作物秸秆及其它废弃物栽培食用菌的农业生态效益研究

一、引言当前,世界上五大问题(环境、粮食、人口、资源和能源)日趋严重,在发展中国家解决饥饿、营养不良和贫困问题已成为人们关注的焦点。与此同时,人们也开始重视食用菌在利用农业有机废物转化为人类食物方面的积极     

Rice straw fermentation by Schizophyllum commune ARC-11 to produce high level of xylanase for its application in pre-bleaching

Rice straw is valuable resource that has been used as substrate for cost effective production of xylanase under solid-state fermentation by a newly isolated white rot fungi, S. commune ARC-11. Out of eleven carbon sources tested, rice straw was found most effective for the induction of xylanase that produced 4288.3?IU/gds of xylanase by S. commune ARC-11. Maximum xylanase production (6721.9?IU/gds) was observed on 8^th day of incubation at temperature (30?°C), initial pH (7.0) and initial moisture content (70.0%). The supplementation of ammonium sulphate (0.08% N, as available nitrogen) enhanced the xylanase production up to 8591.4?IU/gds. The xylanase production by S. commune ARC-11 was further improved by the addition of 0.10%, (w/v) of Tween-20 as surfactant. The maximum xylanase activities were found at pH 5.0 and temperature 55?°C with a longer stability (180?min) at temperature 45, 50 and 55?°C. This xylanase preparation was also evaluated for the pre-bleaching of ethanol-soda pulp from Eulaliopsis binata. An enzyme dosage of 10?IU/g of xylanase resulted maximum decrease in kappa number (14.51%) with a maximum improvement 2.9% in ISO brightness compared to control.     

水分胁迫下秸秆还田对玉米产量和根系空间分布的影响

为了探究水分胁迫条件下秸秆还田对玉米产量和根系空间分布的影响,自2016年起连续2年在沈阳农业大学试验田设置了秸秆还田控水试验.于大型遮雨棚内采用滴灌控水的方法,设置行间秸秆翻埋(T₁)与混拌(T₂)两种还田方式,15 cm (D₁)、30 cm (D₂)、45 cm (D₃) 3个还田深度,以秸秆不还田3个翻埋深度为对照,在玉米苗期和吐丝期分别进行旱、涝处理,分析水分胁迫条件下玉米产量和根系空间分布特征. 结果表明: 2016年S₁T₁D₂(秸秆翻埋还田30 cm)产量显著高于对照处理,增产幅度为5.7%～7.1%;侧根和深层根系根干质量较其他处理分别高67.3%～149.9%和17.9%～116.4%;植株地上部干物质积累量显著低于其他处理,降低幅度为2.1%～35.8%. S₁T₁D₂可以提高玉米根系生长量,扩展根长的空间分布范围,缓解了旱涝危害,实现降雨不均条件下的增产和稳产. 因此,在东北地区先旱后涝的气候条件下,春玉米生产推荐行间翻埋30 cm的秸秆还田方式.     

用于分析土壤微生物结构变化规律的变性梯度凝胶电泳条件研究

研究确定土壤微生物基因组DNA提取方法、PCR扩增条件、DGGE电泳条件,为进一步研究分析土壤中微生物结构变化规律提供理论依据。土壤微生物基因组DNA提取采用直接法和间接法进行比较; PCR扩增条件调整扩增体系、DGGE电泳条件调整变性剂范围,并对其结果进行比较分析。通过对DGGE电泳相关条件的研究,结果显示,土壤中粗基因组DNA采用直接法提取,然后进行纯化; PCR扩增体系中加入BSA,DGGE电泳系统组成中变性剂浓度范围为35%～55%。确定了土壤微生物基因组DNA提取方法、PCR扩增条件、DGGE电泳条件,为后续的相关研究提供理论依据。     

Which is the most preventive measure against tail damage in finisher pigs: tail docking,straw provision or lowered stocking density?

One challenge of intensive pig production is tail damage caused by tail biting, and farmers often decrease the prevalence of tail damage through tail docking. However, tail docking is not an optimal preventive measure against tail damage and thus, it would be preferable to replace it. The aim of the current study was to investigate the relative effect of three possible preventive measures against tail damage. The study included 112 pens with 1624 finisher pigs divided between four batches. Pens were randomly assigned to one level of each of three treatments: (1) tail-docked (n=60 pens) v. undocked (n=52 pens), (2) 150 g of straw provided per pig per day on the solid floor (n=56 pens) v. no straw provided (n=56 pens), (3) stocking density of 1.21 m²/pig (11 pig/pen; n=56 pens) v. 0.73 m²/pig (18 pigs/pen; n=56 pens). Tail damage was recorded three times per week throughout the finisher period by scoring the tail of each individual pig. A pen was recorded as a tail damage pen and no longer included in the study if at least one pig in a pen had a bleeding tail wound; thus, only the first incidence of tail damage on pen level was recorded. Data were analysed by a Cox regression for survival analysis assuming proportional hazards. Results are presented as hazards, and a higher hazard means that a pen has a higher risk of tail damage and of it happening earlier in the finisher period. Pens with undocked pigs had a 4.32-fold higher hazard of tail damage compared with pens with docked pigs (P<0.001). Pens with no straw provided had a 2.22-fold higher hazard of tail damage compared with pens with straw provided (P<0.01). No interactions was seen between the treatments, but the effect of tail docking was higher than the effect of straw provision (P<0.001). Stocking density did not have a significant effect on the hazard of tail damage (hazard rate ratios (HRR)=1.67; P=0.064). However, a combination of straw provision and lowered stocking density showed a similar hazard of tail damage as seen with only tail docking (HRR=1.58; P=0.39). In conclusion, tail docking and straw provision were preventive measures against tail damage, and tail docking reduced the risk more than straw provision. A combination of other preventive measures is necessary to reduce the risk of tail damage in undocked pigs to the same level as in docked pigs.     

Estimation of the increase in CH4 emission from paddy soils by rice straw application

The relationship between the amount of CH₄ emission to the atmosphere from submerged paddy soils with rice plants and the application level (0–8 g kg^-1) of rice straw (RS) in soil was investigated in a pot experiment. Amounts of CH₄ emitted from pots with respective RS levels differed between a clayey yellow soil and a silty gray lowland soil. However, the increase in cumulative amounts of CH₄ emission with the increase in the application level of RS was similar in pattern between the two soils, and the increase (Y) was formulated with a logistic curve: x, application level of RS; k, a coefficient for relative CH₄ emission.Since the seasonal variations in coefficients a, b, and c in the logistic equation were also formulated as the function of the sum of effective temperature (E, (T–15); T, daily average temperature), the increase in cumulative amounts of CH₄ emission from any paddy soil by any level of RS application was known to be estimated by the following equation:     

Biological N2 fixation by heterotrophic and phototrophic bacteria in association with straw

Much of the crop residues, including cereal straw, that are produced worldwide are lost by burning. Plant residues, and in particular straw, contain large amounts of carbon (cellulose and hemicellulose) which can serve as substrates for the production of microbial biomass and for biological N₂ fixation by a range of free-living, diazotrophic bacteria. Microorganisms with the dual ability to utilise cellulose and fix N₂ are rate, but some strains that utilize hemicellulose and fix N₂ have been found. Generally, cellulolysis and diazotrophy are carried out by a mixed microbial community in which N₂-fixing bacteria utilise cellobiose and glucose produced from straw by cellulolytic microorganisms. N₂-fixing bacteria include heterotrophic and phototrophic organisms and the latter are apparently more prominent in flooded soils such as rice paddies than in dryland soils. The relative contributions of N₂ fixed by heterotrophic diazotrophic bacteria compared with cyanobacteria and other phototrophic bacteria depend on the availability of substrates from straw decomposition and on environmental pressures. Measurements of asymbiotic N₂ fixation are limited and variable but, in rice paddy systems, rates of 25 kg N ha^-1 over 30 days have been found, whereas in dryland systems with wheat straw, in situ measurements have indicated up to 12 kg N ha^-1 over 22 days. Straw-associated N₂ fixation is directly affected by environmental factors such as temperature, moisture, oxygen concentration, soil pH and clay content as well as farm management practices. Modification of managements and use of inoculants offer ways of improving asymbiotic N₂ fixation.In laboratory culture systems, inoculation of straws with cellulolytic and diazotrophic microorganisms has resulted in significant increases in N₂ fixation in comparison to uninoculated controls and gains of N of up to 72 mg N fixed g^-1 straw consumed have been obtained, indicating the potential of inoculation to improve N gains in composts that can then be used as biofertilisers. Soils, on the other hand, contain established, indigenous microbial populations which tend to exclude inoculant microorganisms by competition. As a consequence, improvements in straw-associated N₂ fixation in soils have been achieved mostly by specific straw-management practices which encourage microbial activity by straw-decomposing and N₂-fixing microorganisms.Further research is needed to quantify more accurately the contribution of asymbiotic N₂ fixation to cropping systems. New strains of inoculants, including those capable of both cellulolytic and N₂-fixing activity, are needed to improve the N content of biofertilisers produced from composts. Developments of management practices in farming systems may result in further improvements in N₂ fixation in the field.     

辽西半干旱地区冬灌后覆盖的抗旱增产作用

辽西半干旱地区冬灌后覆盖的抗旱增产作用王仕新,庄季屏（中国科学院沈阳应用生态研究所,１１００１５）ＥｆｆｅｃｔｏｆＭｕｌｃｂｉｎｇＡｆｔｅｒＷｉｎｔｅｒＩｒｒｉｇａｔｉｏｎｏｎＤｒｏｕｇｂｔＲｅｓｉｓｔａｎｃｅａｎｄＹｉｅｌｄＩｎｃｒｅｍｅｎｔｉｎＳ...     

Mild alkaline/oxidative pretreatment of wheat straw

A new mild alkaline/oxidative pretreatment of wheat straw prior to enzymic hydrolysis was carried out. It consists of a first alkaline (1% NaOH for 24 h) step, which mainly solubilises hemicellullose and renders the material more accessible to further chemical attack, and a second alkaline/oxidative step (1% NaOH and 0·3% H₂O₂ for 24 h), which solubilises and oxidises lignin to minor polluting compounds. The entire process was carried out at low temperature (25–40°C) using a low concentration of chemicals, resulting in a relatively low cost and waste liquors containing only trace amounts of dangerous pollutants derived from lignin. Recovery of cellulose after the double pretreatment reached 90% of that contained in the starting material, with a concomitant 81% degradation of lignin. The action of a commercial cellulase on the cellulose obtained produced a syrup with a high concentration of reducing sugars (220 mg/ml), of which a large percentage was glucose.     

烟杆还田对水稻产量和养分吸收的影响及其替代钾肥的效果

选择不同供钾能力的烟-稻轮作区稻田,研究了烟杆还田对水稻产量、钾素吸收利用的影响及其替代钾肥的效果.结果表明: 烟杆还田(2250 kg·hm^-2)和施钾肥(K₂O 75 kg·hm^-2)均能增加水稻产量和地上部钾素的累积量,其中烟杆还田配施钾肥的增幅最大,低钾(土壤速效钾含量＜100 mg·kg^-1)、中钾(土壤速效钾含量100～150 mg·kg^-1)和高钾(土壤速效钾含量＞150 mg·kg^-1)土壤的水稻分别增产13.3%、17.1%和13.5%.烟杆还田(St+NP)可以提高钾素吸收利用率和农学效率.但在水稻当前推荐施肥量(75 kg·hm^-2)条件下,烟杆还田配施钾肥(St+NPK)对钾肥(素)吸收利用率和农学效率无显著影响,说明当前推荐施钾量可能偏高.通过对烟杆还田替代钾肥的计算,发现还田烟杆可以替代10%～22%的化肥钾(K₂O),烟后晚稻在烟杆还田时钾肥施用可以减少7.2～16.5 kg·hm^-2.因此,在烟杆还田条件下,高钾田块可减少化学钾肥的施用,而中钾和低钾田块为稳定水稻产量和维持土壤钾素平衡,则应保证目前推荐钾肥量的投入.