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1.
Sustainable soil and crop management practices that reduce soil erosion and nitrogen (N) leaching, conserve soil organic matter, and optimize cotton and sorghum yields still remain a challenge. We examined the influence of three tillage practices (no-till, strip till and chisel till), four cover crops {legume [hairy vetch (Vicia villosa Roth)], nonlegume [rye (Secaele cereale L.)], vetch/rye biculture and winter weeds or no cover crop}, and three N fertilization rates (0, 60–65 and 120–130 kg N ha−1) on soil inorganic N content at the 0–30 cm depth and yields and N uptake of cotton (Gossypium hirsutum L.) and sorghum [Sorghum bicolor (L.) Moench]. A field experiment was conducted on Dothan sandy loam (fine-loamy, siliceous, thermic, Plinthic Paleudults) from 1999 to 2002 in Georgia, USA. Nitrogen supplied by cover crops was greater with vetch and vetch/rye biculture than with rye and weeds. Soil inorganic N at the 0–10 and 10–30 cm depths increased with increasing N rate and were greater with vetch than with rye and weeds in April 2000 and 2002. Inorganic N at 0–10 cm was also greater with vetch than with rye in no-till, greater with vetch/rye than with rye and weeds in strip till, and greater with vetch than with rye and weeds in chisel till. In 2000, cotton lint yield and N uptake were greater in no-till with rye or 60 kg N ha−1 than in other treatments, but biomass (stems + leaves) yield and N uptake were greater with vetch and vetch/rye than with rye or weeds, and greater with 60 and 120 than with 0 kg N ha−1. In 2001, sorghum grain yield, biomass yield, and N uptake were greater in strip till and chisel till than in no-till, and greater in vetch and vetch/rye with or without N than in rye and weeds with 0 or 65 kg N ha−1. In 2002, cotton lint yield and N uptake were greater in chisel till, rye and weeds with 0 or 60 kg N ha−1 than in other treatments, but biomass N uptake was greater in vetch/rye with 60 kg N ha−1 than in rye and weeds with 0 or 60 kg N ha−1. Increased N supplied by hairy vetch or 120–130 kg N ha−1 increased soil N availability, sorghum grain yield, cotton and sorghum biomass yields, and N uptake but decreased cotton lint yield and lint N uptake compared with rye, weeds or 0 kg N ha−1. Cotton and sorghum yields and N uptake can be optimized and potentials for soil erosion and N leaching can be reduced by using conservation tillage, such as no-till or strip till, with vetch/rye biculture cover crop and 60–65 kg N ha−1. The results can be applied in regions where cover crops can be grown in the winter to reduce soil erosion and N leaching and where tillage intensity and N fertilization rates can be minimized to reduce the costs of energy requirement for tillage and N fertilization while optimizing crop production.  相似文献   

2.
A relay cropping system of cereals, whereby winter wheat (Triticum aestivum L.) was undersown in two‐row spring barley (Hordeum distichum L.), was established in a field trial in central Sweden in 1999 and continued until 2000. The purpose of the study was to examine crop and weed responses to different plant densities of the undersown winter crop. Winter wheat was sown at four seed rates (187, 94, 47 and 0 kg ha?1) immediately after the sowing of barley. Barley was harvested in the first autumn after sowing and winter wheat in the second autumn. The grain yield of barley was not affected by the seed rate of wheat, and averaged 4580 kg ha?1. Winter wheat did not vernalize during the first growing season but remained at the vegetative stage. The grain yield of wheat was 1990 kg ha?1 for the lowest and 5610 kg ha?1 for the highest seed rate of wheat. Whilst the undersowing process itself stimulated weed emergence in this experiment, increasing the undersowing seed rate reduced the population of perennial weeds by 40–70 %. In the second growing season, the total biomass of weeds was 66 % higher at the highest seed rate compared with the lowest seed rate.  相似文献   

3.
Preplant‐applied, urea‐based fertilizer management in high‐residue, no‐till (NT) corn (Zea mays L.) is challenging because of potential N loss due to cool, wet conditions in the spring and dry conditions during the summer months. Field research evaluated the effects of polymer‐coated urea (PCU) application timing, placement and cropping system on urea release for corn and determined corn yield response to PCU on claypan soils following wheat (Triticum aestivum L.) cropping systems [reduced‐till corn following wheat, no‐till corn following wheat with double‐cropped (DC) soybean [Glycine max (L.) Merr.] and no‐till corn following wheat with a frost‐seeded red clover (FSC) (Trifolium pratense L.) cover crop]. Urea release from PCU was <35 % from fall through winter (November–January) and <20 % for early preplant (February–March) applications until 1 April. By 1 August, less urea was released in some instances from surface applications of PCU following FSC or DC soybean, but release was generally greater than in the absence of soil. No‐till corn following DC soybean or FSC had yields that were 1.01–1.32 Mg ha?1 greater when grown with PCU compared to urea at 168 kg N ha?1. Grain yields were similar within no‐till cropping systems with PCU, anhydrous ammonia and sidedressed urea ammonium nitrate (UAN) at 168 kg N ha?1. Farmers should recognize that high yields may not be obtained if PCU rates are reduced by 50 % (84 kg N ha?1) in high‐residue (DC soybean or FSC), no‐till production systems. Several N sources such as PCU, anhydrous ammonia and sidedressed UAN worked similarly in high‐residue, no‐till systems, although no differences between N sources were observed in a reduced‐tillage system.  相似文献   

4.
Field experiments were conducted in two successive seasons at the Agricultural Research Centre, Giza, Egypt (on a clay loam soil), to determine the effects of N fertilization (added at rates of 107 and 161 kg N ha–1) and foliar application of plant growth retardants (Pix, Cycocel and Alar; each applied once at 300 p.p.m., 75 days after planting) and zinc (applied at 0.0 and 50 p.p.m., two times, 80 and 95 days after planting) on cottonseed, protein and oil yields and oil properties of the Egyptian cotton cultivar Giza 75. The higher N rate, as well as the application of all growth retardants and zinc, resulted in an increase in cottonseed yield ha–1, seed index, seed protein content, oil and protein yields ha–1, seed oil refractive index, unsaponifiable matter and total unsaturated fatty acid content (oleic and linoleic). However, those treatments decreased the oil acid value, saponification value, and total saturated fatty acid content. The seed oil content tended to decrease when the high N rate was applied, but tended to increase with the application of all growth retardants and zinc. There were some differences between Pix, Cycocel and Alar regarding their effects on the studied characters. The highest increase in seed yield ha–1, seed index, and oil and protein yields ha–1 was found with Pix, followed by Cycocel. The Cycocel treatment gave the lowest total saturated fatty acid oil content, followed by Alar.  相似文献   

5.
A field study was conducted to investigate the influence of variable rates of application of N and P fertilizers in splits at various times on the growth and the seed and oil yields of canola (Brassica napus L.) during 1995–97. Rates of fertilizer application were 0 and 0 (F0), 60 and 0 (F1), 0 and 30 (F2), 60 and 30 (F3), 90 and 60 (F4) and 120 and 90 (F5) kg N ha?1 and kg P2O5 ha?1. All the P was applied at sowing while N was applied in splits, i.e. all at sowing, half at sowing and half with first irrigation, or half at sowing and half at flowering. The responses of growth, seed yield and components of yield were consistent in both years. Increasing the rate of fertilizer application from F4 (90/60 kg N/P2O5 ha?1) to F5 (120/90 kg N/P2O5 ha?1) increased the leaf area index (LAI) relative to the control and to lower rates of fertilizer application. For both crops, application of 90/60 kg N/P2O5 ha?1 significantly enhanced total dry matter (TDM) and seed yield. Seed yield increased mainly due to a greater number of pods per plant and seeds per seed‐pod. The time of fertilizer application did not significantly affect seed yield or components of yield in either season. Oil yield generally followed seed yield, increasing with increasing rate of fertilizer application up to 90/60 kg N/P2O5 ha?1. The maximum oil contents were obtained from the control. The results show that seed and oil yields of canola were maximized at the F4 (90/60 kg N/P2O5 ha?1) rate of application under the agro‐ecological conditions of Faisalabad, Pakistan.  相似文献   

6.
The effects of four row spacings (17.5, 35.0, 52.5 and 70.0 cm) and five seeding rates (50, 100, 200, 400 and 800 viable seeds m?2) on seed yield and some yield components of forage turnip (Brassica rapa L.) were evaluated under rainfed conditions in Bursa, Turkey in the 1998–1999 and 1999–2000 growing seasons. Plant height, stem diameter, pods/terminal raceme, total pods/plant, seeds/pod and primary branches/plant were measured individually. The number of plants per unit area was counted and the lodging rate of the plots was scored. The seed yield and 1000‐seed weight were also determined. Row spacing and seeding rate significantly affected most yield components measured. The number of plants per unit area increased with increasing seeding rate and decreasing row spacing. Plant height was not greatly influenced by row spacing and seeding rate, but higher seeding rates reduced the number of primary branches and the stem diameter. The number of pods/main stem was affected by row spacing and but not by the seeding rate. Also, the number of seeds per pod was not affected by either the row spacing or the seeding rate. In contrast, the number of pods per plant clearly increased with increasing row spacing, but decreased with increasing seeding rate. The plots seeded at narrow row spacings and at high seeding rates were more sensitive to lodging. Seeding rate had no significant effect on seed yield in both years. Seed yield was similar at all seeding rates, averaging 1151 kg ha?1. However, row spacing was associated with seed yield. The highest seed yield (1409 kg ha?1) was obtained for the 35.0‐cm row spacing and 200 seeds m?2 seeding rate combination without serious lodging problems.  相似文献   

7.
The aim of the present study was to compare the potential seed yield of eight quinoa varieties, to explore their mineral composition of seeds and to identify superior varieties in two locations with different soil properties. Compared with neutral soil conditions, seed yield in the marginal (saline–sodic) soil was decreased by 45 %. Under the latter soil conditions seed yield was negatively correlated with crop density, indicating that a considerable yield loss was due to poor and uneven plant density caused by adverse soil properties. Among the varieties, ‘RU–5–PQCIP–DANIDA–UNA’ produced the highest seed yield (>20 dt ha?1) when grown under neutral soil conditions. Under marginal conditions, the above‐mentioned variety and ‘N 407’ produced seed yields up to 10 dt ha?1 whereas the rest reached yields of only about 5 dt ha?1. The majority of the varieties accumulated significantly more protein (20 %) in the seeds under saline–sodic soil conditions (lower yielding environment). The varieties originated from South America were superior in accumulating protein in the seeds at both locations. Mineral contents of calcium (Ca), magnesium (Mg), zinc (Zn) and manganese (Mn) in the seeds were significantly higher in the neutral soil. No differences were found for phosphorous (P), iron (Fe), copper (Cu) and boron (B) between the two locations. The South American varieties were again superior in mineral composition. Adaptation of certain quinoa varieties even under marginal environments seems promising for seed production and/or protein and mineral content in the seeds. Agronomic data are needed in a due course, over a higher number of locations and/or various climatic conditions.  相似文献   

8.
Breeding has developed better yielding maize hybrids for low N environments, which also have delayed leaf senescence (‘stay green’ trait, SG). Here, we studied whether the SG trait can further improve yield of modern hybrids under N‐limiting conditions. In two field experiments, four maize hybrids with different senescence behaviour were grown under three N fertilization levels, from 0 to 200 kg N ha?1 (N0, N100 and N200). After silking, hybrids differed for senescence depending on the canopy layer (P < 0.05): the SG AX878 only delayed senescence at the mid and upper canopy layers while the SG NK880 delayed senescence of all layers. Across N doses, higher yields were achieved by both SG hybrids, AX878 and NK880 (P < 0.05) but yield was not only determined by senescence behaviour. Kernel weight (KW) response to N availability was larger for SGs than for their non‐‘stay green’ counterparts. Delayed senescence in SG hybrids was not related to higher post‐silking N uptake but to higher (P < 0.05) %N in leaves and lower (P < 0.05) %N in kernels at harvest (below the critical 1.1 % under N deficiency). Across N levels, KW positively related to N content per kernel, with a steeper slope (P < 0.05) for the SG hybrids. Taken together, our results suggest that a condition where N limits kernel growth, in a scenario of saturating C availability, may be common to stay green genotypes of maize.  相似文献   

9.
In a 2‐year experiment on Typic Ustochrept soils of the North Plain Zone of India, the effect of different row ratios (3 : 1, 6 : 2, 4 : 1 and 8 : 2) and staggered sowing of mustard (simultaneous and 15 days later) was studied in intercropping of chickpea (Cicer arietinum) and mustard (Brassica juncea L.). Nodule number, dry weight, grain yield, protein content and yield were higher in monocrop chickpea compared with intercropping. Among row ratios, except for protein content in grain, all the above parameters were significantly higher in the 4 : 1 intercropping of chickpea + mustard. Similarly, delayed sowing of mustard by 15 days also gave higher plant dry weight (1.80–2.36 g plant?1), nodule number (0.41–1.56 and 0.5–3.0 at 55‐ and 70‐day stages, respectively), protein yield (63 kg ha?1), grain yield (290 kg ha?1) and biological yield (1104 kg ha?1) than sowing with chickpea. Widening the row ratio and pairing of the rows of mustard were also found to be beneficial in increasing chickpea growth and yield. Like chickpea, sowing of mustard as a monocrop gave higher growth and yield. Delayed sowing by 15 days reduced the growth and yield of mustard drastically. Productivity, measured in terms of land equivalent ratio, was higher for intercropping of chickpea and mustard in the 4 : 1 row ratio than for sowing of chickpea and mustard in sole stands. Interestingly, the land equivalent ratio was also higher in the simultaneously sown crop than for staggered sowing.  相似文献   

10.
In the Mediterranean zone, efforts to optimize combinations of supplemental irrigation (SI), improved varieties, nitrogen (N) and sowing dates aim to improve and stabilize cereal yields and maintain quality, especially for durum wheat. Thus, a 4 year field study (1992/1993 to 1995/1996) on a deep clay soil in northern Syria assessed the impact of SI (rain-fed, 1/3, 2/3 and full SI) combined with variable N application rates (0, 50, 100, 150 kg ha−1) and sowing date (early, normal, late) for four improved durum wheat varieties adapted to rain-fed and irrigated conditions. As rainfall and evapotranspiration varied over the 4 years, the amount of SI water required also varied. Yields varied with the season, and the main factors, except variety, were significant. Delaying sowing from November to January reduced yields and response to both SI and N. With irrigation, crop responses were generally significant up to 100 N ha−1, whereas the optimum response for rain-fed conditions occurred with 50 kg N ha−1. Limited SI (1/3) significantly increased yields, but almost maximum yields were obtained by 2/3 of full SI. Water- and N-use efficiencies were greatly increased by SI, with little variation among varieties. However, irrigation and delayed sowing decreased grain protein levels, which were partially compensated for by added N. A similar effect was observed for kernel vitreousness. Models developed from the response data can facilitate the potential transfer of these findings. Thus, in most growing seasons, minimum irrigation during the winter growing season, combined with appropriate fertilization, can enhance wheat output and yet maintain grain quality.  相似文献   

11.
Annual Medicago as a Smother Crop in Soybean   总被引：2，自引：0，他引：2  
Use of conservation tillage and narrow row spacing in soybean [Glycine max (L.) Merr.] production has led to increased use of herbicides for weed control. Some producers are seeking alternative weed control methods, such as smother crops, that would reduce dependence on chemical weed control. A successful smother crop must compete strongly with weeds but minimally with the crop. In four environments, we intercropped three annual Medicago spp. (medics) with soybean to test their utility as a smother crop for weed control. Annual medics were intercropped with soybean at rates of 0, 85, 258, or 775 seeds m?2, and the intercrops were grown with and without weed control. Increasing medic seeding rate decreased weed yields but also reduced soybean herbage and grain yields. For the weed‐controlled treatment, average soybean grain yields declined 7 kg ha?1 for every 10 seeds m?2 increase in medic seeding rate. Soybean grain yield was lower when grown with Medicago scutellata L. cv. Sava than when grown with Medicago polymorpha L. cv. Santiago or Medicago lupilina L. cv. George. Soybean grain yield was negatively related (r=?81) to medic herbage production. In the autumn following soybean harvest, medic residue ranged from 200 to 3700 kg ha?1 depending on the location and seeding rate. Medics provided residue for soil protection, suppressed weeds, but also reduced soybean yields.  相似文献   

12.
In a crop rotation trial, conducted from 1985 to 1988 at TU-Munich's research station in Roggenstein, the transfer of grain legume nitrogen was evaluated in crop rotations containing fababeans and dry peas as well as oats (reference crop) and winter wheat and winter barley as following crops. The results obtained can be summarized as follows: Dinitrogen fixation by fababeans ranged from 165 to 240 kg N ha1, whereas N2-fixation by peas amounted from 215 to 246 kg N ha?1. In all seasons the calculated N-balance where only grain was removed was positive, with a net gain being on average 106 (peas) and 84 (fababeans) kg N ha?1. After the harvest of peas 202 kg N ha?1 remained on the field on average over seasons (158 kg N ha?1 in the above ground biomass and 44 kg N ha?1 as NO3-N in 0–90 cm depth). As compared to peas, fababeans left 41 kg N ha?1 less due to smaller amounts of nitrogen in the straw. After oats very small amounts of residual nitrogen (33 kg N ha?1) were detected. After the harvest of grain legumes always a very high nitrogen mineralization was observed during autumn especially after peas due to a close C/N-relationship and higher amounts of nitrogen in the straw as compared to fababeans. In comparison with fababeans, N-mineralization after the cultivation of oats remained lower by more than 50%. During winter, seepage water regularly led to a considerable decrease of soil NO3-N content. The N-leaching losses were especially high after cultivation of peas (80 kg N ha ?1) and considerably lower after fababeans (50 kg N ha?1) and oats (20 kg N ha?1). As compared to oats, a higher NO3-N content in soil was determined at the beginning of the growing period after preceding grain legumes. Therefore, winter wheat yielded highest after preceding peas (68 dt ha?1) and fababeans (60 dt ha?1) and lowest after preceding oats (42 dt ha?1). The cultivation of grain legumes had no measurable effect on yield formation of the third crop winter barley in either of the growing seasons.  相似文献   

13.
Previous experiments have shown that, at harvest of winter wheat, recovery of fertilizer N applied in early spring [tillering, Zadok’s growth stage (GS) 25] is lower than that of N applied later in the growth period. This can be explained by losses and immobilization of N, which might be higher between GS 25 and stem elongation (GS 31). It was hypothesized that a higher crop density (i.e. more plants per unit area) results in an increased uptake of fertilizer N applied at GS 25, so that less fertilizer N is subject to losses and immobilization. Different crop densities of winter wheat at GS 25 were established by sowing densities of 100 seeds m–2 (Slow), 375 seeds m–2 (Scfp= common farming practice) and 650 seeds m–2 (Shigh) in autumn. The effect of sowing density on crop N uptake and apparent fertilizer N recovery (aFNrec = N in fertilized treatments ? N in unfertilized treatments) in crops and soil mineral N (Nmin), as well as on lost and immobilized N (i.e. non‐recovered N = N rate ? aFNrec), was investigated for two periods after N application at GS 25 [i.e. from GS 25 to 15 days later (GS 25 + 15d), and from GS 25 + 15d to GS 31] and in a third period between GS 31 and harvest (i.e. after second and third N applications). Fertilizer N rates varied at GS 25 (0, 43 and 103 kg N ha–1), GS 31 (0 and 30 kg N ha–1) and ear emergence (0, 30 and 60 kg ha–1). At GS 25 + 15d, non‐recovered N was highest (up to 33 kg N ha–1 and up to 74 kg N ha–1 at N rates of 43 and 103 kg N ha–1, respectively) due to low crop N uptake after the first N dressing. Non‐recovered N was not affected by sowing density. Re‐mineralization during later growth stages indicated that non‐recovered N had been immobilized. N uptake rates from the second and third N applications were lowest for Slow, so non‐recovered N at harvest was highest for Slow. Although non‐recovered N was similar for Scfp and Shigh, the highest grain yields were found at Scfp and N dressings of 43 + 30 + 60 kg N ha–1. This combination of sowing density and N rates was the closest to common farming practice. Grain yields were lower for Shigh than for Scfp, presumably due to high competition between plants for nutrients and water. In conclusion, reducing or increasing sowing density compared to Scfp did not reduce immobilization (and losses) of fertilizer N and did not result in increased fertilizer N use efficiency or grain yields.  相似文献   

14.
The effects of row spacing (17.5 or 35.0 cm), support plant species (barley or triticale) and the proportion of crops in mixtures (no support plant or support plant 20, 40 or 60 %, respectively) on the seed yield and yield characteristics of Hungarian vetch (Vicia pannonica Crantz) were investigated. Increasing the row spacing increased the seed yield of V. pannonica from 881.0 to 1248.0 kg ha?1. On average, in a pure stand the seed yield of V. pannonica was 1141.0 kg ha?1. In mixtures with barley and triticale, the seed yield of V. pannonica averaged 986.0 and 1143.0 kg ha?1, respectively. In single mixed stands the seed yield of V. pannonica varied between 551.0 kg ha?1 (60 % support plant barley) and 1603.0 kg ha?1 (20 % support plant triticale). The yield advantage of V. pannonica in this triticale mixture was 40 % compared to the V. pannonica pure stand. With respect to the total yield in the mixture with 20 % triticale (1902.0 kg ha?1) the yield advantage over the V. pannonica pure stand was as high as 65.1 %. In the mixed stands the number of seeds per pod and the thousand‐seed weight of V. pannonica were higher than in V. pannonica pure stands.  相似文献   

15.
In a two year factorial field trial the influence of slight shading (daylight reduced by 27 %), row spacing (15 and 30 cm respectively) and N fertilization (60 and 120 kg* ha?1*cut?1 respectively) on yield and nutritive value of Lolium multiflorum (Lam.) was investigated. Three cuts were taken in the seeding year and four in the full harvest year. Shading reduced DM yield by 4 % at low and 16 % at high level of N fertilization. Higher amount of N fertilizer increased yield by 28 % without and 12 % with shading. Row spacing was of minor importance; on average wider spacing decreased yield by 9 %. Increasing N fertilization and shading had the same effects on nutritive value: crude protein (CP), nitrate content and protein/energy ratio (P/E) went up, whereas energy value (NEL) went down. Compared to the effects of shading or N fertilization, the influence of sward density on nutritive value was small. The effect of shading and high fertilization on nutritive value was similar in both years. However for vegetatively grown forage in the seeding year shading caused P/E values and nitrate contents too high for an adequate ruminant feeding which was already evident at low level of N fertilization; also increased supply of N fertilizer without shading deteriorated the nutritive value. On the other hand forage of the full harvest year (at reproductive stages) showed too high P/E values only in shaded and highly fertilized plots. Therefore N fertilization ought to be limited at periods when the grass only grows vegetatively and/or light intensity is low, like e.g. in autumn. None of the experimental treatments had any marked effect on the fibre content of the forage (ADF) in the seeding year; in the full harvest year, however, when plants grew reproductively, shading as well as higher N fertilization increased ADF content. There was no significant correlation between ADF and NEL for vegetatively grown plants but a close relation for plants which were at reproductive stages.  相似文献   

16.
To determine the effect of different preceding crops and crop rotations on the grain yield of oil-seed rape, a long-term rotation experiment was conducted at the Hohenschulen experimental station in Kiel, NW Germany. Additional factors included the nitrogen fertilization and the fungicide application. The results reported herein are based upon the harvest years 1988 to 1993. Averaged over the different rotations and husbandry treatments, the grain yields in the 6 experimental years varied between 2.71 t ha?1 and 3.99 t ha?1. In contrast, the effect of the different husbandry treatments was smaller and non significant. Averaged over 6 years, only the fungicide application caused small yield increase of 0.2 t ha?1. The highest grain yields of 3.77 t ha?1 or 3.65 t ha?1 occurred when oil-seed rape was directly following peas. Low yields between 3.15 tha?1 and 3.33 tha?1 were obtained when oil-seed rape was grown after oilseed rape. The lowest grain yield of 3.13 t ha?1 was produced with oil-seed rape grown in monoculture only. In rotations with oil-seed rape following a preceding cereal crop (wheat or barley), the grain yields averaged between 3.22 tha?1 in a two course rotation and up to 3.44 tha?1 in a four course rotation. In general, the yields of oil-seed rape increase with the length of the rotation and the length of the break between two oilseed rape crops. The yield component number of seeds per m2 was affected by the previous cropping accordingly, whereas the thousand seed weight did not respond to the cropping history. Based upon disease assessments in the first years of this experiment, we argue that an increase in the incidence of fungal diseases has considerably contributed to the yield decrease of oil-seed rape in short rotations.  相似文献   

17.
The ability to predict grain protein concentration at harvest (CP) in Swedish malting barley (Hordeum distichum) from observations of soil conditions, sowing day, fertilisation rate, remote sensing at early stem elongation and the temperature sum during grain filling, was tested for two cultivars; Astoria (Secobra, France) and Wikingett (Svalöf-Weibulls, Sweden) in 16 fertilisation trials in southern Sweden, encompassing 3 years (2001–2003). Fertilisation was applied either as a single dose at sowing, or as both a starting application and an application at early stem elongation. The highest total application rate was 160 kg N ha−1 y−1. The soil was analysed for phosphorus, potassium, magnesium and calcium in the layer 0–0.3 m, and mineral N down to 0.6 m. Canopy reflectance observations at BBCH 32 was used to calculate a vegetation index (TCARI(32)) to reflect the canopy (leaf and straw) chlorophyll concentration. Harvested grain CP correlated only marginally with the observed soil variables. It was, however, for a specific cultivar, possible to make a prediction of grain CP based on day of sowing and TCARI(32) with . Part of the sowing day effect might be due to thermal stress during grain filling, as the risk for high temperatures during this phase was higher when sowing was late. This might also explain why the introduction of accumulated temperature during grain filling, into a model already including sowing day and TCARI(32) as independent variables, did not improve the predictability of grain CP.  相似文献   

18.
Undersowing a main crop enables establishment of a catch crop in areas characterized by a short post-harvest period before the onset of winter. Techniques with lower costs than conventional undersowing by separate drilling are often regarded as unreliable. Undersowing by drilling after sowing spring barley ( Hordeum vulgare L.) was compared with broadcast sowing simultaneously with drilling barley. Various implements were coupled behind the combined drill in cases where seed was broadcast: a press-wheel attachment, a long-tined harrow and a cage roller. A fourth treatment did not include an implement coupled behind the drill. The undersown crop was sown as a seed mixture of 3 kg ha–1 red clover ( Trifolium pratense L.) and 6 kg ha–1 meadow fescue ( Festuca pratensis Hudson). The numbers of plants and weeds and the plant height were measured five times during the growing season. Above-ground biomass of the undersown species was determined at barley harvest and in late autumn. Grain yield of spring barley was recorded. Drilling resulted in the highest yield of undersown crop when an early summer drought occurred, but broadcasting in combination with use of seed covering equipment led to the least variation in biomass production over the 4 years the experiment was conducted. The relative proportion of meadow fescue in the crop was low in three years, and lower when broadcast than when drilled. Barley grain yield was highest when the seed was broadcast and seed covering equipment was used. Use of a cage roller increased weed biomass, but press-wheels and a long-tined harrow did not. Separate rolling after undersowing increased undersown crop yield in one year, but decreased grain yield in some cases.  相似文献   

19.
Twenty wheat ( Triticum aestivum L.) varieties differing in plant height were grown in soil culture and evaluated for differences in nitrogen uptake and nitrogen utilization efficiency (NUE) at limited (40 kg N ha−1) and normal (120 kg N ha−1) nitrogen supply. Nitrogen uptake showed 1.4- and 1.5-fold varietal variation at harvest for limited and normal N supply, respectively. NUE for dry matter production (NE1) exhibited 1.28- and 1.38-fold genotypic variation while NUE for grain production (NE2) varied by 1.25- and 1.21-fold at limited and normal N supply, respectively. Tall varieties were found to have higher N uptake and NUE for dry matter production, while dwarf cultivars had greater NUE for grain production. Nitrogen uptake was found to be strongly positively associated with dry matter production (r=0.85 and r =0.77 at limited and normal N supply, respectively), indicating an important effect of growth rate on N uptake. NUE for biomass production, as well as for grain production, was reduced as the supply of nitrogen was increased.  相似文献   

20.
Soil and climatic conditions in Newfoundland are on the margins of agricultural capability, and almost all feed grain is imported. The overall objective of this work was to develop guidelines for the production of barley in Newfoundland, with the goal of establishing modern cropping recommendations. We conducted a 4-year study near St. John's to examine the effect of seeding rate and topdress ammonium nitrate (N) fertilization rate on Chapais six-row barley ( Hordeum vulgare L.) yield components and grain yield. Increasing seeding rate from 200 to 380 seeds m–2 did not alter grain yield in any year. Increasing topdress fertilization from 0 to 60 kg N ha–1 increased spike density m–2 at harvest, resulting in linear increases in grain yield in all years. Highest N rates had greatest lodging in two years. Based on our results, agronomic recommendations for eastern Newfoundland now include barley seeding rates of 250 ± 50 seeds m–2, with topdress applications up to at least 30 kg N ha–1.  相似文献   

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