the absence of N fertilization, the relative carbon partitioningto the roots averaged 31 3, 26 5, and 26 7 in the summer, autumn,and spring regrowths, respectively The results were interpretedin terms of a functional equilibrium between the shoots andthe roots It was concluded that, for a dense canopy of a perennialgrass growing under fluctuating conditions of solar radiationand temperature, the relative growth of the roots compared tothe relative growth of the total biomass is primarily a functionof the shoot biomass Festuca arundinacea Schreb, carbon, partitioning, nitrogen, root growth, fertilization, grass     

The role of the photosynthetic apparatus in cold acclimation of <Emphasis Type="Italic">Lolium multiflorum</Emphasis>. Characteristics of novel genotypes low-sensitive to PSII over-reduction

During cold acclimation by higher plants, temperature perception via changes in redox state of Photosystem II (PSII) and subsequent acclimation of the photosynthetic apparatus to cold is very important for achieving freezing tolerance. These properties were studied in two groups (A and B) of the same backcross 3 (BC₃) progeny derived from a triploid hybrid of Festuca pratensis (2×) × Lolium multiflorum (4×) backcrossed three times onto diploid L. multiflorum cultivars. Leaves of Group A plants formed at 20°C at medium-low light were unable to acclimate their photosynthetic apparatus to cold. Compared to Group B, the Group A plants were also more frost sensitive. This acclimation ability correlated with the freezing tolerance of the plants. However, leaves of the same Group A plants developed at 20°C, but under higher-light conditions had increased ability to acclimate their photosynthetic apparatus to cold. It was concluded that Group A plants may have impaired PSII temperature perception, and this then resulted in their poor capability to cold acclimate.     

Flowers for <Emphasis Type="Italic">Neotyphodium</Emphasis> endophytes detection: a new observation method using flowers of host grasses

Neotyphodium endophytes are vertically transmitted fungal symbionts of grasses. Being pest-repelling and growth-promoting agents for their hosts, and also potential mycotoxin producers, their detection in plants is important. Observation of chemically cleared flowers of infected grasses (Festuca arundinacea, F. pratensis, Lolium perenne, and L. multiflorum) using differential interference contrast microscopy revealed the existence of endophytes within immature ovaries of host plants. This observation method provides an accurate and easy way to detect and distinguish Neotyphodium endophytes in flowering host grasses and to investigate the seed transmission process, which is critical to their life cycle, and the practical use of infected plants.     

Invasive Grass Alters Litter Decomposition by Influencing Macrodetritivores

The results of nitrogen (N) fertilization experiments have shown inconsistent rates of plant litter decomposition, a phenomenon that may be explained by dispropotionate influence of animal detritivores (macro-detritivores) on litter mass loss versus that of microbial decomposers, whose activity may be dependent on inorganic N. In turn, macrodetritivores may be influenced by plant species composition via their selection of optimal food resources and habitats. In our experiment, fertilizer had no apparent effect on litter decomposition, suggesting that microbial decomposers did not use the additional inorganic N and/or that macrodetritivores had a greater influence on decomposition. Manipulation of macrodetritivores suggested that plant species composition—dominated in this study by Festuca arundinacea, an exotic, invasive grass, and Aster ericoides, a native forb—caused shifts in detrivore communities and/or feeding patterns that tended to increase litter mass loss. Canopy cover of F. arundinacea and A. ericoides ranged from 0% to 11%, suggesting that low-intensity invasion may produce significant changes in ecosystem function, such as decomposition.     

Effect of Cutting on Production and Tillering in Prairie Grass (Bromus willdenowii Kunth) Compared With Two Ryegrass (Lolium) species. 2. Reproductive Plants

Effects of time of initial cut and subsequent cutting interval(1, 2 or 4 weeks) were examined in a glasshouse during summer1988 for reproductive plants of three prairie grass cultivars(Bromus willdenowii Kunth), Westerwolds ryegrass (Lolium multiflorumLam.) and perennial ryegrass (Lolium perenne L.). Measurementswere made of tiller and leaf numbers, sites of tillering, reproductivedevelopment, and herbage quality and yields. Effect of timeof initial cutting on regrowth appeared to be independent ofstage of reproductive development and unrelated to any of themeasured plant parameters. Characteristics for each cultivaras identified during undisturbed growth prior to the initialcuts, were modified by the subsequent cutting frequencies. Perennial ryegrass had the highest yields under frequent cuttingwith high herbage quality. Westenwolds ryegrass and the prairiegrass cultivars ‘Grasslands Matua’ and ‘Primabel’had the highest yields with infrequent cutting, but lower herbagequality than in perennial ryegrass. At each cut, tiller deathin prairie grass was determined by the number of reproductivetillers, and in the ryegrasses also by the numbers of elongatedvegetative tillers. Recovery of tiller numbers was rapid andprimarily from inhibited tiller buds at the base of reproductivetillers. In prairie grass, tiller numbers were relatively unaffectedby cutting frequency, but at frequent cutting, many axillarytillers originated from vegetative tillers rather than frominhibited tiller buds at the base of reproductive tillers. Prairie grass, Bromus willdenowii Kunth, Westerwolds ryegrass, Lolium multiflorum Lam., perennial ryegrass, Lolium perenne L., first (initial) cut, cutting frequency, regrowth, leaf appearance, tillering, yield, nitrogen, water-soluble carbohydrates, herbage quality     

Effect of Cutting on Production and Tillering in Prairie Grass (Bromus willdenowii Kunth) Compared With Two Ryegrass (Loliunt) Species. 1. Vegetative Plants

Effects of cutting to 3 or 6 cm stubble height at frequenciesof 1, 2 or 4 weeks were investigated in young, vegetative, spacedplants of prairie grass (Bromus willdenowii Kunth), a tetraploidWesterwolds ryegrass (Lolium multiflorum Lam.) and perennialryegrass (Lolium perenne L.). Plants were grown for 8 weekson nutrient solution in a growth cabinet at day/night temperaturesof 15/10°C and in a short photoperiod. Leaf appearance,site filling and tiller numbers were all reduced by both increasedcutting frequency and a lower cutting height. The extent ofthese reductions was least in prairie grass and greatest inWesterwolds ryegrass. Relative growth rates in all species respondedin a similar manner with more frequent cutting and a lower cuttingheight. Cutting frequency had the greatest effect on growthrates, although the effect of cutting height increased withtime. Results confirm general recommendations of long intervalsbetween defoliations to achieve high yields for vegetative prairiegrass, but the relative amounts of dry matter harvested underthe different cutting regimes may be no different to that obtainedin ryegrass. Stubble height was of lesser importance in determiningyields. A typical U-shaped curve for depletion and recovery in water-solublecarbohydrates occurred after defoliation in all species, butlevels remained low at frequent cutting. Water-soluble carbohydratelevels in stubble and roots were higher in prairie grass. Regrowthat the end of the experiment was highly correlated with totalstubble and root weights (r = 0.84), while regrowth per tillershowed a good correlation with water-soluble carbohydrate content,although the response varied between species. Prairie grass, Bromus willdenowii Kunth, perennial ryegrass, Lolium perenne L., Westerwolds ryegrass, Lolium multiflorum Lam., cutting frequency, cutting height, leaf appearance, tillering, site filling, yield, regrowth, nitrogen, water-soluble carbohydrates     

Improvement of degraded physical properties of a saline-sodic soil by reclamation with kallar grass (Leptochloa fusca)

A field experiment was conducted to evaluate the effectiveness of growing salt tolerant plants to improve the physical characteristics of a saline-sodic soil. Kallar grass [Leptochloa fusca (L.) Kunth], a species tolerant to salinity, sodicity and alkalinity, was irrigated for five years with poor quality ground water (EC = 0.14 S m^–1, SAR_adj=19.3, RSC = 9.7 meq L^–1). The soil physical properties of plant available water, saturated hydraulic conductivity, structural stability, bulk density and porosity were determined at the end of each year. The growth of kallar grass for three years significantly improved the physical properties of the soil and these were maintained with further growth of grass up to five years. Kallar grass significantly increased plant available water with time (r=0.97^**). The available water was highly correlated (r=0.92^**) with increases in soil organic matter content, porosity (r=0.99^**) and other physical properties. Soil hydraulic conductivity increased substantially with time from 0.035 to 55.6 mm d^–1 in the topsoil (0–20 cm) in five years and was significantly correlated with porosity, water retention, structural stability and organic matter content of soil. The soil structural stability index improved significantly from 32 to 151 with kallar grass and showed greater increases in the surface soil than at depth. The cropping of kallar grass resulted in a linear increase of soil organic matter content (r=0.92^**) which improved porosity and other soil physical properties (r0.82^*). This study confirmed that kallar grass is effective for rehabilitation and restoration of soil fertility in saline-sodic areas on a sustainable basis.     

Efficacy of Biosolids in Assisted Phytostabilization of Metalliferous Acidic Sandy Soils with Five Grass Species

The role of sewage sludge as an immobilising agent in the phytostabilization of metal-contaminated soil was evaluated using five grass species viz., Dactylis glomerata L., Festuca arundinacea Schreb., F. rubra L., Lolium perenne L., L. westerwoldicum L. The function of metal immobilization was investigated by monitoring pH, Eh and Cd, Pb, and Zn levels in column experiment over a period of 5-months. Grasses grown on sewage sludge-amendments produced high biomass in comparison to controls. A significant reduction in metal uptake by plants was also observed as a result of sewage sludge application, which was attributed to decreased bioavailability through soil stabilisation. We have observed that the sludge amendment decreased metal bioavailability and concentrations in soil at a depth of 25 cm, in contrast to untreated columns, where metal concentrations in the soil solution were very high.     

Winter grass cover crop effects on nematodes and yields of double cropped soybean

Rye (Secale cereale L.), wheat (Triticum aestivum L.), and annual ryegrass (Lolium multiflorum Lam.) are commonly double cropped with soybean (Glycine max L.). Recent greenhouse studies have shown variability in plant-parasitic nematode response to cool season grass species and cultivars. However, subsequent soybean performance was not affected by previous annual ryegrass cultivar in the green-house. The objective of this research was to determine whether winter cover crop species or cultivars affected nematode populations and subsequent performance of soybean in teh field. Four cultivars of annual ryegrass, wheat, and rye, and a fallow control were seeded on a Suffolk sandy loam (fine-loamy, siliceous, thermic Typic Hapuldult) soil in each of three years. Nematode-susceptible soybeans were seeded following forage removal. Soil samples for nematode counts were taken immediately before soybean harvest each year. In another experiment, one cultivar each of annual ryegrass, wheat, and rye, and a fallow control were followed by three soybean cultivars selected for differing nematode susceptibility. Grass cultivars did not affect nematode populations under succedding soybean. The only nematodes affected by grass species in either experiment were Pratylenchus spp., Heterodera glycines Ichinohe, and Tylenchorhynchus claytoni (Kofoid and White) Chitwood. Nematode population means were usually low following ryegrass and high following the fallow control. High soybean yields followed the fallow control, and low soybean yields followed annual ryegrass.