耕作方式及秸秆还田对土壤性质、微生物碳源代谢及小麦产量的影响

以小麦品种济麦22为试验材料,采用裂区试验设计,耕作方式为主区,分别设常规翻耕(C)、深松(S)、旋耕(R)处理,副区为秸秆还田量,分别设秸秆全还田(P)和秸秆不还田(A)处理,采用Biolog Eco技术测定土壤微生物碳源代谢功能,并分析土壤基本理化性质和作物产量。结果显示:深松与秸秆还田均有利于土壤含水量和有机碳含量的提高,0～15 cm土层分别提高了9.78%和24.00%,15～30 cm土层分别提高了7.08%和15.81%;深松提高了15～30 cm土层的pH值6.67%,秸秆还田提高了0～15 cm土层的pH值4.32%。深松和秸秆还田均有利于代谢多样性(丰富度指数、香浓多样性指数)、碳源代谢强度的提高,0～15 cm土层分别提高了26.84%、3.84%和38.02%,15～30 cm土层分别提高了11.87%、 3.63%和14.74%。主成分分析表明常规翻耕秸秆不还田和旋耕耕作秸秆不还田碳源代谢功能相近,15～30 cm层次内常规翻耕秸秆全还田碳源代谢功能和深松耕作秸秆全还田处理相近。深松和秸秆还田平均提高了小麦产量5.82%,微生物碳源代谢功能与小麦产量具有极显著的相关性。     

水稻秸秆还田结合炔草酯对禾本科杂草和小麦生长发育的影响

为改进水稻秸秆还田条件下小麦田杂草治理技术,通过田间小区试验研究了不同还田量单独或结合炔草酯施用对后茬小麦田禾本科杂草的控制效果和小麦生长发育及产量的影响。结果表明,随着水稻秸秆单独还田量从1 125 kg/hm2增至4 500 kg/hm2,小麦田杂草发生密度显著下降,4 500 kg/hm2秸秆还田量下小麦分蘖期前杂草发生密度下降60%左右;结合炔草酯施用时,杂草发生密度随秸秆还田量的增加而下降,但不同还田量之间无显著差异,且炔草酯除草活性未受到影响。秸秆还田或炔草酯单独或结合施用均对小麦生长发育无明显的胁迫影响,4500 kg/hm2秸秆单独还田量下,小麦苗期功能叶SPAD值较对照增加7.0%,净光合速率和蒸腾速率分别增加14.9%和12.2%;抽穗期净光合速率、气孔导度、蒸腾速率分别增加28.3%、85.2%和100.0%;千粒重、有效穗数和产量分别增加3.9%、6.7%和16.1%。4 500 kg/hm2秸秆单独还田量对杂草控制效果、小麦生长及产量的影响均与炔草酯推荐剂量单独施用无显著差异,表明该秸秆还田量具有良好的农田生态效应。     

进境美国高粱携带杂草种子萌发率测定

收集并整理2014~2016年从黄埔和南沙口岸进境美国高粱中截获的杂草种子,对截获频次进行统计,并对截获频次较高的9种检疫性杂草、14种非检疫性杂草进行萌发试验,结果表明,供试杂草种子几乎均能萌发,且萌发率较高,如长芒苋和裂叶牵牛萌发率达58%以上、糙果苋19.17%、假高粱和豚草的萌发率也达到7.50%和5.00%。因此要重视美国高粱中携带的杂草种子检疫以及杂草监测工作,防止这些杂草种子的定殖传播。     

根寄生杂草种子萌发剂概述

独脚金属（Striga spp.）及列当属（Orobanche spp.和Phelipanchce spp.）杂草是世界范围内对农业生产危害严重的根寄生杂草,主要依靠寄生茄科、豆科、谷类等作物获得水分和营养。根寄生杂草种子只有在合适的萌发诱导物（如独脚金内酯）刺激下才能萌发。文章从根寄生杂草的分类、分布及危害,种子萌发剂类型及适用范围,种子萌发剂独脚金内酯的生物合成及分离鉴定,根寄生杂草种子萌发诱导剂的作用机制以及种子萌发过程中激素间协同调控作用等方面进行了综述,并展望了种子萌发剂设计筛选及其在根寄生杂草化学防控中的潜在应用前景。     

草甘膦影响假高粱种子萌发的试验

经草甘膦4个剂量处理的假高梁种子均有一定的发芽能力，发芽率在3.3％-41.7％，发芽率随着剂量的增大而下降，但在萌发后10天内所有处理的萌发株全部死亡，即发芽死亡率为100％，而未萌发的种子霉烂失去活性；对照种子发芽率为43.3％，发芽死亡率为0。试验结果表明，2000g.a.i/hm^2剂量的草甘膦即可杀死假高梁的幼苗，6000g.a.i/hm^2以上剂量能有效抑制假高梁种子萌发。     

吸水剂对促进种子萌发作用的置疑

对两种吸水剂在不同相对湿度条件下的吸水能力和保水能力等特性进行了研究，并以小麦种子为植物材料，观察了不同吸水程度的吸水剂与干种子对水分的竞争能力。结果表明，吸水剂对环境中水分的吸收及圣种子释放水分是相互矛盾，一般情况下，吸水剂不可能向环境中吸收水分而后供给种子萌发。     

整合微生物组菌剂对番茄种子萌发和幼苗生长的影响及其对青枯病的防治效果

整合微生物组菌剂是利用微生物发酵床作为发酵槽,通过二次好氧发酵生产含有多个功能微生物组的一种新型土壤连作障碍修复剂。本研究采用室内培养皿法,研究整合微生物组菌剂不同浸提液体浓度对番茄种子萌发的影响,结果表明,整合微生物组菌剂浸提液的100倍稀释液处理的番茄种子发芽指数（36.75）和种子活力指数（106.07）均显著高于无菌水对照（发芽指数33.98,种子活力指数65.26）;整合微生物组菌剂浸提液的稀释倍数低于50倍会抑制番茄种子萌发,其发芽率、发芽指数和种子活力指数均显著低于无菌水对照。通过盆栽试验,研究不同添加量整合微生物组菌剂对番茄植株生长及青枯病害的防治效果,结果表明,低浓度整合微生物组菌剂（添加量为小于60%）会促进番茄植株生长,而高浓度整合生物组菌剂（添加量大于80%）抑制番茄植株生长;添加量为40%,其促长效果最好,植株的株高、茎粗和根长分别比对照增加13.77%、26.00%和79.51%,其根系活力31.15 μg/（g·h）,也显著高于对照组24.72 μg/（g·h）;整合微生物组菌剂对番茄青枯病的防治效果随添加量增大而增加,添加量大等于40%,其对番茄青枯病的防治效果均大于65%,添加量为100%的防治效果最好,为77.37%。综合促长效果、青枯病的防治效果及成本,建议整合微生物组菌剂使用剂量为添加量40%。     

γ射线辐照对3种杂草种子发芽率的影响初报

本文利用60Co-γ射线对芜菁、猪殃殃和反枝苋3种杂草种子进行了50~1000Gy的辐照处理,研究了不同剂量对3种杂草种子萌发的影响,结果表明,发芽7d后,1kGy以下剂量的辐照对3种杂草种子的发芽具有一定的抑制作用,抑制效果因杂草种类的不同而有差异。     

小麦秸秆焚烧对土壤有机质及微生物和玉米产量的影响

选取不同秸秆量焚烧后的耕层土壤为对象,研究秸秆焚烧对土壤有机质和微生物的影响,并探讨秸秆焚烧量与土壤有机质和微生物之间的相关性.结果表明:(1)秸秆焚烧对土壤有机质和微生物的影响主要集中在0～～5 cm表层土壤中,5 cm以下影响较小.焚烧造成表层土壤有机质含量下降10.72％ ～ 17.08％,真菌数量下降43.68％ ～ 74.43％,放线菌数量下降49.32％ ～ 74.83％,细菌数量下降58.93％ ～ 81.44％.同时还造成下茬玉米产量下降7.04％～ 20.63％,地上生物量下降9.23％～18.76％.(2)秸秆焚烧量与土壤细菌、真菌和放线菌数量之间呈显著负相关关系,秸秆焚烧量与土壤有机质、玉米产量和地上生物量呈极显著负相关关系.     

渗透胁迫下氯化胆碱对小麦种子萌发的影响

在15％PEG6000胁迫条件下,研究了氯化胆碱（choline chloride,CC)对小麦种子萌发的影响。研究结果表明,CC对受15％PEG6000胁迫的小麦种子的萌发及根、芽的生长具有明显的促进作用,且以60mg/L CC的效果最好。与对照相比,在该浓度下,平均根长及平均芽长分别可提高14．6％和12．9％,总鲜重可提高17．7％,根／芽比值及萌发率也有所提高,但对生根数无多大影响。同时,CC可使小麦种子α－淀粉酶的活力提高28．0％,使培养介质电导率增长率显著降低,还可使POD活性上升幅度低30．6％。表明,CC促进小麦种子萌发及根、芽生长与提高α－淀粉酶酶活力、降低萌发种子中电解质外渗量及降低POD活性有密切联系。     

土层深度对三种麦田禾本科杂草出苗及生长的影响

为明确小麦田禾本科杂草在不同土层深度的出苗及生长情况,选取雀麦Bromus japonicas、节节麦Aegilops tauschii和野燕麦Avena fatua三种小麦田常见禾本科杂草,采用盆栽法系统研究不同土层深度对杂草出苗及生长的影响。结果表明,小麦田禾本科杂草雀麦、节节麦和野燕麦出苗和生长与不同土层深度密切相关,在浅土层中均有较好的出苗率,且后期生长也正常。从出苗时间来看,雀麦和野燕麦集中出苗时间在播种后5～11 d,节节麦略晚于这2种杂草;从最适出苗土层深度来看,雀麦最适出苗土层深度为0.5～3.5 cm,出苗率在76.0%～87.0%之间,节节麦的最适出苗深度为0.5～8.0 cm,出苗率在66.7%～79.3%之间,而野燕麦的最适土层深度为0.5～18.0 cm,出苗率达84.2%～94.4%;从出苗后生长影响来看,0～20 cm土层对野燕麦后期生长没有显著影响,土层深度大于10.0 cm对节节麦生长有显著抑制作用,大于6.0 cm即对雀麦有显著影响。研究表明通过深翻土地可以对雀麦和节节麦达到一定的控制作用,但对野燕麦控制效果相对略差。     

Assessment of the differential response of weeds to soil solarization by two methods

The efficacy of solarization in weed control under field conditions of the United Arab Emirates was evaluated by two methods: on-farm weed assessment and a seed germination test. In the on-farm weed assessment method, the weed frequency, density, and dry weight were compared in the solarized and non-solarized plots that were cultivated with cabbage. Prior to solarization, the soil was artificially infested with the seeds of 10 weeds. Generally, the densities of seven species and dry weights of five species were significantly lower in the solarized plots as compared to the control. Launea mucronata , Capsella bursa-pastoris , and Echinochloa colona were very sensitive to solarization, as they did not appear in the solarized plots. However, Portulaca oleracea and Melilotus indica were not significantly affected by soil solarization. In the second method, the germination was assessed for the seeds of four weedy species buried at three depths for different durations of solarization. The results confirmed the great sensitivity of L. mucronata and C. bursa-pastoris seeds to solarization, as all had not germinated after 15 days of solarization, even at the 15 cm depth. The seeds of E. colona , however, were less sensitive after 15 days of solarization, especially at 7.5 cm and 15 cm, respectively. The seed germination method confirmed the resistance of the P. oleracea seeds to solarization. The results emphasized the importance of the germination test to provide accurate predictions about the spatial and temporal changes of the soil seed bank in solarized farms. This would help to determine the optimal duration of solarization in each farm, depending on the kind of weeds infesting the farm.     

Effects of ferrous iron (Fe) on the germination and root elongation of paddy rice and weeds

Laboratory experiments were conducted to analyze the iron (Fe) tolerance of paddy weeds and rice varieties (Oryza sativa) for germination and root elongation. Under a waterlogged soil condition, the Fe(II) content in a soil solution increased with an increase in the ratio of rice straw to the soil. In the presence of 0.9% (w/w) straw to soil, which corresponds approximately to 8 t of straw applied to an area of 1 ha × 10 cm depth in the field, ～80 mg L^?1 of Fe(II) was produced in the soil solution. Based on this result, the seeds of rice and the weeds were incubated in a solution with <100 mg L^?1 of Fe(II). The presence of 100 mg L^?1 of Fe(II) suppressed the germination of Echinochloa crus‐galli var. crus‐galli, Cyperus serotinus, Cyperus difformis, and Monochoria korsakowii. However, it had no effect on the germination of Echinochloa oryzicola, Schoenoplectus juncoides (= Scirpus juncoides var. ohwianus), and Monochoria vaginalis. This level of Fe tolerance was the same as that of rice. These findings suggest that E. oryzicola, S. juncoides, and M. vaginalis can grow under more severe conditions than E. crus‐galli, C. serotinus, C. difformis, and M. korsakowii. In relation to seminal root elongation, the order of tolerance of Fe toxicity was O. sativa cv. Dunghan Shali > O. sativa cv. Hoshinoyume > E. oryzicola > M. vaginalis > S. juncoides. Thus, the results show that the tolerance of rice is greater than that of E. oryzicola, which had a comparatively strong tolerance among the weeds examined, and also that there are differences in tolerance among the rice varieties. These findings suggest that the difference in Fe tolerance is involved in weed control systems when organic materials are applied. If this difference is an important factor in the weed control system, Fe‐tolerant rice varieties, like cv. D. Shali, could facilitate weed control systems due to their higher Fe tolerance ability.     

生草对沙地葡萄园土壤微生物群落碳源利用特征的影响

为了研究葡萄园行间生草处理对土壤微生物群落功能多样性的影响,以清耕为对照,运用BiologEco板技术,分析生草处理下的土壤微生物群落碳源利用特征。结果表明:生草处理的AWCD值和多样性指数(Shannon-Wiener多样性指数、Simpson优势度指数和丰富度指数)均显著高于清耕对照,且随土层深度的增加均呈下降趋势,以生草0~20 cm土层处理最高;与清耕对照相比,生草处理土壤微生物对6类碳源利用强度均显著增加,平均增幅顺序为:羧酸类化合物酚酸类化合物胺类化合物碳水化合物类氨基酸类聚合物。主成份分析表明,清耕对照和生草处理分布在不同区域,表明两处理土壤微生物存在一定的代谢差异性,生草显著改变了土壤微生物群落功能,并对土壤微生物代谢羧酸类化合物、碳水化合物和酚酸类化合物3类碳源的影响最为明显。结果提示,生草有利于葡萄园土壤微生物群落结构的改善。     

Assessing potential germination period of weeds with base temperatures and base water potentials

Seed germination partly depends on both base temperature (T_b) and base water potential (Ψ_b), which currently are known only for a small number of species. Laboratory experiments were conducted to estimate these parameters for 14 weed species using the ‘x‐intercept’ method. T_b and Ψ_b (°C and MPa) for the 14 weed species were as follows: Amaranthus retroflexus (8.9 and ?0.95), Ambrosia artemisiifolia (3.6 and ?1.28), Avena fatua (2.2 and ?1.02), Capsella bursa‐pastoris (4.5 and ?0.95), Chenopodium album (5.9 and ?0.80), Echinochloa crus‐galli (6.2 and ?1.19), Geranium dissectum (0.6 and ?3.31), Matricaria perforata (2.0 and ?0.75), Picris echioides (5.2 and ?0.79), Polygonum lapathifolium (5.8 and ?1.55), Senecio vulgaris (2.5 and ?1.23), Setaria pumila (8.6 and ?0.75), Solanum nigrum (11.6 and ?0.89) and Veronica hederifolia (0.2 and ?1.67). The two parameters were used to determine potential germination times during expected non‐dormancy periods for three contrasting climatic years in Dijon, France. The number of potential germination days varied little among the tested climatic years, but substantially among species, ranging from 95 ± 9 days for V. hederifolia to 280 ± 7 days for M. perforata. These results may be of value for development of predictive growth models and understanding times when weed control may be most feasible.     

三唑酮种子包衣对冬小麦种子萌发和幼芽抗逆因子的影响

为评价三唑酮种子包衣对冬小麦种子萌发的安全性,以苯醚甲环唑为对照药剂,研究了不同包衣剂量三唑酮对周麦22和铭贤169小麦种子发芽及周麦22抗逆相关生化因子的影响。结果表明:周麦22和铭贤169小麦种子发芽指数、种子活力指数和发芽率均与三唑酮包衣剂量呈负相关,且符合指数方程Y=A+B×e(-x/k),但铭贤169种子发芽指数、种子活力指数和发芽率对三唑酮剂量变化更敏感;三唑酮种子包衣能引起小麦幼芽体内赤霉素(gibberellins,GAs)含量降低和脱落酸(abscisic acid,ABA)含量升高,且GAs含量下降程度和ABA水平升高程度均随三唑酮包衣剂量的增加而增加,从理论上解释了三唑酮可对小麦种子萌发产生抑制作用且抑制作用与包衣剂量相关的原因。但通过对幼芽相关抗逆因子的研究表明,三唑酮包衣有利于新长成幼芽中叶绿素含量、根系呼吸速率、可溶性蛋白质含量和α-淀粉酶活性的增加以及细胞膜通透性降低,说明三唑酮包衣在一定程度上有助于新长出幼芽抗逆性的增加。相比之下,苯醚甲环唑对小麦种子萌发的抑制作用比三唑酮小,且更有利于幼芽抗逆性增加。     

Weed seed germination and the light environment: Implications for weed management

Light regulates dormancy termination and the subsequent germination in many weed species. Under field conditions, the light environment of the seeds, which is perceived mainly by photoreceptors of the phytochrome family, provides essential information for cueing germination in the proper environmental situation. The light environment's spectral composition and irradiance allow weed seeds to sense their position in the soil profile, the presence of a leaf canopy capturing light and other resources and the occurrence of soil cultivation. From an agronomical point of view, the control of germination by light represents a potentially useful step in the life cycle of weeds for developing effective control practices. The goal of this article is to place current knowledge regarding photoreceptors, physiological and molecular bases of seed responses to light and their ecological implications within the context of weed management in agricultural systems. With that final objective, the authors intend to show how a better understanding of the way in which the light environment regulates dormancy termination and the subsequent germination of weed seeds could be used to develop more accurate control practices and to improve weed management strategies.