Hybridum Hausskn Research Articles

Impact of Various Grass Species on Soil Bacteriobiome

Today, various grass species are important not only in animal feeding but, increasingly often, also in energetics and, due to esthetic and cultural values, in landscape architecture. Therefore, it is essential to establish the roles various grass species and their functional forms play in modifying soil bacteriobiome and enzymatic activity. To this end, a pot experiment was conducted to examine effects of various fodder grass and lawn grass species on the bacteriobiome and biochemical properties of soil. Nonsown soil served as the control for data interpretation. Analyses were carried out with standard and metagenomic methods. The intensity of effects elicited by grasses depended on both their species and functional form. More favorable living conditions promoting the development of soil bacteria and, thereby, enzymatic activity were offered by fodder than by lawn grass species. Among the fodder grasses, the greatest bacteriobiome diversity was caused by sowing the soil with Phleum pratense (Pp), whereas among lawn grasses in the soil sown with Poa pratensis (Pr). Among the fodder grasses, the highest enzymatic activity was determined in the soil sown with Lolium x hybridum Hausskn (Lh), and among the lawn grasses—in the soil sown with Lolium perenne. Sowing the soil with grasses caused the succession of a population of bacterial communities from r strategy to k strategy.

The resistance of Lolium perenne L. × hybridum, Poa pratensis, Festuca rubra, F. arundinacea, Phleum pratense and Dactylis glomerata to soil pollution by diesel oil and petroleum

Resistance of common European grasses to diesel oil and petroleum pollution is not well-known. Therefore, this study aimed at determining the level of resistance of selected grasses to pollution by diesel and petroleum using the pot experiment. The achieved results were compared with those determined for grasses grown on the non-polluted soil. Soil pollution with the tested products was found to significantly decrease the yield of all grasses, with the decrease being lower upon soil pollution with petroleum than with diesel oil. The most resistant to the pollution with diesel oil and petroleum were Phleum pratense L., Lolium perenne L. and Lolium × hybridum Hausskn. The degradation of particular groups of polycyclic aromatic hydrocarbons (PAHs) depended on their chemical properties, on the type of pollutant and grass species. The greatest degradation was determined in the case of BTEX, C<sub>6</sub>–C<sub>12</sub> benzines as well as 2- and 3-ring hydrocarbons, whereas the lowest in the case of 5-and 6-ring hydrocarbons and C<sub>12</sub>–C<sub>25</sub> oils. The most useful species in the remediation of soils polluted with diesel oil and petroleum turned out to be: Lolium perenne L., Lolium × hybridum Hausskn and Phleum pratense L., whereas the least useful appeared to be: Festuca rubra, Dactylis glomerata L. and Poa pratensis L.

Dietary preference of European wild boar (Sus scrofa L.) grazing grass and legume at two contrasting plant heights: A pilot study

There were two objectives: checking a methodology to test diet preferences in a natural environment and secondly to assess diet preferences of European wild boar in terms of species and plant characteristics when offered in a situation with minimal physical constraints. Five hundred pots (100mm upper diameter, 450 cc volume) were completely filled with soil. Half of the pots were sown with red clover (Trifolium pretense) and half with hybrid ryegrass (Lolium hybridum Hausskn). All pots were irrigated, periodically cut, and maintained outdoors. Then 220 leaves of ryegrass, 201 leaflets of clover and 188 petioles of clover were used to establish a relationship between plant structure dimensions and their dry matter mass. The preference study was conducted in a fenced area (18m length and 11,1m width) with a pasture cut to a height of 3cm (lowest height possible to cover the soil). Four transects were marked separated 2m from each other, and 16 holes within each transect were made 1m apart, in which the pots were buried and anchored. Treatments consisted of the factorial combination of two plant species (red clover and hybrid ryegrass) and two plant heights (12 and 18cm, tall and short, respectively), randomized within each transect (block). During three days, four nose-ringed wild boars grazed the experimental area for one hour and the treatments which they were grazing were recorded every two minutes. Plants structures were measured pre-and post-grazing from marked plants (green thread tied at the base) in each pot to detect consumption and to estimate the amount consumed. Strong correlations were found between plant structures and their dry mass (R2 between 0,83 and 0,89). The methodology was able to show that more dry matter was apparently consumed from clover than ryegrass (P<0.001) and clover had a greater probability of being grazed than ryegrass (P<0.05). Also, the tall plants were consumed more than the short plants (P<0.001) with individual tall plants having a higher probability of being grazed (P<0.05). It is concluded that the novel method proposed was able to detect the diet preferences of wild boar during grazing. Additionally, in this study European wild boar discriminated between plant species and between plant heights, preferring legume over ryegrass and taller over shorter plants. However, more studies with a greater number of animals are necessary to validate these results.

USAGE OF PLANTS FOR FAT-POLLUTED SOIL TREATMENT / RIEBALAIS UŽERŠTO GRUNTO VALYMAS NAUDOJANT AUGALUS / ОЧИСТКА ЗАГРЯЗНЕННЫХ ЖИРАМИ ГРУНТОВ С ИСПОЛЬЗОВАНИЕМ РАСТЕНИЙ

Following the complex technology for greasy waste utilization, which is under development, two stages of fat degradation – biodegradation and phytoremediation – were applied for treatment of fat-polluted soil. Biodegradation was used in the first stage, and phytoremediation was applied for degradation of residual fat and final restoration of soil structure. The latter technology was used to evaluate the ability of three following species of herbaceous plants to degrade fat in soil: red clover (Trifolium pratense L.), meadow fescue (Festuca pratensis Huds.), and hybrid ryegrass (Lolium hybridum Hausskn.). The evaluation after the stages of phytoremediation showed that hybrid ryegrass was the most effective in fat degradation in soils with high initial fat concentrations (100 g/kg and 55.1 g/kg), i.e. 53% and 67% respectively. With lower initial fat contents in soil (up to 12.7 g/kg), the best ability in fat degradation was determined in hybrid ryegrass and red clover, i.e. 76%. Application of stages of biodegradation and phytoremediation for treatment of soil polluted with greasy contaminants helped to reduce fat contents by 99% with the initial fat concentration of 138.9 g/kg, and 90% with 222.2 g/kg. Santrauka Gruntui, užterštam riebalinėmis atliekomis, valyti pagal kuriamą kompleksinę riebalinių atliekų utilizavimo technologiją numatyti du riebalų skaidymo etapai – biologinis skaidymas ir fitoremediacija. Pirmuoju etapu taikyta biodegradacija, o likusiems riebalams skaidyti ir grunto struktūrai galutinai atkurti – fitoremediacija, kurios metu įvertinta trijų pasirinktų žolinės augalijos rūšių – raudonųjų dobilų (Trifolium pratense L.), tikrųjų eraičinų (Festuca pratensis Huds.) ir hibridinių svidrių (Lolium hybridum Hausskn.) geba skaidyti riebalus grunte. Po fitoremediacijos etapo nustatyta, kad, esant didelėms pradinėms riebalų koncentracijoms grunte (100 g/kg ir 55,1 g/kg), efektyviausiai riebalus skaidė hibridinės svidrės – atitinkamai 53% ir 67%. Esant mažesnėms riebalų koncentracijoms grunte (iki 12,7 g/kg), geriausiai riebalus skaidė hibridinės svidrės ir raudonieji dobilai – 76%. Riebalais užterštam gruntui valyti etapais taikant biodegradaciją ir fitoremediaciją, riebalų kiekis grunte sumažėjo 99%, kai pradinė riebalų koncentracija buvo 138,9 g/kg, o kai riebalų koncentracijai 222,2 g/kg – 90%. Резюме Согласно создаваемой комплексной технологии утилизации жировых отходов с целью очистки грунта, загрязненного жирами, были применены два этапа для расщепления жиров – биодеградация и фиторемедиация. На первомэтапе была применена биодеградация, а для расщепления оставшихся жиров и окончательного восстановленияструктуры грунта – фиторемедиация, во время которой оценивалась способность трех травянистых видов – клевера лугового (Trifolium pratense L.), овсяницы луговой (Festuca pratensis Huds.) и плевела гибридного (Lolium hybridum Hausskn.) – расщеплять жиры в грунте. После этапа фиторемедиации было установлено, что при высокихзаданных начальных концентрациях жиров в грунте (100 и 55,1 г/кг) наиболее эффективно расщеплял жиры плевел гибридный – 53% и 67% соответственно. При более низких начальных концентрациях жиров (до 12,7 г/кг грунта) наиболее высокий процент расщепленных жиров достигался при применении плевела гибридного и клевера лугового – 76%. После применения этапов биодеградации и фиторемедиации для очистки грунта, загрязненного жирами, количество жиров в грунте снизилось на 99% при их начальной концентрации 138,9 г/кг и на 90%при их концентрации 222,2 г/кг грунта.

Salinity Tolerance of Ryegrass Turf Cultivars

Relative salinity tolerance of 32 perennial (Lolium perenne L.) and three intermediate (Lolium ×hybridum Hausskn.) ryegrass turf cultivars was determined by measuring turf leaf clipping dry weight, root weight, rooting depth, and percent green leaf canopy area relative to control (non-salinized) plants. After gradual acclimation, grasses were exposed to moderate salinity stress (6 dS·m−1) for 6 weeks through solution culture in a controlled environment greenhouse. Shoot parameters were highly correlated, being mutually effective predictors of salinity tolerance. After 6 weeks of salinity stress, percent green leaf canopy area (GL) was correlated with relative (to control) final week leaf clipping weight (LWREL) (r = 0.90) and with linear slope of decline of weekly leaf clipping weight over the 6-week exposure to salinity (LWSLOPE) (r = 0.66). Rooting parameters root dry weight (RW) and rooting depth (RD), although significantly correlated with all shoot parameters, were only moderately effective in predicting relative salinity tolerance. ‘Paragon’ was the most salt-tolerant as indicated by all parameters. Other salt-tolerant cultivars included Divine and Williamsburg. Intermediate ryegrass cultivars (Froghair, Midway, and Transist) were invariably found within the most salt-sensitive category for all parameters.

Carbon Isotope Discrimination in Orchardgrass and Ryegrasses at Four Irrigation Levels

Availability of irrigation water is often the limiting factor in the establishment of improved pastures in the U.S. Intermountain Region, and grasses used for pasture should have enhanced water-use efficiency (WUE). Objectives of this study were to describe (i) relationships between carbon isotope discrimination (Δ) and dry matter (DM) yield, and (ii) trends in Δ across four water levels (WL 2, wettest, to WL 5, driest) and two harvest dates under frequent defoliation in cultivars of orchardgrass (Dactylis glomerata L.) perennial ryegrass, (Lolium perenne L.), intermediate ryegrass (L. ×hybridum Hausskn), and festulolium [×festulolium braunii (K. Richt.) A. Camus.]. Within all WLs, orchardgrass cultivars exhibited higher WUE than the ryegrasses, which includes intermediate ryegrass and festulolium. Significantly more variation for Δ within WLs was observed in the ryegrasses than orchardgrass. For orchardgrass, DM yield and Δ were not correlated at WLs 2 to 4. However, they were negatively correlated at WL 5. Correlations between Δ and DM yield were not significant at WLs 2 and 3 for the ryegrasses, but were positive at WLs 4 and 5. To avoid possible declines in DM yield in breeding programs to increase WUE in orchardgrass and the ryegrasses, DM yield should also be monitored.

Carbon residence times obtained from labelled ryegrass decomposition in soils under contrasting environmental conditions

The rate of decomposition of ryegrass in New Zealand soils was studied. Six soils from contrasting New Zealand environments were amended with 14C-labelled ryegrass ( Lolium hybridum Hausskn), which was allowed to decompose in micro-lysimeters under field conditions for 2 yr. Periodically, the micro-lysimeters were destructively sampled, and the amount of 14C remaining in the soil and the fraction of 14C incorporated into microbial biomass measured. After 2 yr of exposure, 18 to 32% of the labelled 14C was retained by the soils. Decomposition was initially rapid, with almost one-half of the labelled 14C being lost after 2 months. Thereafter, the rate of decomposition was much reduced. During the initial phase of decomposition (2 months), a larger portion of the 14C was retained by one soil which had major water deficits. The influence of environmental factors on decomposition rate was assessed by assuming a three compartment model and calculating the mean and variances of residence times of biomass- 14C and residual- 14C. Analytical solutions are presented to the model equations. The 14C residence times, adjusted for soil surface area, were related to rainfall. The residence times were compared with times obtained in our earlier study on soils varying in clay content and mineralogy. This provides a range of 14C residence times for decomposition of ryegrass in New Zealand soils. These results may be used to validate rate-reduction factors in soil organic matter models.

Repeated measures vs. repeated plantings in perennial forage grass trials : an empirical analysis of precision and accuracy

Cultivar evaluations of perennial cool-season forage grasses are an integral part of both breeding and extension programs. There is some doubt that a single trial will result in an accurate representation of cultivar means or rankings, even for a single location. The objective of this study was to quantify the additional precision and accuracy accrued in perennial cool-season forage grass cultivar evaluations resulting from collecting data on additional years of a single planting vs. repeated plantings. The study used data on forage yield, maturity, crown rust reaction (caused by Puccinia coronata Corda), and ground cover of 20 trials of orchardgrass (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb.), timothy (Phleum pratense L.), and ryegrass [perennial (Lolium perenne L.) and intermediate (L. hybridum Hausskn.) ryegrasses and festulolium (Festulolium braunii K.A.)]. The study was conducted at Arlington, WI between 1981 and 1991. Common cultivars in pairs of trials, planted in adjacent fields in consecutive years, were analyzed by analysis of variance. Seven hypothetical cultivar evaluation schemes were created, involving various numbers of harvest years of one or two plantings made in consecutive years. Precision of each scheme was measured by the predicted standard error of a cultivar mean (SECM); accuracy was measured by the correlation between cultivar ranks of a scheme with cultivar ranks from means over all 3 years of both plantings. In most cases, there were dramatic reductions in SECM associated with use of a second planting, regardless of the number of harvest years per planting. Forage yield was the only variable for which there was almost no decrease in SECM due to additional harvest years per planting. Rank correlation coefficients for forage yield were high (r ≥ 0.86) for timothy regardless of the evaluation scheme, but increased linearly with additional harvest years for the other three species. For maturity, rust reaction, and ground cover, most rank correlations were greater than 0.9, suggesting a reasonably accurate ranking for all schemes. Because of this and the importance of forage yield per se, the accuracy and precision of forage yield is the primary consideration. An evaluation scheme of two plantings and 3 harvest years for the first planting plus 2 harvest years for the second planting was recommended for this location.

14C-labelled ryegrass turnover and residence times in soils varying in clay content and mineralogy

The influence of soil texture and clay mineral composition on the decomposition of uniformly-labelled ( 14C) ryegrass ( Lolium hybridum Hausskn) has been investigated. Two clay and two silt loam soils amended with 14C-labelled ryegrass were allowed to decompose in micro-lysimeters under field conditions for 5 years. Periodically the micro-lysimeters were destructively harvested and the total amount of 14C remaining in the soil and the fraction of the 14C incorporated into microbial biomass measured. The influence of the amount and surface area of clay was assessed by calculating the mean and variances of residence times of biomass- 14C and residual- 14C. Surface areas were estimated from the mineralogical composition of the soil, and also measured by adsorption of p-nitrophenol. After 5 years' of incubation, 12–25% of the labelled- 14C was retained by the soils. Decomposition was initially very rapid, between one-third to one-half of the labelled 14C being lost after 9 weeks. Thereafter, the rate of decomposition was much reduced. During the initial phase of decomposition (9 weeks), a greater portion of the 14C was retained by the two clay soils than by silt loam soils. In amorphic and smectitic soils the residence times for 14C were increased because of the protection of microbial metabolites by clay surfaces. The amount of 14C remaining in the soil did not relate to the amount of clay but correlated with the surface area, as measured by p-nitrophenol adsorption. Apparently, the type of clay, expressed in terms of surface area, controlled carbon turnover rates and residence times. This parameter may provide a reasonable predictor of organic matter decomposition rates and stabilization in different soils.

Selection for Persistence of Tetraploid Ryegrasses and Festulolium in Mixture with Perennial Legumes

Forage ryegrass species (Lolium spp.) are seldom utilized in north central and northeastern U.S. hay and pasture systems because of poor persistence in mixtures with common forage legumes. This study was conducted to (i) evaluate genetic responses to one cycle of phenotypic recurrent selection for persistence in tetrapioid perennial ryegrass (L. perenne L.), intermediate ryegrass (L. hybridum Hausskn.), and the meadow fescue (Festuca pratensis Hudson) × Italian ryegrass (L. multiflorum Lam.) intergeneric hybrid, festulolium (Festulolium braunii K.A.), and (ii) identify specific adaptation responses of these populations selected in mLxture with alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), and birdsfoot trefoil (Lotus corniculatus L.). Surviving ryegrass and festulolium plants were selected in 1986 after 3 yr of hay production in mixtures with alfalfa, red clover, and birdsfoot trefoil at Arlington, WI, and Rock Springs, PA. The ability of Cycle 1 progeny to persist with each legume species was compared with those of parental cultivars in 1989, 1990, and 1991 at Arlington and Marshfleld, WI. Selection resulted in an increase in mixed‐stand performance for perennial and intermediate ryegrass; grass ground cover increased by 5.2 and 3.6 percentage units for perennial and intermediate ryegrass, respectively, and the perennial ryegrass component of mixtures increased by 69 g kg−1. Mixture yield was usually unaffected by selection. Evidence for adaptive responses of the ryegrasses and festulolium to specific legume species was scant and inconsistent. Nevertheless, heritable variation for persistence in mixture with legumes was found, suggesting that small gains can be made toward breeding ryegrasses for improved adaptation to Wisconsin.

Ryegrass Companion Crops for Alfalfa Establishment: II. Forage Quality in the Seeding Year

AbstractRyegrass (Lolium spp.) use in the northcentral USA has been limited by its lack of winterhardiness. But potential exists for its use in this region as a companion crop for alfalfa (Medicago sativa L.) establishment. This study was conducted to determine nutritional value of forage from ryegrass‐alfalfa mixtures in the seeding year. Five ryegrass cultivars, representing four species, were sown at 215, 430, and 645 seeds per square meter with alfalfa at two locations in Wisconsin in April of 1988, 1989, and 1990. Alfalfa was also established alone and with oat (Avena sativa L. ‘Ensiler’). Forage from mixtures of annual ryrgrass (L. multiflorum Lam.) was usually lower in crude protein (CP) concentration and higher in fiber concentration (neutral‐and acid‐detergent fiber) than forage from intermediate ryrgrass (L. hybridum Hausskn.) or perennial ryegrass (L. perenne L. and Festulolium braunii K. A.) mixtures. A threefold increase in ryegrass seeding rate usually reduced nutritional value of the forage. At the first harvest, forage from all ryegrass‐alfalfa mixtures was higher in CP concentration and lower in fiber concentration than the oat‐alfalfa forage. At subsequent harvests, the nutritional value of ryegrass‐alfalfa forage was inferior to that of forage regrowth in the oat companion crop seeding, except in dry environments when alfalfa predominated in the ryegrass‐alfalfa mixtures. We conclude that ryegrass‐alfalfa mixtures in the northcentral USA can provide forage with higher nutritional value than oat companion crop seedings at the first harvest in the establishment year, but not at subsequent harvests, especially when adequate rainfall promotes vigorous ryegrass growth.

Influence ofAcremonium loliipresence on emergence and growth of ryegrass seedlings

Abstract An experiment was carried out during winter in a heated glasshouse to assess the influence of the presence of the fungal endophyte, A. lolii Latch, Christensen & Samuels, on the emergence and growth of seedlings of ‘Grasslands Ariki’ ryegrass (Lolium × hybridum Hausskn) in the absence of insect pests. Tiller numbers, shoot and root dry weights, and presence or absence of A. lolii were determined when seedlings were harvested 40 days after emergence. The endophyte was detected in 125 of 318 seedlings harvested. The rate of emergence of seedlings was unaffected by A. lolii presence. Tiller numbers, shoot, root, and tiller weights at harvest were influenced by seed weight (1, 2, 3, and 4 mg seed weight categories) but not by A. lolii presence. There was, however, an interaction between seed weight category and endophyte presence: endophyte-infected seedlings derived from the 3 mg seed weight category had fewer tillers and lower shoot weights than did the comparable endophyte-free seedlings.

EARLY SENESCENCE OF THE ROOT CORTEX OF AGRICULTURAL GRASSES, AND OF WHEAT FOLLOWING ROOT AMPUTATION OR INFECTION BY THE TAKE‐ALL FUNGUS

Nuclear fluorescence following acridine orange staining was used to assess patterns and rates of death of the root cortex (RCD) in Lolium perenne L., L.×hybridum Hausskn. and Dactylis glomerata L. grown in pathogen-free soil in a glasshouse. The pattern of RCD was as previously described for cereals. The rate of RCD differed significantly between grasses and between cultivates of L. pefenne, but in most instances the cortex was anucleate, except for the innermost cell layer next to the endodermis, in 26 to 27 d old regions of seminal root axes. Root impedance caused by a nylon gauze barrier in soil significantly increased the rate of RCD in one tested cultivar of L. perenne. RCD was more rapid in wheat than in grasses. In 8 d old regions of wheat seminal root axes the cortex contained only 54% of the nuclei initially present. Infection of wheat roots by the take-all fungus, Gaeumannomyces graminis (Sacc.) Arx & Olivier var tritici Walker, caused vascular disruption followed by more rapid RCD than in uninfected roots. Similarly rapid RCD occurred in amputated roots, though in all instances the pattern of RCD was unchanged. The rate of RCD was slower in long than in short lengths of amputated root, perhaps because of remobilization of nutrients from dying cells. Nuclei persisted for at least 10 d in the inner cortex of 2 cm lengths of young roots of wheat, barley and L. perenne buried in soil at 20 °C. The pattern of nuclear deletion from the root pieces was the same as in whole roots, and the rate of RCD was faster in wheat than in barley, as also found for roots attached to plants. All these results demonstrate a consistent pattern of cortical senescence in graminaceous roots and suggest that it is a programmed phenomenon.

Variation in ethofumesate tolerance in Lolium species and cultivars

SummaryThe ethofumesate tolerances of seventy cultivars of Lolium perenne L., L. multiflorum Lam. and L. x hybridum Hausskn. were investigated by growing seedlings in a glasshouse in a potting compost treated with a critical level of the herbicide. The incidence of seedling deformity and death varied among cultivars, and was generally higher in diploids than in tetraploids, and in L. perenne than in L. multiflorum. Cv. Palaver was outstandingly tolerant. Eight cultivars were re‐tested in pre‐ and post‐emergence field experiments and relative tolerances were similar to those observed in the glasshouse. At the recommended doses for selective weed control, ethofumesate caused some seedling death in susceptible varieties in the pre‐emergence experiment, and both seedling death and reduced herbage production in the post‐emergence experiment. It is concluded that both varietal genotype and environmental factors contribute to the risk of ethofumesate damage in the field.

‘Grasslands Roa’ tall fescue: Herbage dry matter production and quality under mowing

Abstract In pure swards at sites in 4 regions of New Zealand, Roa and S170 tall fescue (Festuca arundinacea Schreb.) established slower than Ariki ryegrass (Lolium × hybridum Hausskn). Ariki ryegrass was generally superior to tall fescue at sites where soil moisture levels were maintained throughout the year (because of even rainfall or heavier soils), whereas tall fescue was more productive in areas prone to long periods of moisture stress (summer drought and/or light soils) particularly over the summer-autumn period. Roa tall fescue was better than S170 under frequent cutting but similar under infrequent cutting. Herbage of Roa tall fescue had a higher acceptability to sheep than S170.

The influence of lead, cadmium, and nickel on the growth of ryegrass and oats

A 24 factorial experiment was conducted under greenhouse conditions. Factors and levels in the experiment were soil pH at 4.5 and 6.4, and cadmium, lead, and nickel added to the soil to provide soil concentrations of 50, 250, and 50 ppm, respectively, above background levels. Two species were grown in succession in the same experimental pots. Ryegrass (Lolium hybridum Hausskn. cv. Tetrelite) was harvested three times and then one crop of oats (Avena sativa L. cv. Garry) was grown and harvested. Plant tissue concentrations of cadmium, lead, and nickel were monitored throughout the experiment. Addition of cadmium to the soil lowered the dry matter yields in all three ryegrass harvests and also reduced the yield of oat grain. The application of lead nitrate to the soil enhanced the yield of ryegrass obtained at the first harvest and also increased the yield of oat grain. Nickel, added to the soil at 50 ppm, was relatively innocuous to ryegrass and oats. The presence of added cadmium, lead, or nickel to the soil resulted in enhanced tissue concentrations of these metals in both ryegrass and oats. This effect was particularly enhanced by a soil pH of 4.5. A single exception to this observation was that lead was not detected, under any of the conditions of this experiment, in oat grain. The presence of lead in the soil enhanced cadmium concentrations in ryegrass tissues. The presence of cadmium in the soil decreased lead tissue concentrations in ryegrass and oat straw. Soil pH interacted with both nickel and lead in the second ryegrass harvest with subsequent changes in tissue cadmium concentrations. At a soil pH of 4.5, the presence of added lead or nickel to the soil significantly increased the ryegrass tissue cadmium concentration beyond that observed at a soil pH of 6.4 with or without enhanced nickel or lead concentrations.

Comparison of ryegrass—white clover pastures with and without paspalum and kikuyu grass

Abstract Three pasture types were compared under 2 sheep management systems over 3 years. A basic temperate species mixture of ryegrass (Lolium × hybridum Hausskn. ‘Grasslands Ariki’) and white clover ( Trifolium repens L. ‘Grasslands Huia’) (pasture R) was compared with the same mixture plus either paspalum (Paspalum dilatatum Poir.) or kikuyu grass (Pennisetum clandestinum Hochst.) (pastures P and K respectively). Subtreatments consisted of a ewe/lamb system stocked at 19.8 ewes/ha, and a put-and-take hogget system in which numbers were adjusted to match feed supply on a 20-day cycle. There were no significant differences in sheep production between R and P pastures in the ewe system (ewe and lamb live weights, greasy fleece weights) but there was a 7% advantage to P under the hogget system (intake of metabolisable energy/ha). Under the stocking rates used, paspalum content fell to low levels. Live weights of ewes on K pastures fell further in spring than those on other pastures but they recovered faster after lactation. Greasy fleece weights were also lower at spring shearing and on an annual basis but there were no differences at autumn shearing. Lamb production (live weight/ha) did not differ significantly among pastures during the 21 weeks lambs remained on the trial. Under the hogget system, estimated annual metabolisable energy intake of K pasture was 10% less than that on R with K yield being lower in spring and higher in autumn.

I. Pasture production and botanical composition

Abstract Effects of superphosphate, lime, and stocking rate on pasture production were studied over a 5-year period on a central yellow-grey earth on the Wairarapa Plains at the Masterton Field Research Area. A high annual rate of superphosphate (500 kg/ha) did not increase pasture production above that obtained from a low annual rate (125 kg/ha), but lime (6300 kg/ha) increased pasture production. A high stocking rate (22 ewes/ha) decreased pasture production in 2 years. Point analysis of botanical composition showed that browntop (Agrostis tenuis Sibth.) cover increased to a maximum in the third year and then declined. Both the high rate of superphosphate and the lime significantly reduced browntop cover. Ryegrass (Lolium × hybridum Hausskn.) and white clover (Trifolium repens L.) cover increased linearly with time, the spring recordings being significantly correlated with the previous summer's rainfall.