Harvest Height Research Articles

Avaliação de fenos de capim-buffel colhido em diferentes alturas de corte

Objetivou-se avaliar o rendimento forrageiro, composição bromatológica e recuperação de matéria seca do feno de capim-buffel (Cenchrus ciliaris L.), colhido em diferentes alturas de corte. O experimento foi realizado na Estação Experimental Pendência, da Empresa Estadual de Pesquisa Agropecuária da Paraíba S.A. (EMEPA), situada no Município de Soledade-PB. Utilizou-se um delineamento experimental em blocos casualizados, com quatro alturas de corte (30; 40; 50 e 60cm) e cinco repetições. O rendimento forrageiro foi influenciado pela altura de colheita, com aumento linear alcançando produção de matéria seca de 7206,78kg/ha a 60cm de altura. Observou-se efeito de altura de colheita para os conteúdos de lâmina, colmo e relação lâmina:colmo na matéria seca, em que os valores da relação lâmina:colmo diminuíram com o aumento da altura de colheita, obtendo valores de 0,87 e 0,48 quando colhidos aos 30 e 60cm de altura, respectivamente. Obteve-se efeito quadrático de altura de colheita apenas para o teor de fibra em detergente neutro, com teores variando de 71,82 a 77,08% na matéria seca. Os valores médios de matéria seca do feno variaram entre 82,44 e 84,48%. A recuperação de matéria seca durante a desidratação diminuiu em função das alturas de colheita, apresentando comportamento linear com menor média observada no capim colhido a 60cm de altura (76,58%). A ausência de variação nos constituintes bromatológicos e nas perdas de matéria seca final e as maiores produções de biomassa nas maiores alturas de colheita permite concluir que o capim-buffel seja colhido nas alturas de colheita que possibilite maior produção.

Effect of Harvesting at Different Heights on Growth and Flower Yield of Carnation (Dianthus caryophyllus L.) in Second Season Crop

The present study was under taken in a commercial floriculture farm under protected cultivation with three cultivarsof carnation during July 2010 to February 2011. The experiment was laid out in randomized block design with factorialconcept. Harvesting of carnation flower stalk at 10 cm height from the ground level recorded minimum number of days to sprouting of buds than other harvesting heights i.e., 5, 15 and 20 cm height. Days to first flower bud appearance, color break stage and days to harvest was also minimum with harvesting at 10 cm height in cultivars Domingo, Dover and Keiro. And the length of lateral, length of flower stalk and flower, diameter of flower stalk and flower, number of flower stalks per plant, fresh flower weight and vase life was maximum with harvesting 10 cm height than other harvesting heights in cultivar Domingo.

Yield and Stand Persistence of Switchgrass as Affected by Cutting Height and Variety

Switchgrass (Panicum virgatum L.) is a high-yielding forage species with low input demands on marginal soils. However, long-term response of prominent varieties to cutting heights is not well documented. To examine varietal type and cutting height impacts, three varieties of switchgrass (‘Cave-in-Rock’, ‘Kanlow’, and ‘Alamo’) that were established in 1992 for a previous study were evaluated in Knoxville, TN, from 2008 to 2011. Switchgrass plots were harvested at 10-, 20-, 30-, and 41-cm cutting heights in a two-cut system (June and September annually) to determine if lower harvest height affected forage yield and stand persistence. Plots were visually rated during the final year (2011) to assess stand vigor. Interactions were detected for total yield by cutting height and year (P < 0.05); shorter cutting heights appeared to negatively impact yields in subsequent years and the highest cutting height resulted in lower yields. However, there were no varietal yield responses to cutting heights. Shorter cutting height treatments (10 and 20 cm) had reduced Alamo and Kanlow presence (P < 0.05) by the end of the 4-yr study period. Consequently, lower switchgrass cutting heights (10 and 20 cm) may maximize short-term forage yield; however, stand persistence may be compromised long term, especially in lowland varieties.

Weed Suppression Potential of ‘Rondo’ and Other Indica Rice Germplasm Lines

Research was conducted to evaluate the weed suppression potential of ‘Rondo’ (4484-1693; PI 657830), a sister line (4484-1665), and other indica rice lines against barnyardgrass in field plots in Stuttgart, AR, using minimal herbicide inputs in two separate 3-yr experiments. Under weed pressure, Rondo and the sister line (4484-1665) generally produced yields that were comparable to those of weed-suppressive indica standards and approximately 50% greater than those of the least-suppressive commercial cultivars, such as ‘Kaybonnet’, ‘Katy’, and ‘Lemont’. Rice yield under weed pressure was correlated with weed-free yield and harvest height. Indica lines tended to produce more tillers than did the commercial cultivars. Tillering potential under weed-free conditions was not correlated with weed suppression or yield loss; however, tillering under weed pressure was strongly correlated with weed suppression and biomass, and yield and yield loss under the weed densities in these experiments. Rondo is presently being used for commercial organic rice production in Texas, in part due to its high yield potential and ability to suppress or tolerate rice pests, including weeds. Our results suggest that the weed-suppressive ability of Rondo and the other indica lines evaluated in these experiments is superior to that of many commercial cultivars.

FATORES QUE AFETAM A GERMINAÇÃO DAS SEMENTES E A BIOMASSA DE PLÂNTULAS DE Tabebuia heptaphylla

Informações sobre Tabebuia heptaphylla são fundamentais durante a coleta das sementes e produção de mudas. Objetivou-se, no presente estudo, analisar a relação entre os fatores altura de coleta das sementes na planta, peso das sementes, posição da semente no substrato e tipos de substratos com as variáveis germinação de sementes e massa fresca de plântulas. O delineamento experimental utilizado nos 2 experimentos foi o inteiramente casualizado em esquema fatorial composto por tratamentos com 4 repetições de 20 sementes cada. Avaliaram-se duas alturas de coleta das sementes na planta (experimento 1), duas posições das sementes no substrato (experimentos 1 e 2), duas categorias de peso de sementes e quatro tipos de substratos diferentes (experimento 2). Realizados os testes estatísticos, concluiu-se que a altura de coleta, a posição da semente no substrato, o peso das sementes e o tipo de substrato são fatores que atuam isoladamente nas variáveis em estudo. A coleta de sementes de Tabebuia heptaphylla deve ser realizada no terço superior da planta, e a semeadura deve ser feita com as sementes mais pesadas.

Respostas morfogênicas e estruturais de dosséis de espécies de Braquiária à intensidade de desfolhação

O objetivo deste trabalho foi avaliar as respostas morfogênicas e estruturais de duas espécies e cinco cultivares de braquiária a intensidades de desfolhação. As cultivares Marandu, Xaraés, Arapoty, Capiporã (Urochloa brizantha) e Basilisk (U. Decumbens) foram desfolhadas mecanicamente a 15 e 7,5 cm de altura, durante o verão e o inverno. Utilizaram-se unidades experimentais de 9x4 m, irrigadas e adubadas com 220 kg ha-1 por ano de N e K2O. As características morfogênicas avaliadas foram: filocrono e senescência, duração de vida e taxas de aparecimento e alongamento de folhas. As características estruturais foram: número de folhas vivas por perfilho, comprimento final das folhas expandidas e de colmos, relação senescência/crescimento e densidade populacional de perfilhos. Variações nas condições meteorológicas, em cada estação, promoveram aumentos nas taxas de aparecimento e alongamento, diminuição do filocrono e duração de vida das folhas. As características estruturais mais responsivas ao gradiente promovido pelas alturas de corte foram o comprimento final de folhas expandidas e a densidade populacional de perfilhos. A altura de corte mais baixa exerceu maior impacto na dinâmica de crescimento do que na senescência, em perfilhos individuais. As cultivares Xaraés e Capiporã foram as mais produtivas, em razão das maiores taxas de alongamento foliar e maior densidade populacional de perfilhos.

Integrated Harvesting Techniques for African Egg Plant (Solanum macrocarpon L., cv. Igbagba)

This study elucidated the influence of harvesting height and frequency on concurrent seed and shoots production of the African Eggplant, Solanum macrocarpon L., cv. Igbagba/Igbo. The overall aim was to use the outcome to make recommendations that would enable African resource poor farmers secure the much needed increase in income for improved livelihoods. The study was carried out between April to November 2004 on the National Horticultural Research Institute (NIHORT) Ibadan, Nigeria commercial vegetable production fields. Result shows that harvesting at 0.08 m above ground level was optimal and significantly highest for leaf, stem, shoot, seed and total yields except at 0.12 m above ground level for seed production. The result of financial profitability analysis shows that harvesting 0.08 m above ground level and fortnightly was most profitable for leaf, shoot and total yields compared to all the treatment combinations. Harvesting 0.12 m above ground level and monthly, however, was most profitable for seed production when compared to all treatments combinations. The study concluded noting that integrated harvesting techniques for shoot (leaf + stem) and seed production proved economically viable and optimize resource use efficiency better than growing S. macrocarpon sole either for shoot or seed.

EFEITOS DA ALTURA DE COLHEITA DA SILAGEM DE MILHO E DO NÍVEL DE CONCENTRADO SOBRE AS CARACTERÍSTICAS DA CARCAÇA E DA CARNE DE NOVILHOS SUPERJOVENS

This work was conducted with the objective of verifying the effects of increasing the corn silage harvest height from 16 to 46 cm, associated to 16 or 30% of concentrate level on total dry matter offered, on carcass and meat characteristics of young steers. Twenty-four Braford calves, weaned at three months of age, were finished in feedlot from seven to twelve months, when they were slaughtered. The commercial carcass cuts, metric carcass measurements, such as the bone, muscle and fat percentages and carcass tissues ratios were not affected by the silage harvest height and diet concentrate level used. On the other hand, meat of steers fed with low concentrate level had lower thawing loss (5.05 vs. 8.03%) resulting in higher juiciness (7.14 vs. 6.74 points), although the meat showed darker coloration than the meat of the other steers (3.17 vs. 4.00 points). The comparison between harvest heights showed that meat of steers fed with silage harvested at 16 cm from the soil had higher juiciness (7.18 vs. 6.69 points), as the result showed lower thawing loss (4.70 vs. 8.38%) and lower cooking loss (17.11 vs. 22.33%).KEYWORDS: Braford, carcass composition, meat quality, roughage, silage quality.

Evaluation of main-crop stubble height on ratoon rice growth and development

Rice ( Oryza sativa L.) ratooning is the production of a second rice crop from the stubble left behind after the main-crop harvest. Lowering the main-crop stubble height by harvesting the main crop at a lower than traditional height is believed to alter growth parameters and increase ratoon yields. The objectives of this study were to evaluate the effect of main-crop stubble height on ratoon grain yield, agronomics, and cumulative/weekly panicle growth parameters (density, point of origin, and weight). Main-crop ‘Cocodrie’ and ‘Trenasse’ rice cultivars were harvested to leave either a 40- or 20-cm stubble height. When the main-crop stubble was harvested at 20 cm, ratoon rice grain yield in 2007 was increased by 375 and 190 kg ha −1 for Cocodrie and Trenasse, respectively. Yield was not improved in 2006 using the low (20 cm) harvest height. The yield advantage in 2007 was associated with the increased weight of the basal panicles when the main crop was harvested at 20 cm. When the main-crop stubble was 20 cm, basal and axial panicle points of origin were numerically similar 5 weeks after main-crop harvest (WAH), while panicles originating from basal nodes were predominant 6 WAH and beyond. In contrast, when the main-crop stubble was 40 cm, approximately 75% of the emerged panicles originated from axial nodes 5 WAH, panicles from both axial and basal points of origin were nearly identical 6 WAH, and basal panicles were dominant thereafter. Results from this study indicate that when the initial stubble height is reduced from 40 to 20 cm the growth of the ratoon crop is altered by shifting panicle point of origin during the early growth period and delaying maturity.

Defoliation of Panicled Tick‐Clover, Tweedy's Tick‐Clover, and Tall Bush‐Clover: II. Herbage Nutritive Value and Condensed Tannin Concentrations

Few native herbaceous perennial warm‐season legumes are available for cultivation in the southern United States. These would be useful for pastures, biomass production, wildlife plantings, rangeland reseeding, or native prairie restoration. Three native perennial legumes were selected from an initial screening of north Texas germplasm for potential domestication based on successful establishment, ease of seed harvest, and herbage production. Response to herbage removal was evaluated by measuring forage nutritive value when clipped at 10‐, 20‐ and 40‐cm height (whenever regrowth exceeded 20 cm above cutting height) over three seasons in 2‐ by 2‐m plots with 0.5 m between plants. Tweedy's tick‐clover (Desmodium tweedyi Britton) became reproductive in June so herbage acid detergent fiber (ADF) (338–373 g kg−1) was greater (P &lt; 0.05) than tall bush‐cover (Lespedeza stuevei Nutt.) and panicled tick‐clover [D. paniculatum (L.) DC.] that both flowered primarily in September. Herbage N concentrations were uniformly (P &gt; 0.05) high (31.7 g kg−1) the first year and unaffected by harvest height all 3 yr; by the third year, however, tall bush‐cover had the lowest (P &lt; 0.05) N concentration (22.6 g kg−1) and in vitro dry matter disappearance (IVDMD; 651 g kg−1). Condensed tannin (CT) concentrations exceeded 120 g kg−1 for both the panicled tick‐clover and the tall bush‐clover although fraction distribution varied among entries. These three native North American legumes show potential as nutritious forage components to natural and cultivated systems.

The Effect of Silage Cutting Height on the Nutritive Value of a Normal Corn Silage Hybrid Compared with Brown Midrib Corn Silage Fed to Lactating Cows

A brown midrib (BMR) hybrid and a silage-specific non-BMR (7511FQ) hybrid were harvested at a normal cut height leaving 10 to 15cm of stalk in the field. The non-BMR hybrid was also cut at a greater height leaving 45 to 50cm of stalk. Cutting high increased the concentrations of dry matter (+4%), crude protein (+5%), net energy for lactation (+3%), and starch (+7%), but decreased the concentrations of acid detergent fiber (−9%), neutral detergent fiber (−8%), and acid detergent lignin (−13%) for 7511FQ. As expected, the BMR corn silage was 30% lower in lignin concentration than 7511FQ. After 30h of in vitro ruminal fermentation, the digestibility of neutral detergent fiber for normal cut 7511FQ, the same hybrid cut high, and the normal cut BMR hybrid were 51.7, 51.4, and 63.5%, respectively. Twenty-seven multiparous lactating cows were fed a total mixed ration composed of the respective silages (45% of dry matter) with alfalfa haylage (5%), alfalfa hay (5%), and concentrate (45%) (to make the TMR isocaloric and isonitrogenous) in a study with a 3×3 Latin square design with 21-d periods. Milk production was greater for cows fed the BMR hybrid (48.8kg/d) compared with those fed the normal cut 7511FQ (46.8kg/d) or cut high (47.7kg/d). Dry matter intake was not affected by treatment. Feed efficiency for cows fed the BMR silage (1.83) was greater than for those fed high-cut 7511FQ (1.75), but was not different from cows fed the normal cut 7511FQ (1.77). Cows fed the BMR silage had milk with greater concentrations of lactose but lower milk urea nitrogen than cows on other treatments. Harvesting a silage-specific, non-BMR corn hybrid at a high harvest height improved its nutritive content, but the improvement in feeding value was not equivalent to that found when cows were fed BMR corn silage.

Mechanical Harvesting of Leucadendron Flowers

A unique mechanical harvester for leucadendron cut flowers has been developed. A tractor-mounted harvester was developed initially and tested in commercial farms. It holds the flowers gently before they are cut from their plants, cuts them at a desired height, and conveys them away from the cutting line to a collecting bed. It is operated by a driver and two additional workers. Compared with manual harvesting, the mechanical harvester saves work in the field but adds some work in the packinghouse because it harvests more substandard ('cull') flowers, which will have to be rejected. Detailed work studies showed that the mechanical harvester is beneficial in labor saving and is economically viable for farms of at least 8 ha. A self-propelled harvester was developed for improved harvest height control, stability on slopes, and maneuverability.

Effects of cutting frequency on plant production, N‐uptake and N2 fixation in above‐ and below‐ground plant biomass of perennial ryegrass–white clover swards

AbstractNitrogen (N), accumulating in stubble, stolons and roots, is an important component in N balances in perennial ryegrass–white clover swards, and the effects of cutting frequency on the biomass of above‐ and below‐harvest height were studied during two consecutive years. Total dry matter (DM) and total N production, and N2 fixation, were measured at two cutting frequencies imposed in the summers of two years either by cutting infrequently at monthly intervals to simulate mowing or by frequent cutting at weekly intervals to simulate grazing. Total DM production harvested was in the range of 3000–7000 kg DM ha−1 with lower DM production associated with the frequent cutting treatment, and it was significantly affected by the different weather conditions in the two years. The higher cutting frequency also reduced the biomass below harvest height but the different weather conditions between years had less effect on stubble and, in particular, biomass of roots. The biomass of roots of white clover was significantly lower than that of roots of perennial ryegrass and remained at a relatively constant level (200–500 kg DM ha−1) throughout the experiment, whereas the biomass of perennial ryegrass roots increased from 2400 kg DM ha−1 in the year of establishment to 10 200 kg DM ha−1 in the infrequent cutting treatment and 6650 kg DM ha−1 in the frequent cutting treatment by the end of the experiment, giving shoot:root ratios of 4·7–16·6 and 0·5–1·6 for white clover and perennial ryegrass respectively. Annual N2 fixation was in the range of 28–214 kg N ha−1, and the proportion of N fixed in stolons and roots was on average 0·28. However, as weather conditions affect the harvested DM production and the shoot:root ratio, care must be taken when estimating total N2 fixation based on an assumed or fixed shoot:root ratio.

Yield and Chemical Composition of Cassava Foliage and Tuber Yield as Influenced by Harvesting Height and Cutting Interval

A 3x4 factorial field experiment with a complete randomised split-plot design with four replicates was conducted from June 2002 to March 2003 at the experimental farm of the Nong Lam University, Ho Chi Minh City, Vietnam,to determine effects of different harvesting heights (10, 30 and 50 cm above the ground) and cutting intervals (45, 60, 90 and 285 days) on yield of foliage and tubers, and chemical composition of the foliage. Cassava of the variety KM 94 grown in plots of 5 m×10 m at a planting distance of 30 cm×50 cm was hand-harvested according to respective treatments, starting 105 days after planting. Foliage from the control treatment (285 days) and all tubers were only harvested at the final harvest 285 days after planting. Dry matter and crude protein foliage yields increased in all treatments compared to the control. Mean foliage dry matter (DM) and crude protein (CP) yields were 4.57, 3.53, 2.49, and 0.64 tonnes DM ha - 1 and 939, 684, 495 and 123 kg CP ha - 1 with 45, 60, 90 and 285 day cutting intervals, respectively. At harvesting heights of 10, 30 and 50 cm the DM yields were 4.27, 3.67 and 2.65 tonnes ha - 1 and the CP yields were 810, 745 and 564 kg ha - 1 , respectively. The leaf DM proportion was high, ranging from 47 to 65%. The proportion of leaf and petiole increased and the stem decreased with increasing harvesting heights and decreasing cutting intervals. Crude protein content in cassava foliage ranged from 17.7 to 22.6% and was affected by harvesting height and cutting interval. The ADF and NDF contents of foliage varied between 22.6 and 30.2%, and 34.2 and 41.2% of DM, respectively. The fresh tuber yield in the control treatment was 34.5 tonnes ha - 1 . Cutting interval and harvesting height had significant negative effects on tuber yield. The most extreme effect was for the frequent foliage harvesting at 10 cm harvesting height, which reduced the tuber yield by 72%, while the 90 day cutting intervals and 50 cm harvesting height only reduced the yield by 7%. The mean fresh tuber yield decreased by 56, 45 and 27% in total when the foliage was harvested at 45, 60 and 90 day cutting intervals, respectively. It is concluded that the clear effects on quantity and quality of foliage and the effect on tuber yield allow alternative foliage harvesting principles depending on the need of fodder for animals, value of tubers and harvesting cost. An initial foliage harvest 105 days after planting and later harvests with 90 days intervals at 50 cm harvesting height increased the foliage DM and CP yield threefold, but showed only marginal negative effect on tuber yield.

Harvesting sulla for yield and quality

Deciding when to harvest sulla (Hedysarum coronarium) can be a compromise between herbage yield and forage nutritive quality. Sulla, which grows up to 1.5 m tall, is tolerant of dry conditions and has been shown to have beneficial effects on ruminant production and health. A trial was conducted at Hamilton, New Zealand, to compare crop yield and nutritive quality of sulla harvested when it reached 30, 45, 60 and 75 cm high (retaining a stubble of 15 cm) over one growing season. Results show harvesting at 75 cm versus 30 cm increased total dry matter (DM) yield by 30%. Increasing harvest height increased total fibre content from 13.1 to 20.1 g/100g DM, (P

Effects of bending and harvesting height combinations on cut rose yield in a dense plantation with high intensity lighting

The study aimed at improved rose production through the use of different bending and harvesting height combinations in a dense plantation (31.25 plants m −2) with high intensity lighting (220 μmol m −2 s −1) and CO 2 (800 ppm). The cultivars in the study were ‘Sacha’, ‘Indian Femma’, ‘Lorena’, ‘Frisco’ and ‘Dream’ and the production time was 5–17 months. The nodal position of cuttings had no significant effect on the time from planting to harvest, flower yield, most of the quality parameters or vase life. Growing method affected flower quantity and quality, the number of bottom breaks and plant mortality. In 8 out of 9 experiments, bending above 5 buds and harvesting at different heights (Method 5 B) gave higher yield than did bending at base and harvesting above 1 bud (Method B). In 5 out of 9 experiments, bending above 3 buds and harvesting at different heights (Method 3 B) resulted in higher yield than did Method B, and in 6 out of 9 experiments, Method 5 B gave greater yield than did Method 3 B. There were differences in response between the cultivars; e.g. in ‘Sacha’ the total number of flowering shoots per square meter over a 17-month cultivation period was 2039 with Method 5 B, 1501 with Method 3 B and 847 with Method B. Shoots were longer and the quality of flowers was proportionally better with Method B than with the other methods. For ‘Sacha’, ‘Indian Femma’ and ‘Lorena’ the number of high grade flowers per square meter was higher with Method 5 B than Method B. The number of good bottom breaks was higher with Method 5 B than Method 3 B. Plant mortality was greater with Method B than with the other methods. The median vase life of flowers in winter time was 20 days for ‘Frisco’, 18 days for ‘Dream’ and 12 days for ‘Sacha’. Dense production was profitable.

Genetic Variation in Nitrogen Uptake and Growth in Mycorrhizal and Nonmycorrhizal Picea abies (L.) Karst. Seedlings

Abstract The purpose of this study was to estimate genetic variation in nitrogen uptake and growth of mycorrhizal and nonmycorrhizal seedlings from 30 open-pollinated families of Norway spruce (Picea abies), at two levels of nitrogen (N) supply. Six-week-old seedlings were transplanted into 1.7 L pots filled with pumice, and one-half of them was inoculated with the ectomycorrhizal symbiont Laccaria bicolor. A 2 × 2 factorial combination of the presence or absence of the fungus and two nitrogen concentrations (200 mg N/L and 25 mg N/L) was used during 2 wk of establishment. During the following 10 wk, no water or nutrients were supplied. At harvest (week 18) height, shoot and root dry weights, as well as the amount of nitrogen in the shoot and nitrogen acquisition capacity, were determined. There was a strong treatment effect, and most of the traits ranked in increasing order: low N, low N + Mycorrhiza, high N, high N + Mycorrhiza. With low N, plants with mycorrhiza had a shoot dry weight twice that of nonmycorrhizal plants. Significant differences among families were found for most traits in treatments without mycorrhiza, while mycorrhiza strongly reduced the number of significant family differences. The amount of nitrogen in the shoot and all biomass traits showed a significant family × mycorrhiza × nitrogen interaction. Of the two traits related to nitrogen uptake, shoot nitrogen amount showed strong genetic correlations with biomass traits in all treatments (rg within the range 0.92 to 0.99) whereas nitrogen acquisition capacity did not (rg within the range -0.53 to +0.23), which implies that the amount of nitrogen in the shoot is a better predictor of growth than nitrogen acquisition capacity. FOR. SCI. 49(2):258–267.

Comparison of European Fibre Flax (Linum usitatissimum) Cultivars under Eastern Canadian Growing Conditions

AbstractRenewed interest in natural fibres, decreasing subsidies to European producers, and high production costs have led the move to reintroduce fibre flax (Linum usitatissimum L.) production into eastern Canada. Research was conducted at the Macdonald Campus of McGill University, Québec, Canada in 1998 and 1999 and at Winchester and Kemptville, Ontario, Canada in 1998, to assess the performance of seven European fibre flax cultivars. Parameters evaluated included plant density, branching ratio, stem diameter, fresh and dry biomass, and mean harvest height. Data from all sites and years were subjected to a pooled anova where appropriate. The cultivar main effect was detected for all parameters measured, with the exception of mean fresh weight and mean height at harvest. There was also a site main effect for all parameters except for branching ratio. A cultivar–site interaction was found for all parameters except for mean stem diameter and mean dry weight. Results indicate a strong potential for producing fibre flax in eastern Canada using currently available European cultivars.

Effect of early season nitrogen on nitrogen fixation and fertilizer-use efficiency in grass-clover pastures

Grass-legume pastures rely on biologically fixed nitrogen (N) and thus are often N deficient in the spring. To overcome this period of N deficiency, researchers in the United Kingdom (UK), New Zealand (NZ), and recently the United States (US), have developed programs of early season N applications to clover/grass pastures. However, the effect of such early season N application on clover N fixation and N fertilizer N use efficiency of clover/grass swards is not known in the climate of the northeast US. A three-year study was conducted in Pennsylvania on a white clover (Trifolium repens)/orchardgrass (Dactyls glomerata) sward, fertilized with three rates of 15N (22.4, 44.8, and 89.6 kg N ha−1) and cut at three target sward harvest heights (TSHH) (15, 22.5, and 30 cm). The objective of the study was to determine the effects of N fertilization and TSHH on the fraction of clover N derived from fixation (FNDF), the total clover N derived from fixation (TNDF), and fertilizer N use efficiency (FNUE) of the combined sward. Over the three years of the study, full season FNDF in the clover was about 0.90 and the TNDF was about 135 kg N ha−1. The TSHH decreased TNDF during April and May, but this effect disappeared by the end of September. Nitrogen fertilizer use efficiency at the two lowest fertilization rates was greater than 0.50, but decreased to 0.36 at the highest N fertilization rate. The data indicates that, at a 44.6-kg N ha−1 rate and a 15-cm TSHH, the TNDF and the FNUE will be maximized.

Effects of Early Season Nitrogen on Grass–Clover Swards in the Northeastern USA

Grass–legume pastures that rely on biologically fixed N are often N deficient in the spring. Early season N applications to grass–clover pastures can help overcome this deficiency. Our objective was to test the effects of early season N application and harvest height on total dry matter (DM) yield and clover fraction of a grass–clover sward in the northeast USA. The study was conducted for 3 yr (1996–1998) at the Russell Larson Agricultural Research Center in Rock Spring, PA (40°48′N, 77°52′W; 330 m above sea level). The soil on the site is a Hagerstown silt loam (Typic Hapludalf, fine, mixed, mesic). The effect of early season N fertilization (0, 22.4, 44.8, and 89.6 kg ha−1) was measured on an orchardgrass (Dactyls glomerata L. cv. Pennlate)–white clover (Trifolium repens L. cv. Will) sward harvested at three sward heights (15, 22.5, and 30 cm). Increasing N fertilization and target sward harvest height (TSHH) generally increased the early season total DM yield and reduced the clover fraction in the sward. However, by the end of the growing season, the clover fraction from the fertilized treatments was identical to that of the unfertilized treatments. Total early season DM yields on mixed grass–clover swards were increased by 20% with an application of 45 kg N ha−1. Also, maintaining a 15‐cm TSHH along with 45 kg N ha−1 would maximize the clover fraction in the sward.