Survival of plants of common sainfoin (Onobrychis viciifolia Scop.) in competition with two companion grass species

A 2-year experiment on competition between sainfoin ( Onobrychis viciifolia Scop.), meadow fescue ( Festuca pratensis ) and tetraploid perennial ryegrass ( Lolium perenne ) was conducted using plants grown in plastic containers outdoors. Root and shoot systems of sainfoin and the grasses were separated in order to investigate full and no competition of root and shoots, at two planting ratios (0·33 grass:0·66 sainfoin and 0·66 grass:0·33 sainfoin). Survival of sainfoin plants was lower at the higher grass:sainfoin ratio. More sainfoin plants died in the winter than during the growing season. Root competition had no effect on survival of sainfoin plants, but shoot competition reduced survival of sainfoin plants during one growing season. Companion grass species had no effect on survival of sainfoin plants, except in the first winter, when fewer sainfoin plants survived when grown with meadow fescue than perennial ryegrass.     

Alfalfa production as influenced by pest stress and early first harvest in Oklahoma

Alfalfa forage yield, stand persistence and root total non-structural carbohydrate (TNC) reserves under variable first-harvest schedules were investigated with or without pest stress during a 4-year period in Oklahoma. Combined stresses due to weeds, alfalfa weevil and aphids reduced alfalfa forage yield in three cultivars by some 2 · 1 t/ha with significant reductions in OK08 and Arc, but not in WL 318. In addition, combined stresses significantly reduced stand persistence and TNC reserves. No significant cultivar x pesticide, cultivar x harvest schedule, or harvest schedule x pesticide interactions occurred. These data suggest that pesticide applications did help to preserve alfalfa stands and productivity. The need for such applications was much less in the pest-resistant cultivar WL 318. Early bud harvesting did not consistently result in reduced productivity of alfalfa relative to other harvest schedules, regardless of the cultivar being analysed or the pesticides applied.     

Effect of drought on biomass allocation in two invasive and two native grass species dominating the mixed‐grass prairie

Control of exotic plant species invading the native prairie relies on our understanding of the eco‐physiological mechanisms responsible for the spread of these species as they compete with native plants for soil resources. We used a greenhouse pot experiment to study vegetative biomass allocation in response to drought stress in two exotic grass species, Kentucky bluegrass (Poa pratensis L.) and smooth brome (Bromus inermis Leyss), and two native species, western wheatgrass (Pascopyrum smithii (Rydb.) A. Löve) and green needlegrass (Stipa viridula Trin.). The experiment was conducted over 3 months in 2010 and again in 2011 in a factorial design of four species and two drought treatments. The proportional data of biomass allocation to shoots, roots, rhizomes and crowns (shoot base) of grass seedlings were analysed by both the nonparametric Mann–Whitney U‐test on the original data and one‐way anova on the arcsine‐transformed data. Our data suggest a clear distinction between the two invasive and two native species in potential competitiveness in soil resource use, with the two exotic species having higher biomass allocation to roots than the two native species and the native species having a higher biomass allocation to crowns than the two exotic species. It is interesting to note that the strongly rhizomatous smooth brome did not produce rhizomes in the first season's growth, regardless of the water stress level. The effect of drought stress on biomass allocation manifested itself more on rhizomes or crowns than on roots or shoots of the four studied grass species, with the effects species‐specific in nature.     

The production and persistency of different grass species cut at different heights

The effect of two heights of cutting (5 and 8 cm) on the dry matter harvested and persistency of a range of different grass species and varieties were monitored over a 3-year period (1976 to 1978). Dry matter harvested was measured in the second and third harvest year and persistence of sown grass was assessed at the end of the first and third harvest year. The grasses were managed under a frequent cutting system, i.e. simulated grazing. Results showed that at the low cutting height tetraploid hybrid ryegrasses and diploid Italian ryegrasses in the third harvest year gave lower annual dry matter harvests of sown grass and were less persistent than at the high cutting height, whilst, in contrast, perennial ryegrasses gave higher annual harvests of sown grass but persistency was unaffected. In general at the low cutting height varieties of cocksfoot, meadow fescue and tall fescue gave comparatively higher annual harvests of sown grass in the second harvest year but lower yields of sown grass in the third harvest year. A notable exception was Cambria cocksfoot which in the second harvest year gave higher yields of sown grass and was more persistent at the low cutting height.
However, at 5 cm cutting height, the proportions of weed grasses (mainly Poa spp.) in swards sown to tetraploid hybrid ryegrasses and diploid Italian ryegrasses were generally greater, particularly in mid-season.     

Mixed‐grass prairie rhizome biomass is influenced by cattle grazing intensity

This study was conducted on a mixed‐grass prairie in south‐central North Dakota, USA, to test the effect of animal grazing on rhizome biomass. Below‐ground plant biomass samples were collected from pastures with moderate and heavy grazing by beef cattle. Because the biomass data did not meet the normality assumptions, the computer resampling method involving a nested anova was used. A reduction in rhizomes was found under heavy grazing, as compared with moderate grazing. Although rhizomes only accounted for a small fraction of total below‐ground plant biomass, our study suggested that the high rhizome density found in the moderately grazed pastures might be partly responsible for the greater potential of plant regrowth in the moderately grazed pastures than in the heavily grazed pastures on this mixed‐grass prairie.     

Potato top growth as influenced by temperatures

A study was conducted to establish a growth rate response of potato plant (Solanum tuberosum L.) tops to exposure to 72-hr periods of six constant temperature treatments (10, 15, 20, 25, 30, 35°C) and to determine a thermal optimum for vegetative potato growth rates. The plants were maintained under “no stress” soil moisture conditions throughout the study. The temperature treatments were accomplished by inserting the plants into a growth chamber for 72 hours at selected temperatures. Maximum growth (as measured by percent change in leaf area) occurred at 25°C with temperature growth differences significant at the 5% level. Plant height measurements (percent change occurring during treatment time) showed maximum stem elongation at 30°C during an early growth stage and 25°C during stage 2 (4 weeks later). Predictive models developed from the data indicate maximum rates of leaf area increase in both growth stages occur at 24.7°C and that maximum rates of stem elongation occur at 31.3 and 27.4°C for growth stages 1 and 2, respectively. Leaf water potential and stomatal resistance measurements taken at the end of each treatment period indicated that no water stress occurred.     

The choice of grass species to combat desertification in semi‐arid Kenyan rangelands is greatly influenced by their forage value for livestock

Livestock production is the main source of livelihood in the arid and semi‐arid lands in Africa. However, desertification characterized by vegetation degradation and soil erosion is a major threat to the sustainability of land‐based production systems. Native rangeland forage species Cenchrus ciliaris L. (Buffel grass/African foxtail grass), Eragrostis superba Peyr. (Maasai love grass) and Enteropogon macrostachyus (Hochst. Ex A. Rich.) Monro ex Benth. (Bush rye grass) have been used to combat desertification. The objectives of the study were to identify the best‐suited native grass species to combat desertification in a semi‐arid environment in Kenya and to identify the preferred grass species among the agropastoralists in the area. Percentage basal cover, plant densities and frequencies of the three grasses in pure stands and mixtures were estimated. Grass species preferences were through household survey and focus group discussion. Results showed a significant difference (P < 0·05) in plant densities and cover estimates: E. macrostachyus was ranked first; C. ciliaris and E. superba were ranked second and third respectively. The agropastoral farmers, however, preferred E. superba followed by C. ciliaris and E. macrostachyus, a reverse trend. These results suggest that the choice of grass species to combat desertification is influenced more by its contribution as a source of forage for livestock than its contribution for rehabilitation purposes.     

Prevalence of Listeria species as related to chemical quality of farm-ensiled grass

The occurrence of Listeria spp. in pasture grass and grass silage made with various additives and preservation techniques is reported. Silage samples were collected three times (in November, February and May) from eighty dairy farms. The prevalence of Listeria spp. in pasture grass samples was 0.647 and in silage samples 0.227. Only two species, L. monocytogenes and L. innocua were observed. Listeria spp. Were isolated from the silage at least once at thirtynine farms (0.488), and L. monocytogenes at twenty-seven farms (0.338). The occurrence of Listeria was highest among the silage samples collected in November (0.288). Silages preserved with acids had the lowest prevalence of Listeria (0.194). Silages preserved in tower silos were most often free of Listeria, only 0.056 being positive. The highest prevalence of the Listeria spp. (0.324) was detected in clamp silage. The results of chemical analyses of silage statistically reflect the frequency of Listeria.     

Differences in lamina wettability in some permanent pasture grass species and two Lolium perenne cultivars

Lamina wettability, assessed using water droplet contact-angle and surface water-retention measurements on excised leaves, was examined in Lolium perenne cv. Melle, cv. Condesa and an indigenous population from an old pasture, Holcus lanatus, Poa trivialis and Agrostis stolonifera. The species fell into two significantly distinct categories, those with unwettable laminae, namely H. lanatus and A. stolonifera , and those with highly wettable laminae, P. trivialis and the three L. perenne populations. There was no significant difference between the L. perenne populations, which had the most wettable laminae overall. The possible implication of these differences in lamina wettability on animal production is discussed.     

Seed characterization and direct sowing of native grass species as a management tool

There is insufficient information about germination, seed biology and seedling establishment of native grass species of the cerrado (Brazilian savannah) to recommend their use in restoration of disturbed areas. We evaluated the production, percentage of fertile seeds, germination, seedling growth and establishment in the field of eighteen native grass species and one exotic invasive species (Melinis minutiflora) and also the effects of different storage periods on germination. The percentage of fertile seeds varied from 6·0 to 94·2% among native species. Ten species produced a minimum of 800 fertile seeds per gram. Germination rate was in the range of 11·0 to 98·8%. Storage for 1 year reduced the germination rate in one species, did not affect germination of three species and increased germination (by 2–10 times) in 14 species. After 2 years of storage, six species showed reductions in germination. Three different patterns of resource allocation were observed and might provide mechanisms for increasing seedling establishment under different environmental conditions. In the field, only two species flowered in the first year after sowing and an additional eight in the second year of observation. Melinis minutiflora is an aggressive species with more than three times the fertile seed production of native species (2820 seeds per gram), high germination rate (55%) and a high number of germinable seeds (1551 per gram). Despite the wide variation in seed characteristics and the delay in flowering, it is concluded that most native grass species can be used in projects aiming at the restoration and management of degraded areas.     

Aspergillus flavus growth and aflatoxin production as influenced by total lipid content during growth and development of cottonseed

Aspergillus flavus infects several food and feed crops, such as corn (Zea mays L.), cotton (Gossypium hirsutum L.), peanuts (Arachis hypogaea L.), and tree nut crops and contaminates the seed with carcinogenic aflatoxins. These susceptible crops contain rich reserves of lipids and fatty acids. The nature of relationship between lipids and the ability of the fungus to infect and produce aflatoxins in mature cottonseed, a protein-rich animal feed, has been addressed previously. In this study, we tracked lipid accumulation in developing cottonseed (15–35 days post-anthesis [DPA]) and also the ability of an aflatoxigenic strain and an isogenic non-aflatoxigenic strain to grow and produce aflatoxins in planta. The aflatoxigenic strain Af-70 green fluorescent protein (GFP) and the isogenic, non-aflatoxigenic strain SRRC 1500 (fungal collections maintained at the Southern Regional Research Center) did not differ much in infection and colonization of cottonseed. The non-aflatoxigenic strain did not produce aflatoxin at all stages of cottonseed development, whereas the aflatoxigenic strain Af-70 GFP produced copious amounts of aflatoxin and it coincided with the increasing levels of lipids, especially in mature cottonseed (30–35 DPA). Fungal growth, as quantified by the GFP expression in the fungus, was highly correlated with toxin production.     

Reseeding in the Falkland Islands. Herbage production of a range of grass species and cultivars

The productivity of 20 cultivars from a range of 13 grass species was compared by harvesting four times during each of three successive growing seasons. In the experiment, 120 kg N ha⁻¹, 42 kg P₂O₅ ha⁻¹ and 42 kg K₂O ha⁻¹ were applied annually.
Mean annual yield was 3229 kg DM ha⁻¹ and 2147 kg DOM ha⁻¹. Cultivars were arranged in seven groups for comparison. Three of the groups, Lolium, Phleum and 'others' (the latter consisted of Festuca arundinacea cv. Dovey and Poa pratensis cv. Bensun A.34) appeared significantly lower yielding than the Dactylis, Festuca (fine-leaved), Agrostis and Holcus groups.
In the Lolium group, cv. Gremie outyielded cv. Melle every year. No cultivar of Dactylis was significantly better than any other in its group. Phleum CVS Motim and Eskimo were similar and superior to cv. S.50. Festuca ovina cv. Novina and Agrostis canina cv. Kingstown were marginally the best in their respective groups. The two cultivars of Holcus performed virtually identically. Festuca arundinacea cv. Dovey was a good producer of early spring grass. Poa pratensis cv. Bensun A.34 was generally low yielding and subject to fungal rust attack in autumn. The pattern of seasonal DM production was 16% in early spring (cut in October/November), 39% in mid-season (cut in December), 40% in late summer (cut in February/March) and 5% in autumn (cut in April/May). Quality of the herbage was superior to the main indigenous grass Cortaderia pilosa.
It was concluded that although the experiment was conducted under a cutting regime it provided useful guidance for seeds mixture formulation and stock carrying capacity calculations.     

Potato storage quality as influenced by rate of ventilation

Insulated bins containing approximately 1800 kg (2 ton) were ventilated at airflow rates of 0, 2.3, 4.7, 9.4, 18.7, 37.5, and 74.9 m³/h/T(0, 1.25, 2.5, 10, 20, and 40 cfm/t). Replicated trials over a three year period showed that ventilating with an airflow rate of 18.7 m³/h/T (10 cfm/t) resulted in the lowest combined storage loss due to weight, sprouts, and rot. The time required to grade the tubers from the bins ventilated with airflow rates greater than 9.4 m³/h/T (5 cfm/t) was significantly less than that from those receiving lower airflow rates. There was no significant difference in tuber temperature at the top of the bins having an airflow rate of 9.4 m³/h/T (5 cfm/t) or more.     

Properties of sugar-snap cookies as influenced by lauric-based shortenings

The objective of this work was to assess the effect of different lauric-based shortenings with varying solid fat content (SFC) on sugar-snap cookie dough properties and cookie quality. Shortenings were produced by blending high oleic sunflower oil, palm kernel oil and palm stearin in different ratios, obtaining shortenings with different SFCs. It was observed that the SFC of the shortening largely influences the rheological properties of the cookie dough. At small deformations, fat crystals add elasticity to the dough; while at large deformations, fat-structure is disrupted, and it does not contribute to dough hardness. Fats with intermediate SFCs decrease dough resistance due to an enhanced shortening ability. Nevertheless, this effect is only obtained when shortening is homogeneously distributed in the dough. The SFC of the shortening influences dough and cookie structure by preventing gluten polymerization which was observed by a decrease in cookie break strength. A prerequisite for this effect is that shortening is finely dispersed in the dough. Good quality cookies were obtained using lauric-based shortenings, and best results were obtained with SFC between 20 and 25%. Higher SFC (around 45–50%) led to the production of unacceptable sugar-snap cookies.     

Dynamics of structural traits in two competing C3 grass species: influence of neighbours and nitrogen

This work analysed the regulatory structural mechanisms involved in the competitive interactions between the annual grass Bromus willdenowii Kunth. (BW = prairie grass) and the perennial C₃ grass Dactylis glomerata L. (DG = orchardgrass) during pasture establishment. Four combinations of species (pure BW, pure DG, DG flanked by BW and BW flanked by DG plants), with and without winter nitrogen fertilization, were factorially arranged in a randomized complete block design. Data were recorded at two organization levels: tillers (three tiller age cohorts) and target plants. Annual neighbours caused a decrease in the number of living leaves in tillers of intermediate age of both species. This structural regulatory mechanism led to a decrease in tiller number per plant and, therefore, restricted the development of horizontal space occupation. Annual neighbours did not cause an increase in tiller size, measured as lamina length or pseudostem height, but decreased root biomass. As a consequence, annual neighbours did not lead the hierarchy in light capture, but limited species radical colonization and competitive ability for soil resources. Winter nitrogen fertilization only affected tiller size in older tillers. These findings emphasize the importance of the cultural decisions, as sowing densities and nitrogen fertilization, to optimize pasture floristic composition.