耕作方式和秸秆还田对黄淮海夏大豆产量和土壤理化性状的影响

在徐州麦豆一年两熟区进行田间定位试验(2012-2016年),采用两因素试验设计,研究了不同耕作方式(免耕和旋耕)和小麦秸秆还田量(不还田、半量还田和全量还田)对大豆产量和土壤理化性状的影响。结果表明:与旋耕处理相比较,免耕处理对大豆产量、土壤有机质含量和土壤速效K含量没有影响,但减少了土壤NO_3~--N含量,增加了土壤NH_4~+-N含量、土壤速效P含量和播种期至苗期的土壤容重。与不还田处理相比较,秸秆还田处理提高了大豆单株荚数、百粒重和产量以及土壤有机质含量和土壤速效K含量,降低了土壤NO_3~--N含量、NH_4~+-N含量和初花期至初熟期土壤容重。免耕和秸秆还田均降低了土壤p H值、播种期至初花期土壤温度,增加了播种期至初花期土壤湿度。秸秆不还田下免耕处理大豆单株荚数、百粒重、产量、土壤有机质含量、土壤p H值和土壤NO_3~--N含量较旋耕处理显著下降。与之不同,秸秆还田下免耕处理土壤湿度、土壤有机质含量、土壤速效P含量高于旋耕处理,土壤温度、土壤NO_3~--N含量和土壤NH_4~+-N含量低于旋耕处理,而免耕处理与旋耕处理间大豆产量和土壤速效K含量差异均不显著。其中,免耕+秸秆全量还田处理土壤温度、土壤p H值最低,土壤湿度、土壤有机质含量最高。因此,在黄淮海夏大豆区推广免耕技术时,应与秸秆覆盖,尤其是秸秆全量覆盖相结合,同时,在生产中需要注意N肥的补充。     

不同耕作处理对土壤酶活性的影响

通过田间定位试验,研究吉林省西部半干旱区不同耕作处理(常规垄作、平作留茬免耕、平作灭茬覆盖)对土壤酶活性的影响。结果表明,平作灭茬覆盖对播种前表层土土壤酶(脲酶、磷酸酶和过氧化氢酶)活性的影响较大,这与平作灭茬覆盖处理下秸秆覆盖对土壤温度的影响有关;平作留茬免耕和平作灭茬覆盖对玉米生育期间土壤脲酶和过氧化氢酶的影响较大,对土壤磷酸酶活性影响较小;平作留茬免耕对收获后土壤中过氧化氢酶及脲酶活性影响较大。在垂直方向上,随着土壤深度的增加,土壤脲酶和过氧化氢酶的活性都表现为先升高后下降的趋势,土壤磷酸酶活性无规律。     

秸秆还田与覆膜对土壤理化特性及玉米生长发育的影响

试验研究秸秆还田对不同覆膜时期的全膜双垄沟播玉米生长发育与土壤理化特性的影响。结果表明,经秸秆还田后全膜双垄沟播耕层土壤养分含量变化依次表现为整株还田>秸秆粉碎>免耕留茬,不同覆膜时间对土壤养分变化影响不明显;秸秆还田土壤容重明显降低但免耕留茬一膜两年用处理土壤容重增大。在玉米生育前期经秸秆还田后的土壤温度与水分均显著低于对照,其株高、茎粗与叶面积均小于对照;在玉米生育后期秸秆腐解后对土壤水分起到一个补偿效应。玉米产量表现为秋覆膜整株秸秆还田>顶凌覆膜整株秸秆还田>秋覆膜秸秆粉碎还田>顶凌覆膜秸秆粉碎还田>免耕留茬一膜两年用,秸秆还田后玉米产量较对照有增产趋势,而免耕留茬一膜两年用有减产倾向,但处理间差异不显著。     

基于秸秆还田条件下辽北地区适宜耕作方式及施肥量研究

通过两年田间小区试验,在秸秆还田条件下,设不同耕作方式(旋耕、翻压和免耕)和还田周期(连年和隔年),研究不同秸秆还田模式和施肥量对土壤理化性质和玉米产量的影响。结果表明,与常规种植不还田相比,翻压还田处理显著降低耕层土壤容重,免耕还田处理显著增加耕层土壤含水率,秸秆还田提高土壤有机质、氮、磷、钾养分含量。连年翻压还田处理玉米穗部性状最优,子粒产量最高;其次为免耕还田处理,旋耕还田处理不利于玉米产量的提高。在同等氮肥施用水平下,秸秆还田处理使玉米产量显著提高,在此基础上增加氮肥投入量并未带来显著增产效应。相同秸秆还田条件下,减施50%钾肥处理的玉米子粒产量无显著变化。在辽北地区,秸秆还田配合翻压、免耕耕作措施能够改善土壤理化形状,有利于玉米稳产高产,连年翻压还田对玉米增产效应最理想,且秸秆还田配合适宜的化肥减量措施不仅能保证作物产量,可降低养分流失污染环境的风险。     

保护性耕作对土壤部分物理特性及大豆产量的影响

研究了免耕和少耕对松嫩平原地区农田土壤温度、土壤水分、土壤紧实性等物理特性和大豆产量的影响。结果表明:在春季大豆播种期,免耕处理(NT)土壤含水量高于少耕(RT)和传统耕作(CT)。在大豆生长前期,免耕条件下的土壤平均温度低于传统耕作和少耕,传统耕作和少耕接近,免耕模式的土壤温度日较差低于少耕和传统耕作。5~20 cm深度内,免耕条件下的土壤容重高于传统耕作,在10~20 cm深度内,免耕和少耕接近。不同模式间的土壤机械阻力表现出差异,在0~20 cm深度内,免耕高于少耕和传统耕作。不同耕作模式间的大豆产量差异不显著。短期保护性耕作试验结果表明:在当地气候和土壤条件下应用少免耕模式,能够减少春季播种期间土壤水分损失和沙尘暴侵袭造成的危害,同时对大豆产量并没有造成不利影响。     

保护性耕作对旱作玉米土壤微生物和酶活性的影响

研究了玉米关键生育时期不同保护性耕作措施对旱作玉米田土壤微生物和酶活性的影响。结果表明：随着玉米生育时期的推进,免耕留低茬、免耕留低茬＋秸秆覆盖、免耕留高茬＋秸秆覆盖、免耕留高茬4个处理土壤微生物细菌、放线菌、真菌和纤维素分解菌数量均显著增加,土壤过氧化氢酶、脲酶和蔗糖酶的活性增强。在全生育期,保护性耕作处理土壤微生物细菌、放线菌、真菌和纤维素分解菌数量比传统耕作分别提高41.9%、470.1%、67.9%和65.7%,土壤过氧化氢酶、脲酶和蔗糖酶的活性分别提高15.0%、18.5%和57.3%,且此效应受玉米生长发育进程的影响。表明保护性耕作有利于增加土壤有机质的累积,提高土壤肥力。     

秸秆还田方式对土壤理化性质及玉米产量的影响

在辽河平原中西部设两年定点试验,研究秸秆还田方式对土壤理化性质及玉米产量的影响。结果表明,条带旋耕后10~20 cm土层土壤紧实度显著下降,0~40 cm(2016)土壤容重减小、总孔隙度增加;条带旋耕明显增加了丰水年(2016)玉米产量。秸秆还田显著增加10~20 cm土层土壤速效养分含量、提高土壤有机质含量,降低0~30 cm土层土壤容重、增加其总孔隙度。秸秆还田改善土壤理化性质,显著提高玉米产量,干旱年(2015)条带旋耕增产效果最突出。秸秆条带旋耕还田提高土壤通透性、改善土壤结构、增强土壤抗旱能力、提高作物产量,是适宜推广的秸秆还田和耕作组合方式。     

辽西地区垄作保护性耕作方式对玉米产量效应的影响研究

比较研究了不同垄作保护性耕作方式对玉米产量及其形成过程的影响。结果表明,垄作保护性耕作方式具有明显的增产效果,留茬免耕、留茬覆盖和灭茬免耕分别比传统耕作增产12.0%、13.6%和7.8%。垄作保护性耕作方式的干物质积累量和株高均表现为作物生长发育的前期低于传统耕作,在拔节期以后逐渐赶上并超过传统耕作,其单株干物重由大到小的顺序为:留茬覆盖>留茬免耕>灭茬免耕,平均株高整齐度由大到小的顺序为:灭茬免耕>传统耕作>留茬免耕>留茬覆盖。不同耕作方式玉米灌浆速率不同,其中保护性耕作方式玉米灌浆速率的优势表现在授粉15d以后。垄作保护性耕作方式的玉米穗行数、行粒数均优于传统耕作,其中又以留茬覆盖方式最佳,分别比传统耕作高出0.85和1.40个百分点。     

不同耕作措施对土壤质构和玉米产量的影响

通过4年定位试验,研究不同耕作措施对黑钙土区耕地土壤结构和质量以及玉米产量的影响。结果表明,播种前,和常规旋耕(CK)相比,深松旋耕(DP)、秸秆覆盖还田+深松(DSM)和秸秆深翻还田(PS)使土壤容重降低5.22%～11.19%,孔隙度增加5.09%～11.45%;DP、DSM处理土壤含水率分别提高14.99%和18.58%;DSM处理下>5 mm的团粒量与CK差异不显著,DP和PS处理使>5 mm的团粒比例降低,2～1 mm、1～0.5 mm和0.5～0.25 mm团粒比例升高。收获期,DSM、PS和DP处理的有机质含量较CK分别增加3.92、3.03和2.47 g/kg,DSM、PS和DP处理均能提高各时期土壤全量和速效养分含量,最终使玉米增产3.2%、6.8%和1.3%。从综合效应来看,秸秆覆盖还田+深松是黑钙土区更为适宜的耕作措施。     

不同耕作方式对土壤物理性状及玉米产量的影响

通过对土壤容重、土壤坚实度、土壤含水量、土壤田间持水量及玉米产量的测定和分析,研究深松、常规旋耕、免耕不同耕作方式对土壤物理性状及玉米产量的影响。结果表明,不同耕作方式对土壤容重和土壤坚实度的影响效果为深松>常规旋耕>免耕。深松耕作能够打破犁底层,降低深层土壤紧实度。深松耕作后,0~35 cm耕层土壤容重较常规旋耕和免耕分别下降6.5%和8.8%,土壤紧实度分别下降25.6%和32.3%。深松可显著增强接纳灌溉和降水能力,扩大土壤水库容。在21~40、41~60、61~80 cm土层,深松处理土壤含水量比常规旋耕分别提高3.4%、4.5%、2.4%,比免耕分别提高5.6%、4.8%、2.4%。土壤耕层0~35 cm田间持水量,深松和免耕比常规施耕分别提高7.4%和8.1%。不同耕作方式生物产量和经济产量均以深松最高,常规旋耕次之,免耕最小;深松耕作较常规旋耕和免耕分别增产4.3%和5.7%,与免耕处理间差异显著。     

Ramie (Boehmeria nivea (L.) Gaud.) and Spanish Broom (Spartium junceum L.) fibres for composite materials: agronomical aspects,morphology and mechanical properties

The agronomic characteristics of Ramie and Spanish Broom were investigated for seven years in the pedoclimatic conditions of Central Italy. The chemical, physical and mechanical properties of these fibres were also examined in order to evaluate the feasibility to use them in composite materials. Results demonstrate that Ramie grown in the temperate environment can be harvested three times a year. The yield of green Ramie plants per annum was almost 10 000 g m⁻². The fresh Ramie plant is composed, by weight, of 30% green leaves and 70% green stems. The yield dry fibre is almost 3% of the green stems, giving a total yield of 200 g m⁻². Spanish Broom can reach a fresh biomass yield of 4000 g m⁻² per annum, represented by 53% of long slender terete green branches which constitutes the economic products. The dry yield per annum was about 1800 g m⁻² with a dry branchlets yield of 900 g m⁻². Ramie and Spanish Broom cortical fibres are multiple elementary fibres (ultimates) arranged in bundles. In Ramie, the elementary fibres are bound by gums and pectins, while in Spanish Broom they are bound together by lignin. Both species showed a thick secondary cell wall indicating a high cellulose content. Ramie ultimate fibres are flattened and irregular in shape, while those of Spanish Broom are more regular in shape. The diameter of the ultimates varies from 10 to 25 μm in Ramie, while the Spanish Broom ultimates ranges from 5 to 10 μm; the diameter of the whole bundle is about 50 μm for both species. Ramie fibre showed a content of lignin, pentosans and extractives lower than Spanish Broom. Both fibres had a high content of cellulose which, on the base of X-ray analysis, was evaluated to be in excess of 70%. Ramie and Spanish Broom fibres had tensile strength of 950 MPa and 700 MPa, respectively. The elastic moduli were ≈65 and ≈20 GPa, respectively, which well compare with the modulus of E-glass fibres (70–90 GPa). The strength of the fibre-matrix interface was measured using the single filament fragmentation technique and an epoxy resin as the polymer matrix. Values for carbon and glass fibres in the same resin were also measured for comparison. The interface strength for the vegetable fibres was higher than that of carbon and glass, likely due to a mechanical lock mechanism. These values confirm both fibres as potential replacement for man made fibres in composite materials.     

Preferences of lambs offered Italian ryegrass (Lolium multiflorum L.) and barley (Hordeum vulgare L.) herbage as choices

Partial preference for feeds in ruminants is a well-documented phenomenon although their explanation can be elusive. The hypothesis was tested that sheep offered herbage of two annual grass species differing in chemical composition free-choice would select a diet that would maximize the nutritive value of the diet compared with sheep offered each herbage separately through a greater nutrient balance and synchronization of nutrient release for efficient ruminal microbial function. Fifteen male lambs were placed into metabolic cages, and randomly assigned to three treatments ( n  = 5): Italian ryegrass fresh herbage (treatment R), barley fresh herbage (treatment B) or free-choice Italian ryegrass and barley fresh herbage (treatment RB). Both herbages had similar crude protein concentrations but Italian ryegrass herbage had higher concentration of water-soluble carbohydrates and lower concentration of fibre than barley herbage. Lambs were exposed to the treatments for 15 d. Lambs on treatment RB showed a partial preference of 0·82 (s.e. 0·031) for Italian ryegrass. Lambs on treatment RB had higher intakes of digestible dry matter and higher values for nitrogen retention than lambs on treatment B although similar to that of lambs on treatment R. The results for the dietary choices were not always consistent with maximizing the nutritive value of the diet. Other explanations, such as lambs needed to sample and track the nutritive value of dietary options or there was the development of transient food aversions, were also possible.     

Sequential application of soil-incorporated and post-emergence herbicides for controlling wild oat (Avena fatua L.) and green foxtail (Setaria viridis (L.) Beauv.) in spring wheat

The effects of shallow-soil-incorporated tri-allate or trifluralin, applied alone or in sequence with three post-emergence herbicides (barban, difenzoquat or flamprop-methyl), for controlling wild oat (Avena fatua L.) and green foxtail (Setaria viridis (L.) Beauv.) in spring wheat (Triticum aestivum L., cv. Neepawa) were investigated at Brandon, Manitoba in 1977, 1978, 1979 and 1981. All herbicide treatments, except trifluralin alone in 1981, gave good wild-oat control compared with the untreated control. Tri-allate applied alone did not control green foxtail. With tri-allate, subsequent applications of post-emergence herbicides did not further improve wild-oat control and produced a wheat yield similar to that of tri-allate applied alone. The addition of barban in 1981 did provide a significant yield increase. All treatments involving trifluralin gave equal foxtail control superior to that of tri-allate, but the post-emergence herbicides had no activity on green foxtail. Subsequent applications of barban and flamprop-methyl to trifluralin in 4 years and difenzoquat in 3 years improved wild-oat control. As a result, significant increases in yield were recorded from the addition of barban, difenzoquat, and flamprop-methyl in 1981 and in the mean values for 4 years. In one (1979) of the four years, difenzoquat application to tri-allate or trifluralin tended to reduce wheat tolerance based on visual ratings of plant height and growth vigour, but this did not affect wheat yield. Overall, herbicide treatments in 4 years resulted in significant wheat yield increases over the untreated control.     

分子标记在菠萝研究中的应用

介绍了分子标记技术在菠萝上的应用,主要包括种质鉴别、遗传多样性、亲缘关系、连锁图谱构建以及与优良农艺性状相关的分子标记的获得等方面的情况,并对存在的问题和应用前景进行了讨论。     

Tolerance of spring barley (Hordeum vulgare L.), oats (Avena sativa L.) and wheat (Triticum aestivum L.) to saflufenacil

Saflufenacil is a new herbicide being developed by BASF for pre-emergence application for broadleaved weed control in maize and other crops. Three field studies were conducted in Ontario, Canada over a 2-year period (2006 and 2007) to evaluate the tolerance of spring cereals (barley, oats, and wheat) to pre-emergence and post-emergence applications of saflufenacil at 50 and 100 g ai ha⁻¹. Saflufenacil pre-emergence caused minimal visible injury (1% or less) at 3, 7, 14 and 28 days after emergence and had no adverse effect on plant height or yield of barley, oats, and wheat. Saflufenacil plus the surfactant Merge (1% v/v) applied post-emergence caused as much as 76, 60, 52 and 35% visible injury in spring cereals at 3, 7, 14 and 28 DAT, respectively. Injury with saflufenacil plus Merge applied post-emergence decreased over time and was generally greater as dose increased. Saflufenacil plus Merge applied post-emergence reduced plant height by as much as 16% and reduced yield of spring barley and wheat by 24 and 13%, respectively, but had no effect on the yield of spring oats. Based on these results, saflufenacil applied pre-emergence at the proposed dose can be safely used in spring planted barley, oats and wheat; however, the post-emergence application of saflufenacil results in unacceptable injury and yield loss. These results are consistent with the proposed pre-emergence use pattern for saflufenacil.     

Competition between white clover (Trifolium repens L.) and subterranean clover (Trifolium subterraneum L.) in binary mixtures in the field

White clover, (cv. Haifa) and subterranean clover (cv. Seaton Park) were grown in binary replacement series mixtures in the field at proportions of 100:0, 90:10, 50:50. 10:90 and 0:100, and cut every four weeks over three growing seasons from 1985 to 1987 at Scone, New South Wales (NSW) (32°S).
Relatively low plant densities minimized competition in 1985, but in subsequent seasons Haifa and Seaton Park competed vigorously for the same resource;.; usually having relative crowding coefficients greater than 1.0, and relative yield totals greater than 1.0 in spring of 1986 and 1987, and autumn 1987. This over-yielding appeared to be due to some complementarity of leaf morphology and canopy architecture.
Haifa severely depressed seed production of Seaton Park in mixtures. Haifa regenerated as an annual in 1986, but as a perennial, from surviving stolons, in 1987 owing to lower maximum temperatures and better rainfall distribution in late summer and autumn of 1987.
It is concluded that white clover can survive severe competition from subterranean clover as a seedling, and if moisture allows, may severely depress seed production from subterranean clover, regardless of whether plants are annual or perennial in origin. Spatial separation may minimize competition in average years but competition effects may be severe in seasons with sufficient summer rainfall for perennation of white clover, and seasonal autumn rainfall for germination of subterranean clover.     

Relationship between total sulphur and sulphur amino acids in chickpea (Cicer arietinum L.) and pigeonpea (Cajanus cajan [L.] Millsp.)

Total sulphur was determined in seed meal of 30 chickpea and 24 pigeonpea cultivars by the wet digestion procedure and by using the Leco sulphur analyser. Methionine and cystine were determined after performic acid oxidation in an amino acid analyser. The two methods used for total sulphur determinations were highly correlated (r=0.943). Percent meal protein was significantly correlated (r=0.476) with total sulphur in chickpea but not in the case of pigeonpea. Total sulphur content exhibited a significant positive correlation (r=0.651) with sulphur amino acids of pigeonpea when expressed as percent of protein but not in the case of chickpea. Correlation coefficients between total sulphur and sulphur amino acids when the results were expressed as percent of sample were positive for both chickpea (r=0.494) and pigeonpea (r=0.534). The amount of sulphur in methionine and cystine accounted for 54.8% of the total sulphur in chickpea and for 75.5% in pigeonpea. In both chickpea and pigeonpea, methionine was positively and significantly correlated with cystine when they were expressed either as percent of sample or as percent of protein.Submitted as J.A. no. 159 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).     

Competitiveness of rice (Oryza sativa L.) cultivars against Echinochloa crus-galli (L.) Beauv. in water-seeded production systems

Developing more competitive rice cultivars could help improve weed management and reduce dependency on herbicides. To achieve this goal, an understanding of key traits related to competitiveness is critical. Experiments were conducted at Gelemen and Bafra districts of Samsun province in Turkey between 2008 and 2009 to measure the competitiveness of rice cultivars against Echinochloa crus-galli, a problematic weed in rice fields. Five rice cultivars (Osmancık, Kızılırmak, Karadeniz, Koral and Neğiş) and five E. crus-galli densities (0, 5, 10, 20, and 30 plants m⁻²) were used. Koral produced significantly more tillers than the other cultivars irrespective of E. crus-galli densities and reduced E. crus-galli tiller production by about 29.5% at Gelemen and 15.8% at Bafra at the highest weed density. E. crus-galli interference reduced rice height and there was a density dependent relationship. Koral was the most competitive cultivar; it maintained high biomass accumulation in early growth stages and suffered smaller reductions in plant height in the presence of E. crus-galli, compared to the other cultivars. In the absence of weed competition, Koral and Neğiş produced the highest yields at both locations. Stepwise regression analyses of the combined data from both years showed tillering capacity, early growth crop biomass, and plant height were critical traits related to competitiveness. These traits should be considered by plant breeders in their efforts to develop rice cultivars with enhanced competitiveness against weeds. Development of such cultivars could substantially reduce herbicide and labor inputs for rice production.     

Mineral and trace element composition in induced mutants of pigeonpea (Cajanus cajan (L.) millsp.)

In the present investigation several mutants isolated during mutagenic studies of pigeonpea were analysed for Ca, Mg, Fe, Zn, Cu, Mn, Cr, Ni. The results have revealed changes in the concentrations of macro and micro mineral elements in the mutant seed material. These changes in concentrations are attributed to the altered genetic structure; due to mutations, the plant system might have absorbed and stored more or less amounts of the elements in the seeds.     

Response of spring planted barley (Hordeum vulgare L.), oats (Avena sativa L.) and wheat (Triticum aestivum L.) to mesotrione

There is little information on the response of spring planted barley (Hordeum vulgare L.), oats (Avena sativa L.) and wheat (Triticum aestivum L.) to mesotrione under Ontario environmental conditions. Four field studies were conducted in Ontario, Canada over a two-year period (2008 and 2009) to evaluate the sensitivity of spring planted cereals (barley, oats, and wheat) to pre-emergence (PRE) and post-emergence (POST) applications of mesotrione at 50, 100, and 150 g ai ha⁻¹. Mesotrione applied PRE caused minimal visible injury at 3, 7, 14 and 28 days after emergence (DAE) and had no adverse effect on plant height or yield of barley, oats and wheat. Mesotrione applied POST caused as much 11% injury and reduced plant height as much as 6% in spring planted cereals. Injury was higher in wheat compared to barley or oats. Mesotrione applied POST had no adverse effect on the yield of barley or oats but decreased the yield of wheat as much as 14%. Based on this study, mesotrione applied PRE at 50, 100 or 150 g ai ha⁻¹ can be safely used in spring planted barley, oats, and wheat. Mesotrione applied POST at the proposed dose of 50, 100 or 150 g ai ha⁻¹ can also be safely used in spring planted barley and oats. However, mesotrione applied POST results in unacceptable injury in spring planted wheat.