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The effectiveness of four granular wetting agents to decrease water repellency in sandy soils of contrasting organic matter (OM) content and influences on kikuyugrass [ Pennisetum clandestinum (Holst. Ex Chiov)] grown as turfgrass, were evaluated. A laboratory test assessed the wettability of two non-wetting soils (low OM, 4.7%; high OM, 17%) after treatment with granular soil wetting agents, with four being selected for field experimentation. A field experiment included two turfgrass ages (established from 20 week or 20 year old turfgrass in 2005; the latter included a 50 mm 'mat' layer and thus had high OM content in the surface soil), four granular soil wetting agents (plus a 'nil' as control), and five replicates. Surface soil (0-25 mm) water repellency, measured using the molarity of ethanol droplet test (MED), ranged from 0.4 M to 4.3 M during the irrigation season, and repellency was more severe in the soil with high OM (32%) content than low OM (8.6%) content. Soil wetting agents decreased the development of soil water repellency to varying extents, and maintained turfgrass quality; with improvement related to the amount of active ingredient applied. We recommend utilising an effective soil wetting agent, in combination with practices that limit the accumulation of soil OM, to decrease the severity and incidence of soil water repellency in turfgrass grown on sandy soils. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of fertilization and commercial mycorrhizal association and nutrient content of Kikuyu grass (Pennisetum clandestinum). In a factorial arrangement of four levels combined with two mycorrhizal fertilizations, the resulting eight treatments were evaluated in a completely randomized design. We used a native mycorrhizal witness, evaluated independently. As response variables were determined: HMA Association, and the leaf content of N, P, K, Ca, Mg, Fe, Cu, Zn, B and S. The association of the HMA is not favored by fertilization and this was significantly higher when using native inoculum or inoculum basal versus commercial. The type of inoculum influenced the content of P and Mg, native inoculum presenting a positive effect on the content of these two elements. [ABSTRACT FROM AUTHOR]

We investigated the type and extent of degradation at three sites on the Agulhas Plain, South Africa: an old field dominated by the alien grass Pennisetum clandestinum Pers . (kikuyu), an abandoned Eucalyptus plantation, and a natural fynbos community invaded by nitrogen fixing-Australian Acacia species. These forms of degradation are representative of many areas in the region. By identifying the nature and degree of ecosystem degradation we aimed to determine appropriate strategies for restoration in this biodiversity hotspot. Vegetation surveys were conducted at degraded sites and carefully selected reference sites. Soil-stored propagule seed banks and macro- and micro-soil nutrients were determined. Species richness, diversity and native cover under Eucalyptus were extremely low compared to the reference site and alterations of the soil nutrients were the most severe. The cover of indigenous species under Acacia did not differ significantly from that in reference sites, but species richness was lower under Acacia and soils were considerably enriched. Native species richness was much lower in the kikuyu site, but soil nutrient status was similar to the reference site. Removal of the alien species alone may be sufficient to re-initiate ecosystem recovery at the kikuyu site, whereas active restoration is required to restore functioning ecosystems dominated by native species in the Acacia thicket and the Eucalyptus plantation. To restore native plant communities we suggest burning, mulching with sawdust and sowing of native species. [ABSTRACT FROM AUTHOR]

Supplements with corn grain, molasses cane, and different nitrogen sources were evaluated in 16 growing Hosltein heifers [227 ± 33 kg body weight (BW)] grazing kikuyu ( Pennisetum clandestinum) pasture in a 10-ha sward (rotational grazing with electric fences) during 90 days in the summer season. The nitrogen sources were urea (U); urea and blood meal (U + BM); and urea, blood meal, and rumen-protected methionine (U + BM + RPM). Heifers were randomly assigned to four experimental supplements defined as follows: control (no supplementation), U, U + BM, and U + BM + RPM. Two kilograms (as fed) of supplement was offered daily. The final BW of heifers fed U + BM + RPM was higher ( P < 0.05) than heifers not supplemented. The total and average daily weight gain of heifers supplemented with U + BM + RPM were higher than heifers not supplemented or supplemented with U and U + BM ( P < 0.05). The average daily gain of heifers supplemented with U and U + BM were higher than heifers not supplemented ( P < 0.05). Grass intake was not affected by supplementation, but total dry matter intake was increased by supplements with U, U + BM, and U + BM + RPM ( P < 0.05). Feed conversion was improved by U + BM + RPM ( P < 0.05). Total tract digestion was not affected by supplements. Blood urea nitrogen concentrations of heifers supplemented with U, U + BM, and U + BM + RPM were higher than heifers not supplemented ( P < 0.05). It is concluded that supplements with U + BM + RPM improved growth performance and feed conversion in heifers grazing kikuyu pasture. [ABSTRACT FROM AUTHOR]

Gray leaf spot (GLS) disease of perennial ryegrass (Lolium perenne) and kikuyugrass (Pennisetum clandestinum) in golf courses in California was first noted in 2001 and 2003, respectively, and within 5 years had become well established. The causal agent of the disease is the fungus Magnaporthe grisea, which is known to consist primarily of clonal lineages that are highly host specific. Therefore, our objective was to investigate host specificity and population dynamics among isolates associated primarily from perennial ryegrass and kikuyugrass since the disease emerged at similar times in California. We also obtained isolates from additional hosts (tall rescue, St. Augustinegrass, weeping lovegrass, and rice) and from the eastern United States for comparative purposes. A total of 38 polymorphic amplified fragment length polymorphism makers were scored from 450 isolates which clustered by host with high bootstrap support (71 to 100%). Genetic structure between kikuyugrass and perennial ryegrass isolates differed significantly. Isolates from kikuyugrass were genotypically diverse (n = 34), possessed both mating types, and some tests for random mating could not be rejected, whereas isolates from perennial ryegrass were less genotypically diverse (n = 10) and only consisted of a single mating type. Low genotypic diversity was also found among the other host specific isolates which also only consisted of a single mating type. This is the first study to document evidence for the potential of sexual reproduction to occur in M. grisea isolates not associated with rice (Oryza saliva). Moreover, given the significant host specificity and contrasting genetic structures between turfgrass-associated isolates, the recent emergence of GLS on various grass hosts in California suggests that potential cultur01 practices or environmental changes have become conducive for the disease and that the primary inoculum may have already been present in the state, despite the fact that two genotypes associated with perennial ryegrass and St. Augustinegrass in California were the same as isolates collected from the eastern United States. [ABSTRACT FROM AUTHOR]

Green leaves of six grass species in temperate Australia showed considerable circadian variation (especially in summer) in water content, which peaked late in the night and fell from sunrise to an afternoon minimum. In summer, water content of a set of ‘wetter’ species ( Axonopus affinis, Pennisetum clandestinum and Paspalum dilatatum) was consistently higher and varied less profoundly through the 24 h than that of a ‘drier’ set ( Imperata cylindrica, Poa labillardieri and Themeda triandra). Hour-to-hour and day-to-day variation in leaf water content of P. dilatatum in summer partly but imperfectly reflected ambient temperature. Recognizing the risks for herbivores of visiting water sources, we considered leaf water content as a source of free water for leaf-grazing herbivores, eastern grey kangaroos Macropus giganteus and common wombats Vombatus ursinus. Using known field metabolic rates, energy requirements and digestive efficiencies, we calculated these two species' free-water intakes when satisfying their energy needs with these grasses but distributing their grazing in different schedules. Both species would obtain more free water by their observed foraging schedules than by random or daytime-only schedules. We calculated that the measured grasses could satisfy the water requirements of wombats but not always those of kangaroos, who would need to drink when forage water content was less than about 70%. Water content of grass leaf could rise above and fall below this value within a day, creating some scope for kangaroos to manage their need to visit water by adjusting foraging schedules or choice of grass species. In future studies, circadian variation in leaf water content should be considered as a factor (together with their thermal physiology) driving herbivores' activity scheduling, and affecting their dietary selection. [ABSTRACT FROM AUTHOR]

Abstract: The conversion of montane cloud forests into pastures for grazing cattle is the main cause of important impacts on rivers and streams in most of the Andes. In order to evaluate the effects of vegetation changes we need to understand water fluxes, particularly canopy interception. We measured net precipitation responses by the canopies of Pennisetum clandestinum Hochst. ex Chiov. and Melinis minutiflora Beauv. under simulated rainfall. The samples were taken from grazed pastures during 1 year, digging out round mats of grass, placing them on wire-mesh devices after eliminating soil and underground biomass, and irrigating with different water amounts. The resulting data allow us to present a validated model for each species that predicts percentage of interception at different precipitation intensities taking into account previous canopy wetness within determined biomass ranges. We use these models to estimate 2 years of interception values for pastures of both species in the upper watershed of El Cañadón, Capaz River, Venezuelan Andes. Mean annual precipitation of El Cañadón is 1244mm and the estimate of pasture interception was 36.5% and 31.8% for P. clandestinum and M. minutiflora, respectively. Interception models, such as the ones derived in this study, provide a basis for quantifying interception rates as a function of previous wetness of canopies and grass species. [Copyright &y& Elsevier]

The objective of this work was to evaluate changes in soil bulk density (ρa) induced by Holstein and Jersey cattle grazing in kikuyu grass fields. We took 60 soil samples (Typic Hapludands) at two farms more than 15 years ago involved with milk production, in Cascajal and Nubes Coronado districts, San Jose, Costa Rica, 2008. The "known volume method" was used, following a sampling protocol every five meter in relation to the perimeter of the grazing zone and the next sampling point. It was determined that the variables breed, grazing time (before and after) and grazing zone, are significant for quantifying the changes in soil bulk density. Values of ρa before the livestock was allowed inside the paddocks ranged between 0.47 and 0.58 Mg/m³, with a mean value of 0.52 Mg/m³, while after cattle passage, it ranged between 0.52 and 0.77 Mg/m³, with a mean value of 0.64 Mg/m³. When grazing was performed with Jersey cattle, ρa values varied between 0.52 and 0.72 Mg/m³, with a mean of 0.62 Mg/m³, while Holstein cattle grazing induced changes between 0.62 and 0.77 Mg/m³, with a mean of 0.69 Mg/m³. Soil bulk density changes resulting from trampling cattle on kikuyu grass can fluctuate between 14 and 31%. [ABSTRACT FROM AUTHOR]

The effects of N fertiliser regimes on N leaching and turfgrass quality during the establishment and maintenance of Kikuyu turfgrass ( Pennisetum clandestinum (Holst. Ex Chiov)) were evaluated in a 24 month field study. Treatments included two turfgrass ages (established from 20 week or 20 year old turfgrass, the later included a 50 mm ‘mat’ layer), three N application rates (50, 100 or 150 kg N ha−1 yr−1) and three application frequencies (every 4 weeks, 4 applications per year, 2 applications per year); and included turfgrass plots that received no N fertiliser. Nitrogen leaching, measured using soil lysimeters, ranged from 35 to 69 kg N ha−1 by the end of 24 months, and varied with turfgrass age, but not N fertiliser regime. Greatest N losses occurred during turfgrass establishment, with up to 50% of all N leached in the organic form. We recommend measuring both total N and mineral N when assessing N leaching from turfgrass. The quality of the older turfgrass was maintained using less N fertiliser than the younger turfgrass, while increasing N application frequency improved the consistency of turfgrass growth and colour. [ABSTRACT FROM AUTHOR]

Abstract: Eight castrated male lambs (35±4kg live weight), fed a basal diet of kikuyu grass hay, were used in a replicated 4×4 Latin Square experiment with a 2×2 factorial arrangement of treatments to evaluate the effect of supplemental feeding frequency and source of rumen degradable N on intake, digestibility, ruminal fermentation, and microbial protein yield. Treatments were supplementation with cassava meal plus calcium caseinate or cassava meal plus urea offered at a rate of 7g/kg live weight daily in one or two meals per day. Lambs were fed twice daily in such manner to allow ad libitum comsumption of forage. There was significant feeding frequency by N source interaction on variables of intake. In general, intake of feed components was higher (P ≤0.05) by lambs offered the caseinate-supplement twice daily over intake observed in lambs given the others diet treatments. Digestibility of feed components was neither affected by supplemental N source (DM, P =0.541; OM, P =0.585; NDF, P =0.828) nor by feeding frequency (DM, P =0.122; OM, P =0.175; NDF, P =0.591). Urinary excretion of N increased (P ≤0.05) in lambs supplemented twice daily whereas N retention was similar for all treatments (N source, P =0.748; feeding frequency, P =0.418). Microbial protein entering into the small intestine was affected by the interaction between feeding frequency and N source such as an increasing (P <0.10) in this variable was observed when lambs received the caseinate but not the urea supplement twice daily. Efficiency of microbial protein synthesis, however, was not affected by treatments (N source, P =0.588; feeding frequency, P =0.334). Rumen pH averaged 6.70 and it was neither affected by N source (P =0.827) nor by feeding frequency (P =0.740). Ruminal concentration of ammonia N was not affected by feeding frequency (P =0.144) while it increased (P <0.05) when urea rather than caseinate was the supplemental N source (mean of 7.61mg/dl vs. 6.00mg/dl). Concentration of sugars in rumen fluid was higher (P ≤0.05) in lambs supplemented once a day compared to twice daily (mean of 49.4mg/dl vs. 34.4mg/dl) for both N sources. A significant (P ≤0.05) N source by feeding frequency interaction effect was observed for ruminal concentrations of α-amino N compounds. In urea treatment α-amino N concentration increased (P ≤0.05) in lambs receiving the supplement twice daily compared to once a day (mean of 4.59mg/dl vs. 3.70mg/dl) while in caseinate treatment it was higher (P ≤0.05) in lambs offered the supplement in one meal per day compared to twice daily (mean of 5.29mg/dl vs. 4.07mg/dl). In conclusion, for ruminants fed a tropical grass-based diet, starch-rich supplement containing non-protein N as N source may be offered only once a day whereas the supply of nutrients may be improved if degradable true protein is included as N source and supplement is offered in two meals per day. [Copyright &y& Elsevier]

The high dry matter yield of kikuyu (Pennisetum clandestinum) under favourable conditions supports high stocking rates and milk production per hectare. However, the quality of kikuyu is generally low and consequently the milk production per cow is also low. The aim of the study was to determine the grazing capacity, milk production and milk composition from kikuyu, kikuyu over-sown with annual ryegrass (Lolium multiflorum var. westerwoldicum), kikuyu over-sown with a mixture of perennial ryegrass (L. perenne), white clover (Trifolium repens) and red clover (T. pratense), and kikuyu over-sown with a mixture of white and red clovers. Milk production per cow was highest on pasture with high clover content and the grazing capacity of pasture increased as the grass component increased. The milk produced from kikuyu during spring (15 kg cow-1 d-1) and summer (14.4 kg cow-1 d-1) was higher than during the autumn (12.1 kg cow-1 d-1). The total milk production from kikuyu during spring (3 876 kg milk ha-1) increased when kikuyu was over-sown with annual ryegrass (8 133 kg milk ha-1) or with clover (7 370 kg milk ha-1). The summer and autumn grazing capacity of kikuyu and kikuyu-annual ryegrass fertilised with nitrogen was higher than the kikuyu-clover pastures not receiving nitrogen. The clover content of the pastures did not affect the milk protein or butterfat content. The mean annual grazing capacity of kikuyu (6.7 cows ha-1) and kikuyu-annual ryegrass (8 cows ha-1) pasture was higher than the kikuyu-clover (5.3 cows ha-1) pasture. The grazing capacity and milk production per cow from kikuyu over-sown with ryegrass varied less than from kikuyu or kikuyu-clover pastures. This resulted in a similar or higher milk production per hectare from kikuyu-ryegrass compared to that of kikuyu or kikuyu-clover pastures. [ABSTRACT FROM AUTHOR]

The seasonality of growth and low nutritional value of kikuyu (Pennisetum clandestinum) pasture restrict milk production. The aim of the study was to determine the dry matter yield, botanical composition and nutritional value of irrigated kikuyu over-sown with annual ryegrass (Lolium multiflorum var. westerwoldicum), white clover (Trifolium repens) and red clover (T. pratense) or a mixture of perennial ryegrass (Lolium perenne) with white and red clovers under intensive grazing conditions with dairy cows. The incorporation of annual ryegrass, perennial clover or perennial ryegrass-clover into kikuyu pasture changed the seasonal fodder flow and increased the spring dry matter (DM) production. The over-sowing of kikuyu with annual ryegrass had no effect on the DM production of kikuyu during the summer and autumn. Kikuyu and kikuyu-ryegrass, fertilised with nitrogen fertiliser, had a higher DM production rate than kikuyu-clover pastures. Kikuyu-ryegrass pasture transformed from ryegrass-dominant in spring to kikuyu-dominant in summer and only kikuyu in autumn. This led to a decrease in metabolisable energy (ME) and increase in neutral detergent fibre (NDF) content of the pasture during spring, summer and autumn as kikuyu became more dominant. The clover content of kikuyu over-sown with clover decreased annually but was still higher than 30% at the end of two years after establishment. As the kikuyu content of the kikuyu-clover pastures increased, the seasonal growth rate changed from a low autumn growth (37.9 kg DM ha-1 d-1) in the first year to a higher autumn growth (48.5 kg DM ha-1 d-1) in the second year. The over-sowing of kikuyu with clover resulted in lower DM production and NDF values and higher crude protein (CP), ME and calcium (Ca) values. The lowest CP content in kikuyu-ryegrass pasture was during summer and autumn when kikuyu was dominant. The Ca content of the grass pastures (kikuyu and kikuyu-ryegrass) was low. The phosphorus (P) content of both the kikuyu-clover and grass pastures exceeded the requirement needed for dairy production (0.38%). The mean Ca:P ratio of the kikuyu-clover pasture meets the 1.6:1 ratio needed by dairy cows. The kikuyu and kikuyu-ryegrass pasture had a Ca:P ratio lower than 1:1 and Ca supplementation would be needed for dairy cows. The incorporation of annual ryegrass, perennial clover or perennial ryegrass-clover into kikuyu pasture improved the seasonal DM production and nutritional value of the pasture. [ABSTRACT FROM AUTHOR]

The changes in chemical composition of hay of kikuyu grass ( Pennisetum clandestinum) harvested at 50, 70 and 90 d of regrowth, and its effect on intake, digestibility, fermentation and microbial protein synthesis in the rumen (Experiment 1) and oxygen uptake by portal-drained viscera (PDV) (Experiment 2) were evaluated. The experiments were carried out with Polwarth × Texel crossbreed lambs with a mean live weight (s.e.m.) of 35(3·0) kg housed in metabolic cages. Organic matter (OM), neutral-detergent fibre (NDF) and nitrogen (N) intake, as well as rumen ammonia-N concentration, decreased linearly with age of regrowth ( P < 0·05). Acid-detergent fibre (ADF) and indigestible NDF intakes were similar for all treatments. Apparent digestibility of organic matter (OM), NDF and N, as well as true digestibility of OM, microbial protein synthesis in the rumen, N retention, pH of rumen fluid and sugars, amino acids and peptide concentrations in rumen fluid were similar for all treatments. Age of regrowth also did not affect the kinetics of passage of the particulate phase through the digestive tract nor oxygen uptake by PDV. Heat production by PDV represented an average of 0·039 of digestible energy (DE) intake. Increasing the age of regrowth of kikuyu grass from 50 to 90 d did not affect digestibility nor the efficiency of DE use by PDV tissues of lambs but it reduced the nutritive value of the hay due to a lower intake of OM. Intake of hay appeared to be most limited by the ADF and indigestible NDF concentrations of the hay. [ABSTRACT FROM AUTHOR]

At the end of 2001, the AZ-1 cultivar of Pennisetum clandestinum Hochst. ex Chiov. (kikuyugrass) was incorporated into the Argentinean market to be used in sports fields or for ornamental purposes. In order to characterize such commercial variety in the geographic department of Paraná (Entre Ríos, Argentina), its behavior and aptitude were assessed as ornamental grass and/or sports grass both under high quality grass maintenance conditions and under two drainage conditions. Cover, colour, texture, internodes distance, stolon thickness, and dormancy period were evaluated. The trial was carried out in Oro Verde, department of Paraná in the province of Entre Ríos in a Molisol soil and it consisted of two treatments: with and without drainage and each treatment being repeated four times. The plot size was 2.5 x 5.0 m. The experimental design used was the paired -- plot design and measurements were taken from June to November 2005. The area weather conditions are the following: average annual temperature of 18.1°C and an isohydro regimen of 947.6 mm of annual rainfall. The cultivar behaved as suitable for grass under the evaluated management conditions and characteristics, not showing differences as regards the treatments with or without drainage. It presented quick implantation, high cover levels, light and uniform colour, medium texture and thick stolons through time. In winter, cover and colour kept invariable. It was characterized as a grass not suitable for sports fields with high requirements, but advisable for low budget and maintenance condition clubs. [ABSTRACT FROM AUTHOR]

The article presents a study on the kikuyu grass poisoning in cattle in Australia. Such plant refers to a perennial pasture species, which grows during spring and autumn. Despite having no ill effects on animals, incidents of spasms were noted. However, results revealed that the pathogenesis of such poisoning has remained unclear. Thus, it is advised that future studies must focus on the isolation and identification of the toxin, since its seasonal production in such a grass remains unclear.

Soil microorganisms and plants were studied in samples of arsenic-contaminated soil from two cattle dip sites. The aim was to delineate the parameters that will determine the feasibility of future remediation by growing arsenic-accumulating plants, including the identity and characteristics of some rhizosphere soil microbes. The soil samples contained high total, but low soluble arsenic concentrations which, together with other properties, resembled the previously reported characteristics of dip-site soils from this region of rural Australia. A glasshouse trial demonstrated that dip-site rhizosphere microbes promoted arsenic accumulation by the grass Agrostis tenuis on contaminated dip-site soil without inhibition of growth. The arsenic content of the shoots was increased by 45%. We studied the colonization of roots of dip-site plants by mycorrhizal fungi and tentatively identified six genera of other fungi present in the soil samples. Two plant species growing at the sites, Kikuyu grass (the most abundant plant) and Rainbow fern, exhibited mixed infections of their roots by endomycorrhizal fungi (tentatively identified as Acaulospora and Gigaspora) and by soil-born pathogens. Five rhizosphere bacteria were identified to genus level and we determined the effect of arsenic on their growth. The two most prevalent strains differed greatly in their growth sensitivity to arsenate; Arthrobacter sp. Being the most sensitive while Ochrobactrum sp. Exhibited exceptional resistance to arsenate. Of the other, less prevalent strains, two were Bacillus spp. And the last, Serratia sp. , was the most resistant to arsenite. These findings show the importance of understanding plant–soil microbe interactions for developing future strategies aimed at a phytoremediation-based approach to removing arsenic from soil at dip sites. [Copyright &y& Elsevier]

Abstract: The objective of this work was to evaluate the intake (I) of all Buddleia skutchii foliage (BSF), collected from three different sites (places: A, B and C) in feeding sheep (phase 1), and in combination with Pennisetum clandestinum (Pc) (phase 2). Trials of feed intake, in vivo dry matter digestibility (IVDMD), and digestibilities of crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), and nitrogen balance were carried out during phase 1. Diet was given to nine Creole male lambs of 23(±3)kg body weight (BW), located in individual metabolism crates. During phase 2, four treatments were evaluated (T1=100% Pc, T2=20% BSF+80% Pc, T3=40% BSF+60% Pc and T4=60% BSF+40% Pc) in a 4×4 Latin square design, using four ruminal cannulated Creole male rams of 50±2kgBW and remained in individual metabolism crates. In vivo digestibility (DM, CP and gross energy (GE)) and kinetics of in situ disappearance of DM were evaluated. The results in phase 1 indicated that BSF from Site B had relatively higher CP (14.9%), ADF (50.6%) content and nitrogen retention (1.93gd−1). On the other hand, the lambs showed intake levels of 376.29gd−1 DM, 56.21gd−1 CP, 206.24gd−1 ADF and 1418.21kcal gross energy (P >0.05); and digestibilities of 54.23% DM, 47.17% CP and 39.31% NDF. Therefore, BSF from Site B was selected for the second phase of this work as the best result. We observed that the nutrition quality of the diets was higher as a result of increasing BSF concentration in the diet. When sheep were fed on 40% BSF–60% Pc, DM intake levels of 900.6gd−1, and DM, CP and GE digestibility of 70.0, 52.82 and 55.1%, respectively, were observed. There were not significant differences among diets, and in situ disappearance, K d and K p, but the diet with 60% of BSF presented higher ruminal digestibility (42.3%). The results allowed to validate the local knowledge on BSF as a promising forage species, and showed that BSF should be incorporated in a sheep production system. [Copyright &y& Elsevier]

Abstract: In Hawaii, infestations of yellow sugarcane aphid (YSA), Sipha flava (Forbes) (Homoptera: Aphididae) reduced growth of the forage grass, kikuyu (Pennisetum clandestinum Hochst. ex Chiov). To determine the effects of nitrogen (N) and potassium (K) on tolerance of kikuyu grass to YSA, cuttings of eight and five cultivars were grown in the greenhouse using nutrient solutions in two separate trials, respectively. The first trial was conducted during the summer of 1991 and the second during the winter of 1993. In both trials, kikuyu was grown at three N levels (0.05, 0.5 and 3.0mM) and four K levels (0.05, 0.5 1.0 and 3.0mM), with one cultivar comprising a block. Prior to exposure to aphids, representative plants were harvested, and shoots were analyzed for foliar nutrients. Then, plants were confined with aphids and rated visually for YSA injury. Dry matter yields and foliar N concentration increased significantly with increasing N fertilization in both trials. In the first trial, there was a significant interaction between N and K levels, in which the greatest increases of shoot and root dry matter with increasing N levels were found at the highest K level. In the second trial, K fertilization had no effect on dry weight of shoots. In both trials, foliar K concentration increased significantly with increasing K levels. Damage due to YSA tended to increase with increasing N levels, although it was unaffected by K fertilization in both trials. Thus, fertilization with increasing N resulted in greater kikuyu dry matter production, but it also tended to increase the damage caused by YSA feeding. [Copyright &y& Elsevier]

Abstract: Kikuyu grass, Pennisetum clandestinum Hochst. ex Chiov., is an important pasture species in many subtropical areas. Infestations of yellow sugarcane aphid (YSA), Sipha flava (Forbes) (Homoptera: Aphididae), have reduced kikuyu forage production in Hawaii. A novel method was developed to screen cultivars of kikuyu, and species of other forage and turf grasses for resistance to YSA. Kikuyu germplasm differed significantly in response to YSA with certain kikuyu hybrids more resistant to YSA than the common cultivar. However, even the kikuyu cultivars with the lowest damage ratings were considered only to be moderately resistant to YSA. Other forage grass species differed significantly in YSA damage, with Pacific fountain [Pennisetum macrostachys (Brongn.) Trin.], dallis (Paspalum dilatatum Poir.), torpedo (Panicum repens L.), tall fescue (Festuca arundinacea Schreb.), signal [Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster, formerly known as Brachiaria decumbens], bahia (Paspalum notatum Flugge), small buffalo (Panicum coloratum L.), velvet (Holcus lanatus L.), and switch (Panicum virgatum L.) grasses considered to be resistant to YSA. Turf grass species also differed significantly in YSA injury, with seashore paspalum (Paspalum vaginatum Sw.), St. Augustine [Stenotaphrum secundatum (Walter) Kuntze], and Japanese lawn (Zoysia japonica Steud.) grasses evaluated as resistant. Reduction of pasture forage by YSA could be ameliorated either by utilization of moderately tolerant kikuyu hybrids or resistant forage grass species. [Copyright &y& Elsevier]

Two experiments were conducted, with random block designs and five replications each to study the effect of the following combinations of organic fertilizer/mineral fertilizer: a) absolute control (0:0), b) 100 % mineral fertilizer (0:100), c) 100 % organic fertilizer (100:0), d) 75 % organic fertilizer and 25 % mineral fertilizer (75:25), e) 50 % organic fertilizer and 50 % mineral fertilizer (50:50), 25 % organic fertilizer and 75 % mineral fertilizer (25:75), on the yield and bromatological composition of a kikuyo (Pennisetum clandestinum Hoechs) rangeland. In the first experiment, the rangeland was subject to a pass of Creole plow with oxen, before the application of the treatments, whereas in the second experiment this labor was not conducted. In the first case with the plow, the yield of the DM (5.3 to 5.6 t DM/ha), the grass height (26.5 to 29.0 cm), and the depth of the roots (25.4 to 26.2 cm) were significantly higher (P < 0.05) in the treatments with organic fertilizers and different ratios of organic and mineral fertilizers, compared with the mineral fertilizer alone and the absolute control. In the second experiment, without previous plowing, the performance of these indicators was similar to those in the first, but the numeric values were lower. In general, the DM content of the pasture declined with the application of the fertilizers and their combinations, whereas the content of CP and nitrates was higher (P < 0.05) with the mineral fertilizer. The organic and mineral fertilizers and their combinations increased the energy content of the pasture. The application of organic fertilizers (50 t/ha of cattle manure) or the ratios of 75:25 or 50:50 of organic: mineral fertilizer is recommended after the plowing with oxen to recover the productivity and nutritive value of the kikuyo pasture. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the effect of increasing the proportion of concentrate in the diet, on efficiency of feed utilisation, was determined when Holstein–Friesian cows grazed short-rotation ryegrass (Lolium multiflorum) or kikuyu (Pennisetum clandestinum) pastures. The concentrates were energy-dense dairy pellets fed twice-a-day at milking and the roughage component was lucerne hay and the pasture. When cows grazed ryegrass, there was no effect on animal performance as the proportion of concentrate in the diet increased from 0.23 to 0.35 (4.75 to 7.50kg concentrate/cow/day). The substitution rate of concentrates for pasture for the first 1.57kg concentrate/cow/day fed was 0.58 but rose to 1.18 for the next 1.28kg concentrate/cow/day. When cows grazed kikuyu, there was also no effect of increasing the proportion of concentrate in the diet on total dry matter intake (DMI) or milk production. However, there was a substantial increase in the in vivo digestibility of whole diet, pasture and acid detergent fibre (ADF) was observed when the proportion of concentrate in the diet increased from 0.08 to 0.25. However, there was a marked decline in pasture digestibility (72% to 64%), and more so in ADF digestibility (61.3% to 48.4%), as the proportion of concentrate in the diet increased further to 0.29 (5.52kg/cow/day). The intake of kikuyu, when determined by difference between pre- and post-grazing pasture mass, was substantially underestimated compared to the use of the n-alkane technique, and this discrepancy increased as the pasture on offer increased. On both pasture types, the neutral detergent fibre intake, as a % of bodyweight varying from 1.6% to 2.2% for kikuyu and 1.5% to 1.6% for ryegrass was far above the values claimed of 1.2% to restrict intake. The results of this study highlight the limits to the amount of concentrate that can be fed on a typical Australian dairy farm where concentrates can only be fed twice-a-day at milking. The results also provide a more appropriate benchmark for fibre limitation in the ration when cows graze pasture, particularly poorer quality tropical grasses, and this value is well above that found in more intense feeding situations. [Copyright &y& Elsevier]

The turf grass Pennisetum clandestinum Hochst. (kikuyu grass) is one of the candidate plants for utilization and reclamation of salinized areas. The capability of kikuyu grass to grow under saline conditions was tested during 6 months, under various irrigation treatments (tap water control, 80‐mM, 150‐mM, 200‐mM, 240‐mM NaCl). Plant biomass production was visibly affected only at NaCl concentrations greater than 150‐mM NaCl. Plant growth and plant regeneration capability in the 200‐ and 240‐mM NaCl treatments gradually decreased as the experiment progressed in time. The photosynthetic potential of the plants remained unchanged and was neither affected by the treatment nor with time. Proline content of leaves as well as the content of Na + and Cl - increased with increasing salinity stress. Apparently, kikuyu grass can withstand moderate concentrations of NaCl for prolonged periods and under repeated mowing. Thus, this grass can be used as a potential ground cover and as fodder grass in saline habitats. [ABSTRACT FROM AUTHOR]

Pennisetum clandestinum (Kikuyu grass, Graminae ) is an active Si accumulator growing in altitude in Kenya. To verify the influence of Si on mineral uptake, P. clandestinum was cultivated in two different substrata both with low silicon levels. P. clandestinum growing in organic-rich soils (43.3% organic matter) contained much more Cu, Mn and Zn but less Si in the whole plant and Fe in the roots than species growing in a sandy matrix, indicating that Si does not interfere with the uptake of such nutrients. In 90% of the cases, roots have the highest average values regardless of the type of culture considered. Plants in sand substrates (82.2% sand) exhibited much more Si (particularly roots) than plants in organic-rich soils, despite the high carbonate content of both matrices and the acid pH used in the nutrient solution. The more Si is present in shoots and roots, the less P is detected. N/P ratios of shoots of sand culture confirm a nutrient limitation of P. Shoot biomass in organic-rich soils was approximately two times higher than in sand. Conversely, root biomass in sand was almost twice the average value in organic-rich soils. [ABSTRACT FROM AUTHOR]

The response of introduced ( Pennisetum clandestinum Hochst.) and native ( Stipa aristiglumis F. Muell., Themeda australis (R. Br.) Stapf, Danthonia spp. (L.) grasses to the herbicide atrazine was studied in plants with the potential for use in vegetated filters (biofilters) designed to reduce chemical loads in agricultural runoff. The response was detected by photosynthetic inhibition using leaf chlorophyll fluorescence. With continuous short-term (14 days) dosing with atrazine in sand culture, P. clandestinum showed the greatest tolerance, regardless of the dose (20–500 μg/L). In a clay vertosol soil in the glasshouse, the four species were tolerant to longer-term (84 days) application of three successive doses of simulated run-on, each dose containing 100 μg/L atrazine, a concentration which is comparable to the highest reported in runoff from agricultural land in Australia. Even with a subsequent single atrazine dose at ∼ ∼5000 μg/L, established plants of the four species showed signs of quick recovery (7–21 days) to normal photosynthetic activity. In a field experiment with simulated run-on, applied to P. clandestinum pasture in sandy loam soil, repeated doses at concentrations up to 1000 μg/L gave no significant response; only a subsequent single dose of 5000 μg/L had significant effects, from which plants soon recovered. Although damage from atrazine can be demonstrated with continuous dosing in non-adsorbing media, in soil culture the tolerance of the four selected species to repeat doses of atrazine shows they may be used confidently for biofiltering purposes. P. clandestinum was especially tolerant. [ABSTRACT FROM AUTHOR]

Solid-state 15N NMR spectroscopy was used to determine the chemical nature of nitrogen in 15N-enriched material from the roots and stems of wheat ( Triticum aesitivum), field pea ( Pisum sativum) and kikuyu grass ( Pennisetum clandestinum) and from the roots, stems and leaves of a eucalyptus species ( Eucalyptus globulus). Nitrogen-15 cross polarization (CP) spectra of the materials were all very similar, with 64–75% of total signal assigned to amide N. Spin counting analysis indicated that 37–80% of potential signal was accounted for in the CP spectra, and that NMR observability using the CP technique (N obs -CP) was higher for stems and leaves than for roots, and higher for wheat and eucalyptus than for peas and kikuyu. The 15N direct polarization (DP) spectra contained higher proportions of signal assigned to amine (up to 22%) and nitrate (up to 17%), and less assigned to amide N (50–72%) than the corresponding CP spectra. Spin counting analysis indicated that 68–93% of potential signal was accounted for in the DP spectra, confirming the DP technique to be more quantitatively reliable than CP. [ABSTRACT FROM AUTHOR]

This article focuses on the phosphorus (P) content in Hawaiian kikuyugrass pastures and examines the potential phosphorus release to water. Pasture systems in Hawaii are based primarily on kikuyugrass. More specifically, kikuyugrass is the most widespread pasture grass in Hawaii and is common in tropical highland and subtropical environments throughout the world. This species is highly efficient in utilizing soil P and deficiencies appear to occur only in very P-infertile soils. Relationships among kikuyugrass P concentration, animal P requirements, and various soil P determinations are needed to help identify source areas for implementing pasture management strategies to limit P loss via overt land flow. A total of 51 rotationally stocked kikuyugrass pastures with contrasting soil chemical properties were sampled. The current study suggests that while Hawaiian kilruyugrass pastures tend to be sufficient to high in forage P, potential soil P release to water only appeared to be a possible environmental concern for the mollisol and inceptisol sites.

Introduction: One of the problems found in cattle exploitations is to typify the weighting of calves so they can be compared. To the moment, the most common practice in those exploitations is a lineal interpolation between two consecutive weightings, method that imposes severe restrictions concerning the period of time between weightings and determines the elimination of a great number of registrations. Objective: To make a graphic representation of the growth curves of four calves, in order to obtain the most appropriate equation for a better adjustment. Materials and methods: Four calves were monitored during 8 months (two Holstein cow calves, a Holstein bull calf and a mixed male bull calf, all of them born in close dates), the growth system used was bucket-stake. The males consumed milk until they were 85 days old and the females until they were 70, every day they were given 4 litters of milk-replacer: Processed cattle food was given to them until their fifth month, and in this period each animal consumed 12kg for a daily media rate of 80 gr. When they were two months old, the bucket-stake system was changed to a rotatory cattle keeping system on Pennisetum clandestinum grass (kikuyu). Since their first month of life, they were given 10 kg of Arachis pintoi (forage peanut) not dehydrated, coming from the pruning of the garden keepers from the Corporación's facilities. The data collection was made every week using a bovine metric tape. Results: A total number of 31 observations was obtained. The growth speed was higher in the bull calves, fact that can be explained by the higher consuming of milk replacer, because they had more access to it. The daily rate of weight gain was 589gr and 518 for the males and the females, respectively. [ABSTRACT FROM AUTHOR]

A laboratory experiment compared development and kikuyu, Pennisetum clandestinum Hochst. ex Chiov. South, consumption in preimaginal grass webworm, Herpetogramma licarsisalis (Walker), at 15, 18,20, and 25°C. Mean developmental time from oviposition to adult emergence was 25.0 d at 25°C, 43.4 d at 20°C, 50.4 d at 18°C, and 81.4 d at 15°C. Survival decreased with decreasing temperature but not significantly. Total and daily kikuyu leaf area consumed per larva differed significantly with temperature. Leaf consumption increased exponentially with in star. Some larvae developed through six in stars, rather than the usually reported five, at temperatures <25°C. Compared with five-instar H. licarsisalis, those with six in stars spent longer in the egg stage, had smaller head capsule widths at all but first instar, faster developmental rates but lower kikuyu consumption for each stadium above the second, and slower egg-adult development. Developmental time from egg to adult emergence was significantly shorter for females than for males due to a shorter female pupal stage. Results from this experiment support the view that H. licarsisalis is surviving close to its lower developmental limits over the winter period in Northland, New Zealand, and provide data that will be useful in conjunction with field-collected data for predicting potential geographical distribution and survival. [ABSTRACT FROM AUTHOR]

The ability of rhizosphere of four plant species to promote the degradation of charcoal-fixed atrazine and simazine in cement blocks of a long-term contaminated soil when mixed with a normal soil at 1:1 ratio was tested. Of the four selected plants viz., rye grass (Lolium perenne), tall fescue (Festuca arundinacae), Pennisetum (Pennisetum clandestinum) and a spring onion (Allium sp.) used in this study, only P. clandestinum was able to survive in herbicide contaminated soil while other plants died within few days after germination/transplanting. Both atrazine and simazine were degraded at a faster rate in contaminated soil planted to P. clandestinum than in unplanted soil. Within 80 days, nearly 45% and 52% of atrazine and simazine, respectively, were degraded in soil planted to P. clandestinum while only 22% and 20% of the respective herbicide were degraded in the unplanted soil. During 80-day experimental period, both microbial biomass and soil dehydrogenase activity were significantly increased (7-fold) in soil planted to P. clandestinum over that in unplanted soil. The suspension of contaminated rhizosphere soil, planted to P. clandestinum exhibited an exceptional capability to degrade both atrazine (300 μg) and simazine (50 μg) in a mineral salts medium over that of non-rhizosphere soil suspension. Results indicate that P. clandestinum, a C4 plant, may be useful for remediation of soils contaminated with atrazine and simazine. [Copyright &y& Elsevier]

Stockpiling of warm-season perennial grasses for grazing after frost is a management practice that can lower livestock production costs. Six seeded bermudagrass [Cynodon dactylon (L.) Pers.] cultivars, two bahiagrass (Paspalum notatum Flugge) cultivars, and a kikuyugrass (Pennisetum clandestinum Hochst. ex Chiov.) cultivar were compared with 'Coastal' and 'Tifton 85' bermudagrass in a small plot study in northeast Texas. Plots were sampled monthly from October through February in 1999 through 2002 to monitor accumulated dry matter (DM), crude protein (CP), and acid detergent fiber (ADF). Initial standing forage mass was <3000 kg DM ha-1 and remained relatively stable during the sampling period in the first 2 yr. In the third year, initial standing forage mass was >4000 kg DM ha-1 and declined during the sampling period for all entries. Standing forage mass of Tifton 85 bermudagrass was usually greater than the other entries. Crude protein decreased with time, but the rate of decline was related to initial CP concentrations and forage maturity at first frost. Bahiagrass cultivars and kikuyugrass generally had higher CP concentrations than bermudagrass cultivars. Crude protein concentrations were always above the minimum requirements for mature, nonlactating, pregnant beef cows (70-80 g kg-1). Acid detergent fiber increased with time for all entries, with the largest monthly increase usually occurring after December. The ADF concentration in bahiagrass cultivars was always higher than in bermudagrass cultivars and kikuyugrass. Species suitability for stockpiling forage was bermudagrass > kikuyugrass > bahiagrass. Tifton 85 was superior to the other bermuda grasses because of greatest autumn growth. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effect of salinity on growth, nutritive properties and carbohydrate metabolism of Pennisetum clandestinum Hochst. Salt stress was induced by adding NaCl at different concentrations to the nutrient solution: 0, 50, 100, 150 and 200 mM. After 15 days under such stress, plants were actively growing up to 100 mM NaCl. Salinity affected root length more than leaf length. The invertase activity significantly enhanced in leaves and decreased in roots of kikuyu grass at 150 and 200 mM NaCl. In plants exposed to highest salt conditions, we observed an accumulation of hexoses and a lower activity of glucokinase (GK), phosphoglucoisomerase (GPI) and pyruvate kinase (PK). The glucose-6-phosphate dehydrogenase (G6PDH) decreased increasing salt concentration, showing at 200 mM NaCl the strongest reduction. The phosphoenolpyruvate carboxykinase (PEPCK) activity slightly and progressively increased in a concentration-dependent manner. Exposure of kikuyu grass to 150 and 200 mM NaCl caused an increase of NADP+-specific isocitrate dehydrogenase (IDH) activity in leaves and roots. The nutritive properties of kikuyu decreased in grass treated with 150 mM and even more with 200 mM NaCl. These data indicate that kikuyu is a grass tolerant to salinity up to 100 mM, suggesting its possible utilization in saline land where the survival of other fodder species is markedly reduced. [Copyright &y& Elsevier]

Sixteen growing intact male Criollo sheep, 19.9±2.5 kg initial live weight, were randomly allocated to metabolic cages. Four treatments with four replications were evaluated. The treatments were: T1=100% Kikuyu (Pennisetum clandestinum) grass hay (KGH); T2=25% Buddleia skutchii leaves (BSL)+75% KGH; T3=50% BSL+50% KGH, and T4=75% BSL+25% KGH. The highest (P<0.05) dry matter intake (DMI) was for T2; the neutral detergent fibre (NDF) intake for both T1 and T2 (535 and 563 g per day, respectively) were similar (P>0.05) and both were higher in comparison with the rest of the treatments. Digestibilities of dry matter (DM), crude protein (CP), NDF and acid detergent fibre (ADF) were not statistically different (P>0.05) for treatments T1, T2 and T3, and both T1 and T2 were significantly (P<0.05) higher than T4. The daily live weight gains (DLWG; 19.5 and 19.0 g per day, respectively) were similar for both T1 and T2, and significantly higher than T3 and T4. The total wool production (WP) and manure production results were not statistically different between treatments (P>0.05). Nevertheless, there was a clear tendency in reduced DMI, digestibilities and DLWG when replacing KGH with 50 or 75% of BSL. In addition, a basic economic evaluation was carried out. The best net benefit (NB; US $1.01) and direct return rate (DRR; US $0.32) was for T1, but both NB and DRR were reduced for all levels of BSL inclusions. [Copyright &y& Elsevier]

Presents information on a study which compared the alkane method of measuring herbage intake in ruminants with actual intake determined by transponder-controlled feed gates. Material and methods; Grass samples; Chemical analysis of the herbage fed; Measurement of actual kikuyu herbage intake.

Although sewage effluent and sludge provides nutrients for plant growth, its continual use over extended periods can result in the accumulation of heavy metals in soils and in grass to levels that are detrimental to the food chain. This study was carried in 2001 out at Firle farm, owned by the Municipality of Harare, to assess heavy metal loading on a sandy soil and uptake of the metals by pasture grass consisting of a mixture of Cynodon nlemfuensis (star grass) and Pennisetum clandestinum Chiov (kikuyu grass) following sewage effluent and sludge application for 29 years. Firle Farm receives treated effluent and sludge emanating from domestic and industrial sources.Soil and grass samples were taken from the study area, consisting of 3 ha of non-irrigated area (control) and 1.3 ha of irrigated area. Both the soil and grass samples were tested for Cu, Zn, Ni and Pb using atomic absorption spectrophotometry. Sewage sludge addition resulted in high levels of soil pollution, especially in the 20 cm horizon, in the irrigated area when compared to the control. Grasses took up moderate levels of Cu and Zn, and limited levels of Pb. Nickel was not detectable in grasses despite high levels in the irrigated soil. Copper uptake was several times higher than the suggested potentially toxic level of 12 mg/kg [Soil Science Society of America, Micronutrients in agriculture, second ed., Wisconsin, USA, 1991]. Lead uptake averaged 1.0 mg/kg, which was below 10 mg/kg the suggested limit for agronomic crops [E.M. Seaker, Zinc, copper, cadmium and lead in minespoil, water and plants from reclaimed mine land amended with sewage sludge, 1991]. Cu and Zn showed relatively higher mobility down the soil profile than Ni and Pb. Even then, the concentrations in the lower soil layers were very small, suggesting that the metals were unlikely to contaminate groundwater. There was no direct correlation between metal levels in soils and grasses. It was postulated that it is the bio-available metal fraction in the soil that is correlated to plant uptake. The grasses appeared healthy even though they contained moderately high levels of Zn and Cu. This raises the possibility of beef animals grazing on “healthy” looking grass that has very high concentrations of heavy metals. The fact that the total metal concentrations in the experimental soil were very high but did not cause any toxicity symptoms to the grass suggested that the limit soil concentration do not necessarily imply toxicity to all plants. However, limit concentrations are set not only for plant growth, but also for the protection of soil microorganisms and the latter are more sensitive to heavy metal pollution. [Copyright &y& Elsevier]

Thulin M. & Phillips S.: The identity of Pennisetum longistylum (Poaceae). - Willdenowia 45: 173-175. 2015. - Version of record first published online on 06 July 2015 ahead of inclusion in August 2015 issue; ISSN 1868-6397; © 2015 BGBM Berlin. DOI: Pennisetum longistylum, recently stated to be an older name for the well-known P. clandestinum ( Cenchrus clandestinus), is shown to be a hybrid between P. clandestinum and P. villosum ( C. longisetus). This is a rare hybrid only known from a few gatherings from the highlands of Ethiopia and Eritrea, the most recent one made in 1916. The new combination Cenchrus × longistylus is proposed, and the names P. clandestinum and P. villosum are lectotypified. [ABSTRACT FROM AUTHOR]

The investigation entailed four trials in which selenium (Se) was supplemented to lambs grazing kikuyu (Ponnisetum clandestinum) pastures during two summer periods or Italian ryegrass (Lolium multiflorum) pastures during two winter periods. Two methods of supplementing the lambs were tested, via fertilizing the pasture with Se and/or injecting a long-acting parenteral Se supplement, and compared with the unsupplemented controls. Ryegrass was more effective (P < 0.01) in accumulating Se when fertilized than kikuyu where the response was so low that the lambs could not meet their Se requirements through the supplemented kikuyu. The tissue Se concentrations of the lambs on Se fertilized ryegrass were higher (P < 0.001) than those in the controls, for example hepatic Se concentrations of the two control groups were 124 and 137 ng/g dry matter (DM) compared to 965 and 848 ng Se/g DM in the respective groups consuming the Se fertilized ryegrass. Parenteral supplementation was effective in supplying Se requirements of the lambs. However, lambs that lost weight during the second season on kikuyu had higher (P < 0.01) tissue Se concentrations than the parenterally supplemented groups during the other trials. Selenium tended to accumulate in a non-linear and decreasing rate with an increase in level of Se intake. It was concluded that with the present recommendations Se fertilization of kikuyu cannot be recommended as a method of supplementing Se to the grazing animal. [ABSTRACT FROM AUTHOR]

The selenium (Se) status of lambs grazing kikuyu (Pennisetum clandestinum) or ryegrass (Lolium multiflorum) in the KwaZulu-Natal Midlands was determined during four trials and their growth response to Se supplementation was measured. Two methods of Se supplementation were evaluated using a 2 x 2 factorial experimental design per season: a control, Se supplemented via fertilizing the pasture and/or injecting the lambs with a long-acting parenteral Se product. The Se concentrations in the whole blood of the unsupplemented groups at the end of the trial varied between 9 and 26 ng/ml, those in plasma between 5 and 15 ng/ml and in the livers between 96 and 163 ng/g DM. From these parameters it was concluded that the lambs were in state of Se deficiency, even though no symptoms of Se deficiency were observed. The lambs on the kikuyu did not grow well and even lost weight during the second summer. Despite the low weight gain during the first summer, a better (P < 0.05) growth response was obtained in the group receiving the parenteral Se supplementation above that of the unsupplemented group and the one grazing the Se fertilized kikuyu. The cumulative weight gains in both the Se fertilized groups during one ryegrass trial were higher (P < 0.05) than those in the control and parenteral supplemented groups. It was concluded that, although Se supplementation improved the growth of the lambs, the response varied between years. It was suggested that the poor growth of the lambs in some years was caused by factors other than a selenium deficiency and had to be overcome to obtain a positive response to Se supplementation. [ABSTRACT FROM AUTHOR]

Pennisetum clandestinum Hochst ex Chiov. (kikuyugrass) is a C4 grass that has become an invasive weed in temperate climates. We examined ecophysiological mechanisms that have allowed it to become a successful weed in these locations by comparing P. clandestinum and two other common turfgrass species, Festuca arundinacea Schreb. (tall fescue cv. Mojave), a C3 cool-season grass, and Stenotaphrum secundatum (Walt.) Kuntze (St. Augustinegrass), a C4 warm-season grass, grown in a warm or cool growth regime. We measured rates of photosynthesis over a range of leaf temperatures and also measured growth rate parameters of these species. At leaf temperatures between 25°C and 40°C P. clandestinum maintained the highest rates of photosynthesis in both temperature regimes. Under warm temperatures, this species rapidly increased biomass and leaf area to a greater extent than either of the other two grasses. Theoretical whole plant photosynthesis (mean leaf are a X mean photosynthetic rate) was higher for P. clandestinum than for the other two species in both growth regimes and over most leaf temperatures. Our results suggest that P. clandestinum is a successful weed in Mediterranean climates as a result of its capacity to photosynthesize over the full range of temperatures found in those climates, its rapid growth during warm weather and its apparent tolerance to moderately cool temperatures. [ABSTRACT FROM AUTHOR]

Kikuyu grass (Pennisetum elandestinum) is widely used as a grazing pasture in Africa and, although it is extensively cultivated as a lawn for sports fields and domestic gardens, its allergenicity has never been studied in vitro. Using an extract of Kikuyu grass pollen, polyacrylamide gel electrophoresis. Western blotting and a monoclonal anti-human IgE antibody, the specific lgF binding, in the serum of 160 allergic and non-allergic patients in the Cape Town area, to a Kikuyu grass extract was studied. IgE in the sera of 43/104 known grass-allergic individuals bound to Kikuyu grass on the Western blots. In addition, 4/28 'non-allergic" control subjects were found to have Kikuyu grass-specific IgE. Five different profiles of specific IgE reactivity to Kikuyu grass antigens were oberved. In 29/43 patients, IgE bound to two dominant 48 and 70 kD allergens in the Kikuyu extract. Although a degree of cross-reactivity with Bermuda gruss (Cynodon dactylis) was found in immunoabsorption studies, the 48 and 70 kD allergens appear to be unique to Kikuyu grass. Exposure of heparinized blood from Kikuyu grass-positive patients to the Kikuyu extract stimulated the release of histamine from their basophils in vitro. Kikuyu grass pollen is thus identified as an important aero-allergen in South Africa. [ABSTRACT FROM AUTHOR]

The survival and digestion of seeds of 47 tropical and subtropical legume and grass species were studied by placing the seeds in nylon bags in: the rumen of fistulated cattle, followed by acid-pepsin digestion, to identify any differences likely to affect dissemination by grazing cattle. Seeds of only four of the 23 grass species survived in appreciable humors. Digestion for short periods actually increased gemination of Digitaria ciliaris, Axonopus affinis and Paspalum notatum while seeds of Pennisetum clandestinum survived up to (10 days in the rumen. All four are creeping, sward-foxing species, adapted to heavy) grazing Few seeds of the tall tussock grasses survived the digestive protests. Survival of legume seeds was closely related to the hard seed content of the sample. Soft seeds were killed within 6h. The rate of breakdown of bard seeds during digestion varied with Species. Most tropical legumes had sufficient hard seed to ensure some dissemination if ingested. Hard legume seed was little affected by up to 241: h immersion in a rumen. Digestibility of legume seed was inversely related to hard-seededness. The nylon bag: technique with the two stage: diction gave a good prediction of which seeds could survive passage through the digestive tract of cattle. For legumes, the: hard seed content gave an easy and usually reliable indication of the resistance of seed to digestion. [ABSTRACT FROM AUTHOR]

Seeds of 10 legumes and eight grasses found in tropical and subtropical pastures were placed directly into the rumens of cattle. Their survival and rate of passage through the digestive tract was studied over a 160-h period. After excretion, the survival of seed was followed in dung pats. Overall, More legume seeds than grass seeds survived passage through the digestive tract but there was marked variation between species in both grasses (0–64%) and legumes (0–78%). Survival of the legume seeds, both in the animal and in the dung, was largely dependent on the fraction of hard or impermeable seed in the sample. Soft seed swelled on imbibition, the seed-coat ruptured, and seeds became fragmented especially after 70 h in the digestive tract. No common mechanism appeared responsible for the survival of grass seeds in the tract. However, seeds of Pennisetum Clandestinum, which are consumed heavily by cattle, survived better than seeds of tall tussock grasses which are rarely eaten. There was a two-fold difference between legume species in the time for 50% of seed to be excreted. Over 82% of this variability was accounted for by three factors: specific gravity, proportion of hard seeds and seed size (i.e. large, dense seeds with little hard seed had the fastest rate of passage). The results show that there is considerable potential for the dissemination of hard-seeded legumes (e.g. Stylosanthes) by cattle but not tall, tussock grasses. [ABSTRACT FROM AUTHOR]

Temperature is the main factor governing the rate of acetylene reduction by mats of blue-green algae in sub-tropical kikuyu lawns. High midday temperatures (40°C at soil surface) inhibit acetylene reduction and low temperatures prior to dawn reduce the rate of nocturnal acetylene reduction. Data obtained from laboratory studies on algal mats and on Nostoc isolated from the mats are in agreement with those from in situ measurements confirming an acetylene reduction of 30-35°C with inhibition above 40°C. [ABSTRACT FROM AUTHOR]

In situ measurements using the acetylene reduction technique showed that mats of blue-green algae found amongst kikuyu grass fixed nitrogen throughout the day and night. Daylight fixation increased throughout the morning, fell during the hottest part of the day, and reached a peak (19.2 mg C[sub2]H[sub4] m[sup-2] h[sup-1] during the afternoon. Nitrogen fixation was higher on overcast days than on hot sunny days. Nocturnal fixation was also due to blue-green algae and was sensitive to temperature changes. [ABSTRACT FROM AUTHOR]