High Sowing Rates Research Articles

Yield Loss and Integrated Disease Control of Rhizoctonia solani AG2-1 Using Seed Treatment and Sowing Rate of Oilseed Rape.

Rhizoctonia solani anastomosis group (AG) 2-1 is an ubiquitous soilborne pathogen causing severe damping-off of oilseed rape (OSR). In the absence of varietal resistance to AG2-1, there are limited methods for integrated disease management. The objectives of these field studies were to quantify yield losses due to AG2-1 and to determine the effectiveness of integrated control using sedaxane, fludioxonil, and metalaxyl-M applied as seed treatment on two OSR genotypes at a sowing rate of 40 (low) or 80 (high) seeds m-2. Crop assessments of green area index (GAI), vigor, and cabbage stem flea beetle (CSFB) Psylliodes chrysocephala damage were carried out at GS16, while pathogen DNA in soil was quantified using real-time PCR at GS32. Yield and seed weight losses of 41 and 18%, respectively, were associated with reduced establishment, GAI, vigor, and delayed development and flowering of OSR. Seed treatment reduced AG2-1 DNA in soil by 80%, resulting in a 94, 16, and 64% increase of establishment, thousand seed weight (TSW), and yield, respectively. Seed treatment also mitigated the effects of AG2-1 on delaying plant development, resulting in increased uniformity of crop flowering. OSR plants infected with AG2-1 suffered 27% more damage by the CSFB, indicating positive pathogen-pest interaction at the expense of the OSR host. Optimum control of AG2-1 infection was achieved by integrating low sowing rate and seed treatment. However, under dual pest and pathogen attack, high sowing rates should be combined with the use of seed treatment to mitigate seedling death and delayed development caused by AG2-1 and CSFB damage.

Підвищення посівних властивостей насіння сафлору красильного на вібраційній насіннєочисній машині

The purpose of the work is to study the possibility of improving the sowing properties of safflower seeds due to their separation on a vibrating seed cleaning machine with non-perforated friction working surfaces. The article presents the results of cleaning and sorting of the seed mixture of dyed safflower on a vibrating seed cleaning machine after preliminary separation on existing grain cleaning machines. For one pass of the non-standard safflower seed mixture through a vibrating seed cleaning machine, 91.94% (from the mass of the starting material) of the main crop seeds with high sowing rates, which meets the requirements of the state standard of Ukraine, was obtained. The separation of safflower dye seeds on a vibrating seed cleaning machine with the selection of full-fledged seed material for sowing ensures an increase in the main indicators of the sowing qualities of the seeds, which increases the yield of this crop. Experimental studies have established the feasibility of using a vibrating seed cleaning machine with non-perforated working surfaces for further cleaning of seed mixtures of dyeing safflower with simultaneous sorting of the main crop seeds. The machine can be recommended as part of technological lines for post-harvest processing of seed mixtures of safflower for dyeing.

Bioethanol yield from stems of different sugar sorghum hybrids at different sowing rates

Aim. To determine bioethanol yield from sugar sorghum stems at different plant sowing rates. Methods. Field – establishing and conducting research, physical – determining the yield of plant vegetative mass, chemical – determining stem sugar content, analysis and statistical. Results. The article presents the study results of the yield of vegetative and dry mass, stem sugar content, bioethanol yield for the cultivation of various hybrids of sugar sorghum with a sowing rate of 75, 100, 150 and 200 thousand psc/ha. It was found that in the variant with the highest sowing rate, the green mass yield of Mamont, Verbliud and Sokhatyii hybrids increased to 82.9–92.6 t/ha, and that of Zubr, Favoryt and Medovyi ones increased to 72.6–78.6 t/ha. The highest yield of dry mass was obtained at a density of 200 thousand pcs/ha in Zubr and Mamont hybrids – 19.3–20.0 t/ha. The yield of dry mass at the level of 14.0–17.5 t/ha was obtained for the cultivation of Favoryt, Medovyi, Verblid and Sokhatyii hybrids with a sowing rate of 150–200 thousand pcs/ha. The highest yield at sowing rates of 75 thousand pcs/ha was provided by the cultivation of Mamont, Verbluid and Sokhatyi hybrids – 12.4–13.7 t/ha. It was found that stem sugar content decreased significantly with the increase in plant sowing rate. In addition, in the stems of Zubr and Verb­luid hybrids, sugar content was significantly higher compared to other hybrids - 17.0–18.9%, depending on sowing rate. The highest bioethanol yield was provided by the cultivation of Zubr, Mamont, Verbluid and Sokhatyi hybrids with a sowing rate of 200 thousand pcs/ha – 6 467–7 215 l/ha. At this sowing rate, the bioethanol yield in other hybrids was at the level of 5563–5658 l/ha. In addition, stability index varied from 0.31 to 0.88. Conclusions. In the conditions of the Right Bank Forest Steppe, bioethanol yield from sugar sorghum stems varies depending on the hybrid and plant sowing rate. Under the growing conditions of Zubr, Mamont, Verbluid and Sokhatyi hybrids with a sowing rate of 200 thousand units/ha, bioethanol yield is 6467–7215 l/ha. In addition, biothenol yield is affected by weather conditions. In more favorable weather conditions, this indicator is 8.508–9.149 l/ha in Zubr, Mamont, Verbluid, and Sokhatyi hybrids with a sowing rate of 200 thousand pcs/ha, and in less favorable conditions, it is 3.784–5.922 l/ha or less by 1.4–2.4 times.

Simulation of winter wheat response to variable sowing dates and densities in a high-yielding environment.

Crop multi-model ensembles (MME) have proven to be effective in increasing the accuracy of simulations in modelling experiments. However, the ability of MME to capture crop responses to changes in sowing dates and densities has not yet been investigated. These management interventions are some of the main levers for adapting cropping systems to climate change. Here, we explore the performance of a MME of 29 wheat crop models to predict the effect of changing sowing dates and rates on yield and yield components, on two sites located in a high-yielding environment in New Zealand. The experiment was conducted for 6 years and provided 50 combinations of sowing date, sowing density and growing season. We show that the MME simulates seasonal growth of wheat well under standard sowing conditions, but fails under early sowing and high sowing rates. The comparison between observed and simulated in-season fraction of intercepted photosynthetically active radiation (FIPAR) for early sown wheat shows that the MME does not capture the decrease of crop above ground biomass during winter months due to senescence. Models need to better account for tiller competition for light, nutrients, and water during vegetative growth, and early tiller senescence and tiller mortality, which are exacerbated by early sowing, high sowing densities, and warmer winter temperatures.

Field applications of gypsum reduce pH and improve soil C in highly alkaline soils in southern Australia’s dryland cropping region

AbstractHighly alkaline soils are widespread throughout south‐eastern Australia. High pH limits the accumulation and retention of organic carbon (C), and thus the availability of nutrients to crops and is also associated with various elemental deficiencies and toxicities that restrict crop productivity. Applying gypsum and increasing legume production reduce pH and improve soil chemical and physical properties in alkaline, sodic soils, but this strategy has not been explored in alkaline soils in the region where many of the topsoils are non‐sodic. Five short‐term rotation experiments were conducted to examine the potential to reduce pH, improve soil organic C and increase crop production. In the first year, three legumes—field peas (Pisum sativum), vetch (Vicia sativa) and a medic pasture (Medicago spp.)—were grown at low or high inputs of seed and fertilizer and with three rates of gypsum (0, 2.5 t/ha and 5.0 t/ha). In the following seasons, wheat (Triticum aestivum) and barley (Hordeum vulgare) were grown. Using high sowing and fertilizer rates to increase legume biomass had little effect on soil properties; however, applying gypsum consistently resulted in a lower soil pH and dissolved organic C and higher organic C compared with the unamended control to a depth of 0.20–0.30 m. The largest difference occurred with 2.5 t gypsum/ha with little further change at 5 t/ha. Gypsum significantly increased biomass and grain yield at sites with low concentrations of calcium carbonate. Low rates of gypsum may be effective in reducing pH, maintaining soil organic C and improving crop production in regions with alkaline soils low in calcium carbonate.

The effect of sowing rate and variety on the nutrient content of faba beans

ABSTRACT Most faba bean research is about protein content while less attention is paid to nutrient content. Thus, the purpose of this study was to assess the effect of sowing rate and variety on the nutrient content of faba beans. Five varieties were tested: Bauska, Gloria, Julia, Jõgeva, and Lielplatones. Two sowing rates were used: 30 seeds m−2 (100%) and 36 seeds m−2 (120%). The higher sowing rate decreased the K content in varieties Gloria, Julia, and Lielplatones in 2016. In 2015 the higher sowing rate increased the Ca content while in 2016 the sowing rate decreased the Ca content. The higher sowing rate increased the Mg content in varieties Gloria and Jõgeva in 2016. The highest N, K, and Mg contents were found in variety Gloria. In 2015 the highest K content was found in varieties Gloria and Jõgeva, while in 2016 the highest K content was in variety Lielplatones. The highest Ca content was in variety Bauska. In conclusion, an increased sowing rate did not have a consistent effect on the nutrient content of faba beans. Thus, variety Gloria can be recommended for faba bean production in Northern Europe because it was the variety with the highest nutrient content.

Comparative Evaluation of a Seed Planter, the Modified Version and Local (Hand) Seed Planting Method

This study evaluated the performance of a seed planter against the modified version, and hand planting method. A performance test was carried out on the two planters and hand method on a piece of land of known dimension over a period of time. Performance was evaluated using five (5) different parameters; sowing rate, area covered, throughput capacity, efficiency and level of uniformity. Sowing rate showed that hand method had the lowest sowing rate of 1 seed per sec, while the modified planter had the highest sowing rate of 5 seeds per sec. The modified planter had the highest for area covered at 91.5 m2, while the existing planter performed second best at 73.5 m2. Throughput capacity was highest for the modified planter at 292.8 kg/hr and lowest for hand planting method at 29.3 kg/hr. Efficiency result showed that hand method was better than the existing method at an efficiency value of 94 % against 89 % for existing planter; the modified planter performed best at 97 % efficiency value, while uniformity result showed that the modified planter was the best along the row and column arrangement at 97 % for both, while hand method had the lowest for both cases at 85 % and 88 % respectively. This study showed that the modified planter performed better than the two others in all the parameters assessed.

Use of ripening fruits in seed production of early-maturing varieties of melons and gourds in spring and summer sowing

Relevance. In recent years, the price of seeds for melons and gourds of foreign selection has reoriented many agricultural producers to use seeds of domestic varieties. To provide agricultural producers with the required amount of seeds with high sowing rates, it is necessary to apply new technological methods that will allow using the biological potential of varieties and growing commercial volumes of seeds.Material and methods. The research was carried out at the selection and experimental site of the vegetable growing department in the "Federal Scientific Rice Centre " in 2017-2018. The object of research is a new promising variety of watermelon Yubilyar, and two early-ripening varieties of melon Tamanskay and Strelchanka. Sowing terms: spring – from mid-April to the end of the first decade of May, summer – the first and second decades of July. Summer sowing with drip irrigation. When harvesting melon and watermelon fruits, the selection intensity is 90% to obtain reproductive seeds RS-1.Results. It has been established that due to the climatic conditions of the Krasnodar Territory and the varietal characteristics of the melon varieties Tamanskaya, Strelchanka and the watermelon Yubilyar, a short growing season and a neutral reaction to changes in the length of the day, you can get two harvests of seeds in one season using summer sowing. It was noted that low air humidity prevented damage to plants by peronospora, anthracnose and powdery mildew, practically eliminating the need for protective measures. The selected ripe fruits for the selection of seeds by morphological characteristics corresponded to varietal characteristics. It has been established that the seed productivity of melon during summer sowing is higher due to better pollination. From one hectare received up to 97-138 kg of seeds. The use of ripening made it possible to carry out a one-time collection of watermelon and melon fruits.

Interseeding of ruzigrass into soybean: Strategies to improve forage cultivation in no-till systems

No-till (NT) farming is a major soil conservation strategy. In the Brazilian Cerrado, soybean is the main grain crop, and strategies that improve the cultivation of cover crops in the off-season in succession to soybean could facilitate NT for large cultivated areas. In the municipality of Nova Xavantina, MT, Brazil, three experiments were carried out in a randomized block design with four replications. This work aimed to evaluate the establishment of Urochloa ruziziensis (ruzigrass) in succession to soybean as a function of ruzigrass seed treatment, sowing density and phenological stage, and soybean cultivar allelopathic potential. In the first experiment, treatment of ruzigrass seeds with six doses (0, 150, 300, 450, 600 and 750 mL of commercial product 100 kg−1 of seeds) of fipronil + thiophanate-methyl + pyraclostrobin was evaluated. In the second experiment, two ruzigrass interseeding periods (soybean phenological stages R5.5 and R7) and five ruzigrass seed densities (4.3, 6.4, 8.6, 10.7 and 12.9 kg ha−1 VPS) were tested. In the third experiment, the interference of soybean cultivars in the establishment of ruzigrass and the potential allelopathic effect of the cultivars on forage germination were evaluated, six soybean cultivars RR (Roundup Ready®) were used: P98Y70; TMG 115; TMG 132; M 8527; P98Y11; TMG 123. Our results showed that seed treatment facilitated forage establishment in the interseeding system, and the use of high sowing rates at phenological stage R5.5 of soybean promoted greater ruzigrass plant development. The effects of the soybean cultivars on ruzigrass germination varied, suggesting allelopathic effects of the deposition of petioles and soybean leaves on ruzigrass seeds. Thus, an appropriate interseeding strategy can improve forage production in the off-season and favor NT through correct management of forage establishment in succession to soybean.

Establishment of an annual meadow on extensive green roofs in the UK

This study investigated the establishment of annual meadow including native and non-native species in an extensive green roof in Sheffield, UK. The study aimed to determine the feasibility of establishing annual plant species from a seed mixture and to determine the appropriate sowing rate as well as the necessity of watering during the first growing season from June to November 2006. A 22-species seed mixture was sown on an experimental green roof with a substrate depth of 7cm using two sowing rates (2g/m2 and 4g/m2) and two watering regimes (with and without watering). The watering regime consisted of application of water four times over the course of the experiment. Each combination of sowing and watering regime yielded a successful aesthetic annual meadow green roof. Results showed that a low sowing rate resulted in better conditions for individual plant growth when enough water was available. On the other hand, a high sowing rate was necessary to ensure a sufficient number of plants when water resources were not abundant. The watering regime improved growth in most species; however, it was determined that an annual seed mixture could perform well without watering at the study site. The annual meadow possessed an abundance of flowering plants for an extended period of time; plants started flowering one month after sowing and continued until the end of October. Successful species during the first growing season included Alyssum maritimum, Echium plantagineum ‘Blue Bedder’, Gypsophila muralis, Iberis amara, Iberis umbellata ‘Fairy’, Linaria elegans and Linaria maroccana.

Why 0.02%? A review of the basis for current practice in aerial 1080 baiting for rabbits in New Zealand

Sodium fluoroacetate (1080) has been used as an aerially distributed toxin against mammalian pests in New Zealand since the 1950s. Although its use for rabbit (Oryctolagus cuniculus) control ceased temporarily after the illegal release of rabbit haemorrhagic disease virus (RHDV) in 1997, there has been a recent resurgence in the use of aerial baiting with 1080 to control rabbits as the efficacy of RHDV has fallen. Current practices for rabbit control using 1080 have changed little since the 1980s, with high sowing rates and low toxin loadings commonplace. The lack of ongoing development in baiting practices for rabbit control contrasts sharply with continued improvements in the aerial 1080 baiting practices for brushtail possums (Trichosurus vulpecula) in New Zealand, such as a shift to a comparatively high 1080 loading and using much lower application rates of prefeed and toxic bait. These modifications have resulted in an overall reduction in the amount of toxin used for possum control. The disparity in these two approaches prompted a formal review of the rationale on which the current 1080 baiting practices for rabbits are based. Two issues emerged strongly. First, the current low toxin loading used (0.02–0.04% 1080 in bait) is not based on experimental optimisation in New Zealand but, rather, on research conducted several decades earlier in Australia. Second, despite long-standing concerns about the quality of carrot bait used in New Zealand, current bait manufacturing and distribution practices still produce large numbers of small sublethal fragments. Thus, the current New Zealand practice of multiple prefeeds and very high sowing rates of bait with a low 1080 loading used against rabbits seems to have resulted from the need to compensate for the low toxic loading and poor quality control of the bait (carrots). We, therefore, suggest that there is considerable potential to improve current aerial 1080 baiting practices for controlling rabbits in New Zealand. More generally, these findings also help illustrate that ‘best’ pest-management practice may sometimes be based on pragmatic solutions aimed at overcoming unrecognised internal constraints that are in fact avoidable. Refining and modernising vertebrate pest-control programs, so that they better meet efficacy requirements and contemporary public expectations, therefore requires understanding not just that a solution works, but also how it works.

Effect of intercropping forage peas (Pisum sativum L.) with winter wheat (Tritium vulgare L.) or triticale (Triticale hexaploide Lart.) on DM yield, nutritive characteristics when harvested at different stages of growth

An experiment was undertaken over 2 years (2007–09) to determine the effect of intercropping forage peas with either forage winter wheat or triticale for whole-crop silage. Monocultures of triticale (T100), wheat (W100) and forage peas (P100) and plus cereal–pea combinations of 75% triticale : 25% pea (T75), 50% triticale : 50% pea (T50), 25% triticale : 75% pea (T25), 75% wheat : 25% pea (W75), 50% wheat : 50% pea (W50), 25% wheat : 75% pea (W25), with ratios based on sowing rate, were evaluated for DM yield and nutritional characteristics at a range of growth stages. It was hypothesised that an increase in the ratio of peas to cereal would not adversely affect DM yield and would have a positive impact on nutritive characteristics across a range of harvest times based on growth stages of the cereal component of mixes. In Year 1, at the boot stage of growth of cereals, P100 had a lower DM yield than W100 and all triticale-based treatments, while in Year 2 P100 had a lower DM yield than all other treatments. By the soft dough growth stage in Year 1, all triticale treatments except T25 had higher DM yields than P100 and in Year 2 P100 had a lower DM yield than all triticale treatments and W100. The crude protein (CP) concentration of P100 at the boot stage of growth was higher than T100, T75, T50, W100 and W50 in Year 1 and all treatments in Year 2. At soft dough, P100 had a higher CP concentration than all other treatments in both years, while T25 and W25 had higher CP concentrations than their respective monocultures. In Year 1 at soft dough, W100 had a lower estimated ME concentration than other wheat treatments and P100, while in Year 2, T50 and W50 had higher values than T100 and W100, respectively. Bi-cropping forage peas with winter cereal forage crops did not adversely affect DM yields at a range of different harvest times, but did not consistently and significantly improve nutritive characteristics. Despite relatively high sowing rates of forage peas, their total contribution in mixes with cereals to DM yield was low, indicating that their ability to compete with winter cereals under the high fertility conditions of the experiment was low. When grown as a monoculture peas tended to produce lower DM yields but had higher CP concentrations and a higher harvested CP/ha at the soft dough stage of growth. The timing of harvesting will affect DM yields and nutritive characteristics and can be manipulated depending upon the end use of the feed grown and also to allow greater flexibility in the sowing of subsequent forages. Consideration should also be given to the growing of monocultures of winter cereals and forage peas and developing systems to mix during ensiling to capture both DM yield potential and optimum nutritive characteristics.

Effect of prefeeding, sowing rate and sowing pattern on efficacy of aerial 1080 poisoning of small-mammal pests in New Zealand

Context Aerial poisoning using sodium fluoroacetate (1080) is an important but controversial technique used for large-scale control of brushtail possums (Trichosurus vulpecula) and other pests in New Zealand. The technique reliably produces near total kills of possums and rats, provided that many tens of baits (and therefore many tens of individually lethal doses) are sown for each target animal present. Aim The aim of this study was to further refine aerial 1080 poisoning by determining the effect of prefeeding, sowing rate, and sowing pattern on effectiveness. Methods Eighteen experimental treatments comprising all possible combinations of three sowing rates (1, 2, and 5 kg/ha of bait), three frequencies of non-toxic prefeed (0, 1, and 2) and two sowing patterns (parallel and cross-hatched) were applied to each of two forested areas. Treatment effectiveness was assessed from changes in the rate of interference recorded on baited cards for three species: possum, ship rat (Rattus rattus) and mouse (Mus musculus). Key results Outcomes were highly variable, ranging from increases in pest activity to near total reductions. Possum reductions were highest where one or two prefeeds were used, and at the higher sowing rates (2 or 5 kg/ha), but with some interactions between these factors. For rats, two prefeeds resulted in the highest reductions but sowing rate had no effect. For mice, post-poisoning indices were often high, indicating low effectiveness. Conclusions Some treatments were highly effective so poor kills were unlikely to have resulted from pests not encountering bait, or the bait being unpalatable. Rather they appeared to reflect sub-lethal poisoning either as a result of low acceptance (as a result of a lack of familiarity and/or satiation) or bait fragmentation. We infer that for possum and rats prefeeding helps reduce this risk of sub-lethal poisoning not only by increasing familiarity, but also (in conjunction with high sowing rates) by increasing the bait encounter rate, particularly for possums. Implications There is scope to further reduce the amount of toxic bait sown and the cost of poisoning, without compromising efficacy, by fine-tuning the balance between prefeeding and sowing rate based on which species are being targeted and, for possums, reducing bait fragmentation.

Indigenous sward restoration by oversowing Microlaena stipoides into kikuyu (Pennisetum clandestinum) pasture

Management plans for the grazed parklands of the Auckland volcanic cones call for revegetation to restore a more natural and historic vegetation cover. The native grass Microlaena stipoides has been identified as a relevant species, and a field experiment was undertaken to determine the best approach for establishing this species into existing pasture. Seed obtained locally was broadcast or hydro-seeded in May 2007 onto kikuyu pasture, at three sowing rates (100, 250 and 750 seeds/m2) following control of the resident pasture with turf stripping or mowing and spraying, in a replicated factorial trial. After 12 months, the highest levels of Microlaena plant density (mean 56 plants/m2), cover (mean 50%) and accumulated herbage mass were observed on broadcast/sprayed plots at the highest sowing rate. Recovery of the resident pasture (dominantly Pennisetum clandestinum) occurred to a level of ~25% after 12 months, but was inhibited at the highest Microlaena sowing rate. Keywords: broadcast, hydro-seeding, kikuyu, Microlaena stipoides, re-vegetation

Influence of grass suppression and sowing rate on the establishment and persistence of forb dominated urban meadows

In practice in the UK, grasses and ruderal forbs recruited from the urban soil seed bank often have a detrimental impact on establishment and development of sown meadows. This study investigated the effect of graminicide, and sowing rate on establishment, survival and longer term development of sown meadow forbs. A seed mix containing 19 forb species was sown at two sowing rates in a randomized block experiment in Sheffield, UK. The two most abundant grasses recruited, Arrhenatherum elatius, and Holcus lanatus, were highly damaging to survival and development of sown forbs. Cutting the meadow to 50 mm during the first year did not alleviate grass competition. Weedy ruderal forbs had a lesser effect on sown forbs than the perennial grasses. Where a graminicide was used, sown forb density and biomass were significantly higher in the second and third year of the study, and forb richness significantly greater in all 3 years. Sown forb density was higher at the high sowing rate in all three years, and forb richness in years 1 and 2. Sowing rate did not significantly increase forb biomass in any year. In general, suppressing grass growth had a more beneficial effect on sown forb establishment and development than increasing sowing rate.

Agronomic evaluation of a tiller inhibition gene (tin) in wheat. I. Effect on yield, yield components, and grain protein

Reduced tillering cereals have been proposed as being advantageous under terminal drought conditions through their reported reduction in non-productive tiller number and reduced soil water use prior to anthesis. This study was conducted to determine whether wheat (Triticum aestivum L.) lines containing the tiller inhibition (tin) gene have a yield penalty over their commercial near-isogenic counterparts. A terminal drought was experienced in all experiments. The effects of the tin gene were investigated in 4 different near-isogenic pairs of lines grown at 2 sowing densities at 4 locations in the eastern Australian wheatbelt over a 3-year period. Averaged over all experiments and lines, grain yield was unaffected by the presence of the tin gene. However, the highest yielding line contained the tin gene and its yield was 5% higher than all other lines. Averaged across the different genetic backgrounds, the tin gene decreased fertile spike number by 11%, increased the number of kernels/spike by 9%, and there was a 2% increase in kernel weight. The tin gene increased the harvest index by an average of 0.02, whereas above-ground biomass was reduced by 7%. Increasing sowing density from 50 to 100 kg/ha had little influence on yield or yield-related characteristics in both the restricted tillering and freely tillering lines. There was an interaction between sowing rate and the presence of the tin gene on yield, with tin lines yielding 0.2 t/ha more than the freely tillering lines at the higher sowing rate, whereas there was no effect at the lower sowing rate. The response of several lines containing the tin gene to nitrogen fertiliser was also investigated at 2 sites. Nitrogen increased spike number in all lines but the number remained around 20% less than in the freely tillering cultivars. The yield of wheat lines containing the tin gene was 6% greater than their near-isogenic pairs where nitrogen status was high in the presence of terminal drought. Grain protein concentration was unaffected by the presence of the tin gene at high grain protein sites, whereas at lower grain protein sites it had a positive effect.

Native Alternatives for Non‐Native Turfgrasses in Central Florida: Germination and Responses to Cultural Treatments

Abstract Little information exists about the establishment of native longleaf pine flatwoods species for use in restoration efforts and as buffers around natural areas in the southeastern United States. Composition of groundcover in these systems is dominated by perennial graminoid species. Vegetation in current buffers is generally non‐native turfgrass that can escape into natural areas, often reducing establishment and survival of native species. Where management objectives involve actively restoring native groundcover or reducing the probability of invasion by these non‐native turfgrasses, identification of native species and restoration methods is needed. We investigated seed germination and establishment of four species native to longleaf pine flatwoods in central Florida and one species native to the adjacent wetland communities. Paspalum setaceum, Panicum anceps, Eustachys petraea, and Eragrostis refracta were directly seeded, and P. distichum was planted as sprigs into three former P. notatum pastures. Irrigation, fertilization, weed control, and mowing treatments were assessed in terms of cover development of the sown species. Paspalum distichum developed the highest percent cover—over 80% in wet areas after 1 year. Mowing had mixed impacts depending on the species, and fertilization never significantly increased cover. Directly seeded species developed sparse cover (0–40%), probably as a result of drought conditions. However, E. petraea and E. refracta appeared more promising for use on rights‐of‐way when using high sowing rates. A second experiment conducted on a roadside included these two species and sprigged P. distichum. Both E. petraea and P. distichum developed more than 45% cover on the roadside. Establishment of these natives from seed or sprigs was significantly enhanced when site preparation effectively reduced the seedbank of other species present in the soil.

Subterranean clover in North Canterbury sheep pastures

The Hawarden basin is typified by dry, hot conditions over summer, which makes it difficult to retain ryegrass/white clover pastures on the lighter soils. These conditions have led to the introduction of better-adapted species such as the annual, subterranean clover. The mid-flowering cultivar 'Mt Barker' was first sown in the 1930s; then the earlyflowering 'Woogenellup' and late 'Tallarook' were used in the 1960s. The 'Mt Barker' type became dominant in these old pastures. The key factors for good subterranean clover growth were soil fertility (particularly P and S), space following dry summers for seedlings to re-establish, and moisture in the spring to maximise herbage yield. A visit to Australia in 1996 prompted the inclusion in new sowings of the late-flowering 'Leura' at high sowing rates (8-10 kg/ ha). It has taken 5 years for seed stocks to build to a level where we can identify good seedling strikes of 'Leura'. Two of the autumns over this period were very difficult and hindered normal establishment. Rainfall is erratic in North Canterbury, which affects the success of subterranean clover from one year to another. Dry summer conditions are optimal for subterranean clover strikes, as the pasture opens, and when the autumn break occurs, more than 2 000 subterranean clover seedlings/m2 can be produced. Autumn grazing management, when recovering from extreme drought, is critical because pasture must be spelled for 6 weeks to allow the subterranean clover to establish. However, if the autumn is wet, pasture cover must be controlled so that subterranean clover seedlings are not smothered. Set-stocking is best in spring to control pasture cover, but grazing should not be too hard during the flowering and seed set period. Subterranean clover seed yields of up to 250 kg/ha have been achieved from old pastures, but this is less seed than is produced under Australian conditions. Pasture renovation using the baker boot drill to re-introduce grasses and new cultivars of subterranean clover has been successful following very dry summers. Lamb growth rates have been excellent on subterranean clover-based pastures and these have increased the farm's meat production and reduced the cost of maintaining pastures. Key words: grazing management, North Canterbury, seedling establishment, seed set, subterranean clover

Weed establishment in the second year after high pasture sowing rates

A field and an outdoor tray experiment were conducted to determine whether weed control benefits of high sowing rates of perennial ryegrass (Lolium perenne) continue into the second year after sowing Seeds of Scotch thistle (Cirsium vulgare) nodding thistle (Carduus nutans) and hedge mustard (Sisymbrium officinale) were sown into perennial ryegrass swards that were established 12 months earlier at differing densities Emerging weed seedlings were mapped at regular intervals to enable their fate to be followed Weed emergence and survival did not decline with increased ryegrass sowing rates indicating that 12 months after sowing the competitive ability of pasture sown at low density towards weeds equalled that of pasture sown at high density

Managing tillage, sowing rate and nitrogen top-dressing level to sustain rice yield in a low-input, direct-sown, rice - vetch cropping system

Direct sowing of rice into drained soil is a relatively new farming practice, replacing transplanting, being developed for use in External Low Input Sustainable Agriculture in Korea. Field experiments were conducted to investigate the importance of tillage, sowing rate, and top-dressing of fertiliser nitrogen (N) to rice growth and grain yield in a direct-sown, rice–vetch cropping system. From 1993 to 1997, Chinese milk vetch (Astragalus sinicus L. Vetch) was grown during the winter season (October–May) at Uiryong, Korea. Until 1995 transplanted rice (Oryza sativa L.) was grown during the summer season, but in 1996 and 1997 the direct-sowing method was used. In 1996, the treatments applied to rice were either tillage or no-tillage of the paddy before the rice crop was sown, combined with 2 rates (0 or 2 g/m2) of fertiliser N top-dressed onto the paddy just after the panicle initiation stage. In 1997, the treatments were either tillage or no-tillage of the paddy before the rice crop, combined with 2 rice sowing rates (400 or 800 seeds/m2), and 3 rates (0, 2 or 4 g/m2) of fertiliser N top-dressed just after the panicle initiation stage. Rice yielded 243–435 g/m2 in 1996 and 493–678 g/m2 in 1997, the lower yield in 1996 was attributed to fewer established seedlings and productive panicles. There was no effect of tillage treatment. Across years, yield was correlated with shoot N content, and grain N-use efficiency exceeded 50 g grain/g shoot N content. Rice residues contained about 5 g N/m2 and vetch residues released 6–8 g N/m2 during the 4 weeks after submergence, therefore the release of N from residues was potentially sufficient to supply the rice crop demand. In both years, however, the yield of unfertilised rice was N limited, so increasing the shoot N content appeared to be the most important issue to be resolved in sustaining yield in External Low Input Sustainable Agriculture. A low rate of top-dressed fertiliser N (2–4 g N/m2) increased yield by increasing the number of panicles and spikelets, and to a lesser extent, 1000-grain weight. Growing rice using no-tillage practices did not limit the yield of rice, except in 1996 when no fertiliser N was applied and the N uptake by rice was low. A high sowing rate combined with top-dressed fertiliser N in 1997 reduced yield through crop lodging and an increase in the number of unproductive tillers. This problem may be overcome by the use of a variety less susceptible to lodging.