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1.
Grass–legume mixtures have proven successful at improving the sustainability of grasslands. Their ability to suppress unsown species is particularly important for sainfoin (Onobrychis viciifolia), a forage crop with valuable bioactive compounds, yet low competitiveness. In this 3‐year study, the suitability of six partner species cultivated in mixtures with sainfoin at different annual numbers of cuts and partner sowing densities were evaluated. Mixture yields outperformed average monoculture yields by 31%, reduced the ratio of unsown species by 65% and increased the symbiotic N2 fixation up to 158 kg ha?1. A key finding of the study was the highly differential patterns of development of the partner grass species over the 3 years. These patterns of development had a large effect on the persistency of the proportion of sainfoin in the mixtures, which varied in the third year between 17% (when grown with Dactylis glomerata) and 38% (with Lolium perenne). These findings contribute to the further development of sustainable grass–legume systems, as evidence for the successful cultivation of sainfoin as an alternative legume species can help diversification, and knowledge of mixture development supports more persistent legume proportions.  相似文献   

2.
Panicum maximum is important for cattle production in tropical regions, and it responds well to nitrogen (N) fertilization. Many cultivars have exhibited potential for use in silvopastoral systems, although there is limited information on how different levels of N can influence plant growth and nutritive value under shading. Morphogenetic and structural traits, biomass production and nutritive value of two P. maximum cultivars (Tanzânia and Massai) were investigated under three shading levels (0, 37 and 58%) and four N rates (0, 50, 100 and 150 mg N dm?3). Plants were grown in pots under shade. Leaf and stem elongation rate and leaf blade length increased with shading and in response to N. Tiller density was reduced with shading, but showed a linear increase fashion with N under full sun and moderate shading. Under intense shading, the tillering showed a quadratic response to N. Plant biomass production increased linearly with N under full sun and moderate shade, but it increased quadratically under intense shade. Crude protein (CP) content increased with shade and N and was greater for Tanzânia than Massai under shade. Contents of NDF and ADF were greater for Massai than Tanzânia. Acid detergent insoluble protein was reduced in Tanzânia under shade, but it increased for Massai. It is suggested that the positive shading effect on CP content may not result in increased nutritional value. Although N fertilization was important for increasing biomass production under full sun and moderate shade, it should be avoided under intense shading.  相似文献   

3.
The short life span, irregular forage production and susceptibility to weed colonization of cool‐season grass–legume pastures are serious problems in grazing dairy systems in warm‐temperate regions. The inclusion of warm‐season species has the potential to mitigate these problems. In this study, we evaluated the effect of the inclusion of two warm‐season grasses with different growth habits on seasonal forage biomass, soil cover and weed colonization. Three different pasture mixtures were evaluated under grazing: conventional pasture (CP) [tall fescue (Festuca arundinacea), white clover (Trifolium repens) and birdsfoot trefoil (Lotus corniculatus)], CP with Paspalum dilatatum and CP with Paspalum notatum (CP + Pn). Forage biomass and soil cover were sampled thirteen times during a 3‐year trial, and sampling times were grouped by season for the analyses. The mixtures with Paspalum showed higher soil cover in the autumn, while in the winter CP had higher soil cover than CP + Pn. Competition with tall fescue was similar between mixtures with Paspalum, when considering biomass, but it was higher in CP + Pn when considering soil cover. The inclusion of P. notatum increased biomass during the autumn but decreased the mixture performance during winter by reducing tall fescue soil cover. The addition of a warm‐season grass species with a moderate competing ability like P. dilatatum is likely to avoid a negative impact on the cool‐season component of the pasture.  相似文献   

4.
Selective grazing of white clover (Trifolium repens) over grass species in temperate pastures results in reduced clover abundance and availability over time. Within sheep‐ and cattle‐grazed dryland (<800 mm annual rainfall) hill and high country areas of New Zealand, naturalized unsown annual clover species show greater persistence and abundance over sown clovers. With a view to understanding legume abundance in these areas, Merino sheep grazing preference was investigated for pure swards of naturalized species Trifolium dubium, T. glomeratum, T. arvense and T. striatum and commonly sown species T. repens and T. subterraneum. The Chesson–Manly preference index was used to explore the hypothesis that grazing preference differs between these species and changes as plants mature. Herbage offtake was quantified at vegetative (mid–late spring; November) and reproductive (early summer; December) stages of plant maturity. Significant preference distinctions between species (P < 0·05) occurred in December, with relative preference ranging from 0·248 for T. repens to 0·065 for T. dubium. Reduced relative preference for naturalized species was related to decreasing nutritive value from spring to summer, reflecting increased stem and flower sward content. Relative preference was negatively related to increasing acid detergent fibre and neutral detergent fibre and positively related to greater crude protein and dry‐matter digestibility. Naturalized annual clover species of lower grazing preference at reproductive maturity will benefit pasture sustainability via herbage and seed production and associated nitrogen‐fixation inputs.  相似文献   

5.
The inclusion of legumes in semi‐arid native grasslands may promote the productivity and nutritive value of forage. This study was designed to assess the effect of legumes (the introduced legume Medicago sativa or the native legume Dalea purpurea) and soil P fertility (addition of 0, 50, or 200 P2O5 kg/ha at seeding) on the dry matter and nutrient content of native grasses mixtures, compared with the commonly used introduced forage grass Bromus biebersteinii grown with M. sativa. Plant harvests were performed in September 2008, July 2009 and September 2009. Plants nutrient content, δ15N value and dry matter were analysed. Results show that the M. sativa enhanced the N and P concentrations of native grass mixtures early in the summer, as well as the N concentration in Bouteloua gracilis in late summer of the driest year, 2009. The higher AM fungal diversity promoted by M. sativa was positively correlated with the dry matter and nitrogen uptake of M. sativa and with the P concentration of native grasses, in early summer. Overall, this study shows that M. sativa promoted beneficial AM fungal taxa and improved forage production in the semi‐arid prairies.  相似文献   

6.
A symbiosis between grasses and systemic fungal endophytes exists in both natural and agricultural grassland communities. Our objective was to examine the effects of systemic endophytes on the competitive ability of two agronomically important grass species: meadow fescue [Festuca pratensis (Huds.) syn. Schedonorus pratensis (Huds.) P. Beauv] and tall fescue [Festuca arundinacea (Schreb.) syn. Schedonorus phoenix (Scop.)]. Plants of meadow and tall fescue were grown for 48 days in replacement series of interspecific mixture with a legume (red clover, Trifolium pratense L.) in different nutrient environments in a greenhouse. Neither of the grass species gained endophyte‐promoted competitive advantage over red clover in grass–clover mixtures. Endophyte infection increased the growth of meadow fescue monocultures by 89% compared to endophyte‐free monocultures in high‐nutrient soils, but plant competition or the cost of endophyte infection to the meadow fescue decreased the yield in resource‐limited conditions. On average, endophyte‐infected and endophyte‐free meadow fescues produced 0·15 and 0·17 g, and 0·14 and 0·14 g dry biomass per plant in mixtures with red clover in high‐ and low‐nutrient soils respectively. In contrast to meadow fescue, endophyte‐promoted growth of tall fescue monocultures was not detected. Endophyte‐infected and endophyte‐free tall fescue monocultures produced 0·76 and 0·95 g biomass per pot, respectively, in the high‐nutrient environment. Endophyte infection can increase the performance of the host grass, but the positive effects depend on the host species, the species composition and soil nutrient availability.  相似文献   

7.
Botanical diversity has been linked to increased biomass production of grasslands, but these relationships have not been explored as extensively in silvopasture systems where shade impacts on forage mass are variable due to the unique structure and environment of each system. The objective of this study was to evaluate the impact of multiple artificial shade levels on the DM yield and botanical composition of three cool-season forage mixtures near Blackstone, Virginia, USA. Mixtures were as follows: simple = tall fescue [Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.] and white clover (Trifulium repens L.); intermediate = simple + orchardgrass (Dactylis glomerate L.) and red clover (Trifolium pretense L.); and complex = intermediate + Kentucky bluegrass (Poa pratensis L.), birdsfoot trefoil (Lotus corniculatus L.) and alfalfa (Medicago sativa L.). Slatted structures created conditions of 30%, 50% and 70% shade relative to a full sun control. Forages were harvested mechanically (no grazers present). Annual yield (DM kg/ha) did not differ among mixtures. As compared to full sun, annual yield was no different at 30% shade, but was reduced by 22 and 36% at 50 and 70% shade respectively. In contrast to other species in the mixtures, orchardgrass increased in proportion when grown beneath all shade levels and is recommended for silvopasture use. Orchardgrass is not particularly well-adapted to the transition zone between the northern temperate and southern subtropical United States; therefore, these results indicate that silvopastures may be an effective way to integrate marginally adapted, shade-tolerant cool-season forages into transition zone grazing systems.  相似文献   

8.
Intake and performance of sheep or cattle grazing legume‐based swards were assessed over 2 years at four locations in Europe with different climatic conditions: Sardinia (Italy), southern France, northern Germany and south‐west England (UK). Legume species were sown in mixtures with locally appropriate companion grass species. Standard legume species commonly used at the location (Medicago polymorpha in Italy, Medicago sativa in France, and Trifolium repens in Germany and UK) were compared with two alternative legume species characterized by different agronomic or nutritional characteristics. They were: Trifolium subterraneum and Hedysarum coronarium in Italy; Trifolium incarnatum and Onobrychis sativa in France; Trifolium pratense and Lotus corniculatus in Germany; and Trifolium ambiguum and L. corniculatus in the UK. Lactating milk sheep in Italy, non‐lactating ewes in southern France, growing cattle in Germany, and ewes and lambs in the UK were used in three replicates per treatment. Intake and performance of sheep and cattle in various treatments varied with location, year and period within year. In Germany, intake and performance by cattle were not affected by treatment. In contrast, at the other locations, sheep grazing standard or alternative legume species known to contain condensed tannins (sulla, sainfoin and birdsfoot trefoil) had higher proportions of legume and crude protein (CP) concentrations in the diet and higher CP intakes than those grazing the other alternative legume species. Sheep performance paralleled these results. It is concluded that there is potential for a greater use of alternative legume species, at least for sheep‐grazing systems, in both the Mediterranean and cool temperate zones of Europe.  相似文献   

9.
Mixed grass/legume pastures are an alternative to grass monocultures for increased beef cattle production in tropical climates. The objective of this study was to evaluate the productivity of beef cattle grazing either a mixed pasture of Brachiaria brizantha cv. Marandu grass and Arachis pintoi (forage peanut) cv. Belomonte or a Marandu monoculture, under rotational stocking. Five trials were conducted over a period of nine years in north-eastern Brazil where the sward structure (forage, grass and legume mass) and animal performance were compared for a mixed Marandu grass/forage peanut pasture, and a Marandu grass monoculture with 120 kg N ha−1 y−1. Stocking rate was adjusted to maintain forage allowance at 4% body weight/day. A block design was used with four replicates, and warm and cool seasons within each trial were considered, using repeated measurements over time. In the warm season, the forage mass in the mixed pastures was 17% greater than in the monoculture (p = .049), and the stocking rate, average daily gain and liveweight gain per ha were 16.4%, 20.0% and 28.7% greater (p = .004, p < .001 and p < .001 respectively). The average daily gain showed a positive linear relationship with the legume proportion in the sward (p < .001). The mixed forage peanut/Marandu pasture sustained significantly greater beef cattle production (789 kg ha−1 y−1) compared to the N-fertilized grass monoculture (655 kg ha−1 y−1). Appropriately managed, mixed pastures of forage peanut/Brachiaria pastures are sustainable and have high potential for use in the humid tropics.  相似文献   

10.
The aim of this study was to determine a temporary strategy for increasing the legume population in an established pasture of brachiaria grass (Brachiaria brizantha) and forage peanut (Arachis pintoi). The treatments comprised four previous long‐term canopy heights (10, 20, 30 and 40 cm) from the establishment (the first 32 months after treatment initiation). From September 2014, all of the experimental units were kept at 10 cm height. The pastures were evaluated for their forage harvest, forage mass, botanical composition and stolon and tiller density. The tiller density and brachiaria grass mass were maintained in all pastures since the first season of evaluation (p > 0.10). The stolon density and legume mass were initially lesser at 30 and 40 cm than those at 10 and 20 cm, early in the experiment, but progressively increased over time. After 1 year under 10 cm height, the population and mass of legume were similar in all treatments. Therefore, reducing the canopy height to 10 cm at the beginning of the rainy season is an efficient method to increase the botanical composition of forage peanut in mixed pastures with brachiaria grass.  相似文献   

11.
A pre‐existing mechanistic model of grass growth, developed to simulate grass production in the UK, was extended to include a variety of grass–legume mixtures and used to predict comparative yields across a range of sites in northern Europe, using experimental data from a series of experiments at fifteen sites. Specifically, predictions were made of the comparative yields of grass (Lolium perenne L.), white clover (Trifolium repens L.), red clover (T. pratense L.), lucerne (Medicago sativa L.), lotus (Lotus corniculatus L.) and galega (Galega orientalis Lam.). The results indicated that the model could generate simulated differences in yields between forage crops, which accorded with observed rankings. However, the predictions were more accurate for total yields than individual cuts, for a country than for an individual site, and for monocultures than for grass–legume mixtures. Nevertheless, the results appeared sufficiently robust to be used to prepare forecasts of yield productivity in different agro‐climatic zones in northern Europe. Using estimates of the production costs and economic values for the forages, it was also possible to assess their comparative profitability. The study indicated that red clover, whether grown singly or in a mixture with grass economically outperformed all silage systems based on pure grass swards, even those receiving 400 kg N ha?1. White clover and lucerne were also consistently more profitable than grass‐based systems, receiving 200 kg N ha?1. In relative terms, lucerne appeared to be more profitable in the south and east of the region, while white clover outperformed lucerne in the north and west. In the north and east of the region, there was some evidence that galega might also hold promise as a silage crop, but lotus was not found to be viable under north European environmental conditions.  相似文献   

12.
Pintoi peanut (Arachis pintoi Krapov. & W.C. Greg.) is a warm‐season perennial legume with potential for use in grass–legume mixtures in Florida; however, limited information exists about its establishment in mixtures with bahiagrass (Paspalum notatum Flügge). The objective of this experiment was to evaluate the establishment of bahiagrass cv. “Argentine” and pintoi peanut cv. “Amarillo” as monocultures or mixture. The experiment was conducted in Ona, FL, from June to October of 2014 and 2015. Treatments were a split‐plot design of seeding strategies (bahiagrass monoculture, pintoi peanut monoculture or bahiagrass‐pintoi peanut mixtures; main plots) and two N fertilization strategies (30 or 80 kg/ha N; 30N and 80N; subplots), with four replicates. Measurements of plant density and frequency were taken every 4 weeks after seeding. Ground cover and herbage mass (HM) measurements were taken 112 days after seeding. Pintoi peanut ground cover was affected by seeding strategy × N level interaction. Ground cover was greater with 80N than 30N when pintoi was seeded in monoculture (3.6% vs 1.5% respectively) but not when it was seeded with bahiagrass (2.1%). There was no effect of seeding or N strategy on pintoi peanut proportion in HM (1.4%). Bahiagrass ground cover was not affected by seeding or N strategy (15.9%); however, its proportion in the HM was greater in 80N than 30N (12.1% vs 9.4% respectively). Mixed seeding did not negatively affect the establishment of bahiagrass and pintoi peanut and greater N fertilization levels improved some establishment parameters, with no negative effect for pintoi peanut.  相似文献   

13.
Theories suggest that incorporating alfalfa (Medicago sativa L.; Alf) or birdsfoot trefoil (Lotus corniculatus L.; BFT) into endophyte‐infected tall fescue (Festuca arundinaceas Schreb.; E+TF) pasturelands may improve livestock production. We investigated how planting configuration might influence plant secondary metabolites (PSM) and nitrogen concentration in these forages. Total nitrogen (N), in addition to condensed tannins (CT), saponins and ergovaline (EV), was compared in BFT, Alf and E+TF, respectively, when forages grew in monocultures and all possible two‐way “mixtures” using a block design with repeated measures in three blocks. Ergovaline (p < .01) and N (p < .001) concentrations in E+TF were greater when growing adjacent to legumes than when growing in monoculture, and N and EV concentrations in E+TF were positively correlated (r = .51; p = .001). No differences in saponins or CT were found when Alf or BFT grew in monoculture or in two‐way mixtures (p > .10). We conducted an in vitro trial to determine whether CT or saponins isolated from BFT and Alf, respectively, would bind to EV in water. Ergovaline bound to saponins to a greater extent (39%; SE = 0.25) than CT (5.1%; SE = 5.13; p < .05). Because EV was lower in E+TF monocultures than in E+TF–legume mixtures, and because CT and saponins may form complexes with EV which may alleviate fescue toxicosis, animals may benefit from systems which allow them to graze monoculture patches of E+TF and Alf or BFT rather than grass–legume mixtures.  相似文献   

14.
This is the first report on the effect of light intensity and plant growth‐promoting rhizobacteria (PGPR) on the growth of a tropical forage grass, being a relevant study to improve pasture management in conventional farming and integrated crop‐livestock‐forestry systems. In this study, our aim was to evaluate the effects of light intensity and Burkholderia pyrrocinia and Pseudomonas fluorescens inoculation on Brachiaria brizantha cv. BRS Piatã growth, and phenotypic plasticity to shade. The experiment was conducted in a semi‐controlled environment. Seedlings of B. brizantha were allocated to full sun and shade. P. fluorescens and B. pyrrocinia were inoculated individually or co‐inoculated by soil drench, 14 days after seedling emergence. We evaluated morphogenesis, structural and growth parameters. Irrespective of the light regime, co‐inoculated plants had greater leaf area and SPAD index (chlorophyll content). Increase in total biomass production in co‐inoculated plants was over 100% and 300%, under full sun and shade respectively. Co‐inoculated P. fluorescens and B. pyrrocinia increased shade tolerance in B. brizantha, improving plant performance. Co‐inoculation promoted growth in B. brizantha under both sun and shade, indicating its potential as a bio‐fertilizer in conventional and integrated systems, especially in silvopastoral systems, where light availability to pasture growth may be limited.  相似文献   

15.
Echinochloa species are problematic weed species in direct-seeded rice systems in Asia. Because of concern about the continuous use of single herbicides, cultural weed management strategies need to be developed to maintain the sustainability of direct-seeded rice systems. However, the design of such strategies requires an understanding of the differential responses of weeds to shade caused by crop interference. The effects of shade on growth and seed production of Echinochloa colona, Echinochloa crus-galli, and Echinochloa glabrescens were determined. Weeds of three Echinochloa species were grown continuously in full sunlight or in 50% or 25% of full sunlight, or started in full sunlight and transferred to 50% or 25% of full sunlight at 21 days after sowing. The results suggested that changes in shade regime did not affect the plant height of E. colona and E. glabrescens; however, shade reduced the height of E. crus-galli. Compared with the plants grown in full sunlight, 75% of continuous shade reduced E. crus-galli height by 22%. Shade reduced leaf, total shoot, and root biomass and seed production in all the weed species, if occurred during the early growth of the weeds. The weeds responded with increased leaf biomass ratio when grown in shade. Compared with full sunlight, continuous shade of 75% increased leaf biomass ratio by 90% in E. colona and this value was 25% in the other two species. The results of this study show that shade can reduce weed growth and seed production of Echinochloa species but it should not be considered as a stand-alone strategy to manage these weeds in rice. This highlights the need for the integration of other weed management strategies to achieve complete control of these species.  相似文献   

16.
Pasture legumes that persist under challenging agroecological conditions are crucial to ensure high lamb growth rates in dryland pastures. Pasture and lamb production from binary and diverse mixtures (Mix) of tall fescue (TF) with white clover (Whc), balansa clover (Bc), subterranean clover (Sc) and birdsfoot trefoil (Bft) were compared in a summer‐dry hill site in Corvallis, Oregon over a two‐year period. In 2018, all pasture combinations provided similar lamb liveweight gains (LWG, mean 177 g/day) in the first half of spring. Lambs in TF‐Bc and TF‐Mix pastures grew 31 to 41 g/day faster than those grazing TF‐Sc, TF‐Whc and TF‐Bft in the second half of spring (p < .05). Overall, TF‐Bc and TF‐Mix had higher (p < .05) legume contents (32% and 37% respectively) compared to other pasture combinations. In spring 2019, lambs that grazed the TF‐Mix and TF‐Whc pastures had higher LWG than those on other pastures (p < .05). The superior lamb growth rates were associated with the higher legume content and pasture quality maintained into the late spring period. Overall, the legume content of all pastures decreased over the course of the two‐year trial, with the decline being substantial for balansa clover. The present study confirmed that a high legume content of pastures leads to greater lamb growth rates. Total annual yields of pastures that had greater legume contents were superior to others (p < .05). Thus, a combination of self‐regenerating annual clovers with perennial legumes in pasture mixtures may ensure a higher legume content and longer persistence in dryland hill pastures.  相似文献   

17.
Cutting height is an important factor controlling the yield and persistence of grass swards harvested for conserved feed. The objective of this experiment was to determine the effect of four cutting heights (5, 10, 15 and 20 cm) on the yield, composition and productivity based on deviation from a size/density compensation line for swards of orchardgrass (Dactylis glomerata L.) and an orchardgrass/alfalfa (Medicago sativa L.) mixture harvested nine times over three growing seasons. Yield was greatest for the 5 cm cutting height through the course of the experiment but ground cover of orchardgrass declined. Prior to the final harvest, tiller weight and density were determined. The 10‐, 15‐ and 20‐cm treatments fell on an apparent size/density compensation line with slope ‐1·779 (R2 = ·99; p = ·008) while the 5‐cm treatment fell considerably below that line indicating a reduction in productivity or relative persistence. Harvest at 10 cm appears to optimize yield while maintaining stand productivity in infrequently harvested orchardgrass swards.  相似文献   

18.
We evaluated forage production patterns, weight gains and blood parameters when lambs (Ovis aries) and meat‐goat (Caprus hircus) kids were finished on a mixed sward of cocksfoot (Dactylis glomerata L.), red clover (Trifolium pratense L.) and white clover (Trifolium repens L.) with (SUP) and without (UNSUP) supplemental whole cottonseed (Gossypium hirsutum; WCS) in a replicated study. Botanical composition and energy/protein ratios of the sward varied with year and with time during the growing season. Swards had greater amounts of red clover relatively early and more cocksfoot later in the season. Suffolk (SX) lambs had the heaviest body weights, Katahdin (KA) lambs were intermediate, and meat‐goat (GX) kids were the lightest at the end of each year. Overall body weight gain followed a trend of SX > KA > GX, and WCS supplementation increased weight gain for all animals by 18%. Only in 2008 did SUP animals have higher blood urea nitrogen levels, which may indicate less efficient use of dietary nitrogen when grazing grass–legume pastures managed for high nutritive value compared with UNSUP animals. Gossypol in WCS did not affect blood packed cell volume between SUP and UNSUP lambs and meat‐goat kids. Suffolk lambs, Katahdin lambs and cross‐bred Boer meat‐goat kids finished on pasture with and without WCS supplementation produced desirable body weights for most ethnic markets in the USA.  相似文献   

19.
There is a lack of information on the effects of companion species in grass–legume mixtures on herbage yield and quality changes during prolonged growth. Such information is relevant for harvest planning and estimation of consequences for feeding value of conserved feed when harvesting is delayed. Perennial ryegrass was sown with each of four legumes: red clover, white clover, lucerne and birdsfoot trefoil, and white clover was sown with hybrid ryegrass, meadow fescue and timothy. Effects of species composition on herbage yield, contents of N, neutral detergent fibre (NDF), acid detergent fibre (ADF) and lignin, ash and in vitro organic matter digestibility (IVOMD) were studied in entire herbage and in component species during 2 years in a small‐plot cutting trial in Denmark. In May and August, the dynamic development of components of feed value and their interrelationships were investigated by sampling at optimum harvest date (i.e., normal practice) ± 1 week (t = ?1 to t = +1). Herbage digestibility and contents of N and ash decreased while those of fibre compounds increased during the 2 weeks from t = ?1 to t = 1 in all species. In May, contents of ADF and lignin increased at a faster rate in legumes than in grasses; in August, NDF and ADF increased most quickly in legumes. Generally, N contents and IVOMD declined at similar rates in grasses and legumes, but, within each group, differences in yield and quality development occurred among species. The relationship between weekly growth rate and change in quality parameters differed among species and functional groups, i.e., grasses and legumes. Results are discussed in the context of quantifying the impact of delaying the harvest date of grass–legume mixtures and relationships between productivity and components of feed quality.  相似文献   

20.
以培杂泰丰、粤晶丝苗和天优998为材料,分别设置不施氮、中氮和高氮3个不同的氮肥水平(即施纯氮0、120和180kg/hm2,依次记为NN、MN、HN),研究始穗期遮荫(分别为双层遮荫、单层遮荫和不遮荫,依次记为DS、SS、CK)对不同基因型水稻产量及一些生理特性的影响。结果表明,与不施氮处理相比,遮荫处理结束后恢复5d高氮显著增加水稻叶面积指数、茎鞘干质量、总干质量、茎鞘物质输出量和茎鞘物质转运率,水稻剑叶的光合速率和气孔导度也显著提高。高氮处理下水稻的收获产量、有效穗数和每穗总粒数显著高于不施氮处理,而结实率和千粒重却显著降低。与不遮荫相比,双层遮荫处理水稻叶面积指数、茎鞘干质量、总干质量、剑叶的光合速率和气孔导度显著降低,双层遮荫处理水稻的收获产量和有效穗数也显著降低。氮肥和遮荫的互作效应对水稻叶面积指数、茎鞘干质量、总干质量、有效穗数以及收获产量的影响也达到显著水平。在单层遮荫条件下,增施氮肥可以减轻遮荫对水稻叶面积指数、叶片干质量、茎鞘干质量、总干质量、有效穗数和收获产量的不利影响。对不同品种而言,超级杂交稻天优998受到氮肥和遮荫的影响更大。  相似文献   

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