剑麻渣果胶提取与测定

从剑麻的麻渣、纤维中提取果胶，测定果胶的含量、纯度和酯化度。将湿麻渣在密封与敞开空气中自然发酵后提取果胶，探讨湿麻渣在发酵后对果胶品质的影响。结果表明，果胶得率最高的是湿麻渣（13．342％），最低的是直纤维（0．450％），干麻渣的果胶得率（1．662％）略高于湿纤维（1．326％）与乱纤维（1．264％）的；果胶纯度最高的是直纤维（73．360％），最低的是干麻渣（32．567％）。直纤维果胶的酯化度（45．452％）略大于麻渣和乱纤维的（32％～35％）；湿麻渣经过自然发酵后，果胶得率与纯度均降低，但湿麻渣完全发酵后的果胶酯化度（33．432％）接近于干麻渣的（33．156％）。     

Effect of Plasticizers on Properties of Rice Straw Fiber Film

In order to improve the properties of rice straw fiber film, one factor contrast test method was employed. Plasticizer type was chosen as input variable, dry tension strength and elongation, wet tension strength and elongation, bursting strength and tearing strength were chosen as indexes. The results showed that there were significant differences among the means of dry tension strength, dry elongation and bursting strength of different plasticizers; there were not significant differences among the means of wet tension strength, wet elongation and tearing strength of different plasticizers; for dry tension strength and elongation, glycerol had a significant difference with sorbitol and PEG, no significant difference was observed between sorbitol and PEG, dry tension strength added glycerol had been reduced 6.8% compared with that added sorbitol, reduced 9.5% compared with that added PEG; elongation had been improved 6.1% and 9.4%, respectively; for bursting strength, sorbitol had a significant difference with glycerol and PEG, no significant difference was observed between glycerol and PEG; bursting strength added glycerol and added PEG had been improved 6.9% and 5.6%, respectively compared with that of the added sorbitol. The results provided a theoretical reference for further improving the straw fiber film manufacturing process.     

马铃薯及土壤中烯酰吗啉的残留及消解动态研究

烯酰吗啉(dimethomorph,DMM)是一种新型内吸治疗性专用低毒杀菌剂,广泛用于晚疫病等病害的防治。为合理将烯酰吗啉用于马铃薯晚疫病防治,采用液相色谱-质谱联用(UPLC-MS)方法研究不同年份(2015、2016年)不同产地(宁夏回族自治区、黑龙江省)烯酰吗啉在马铃薯块茎、植株和土壤中的消解动态及最终残留量。结果表明:2015年和2016年烯酰吗啉在马铃薯植株中的半衰期分别为22.36 d(宁夏)、12.38 d(黑龙江)和3.69 d(宁夏)、28.88 d(黑龙江);在马铃薯土壤中的半衰期分别为231.05 d(宁夏)、6.48 d(黑龙江)和69.31 d(宁夏)、13.33 d(黑龙江)。烯酰吗啉施药剂量、次数和时间间隔不同,则其在马铃薯植株、块茎及土壤中的最终残留量也不同。施药量为1 345.5～2 018.2 g(a.i)/hm2,施药3～4次,施药间隔7 d,施药后14 d采收,收获马铃薯块茎中烯酰吗啉的残留量即均小于0.02 mg/kg,低于我国制定的马铃薯中烯酰吗啉最大残留限量值0.05 mg/kg。     

不同水平的青贮饲料对饲喂稻草秸秆奶牛瘤胃微生物数量和微生物蛋白合成的影响

本试验的目的是确定饲粮中青贮银合欢添加水平对奶牛瘤胃微生物种群、氮平衡和微生物蛋白合成的影响。试验采用4×4拉丁方设计,选择12头初始体重为163±16 kg、带有瘤胃瘘管的奶牛,随机分为4个组,每组3个重复,每个重复1头牛。基础日粮以100%的水稻秸秆为原料,处理组分别用30%、60%和100%的青贮银合欢替代水稻秸秆,奶牛自由采食水稻秸秆和青贮银合欢,每天按照体重的0.2%补充浓缩料。结果表明,用60%青贮银合欢替代水稻秸秆组奶牛瘤胃微生物群,尤其是纤维素分解菌、蛋白分解菌和厌氧真菌的数量显著增加(P<0.05),各组对淀粉分解菌群无显著影响(P>0.05)。原生动物种群数量随日粮青贮银合欢添加水平的增加呈线性下降(P<0.05)(P<0.05)。此外,氮平衡和微生物蛋白合成均随着日粮青贮银合欢添加水平的升高而升高(P<0.05),其中以60%青贮银合欢组最高。结论:在本试验基础上,用60%青贮银合欢替代水稻秸秆可以显著提高奶牛体内的微生物数量和微生物蛋白的合成。     

棉秆隔层对土壤水分入渗及水盐分布的影响研究

采用室内土柱实验,研究了裸地、棉秆隔层表层放置、棉秆隔层15cm、30cm、45cm和60cm处放置6个处理的土壤入渗特征及入渗后土壤水盐分布,以期对盐碱地改良提供依据。结果表明：棉秆隔层的设置降低了土壤入渗速率和累积入渗量,有利于棉秆隔层以上盐分的淋洗；秸秆隔层的设置降低土壤水分的蒸发,有利于隔层以下土壤水分的保持；各处理盐分均出现表聚,其中秸秆表层覆盖盐分表聚最小。     

蔬菜中农药残留检测方法变更的验证方法探析

检测标准发生变更时,检验检测机构应做好新方法的验证工作。以水果和蔬菜中阿维菌素残留量测定标准变更为实例,详述了如何开展方法验证,以期为大家开展化学分析方法发生变更时的验证工作提供参考。     

广州地区芥蓝、菜心和普通白菜中丙环唑和矮壮素残留及膳食暴露风险

为探明广州地区丙环唑和矮壮素在叶菜的残留以及膳食暴露风险情况,对2016年第2季度广州市9个区农贸市场和超市的芥蓝、菜心和普通白菜样品中丙环唑和矮壮素残留水平进行了分析。应用点评估和基于@Risk评估软件的概率评估方法 ,对这3种蔬菜中丙环唑和矮壮素残留膳食暴露风险进行了研究。结果显示,芥蓝、菜心、普通白菜中丙环唑残留均值为0.162 8~0.002 8 mg/kg,最高为芥蓝,与菜心和普通白菜差异显著,平均检出率为100%~70.25%,最高为芥蓝,与普通白菜差异显著。矮壮素残留平均值为0.010 9~0.001 0 mg/kg,最高为菜心,三者间差异不显著,平均检出率为14.99%~8.46%,最高为芥蓝,三者间差异不显著。通过膳食摄入3种蔬菜,丙环唑残留暴露急性风险熵为1.81~7.93,99%人群暴露慢性风险熵为1.02~25.03,0.1%人群存在芥蓝丙环唑膳食暴露慢性风险;矮壮素残留暴露急性风险熵为55.14~62.26,100%人群暴露慢性风险熵为3.26~8.11。3种蔬菜中丙环唑和矮壮素残留膳食暴露风险在可接受范围。     

我国部分省份秸秆利用情况调查

为了解我国秸秆资源利用情况,通过实地考察、问卷、走访等形式,对我国部分省份的秸秆品种、产量及其利用情况进行了调查。结果表明:在调查的省份内,农民因为受到时间、经济等因素的影响,焚烧和废弃是处理秸秆的首选方法。农民愿意接受新能源,促进秸秆再利用。我国秸秆利用途径不多,方法陈旧。受调查人员中有96.6%对秸秆新能源利用持支持态度,80%受调查人员希望能综合利用秸秆,减少环境污染。最后综合调查结果提出合理利用秸秆的建议。     

Management targets for continuously stocked mixed oat × annual ryegrass pasture in a no-till integrated crop–livestock system

Feeding livestock with cover crops can improve the efficiency and sustainability of integrated crop–livestock systems under no-till. However, no-till systems are based on permanent soil cover by organic material, so grazing livestock can compete for soil cover. Hence, managing stocking rates during the grazing period of the cultivated forage species is a key factor to assure enough herbage mass for maintaining long-term sustainable no-till systems. In this context, the objective of this study was to determine sward management targets for a continuously stocked mixed oat (Avena strigosa) × annual ryegrass (Lolium multiflorum) pasture in rotation with soybean in a no-till integrated crop–livestock system to determine the optimum balance between animal production and herbage mass for soil cover. The effects of sward height management on animal performance and herbage mass covers were evaluated. Treatments corresponded to four sward heights: 10, 20, 30 and 40 cm, maintained throughout the experimental period through continuous stocking and variable stocking rate, plus a no-grazing control area. Treatments were arranged in a randomized complete block design with three replications. Herbage mass and animal performance increased linearly with sward height, but weight gain per hectare decreased. Grazing efficiency fitted to a quadratic regression and conversion efficiency a logarithmic model. Equilibrium between grazing and conversion efficiencies was reached on swards managed at 20 cm, indicating that this sward height provided enough herbage mass to allow both animal performance and no-till crop demand for soil cover.     

Effects of variety, cropping year, location and fertilizer application on nutritive value of durum wheat straw

This study was carried out to assess the effects of variety, year, location and level of fertilizer application on chemical composition and in sacco dry matter (DM) degradability of durum wheat straw as well as to understand the relationship between straw quality and agronomic traits of the crop and to assess the possibilities of selecting wheat varieties that combine high grain yield with desirable straw quality. Two local (Arendeto and Tikur sinde) and two improved (Boohai and Gerardo) varieties of durum wheat (Triticum turgidum Desf.) were used in the experiment. The four varieties were grown at two locations (Akaki and Ejere) in the years 2001/2002 and 2002/2003 in 5 x 5 m plots in three replications. Diammonium phosphate and urea fertilizers were applied at four levels (0/0, 32/23, 41/23 and 64/46 kg/ha of nitrogen/phosphorus). Straw quality was assessed based on chemical composition and in sacco DM degradability. Correlation of straw quality with grain and straw yield and with other agronomic characteristics of the crop was determined. The potential utility index (a measure that integrates grain and digestible straw yield) was used for ranking of the varieties. The local varieties had higher crude protein (CP) and lower neutral detergent fibre contents and higher digestibility than the improved varieties. The cropping year and location had significant effect on CP content and degradability of the straw, which could be due to climatic variation. However, the fertilizer level did not have any significant effect on straw quality except that the CP content of the straw tended to increase with increasing level of fertilizer application. Based on the potential utility index the varieties ranked, in a decreasing order, as Tikur sinde > Arendeto > Gerardo > Boohai and the ranking was consistent across years and locations. Except the CP content, straw quality was not negatively correlated with grain and straw yield. This indicates that there is a possibility of selecting varieties of wheat that combine high grain and straw yield with desirable straw quality.