Seeds Of Perennial Grasses Research Articles

Storage life for seeds of perennial grasses for breeding nurseries

Background. In the breeding of perennial grasses, the availability of a sufficient amount of seed material is of great importance, therefore, there remains a need to maintain a safety reserve of the seeds obtained and monitor their seeding quality. Studying changes in the laboratory seed germination during storage makes it possible to define the maximum period of their use. Materials and methods. The study employed 140 seed samples of awnless bromegrass (Bromopsis inermis (Leyss.) Holub), 300 of red clover (Trifolium pratense L.), and 88 of changeable alfalfa (Medicago varia Martyn), grown in Tyumen Province in 2008–2018. Seeds were permanently stored in a laboratory at a room temperature of 18–22 °С. Laboratory seed germination was assessed according to GOST 12038-84 annually from February to April for six years (2017–2022). The obtained seed germination rates were grouped according to the seed storage duration. Results and conclusions. A majority of awnless bromegrass and red clover seed samples, stored without applying any special conditions, remained viable in terms of their germination (at least 80 %) for 1.5 years after harvesting, and those of changeable alfalfa up to 5.5 years. Variations in seed germination rates among the seeds obtained in different years and those harvested within the same year changed with an increase of the storage period duration (V = 3.6–29.8 %), which attested to a greater heterogeneity of the material under study and could be caused by the presence and development of pathogenic microflora on seeds. Promising seed samples for breeding or for storage, with laboratory germination rates from 79 to 50 %, can be sown with an increased seeding rate on certain plots; meanwhile, the estimated maximum practical use for the seeds of awnless bromegrass is up to 3.5 years; for red clover up to 5.5 years; and for changeable alfalfa up to 8.5 years.

Innovative methods of agrobiological control over perenial grass seed production technology

Purpose. Plant production largely depends on the ability to obtain good quality seeds. Factors that lead to a change in the strategy of forage crop seeding in conditions of the Ukrainian market are the need for further intensification of the feed production industry, which is a prerequisite for the successful development of animal husbandry. In this regard, the main goal of forage crop seeding is to ensure sufficient production of leguminous and cereal grass seeds to improve and expand the areas of cultural pastures and hayfields, to optimize the structure of forage crop sown areas in field and meadow feed production, reclamation of eroded lands, creation of gardens and parks lawns with high aesthetic indicators, as well as for the export of seeds of perennial grasses. Methods. Field, laboratory, visual, measuring, weight, quantitative, test sheaf method, mathematical, statistical. Results. The data of long-term studies on the formation of high yields of leguminous and cereal grasses seeds are highlighted. It has been established that seed yield largely depends on technological factors, in particular, on the fertilization system in crop rotation, harvesting dates, crop preservation, biological characteristics of seed plants of these species. The exclusion of at least one of the operations provided by the technology leads to a significant decrease in the seed productivity of perennial grasses. Conclusions. In order to increase the volume of seed production of perennial leguminous and cereal grasses with high sowing and yield properties of the new generation varieties, innovative energy-saving technologies for their cultivation have been developed based on biologization of the production process, optimization of the mineral nutrition system, the use of chelated fertilizers and growth regulating preparations in the corresponding periods of the development of seed grass stands, which provides a 18-210% increase in seed productivity of perennial grasses, improves the sowing properties of seeds (growth strength, germination ability, weight of 1000 seeds) by 4-12%.

ТЕХНИКА И ТЕХНОЛОГИЯ ПОВЕРХНОСТНОГО УЛУЧШЕНИЯ ПОЙМЕННЫХ ЛУГОВ РЕСПУБЛИКИ ТАТАРСТАН

Research with the aim of developing and implementing highly effective methods of surface improvement of floodplain meadows with partial preservation of old herbage and sowing of new perennial grasses based on the widespread use of modern integrated agricultural machines and implements was carried out in 2016-2020 in the Republic of Tatarstan. The scheme of the experiment included the following options: processing of the sod of the floodplain meadow (factor A) – without processing; disking BDN 4 ×4 + flat-cutting processing to a depth of 22 ...24 cm KPG-2-150; processing with a universal cultivator-planar cutter with piercing action harrows (KPU-5,4) of the Perm Machine-Building Plant; processing with a cultivator-planar cutter equipped with a perforating action harrow (KPBL-3) of the Kazan State Agrarian University design; sowing of perennial grasses and mineral fertilizers (factor B) – without sowing and without fertilizers; sowing of alfalfa-stalk grass mixture at the rate of 12 kg/ha (6 million pcs/ha of germinating seeds) in combination with annual application in spring N45P20K45. The control was a natural grass stand without processing, without sowing and without applying mineral fertilizers. The results of the research have shown high efficiency of the complex application of the following agrotechnical techniques: layer-by-layer tillage using a cultivator-planer equipped with a perforating action harrow (KPBL-3), sowing seeds of perennial grasses and annual spring fertilizing N45P20K45. At the same time, the yield of the green mass of the floodplain meadow increases by 2.74 times compared to the original herbage, the profitability of feed production is 73.6%, the cost price is reduced to 6910 rubles. at the selling price for 1000 feed units, 12,000 rubles. The total energy costs for surface improvement of the floodplain meadow increase from 18.4 in the control variant to 21.6 GJ/ha, however, the accumulation of exchange energy in feed outstrips these costs by 3.2 times.

Improving Pasture Management

Referring to the author's comments and the results of research conducted in the article, it is stated thatexisting problems in pastures: overgrazing, biodiversity erosion, reduction of soil fertility and reduction of soil organic matter and CO2 emissions, soil salinization and alkalinization, development of erosion process, etc.), elimination of their multifunctional characteristics, pasture management. It is known that pastures are a supplier of many agricultural products, it protects soil fertility and biodiversity, protects the soil from wind and water erosion, carbon dioxide in the soil compared to arable land and forests. has good potential for storage, It has a protective effect on the restoration and regulation of groundwater levels, maintaining the quality of irrigation water and creates conditions for its leakage. Seed propagation of local species, soil softening - germination of seeds of perennial grasses and shrubs, conversion of slopes and arable lands into permanent pastures,inclusion of temporary pastures in crop rotation,feed production to support roduction - meat, milk, wool, etc. Given that pastures support agriculture and are a source of livelihood for the population.Restoration and protection of pastures (recreation, surface softening, surface and capital improvement works, creation of temporary pastures, conversion of sown areas on slopes into pastures, etc.) are of special importance;Action Plan of the “State Program approved by the Order of the President of the Republic of Azerbaijan No.

Aspects of the determining the sowing properties of seeds of perennial grasses express method effectiveness in comparison with domestic and international rules

Purpose. To theoretically substantiate the methodology for the accelerated determination of the sowing qualities (express method) of seeds of leguminous and cereal grasses, in particular germination capacity, the amount of hard seeds and viability in comparison with the defining those indicators according to the State standard of Ukraine (SStU 4138-2002), international methodology (ISTA – International seed testing association). Methods. Quantitative, laboratory, mathematical-statistical, observation, comparison, analysis and synthesis. Results. Determination of sowing qualities (germination energy, germination rate, amount of hard seeds) of forage crops according to the methods of SStU 4138-2002; ISTA (international rules for the analysis of seeds) and the express method of accelerated determination, showed the high efficiency and effectiveness of the latter (improved method of swelling seeds of leguminous grasses and preparatory caving of films and swelling of seeds of cereal grasses), which can be used in production conditions to obtain objective information on the sowing properties of seeds of the formed harvest. Conclusions. The express method can be used to determine the viability of legume grass seeds within 3-4 hours by establishing the difference between the number of live and dead seeds. The data obtained are close to the germination rates when analyzing seeds according to the SStU 4138-2002 and ISTA methods and make up 90-95; 93-95; 92-95% respectively. Germination of seeds of cereal grasses using the caryopsis method allows determining the viability of seeds on the 2nd-5th day in species with high germination energy (Bromus inermis, different types of Lolium perenne) and 7th-10th day in species with slow germination (Festuca rubra L). Seed germination of these species according to the express method was 84- 92%, while according to the SStU 4138-2002 and ISTA methods it made up 91-94; 90-96%, and the analysis was carried out on the 10th and 21st day.

Study of the efficiency of drying grass seeds for forage crops on a rotary dryer

In many countries of the world with high climate humidity, grass seeds after their harvesting cannot be preserved without artificial drying. The artificial drying process is associated with high energy costs, and its regimes should not reduce the sowing quality of seeds. Therefore, it is of particular importance to determine the most suitable drying regimes for seeds. For this purpose, for the conditions of seed farms in the North-West of the Russian Federation, experimental studies were performed to obtain information on the parameters and modes of drying seeds of perennial grasses for their various initial states and conditions. Experimental studies were performed on a rotary dryer during the drying of meadow fescue seeds. The experimental data were analyzed in Microsoft Excel 2010 using the methods of mathematical statistics. The obtained mathematical dependencies made it possible to establish that the effective modes of drying the seeds of the studied culture are provided during their layer-by-layer unloading from the drying chamber. Moreover, the lower layer of seeds should be unloaded every 2.5 hours of drying, while adding to the upper layer of the drying chamber a new volume of seeds equal to the unloaded one.

ВЛИЯНИЕ МИНЕРАЛЬНЫХ УДОБРЕНИЙ НА ИЗМЕНЕНИЕ БИОХИМИЧЕСКОГО СОСТАВА ГЕТЕРОГЕННЫХ ПОСЕВОВ ЛЮЦЕРНЫ ИЗМЕНЧИВОЙ С МЯТЛИКОВЫМИ ТРАВАМИ НА СЕРЫХ ЛЕСНЫХ ПОЧВАХ ЦЕНТРАЛЬНОГО РЕГИОНА РОССИИ

Sustainable development of animal husbandry and feed production now can be characterized by a complex approach to the introduction of elements of intensive agricultural technologies, the main direction of which should be the rise of natural resource potential of agrocenoses and, as a result, achievement of the necessary amount of balanced carbohydrate-protein complex of highly nutritious feed. Until now, the structure of seeds of perennial grasses has been dominated mainly by bluegrass species. In the future, agricultural producers plan to expand the area of perennial grasses with an increase in the share of legume species in herbage mixtures. Perennial legumes in single and mixed sows are the main components in solving the problem of protein deficiency in the production of highly nutritious feeds. It is known that mixed (heterogeneous) sows of perennial legumes and bluegrass grasses have a clear advantage in productivity over single-species agrocenosis due to the fact that they are much more efficient in using nutrients from the soil and fertilizers, moisture, solar insolation due to the different structure of bush and root system of perennial grasses. When carrying out experiments in the fields of Bryansk SAU, a modern assortment of variable alfalfa and bluegrass perennial grasses was used. In herbage mixtures, the bean component varied from 40 to 50%. Seeding was carried out under the cover of annual ryegrass westerwold (Lolium westerwoldicum Wittm.), diploid variety Izorsky. As a legume component, we used variable alfalfa (Medicago varia Mart.). The bluegrass component is represented by the meadow Timothy (phlum pratense L.),meadow fescue (Festuca pratensis Huds.), cocksfoot(Dactylis glomerata L.), smooth brome (Bromopsis inermis Leyss.). at the present time, the introduction of modern science-based fertilizer systems and technologies for the cultivation of heterogeneous seeds based on the inclusion of crops with productive longevity in their composition will solve the problem of increasing production highly nutritious feed.

Restoration of degraded mountain pastures of the Сentral Сaucasus by targeted sowing of seeds of perennial grasses

The unsystematic use of mountain pastures with overgrazing of grasses has led to a change in the ecological balance of agrolandscapes, in which 80-85% of the Central Caucasus lands have turned into a state of varying degrees of degradation. In these cases, an important measure in the restoration of degraded mountain forage lands is the sowing of perennial grasses into sparse grass and on bare soil, which increases stiffness. Therefore, the development and creation of a seeder for targeted seeding of grass mixtures in solving the problem is relevant. The authors of the article have developed a new resource-saving way to improve mountain forage lands using a modernized seeder. Tests and studies were carried out at a mountain hospital, located on the southeastern exposition of the Dargavs depression of the North Ossetia-Alania, at an altitude of 1650 m above sea level. It was found that at a concentration of 17.2 MJ of energy in 1 kg of dry matter of feed, the total collection in the control plot was 29.7 GJ, and in the seeded experimental field 85.3 GJ. At the same time, the formation of a dense sod with the accumulation of 104.2 c / ha of root mass is the main factor in the environmental sustainability of mountain agrolandscapes, ensuring environmental safety

Stereotyped seed preferences of the harvester ant Pogonomyrmex mendozanus in the central Monte desert

The harvester ant Pogonomyrmex mendozanus is endemic to the central Monte desert. In this region, extensive grazing reduces grass cover and seed abundance in the soil bank. In previous studies carried out in ungrazed areas, this ant species consumes and prefers seeds of perennial grasses over forbs and shrubs. However, in grazed habitats, P. mendozanus expands its diet by including seeds from other plant groups along with fruits, dead arthropods and other non-seed items. The broader diet could be due to a flexible foraging strategy or could reflect intrinsic, context-dependent food preferences of the populations inhabiting heavy grazed areas, different from those populations studied under ungrazed conditions. We carried out food preference experiments in heavy grazed areas in the central Monte desert in order to discriminate between both hypotheses. We performed choice experiments using a paired comparison design, offering seeds and non-seed food items present in the diet of P. mendozanus. Ants preferred large- and medium-sized perennial grass seeds and, among the non-seed food items, arthropods were preferred. Forb and shrub seeds along with fruits showed intermediate preference levels, whereas the least preferred items were small grass seeds and flowers. Food preferences were similar to those reported previously in ungrazed conditions, supporting the hypothesis that seed preferences are stereotyped in this species and strongly suggesting that it behaves as an expansive specialist by including less preferred items in its diet in heavy grazed habitats where the most preferred seeds are scarce.

Alternative sources of vegetative mass for biofuels in Polissia zone

Aim. To determine the optimal vegetative biological resources in the area of Polissia for the introduction of the domestic green fuel and energy complex. Methods. Field, laboratory, mathematical. The estimation of the biomaterial was carried out, taking into account its biochemical properties and technological growth. Results. Based on the results of the research, the estimation of the biomaterial was carried out, taking into account its biochemical properties and technological growth. It was established that perennial crops can annually provide renewable biomass inputs at the level of 4.6–11.7 t/ha from cereal grasses and 5.5–25.8 t/ha from non-traditional crops, respectively yielding biomethane 722–1857 m 3 /ha and 1161–4715 m 3 /ha per year. The content of useful substances of the processed substrate was determined as follows: N – 0.49–2.58%, P 2 О 5 – 0.14–1.98%, K 2 О – 0.38–2.64 %. Conclusions. The vegetative mass of the seeds of perennial grasses along with other renewable sources can be used as vegetative fi llers of methane tanks in the Polissya zone.

Improvement of Harvesting Methods of Perennial Seed Grass

Abstract In case of traditional harvesting methods the losses of perennial grass seeds may reach 45-50% of the biological yield in unfavourable weather conditions. The paper presents the results of comparative assessment efficiency of various methods of harvesting of perennial seed grass. It was found that the use of special devices and structures in combine harvesters allows increase of yield of technological mixture to the combine tank, degree of seed threshing to 93% and limit the losses of crop to 20-29%. Harvesting of seeds in non-waste technology with harvesting of the entire yield with later transport, drying, threshing and seeds cleaning in stationary devices results in reduction of losses by 5 to 10% but it leads to the increase of energy inputs by 24-25% in comparison to traditional with threshing method. Harvesting with a combing method of plant seeds on a trunk in „Невейки” technology results in the increase of the seeds harvesting to 86-98% of a biological yield.

Survival of seeds from perennial biomass species during commercial‐scale anaerobic digestion

SummaryTall perennial grass species can be utilised as bioenergy feedstocks, but some are considered invasive species. Using biomass from such species as feedstocks for anaerobic digestion (AD) may introduce the risk of disseminating viable seeds onto agricultural lands during digestate application. To evaluate this risk, we investigated the survival rates of perennial grass seeds obtained from biomass species during AD. After removal from the digester, seeds were germinated and stained with tetrazolium chloride to determine viability. During three experimental runs, batches of 100 seeds from four species were exposed to 0, 2, 6, 12, 24, 48, 72 and 168 h of mesophilic (38°C) AD within a commercial‐scale digester. Seed viability of Phalaris arundinacea, Phragmites australis, Panicum virgatum and Solanum lycopersicum was reduced by 95% (LT95) after 29, 52, 98 and 105 h of AD respectively. Commercial digesters that utilise perennial grasses as a feedstock typically have retention times ranging from 240 to 1480 h, which greatly exceeds the LT95 values found in this study. Anaerobic digestion resulted in the rapid death of seeds in all species tested, suggesting unwanted dissemination of perennial grass species via digestate application to agricultural land is unlikely.

The TTC-technique might not appropriately test the physiological stage of plant tissues

The 2,3,5-triphenyltetrazolium chloride (TTC) technique has been used during decades to distinguish between dead and alive tissues of perennial grasses. This technique did not consider, however, that dormant (i.e., viable) tissues could exist within those erroneously considered dead tissues, thus being unable to report the true physiological stage of those plant tissues. Development of a procedure able to distinguish between metabolically active or dormant or dead tissues is then critical. This study developed a procedure to classify plant tissues of perennial grasses (Poa ligularis (Nees ex Steud.), Nassella longiglumis (Phil.) Barkworth, Amelichloa ambigua (Speg.) Arriaga & Barkworth, and Piptochaetium napostaense (Speg.) Hack.) in a more appropriate physiological stage (i.e., metabolically active, dormant or dead) than the traditional TTC-technique. Perennial grass seeds or meristematic buds were immersed in a TTC solution to obtain metabolically active (red or pink staining) or unstained (either dormant or dead) tissues. TTC-unstained tissues were placed in Evans Blue solution to separate dormant from dead tissues. The combination of TTC and Evans Blue techniques allowed the separation of metabolically active, dormant or dead tissues. Use of Evans Blue on TTC-unstained seeds and buds allowed to determine that some of these tissues were not dead but dormant (i.e., viable). Among the TTC-unstained tissues between 2 to 35% of total grass seeds and from 19.5 to 42% of all evaluated buds were dormant (viable and potentially able to growout) but not dead. Combination of TTC and Evans Blue techniques allowed a better classification of the physiological stages of plant tissues (metabolically active, dormant or dead) than the conventional TTC test.

Geometrical and Friction Properties of Perennial Grasses and Their Weeds in View of an Electro-Separation Method

Abstract Many seed mixtures of herbs are difficult to separate. This is confirmed by studies determining the basic geometrical and friction properties of the seeds of perennial grasses and seeds of their weeds. The results show that in most cases the value of their geometrical parameters (length, thickness, and width) and friction properties (friction coefficients for different external surfaces of internal friction coefficients) are substantially similar and differ slightly among each other. This is the evidence that these properties are impractical to use in the process of separation as signs of divisibility. In the paper, a method for electro-separation of seed mixtures of herbs based on the use of complex physical, mechanical properties and electrical components in the separation are presented. The electric field that acts as an additional working body allows considering the surface conditions and biological status of seed mixtures of particles and significantly expands the functionality of the separators. Confirmation of the effectiveness of the proposed method for separation can be seen in the example of purification of red clover and sorrel seeds. By imposition of an electric field on an inclined moving separating plane, we can completely separate weed seeds from the main crop. The results confirm the effectiveness of the electro-separating method.

Aboveground Vegetation and Perennial Grass Seed Bank in Arid Rangelands Disturbed by Grazing

Recruitment by seeds can be an important mechanism for recovery of plant communities following disturbance. Our objective was to assess the density and spatial patterning of perennial grass (highly preferred by herbivores) seeds in litter patches at locations with different aboveground vegetation structure in sites with different grazing history characteristic of the Patagonian Monte (Argentina). We asked whether structural differences in aboveground vegetation are reflected in the density and spatial patterning of perennial grass seeds in litter patches. We selected two study sites characteristic of the Patagonian Monte and within them three locations representing different vegetation states, resulting from different combinations of grazing and/or release from grazing history. At each location, we assessed the density of perennial grass seeds in litter patches at microsites beneath plant patches (canopy) and in interpatch areas without or with scattered vegetation (bare soil) at three dates during the reproductive and seed dispersal periods. The density of perennial grass seeds in litter patches was greater at canopy than at bare soil microsites, and the number of litter patches without seeds increased with decreasing total plant cover at both microsites. The density of perennial grass seeds in litter patches did not vary with differences in total plant cover or litter patch attributes at canopy microsites, while it was reduced with decreasing total plant cover at bare soil microsites. We concluded that differences in aboveground plant cover differentially affected the density of perennial grass seeds in litter patches at contrasting soil microsites. Thus potential microsites for perennial grass recruitment by seeds would increase from litter patches at bare soil microsites to litter patches at canopy microsites at locations with high and low aboveground plant cover, respectively. These issues should be considered for the sustainable management of these rangelands.

Micro-environmental conditions affect grass and shrub seedling emergence in denuded areas of the arid Patagonian Monte, Argentina

Harsh micro-environments in bare soil patches generated by disturbance may affect the emergence of plant species in desert ecosystems. We evaluated the effects of litter addition on the emergence of perennial grass and evergreen shrub species under different conditions of UV radiation and soil water content in disturbed patches of bare soil. We sowed seeds of perennial grasses (Nassella tenuis and Poa ligularis), and shrubs (Atriplex lampa, Larrea divaricata and Schinus johnstonii) in microcosms containing blocks of upper soil (28cm depth) subjected to different levels of three factors: litter (bare soil without litter cover, high quality litter cover from undisturbed plant patches, and low quality litter cover from disturbed plant patches), UV radiation (near ambient and attenuated UV radiation), and soil water (5–15% and 15–25% of volumetric soil water content). The patterns of seedling emergence in relation to litter, UV radiation, and soil water content varied among species independently of life form. Seedling emergence of all species increased under exposure to UV radiation at all combinations of litter and soil water factors. High soil water content had an important positive effect on the emergence of N. tenuis and L. divaricata in combination with UV radiation and litter. In contrast, soil water content did not affect or affected negatively the emergence P. ligularis and A. lampa in combination with litter and UV radiation. The emergence of S. johnstonii occurred only under exposure to UV radiation mostly at high soil water content, independently of litter levels. These results highlight the importance of the combined effects of the presence and type of litter, soil water content, and UV radiation on seedling emergence of perennial grass and shrub species and consequently on the vegetation reestablishment processes at disturbed areas.

Основные факторы формирования урожая семян овсяницы луговой на серых лесных почвах республики Татарстан

The basis of biological farming is expanding the acreage of perennial grasses, which in the coming years should occupy at least 25% of the arable land of our Republic instead of 18-20% currently. To solve this problem annually more than 9 thousands tons of seeds of perennial grasses is reguired, including meadow fescue 0.7 thousands tons. The study revealed that despite the higher production costs of the two-phase method of harvesting and threshing, the profitability of seed production is higher to 7-21%, than the direct harvesting. In traditional two-phase harvesting (mowing in rolls, then threshing rolls), and seed moisture content of 12-14%, the loss of biological crop production reduces by almost twice, comparing with direct harvesting, but it is inferior to in two-phase threshing. The reason is very simple, the fescue panicles on the top reach harvest maturity faster, than the on the bottom. In the case of rainfall, they crumble, which is clearly manifested in the growth of grain dropping after threshing rolls. The each hectare of investigated variants of meadow fescue brings about 10-12 thousand rubles of net profit. Thus, in order to obtain from each hectare of crop 380-400 kg of low-cost uncoated, it is recommended to sow it with row spacing of 30 cm and organize two-phase threshing of harvest.

Freezing Stress Influences Emergence of Germinated Perennial Grass Seeds

In sagebrush rangelands perennial bunchgrasses are typically seeded in fall and a high proportion of planted seeds germinate prior to winter onset but fail to emerge in spring. Our objectives were to evaluate freezing tolerance of germinated but nonemergent bluebunch wheatgrass seeds under laboratory conditions. We used data from a 2-yr pilot study to determine overwinter freezing temperature and duration for soils in southeastern Oregon. We then conducted two experiments to assess freezing tolerance. In experiment 1, bluebunch wheatgrass seeds were planted in control pots and compared to seeds planted at early, mid, or late postgermination stages. Pots from each treatment were placed in a grow room maintained at 12h 40min light/11h 20min dark photoperiod, with a constant temperature of 22°C for 30 d either immediately or following a 30-d freeze. In experiment 2, germinated bluebunch wheatgrass seeds were planted in pots that were left nonfrozen or were frozen for a specified duration prior to a 30-d period in the grow room. Emergence density and tillers · seedling−1 were quantified for both experiments. The number of days per year for freezing soil conditions in the pilot study ranged yearly from 25 to 51; maximum duration of continuous freezing was 16.5 and 11.2 d. Freezing reduced or eliminated seedling emergence at all postgermination stages (P < 0.001) and tiller density was reduced by at least 50% (P < 0.001). Maximum reduction in seedling density (P < 0.001) was realized within 4 d of initiation of freezing and tillers · seedling−1 were reduced 30–70% with > 6 d of freezing (P = 0.001). Our data indicate that freezing-associated mortality of germinated but nonemergent bluebunch wheatgrass seedlings can be extremely high and suggest that management practices to reduce prewinter germination of seeds could improve subsequent emergence and seeding success.

Grassland Response to Herbicides and Seeding of Native Grasses 6 Years Posttreatment

AbstractHerbicides are the primary method used to control exotic, invasive plants. This study evaluated restoration efforts applied to grasslands dominated by an invasive plant, sulfur cinquefoil, 6 yr after treatments. Of the five herbicides we evaluated, picloram continued to provide the best control of sulfur cinquefoil over 6 yr. We found the timing of picloram applications to be important to the native forb community. Plots with picloram applied in the fall had greater native forb cover. However, without the addition of native perennial grass seeds, the sites became dominated by exotic grasses. Seeding resulted in a 20% decrease in exotic grass cover. Successful establishment of native perennial grasses was not apparent until 6 yr after seeding. Our study found integrating herbicide application and the addition of native grass seed to be an effective grassland restoration strategy, at least in the case where livestock are excluded.

Influence of Grazing on Soil Seed Banks Determines the Restoration Potential of Aboveground Vegetation in a Semi‐arid Savanna of Ethiopia

ABSTRACTSpecies composition, number of emerging seedlings, species diversity and functional group of the soil seed banks, and the influence of grazing on the similarity between the soil seed banks and aboveground vegetation, were studied in 2008 and 2009 in a semi‐arid savanna of Ethiopia. We tested whether the availability of persistent seeds in the soil could drive the transition from a degraded system under heavy grazing to healthy vegetation with ample perennial grasses. A total of 77 species emerged from the soil seed bank samples: 21 annual grasses, 12 perennial grasses, 4 herbaceous legumes, 39 forbs, and 1 woody species. Perennial grass species dominated the lightly grazed sites, whereas the heavily grazed sites were dominated by annual forbs. Heavy grazing reduced the number of seeds that can germinate in the seed bank. Species richness in the seed bank was, however, not affected by grazing. With increasing soil depth, the seed density and its species richness declined. There was a higher similarity in species composition between the soil seed bank and aboveground vegetation at the lightly grazed sites compared with the heavily grazed sites. The mean similarity between the seed banks and aboveground vegetation was relatively low, indicating the effect of heavy grazing. Moreover, seeds of perennial grasses were less abundant in the soil seed banks under heavy grazing. We concluded that restoration of grass and woody species from the soil seed banks in the heavily grazed areas could not be successful in semi‐arid savannas of Ethiopia.