切分西红柿微波短时处理常温贮藏保鲜试验研究

目前由于在果蔬的储运中常发生霉变、腐烂,鲜度下降,甚至完全失去商品价值,造成巨大的经济损失,难以满足市场要求。因此,解决果蔬的贮藏特别是运输过程中的保鲜,不仅能满足市场需要,增加果蔬市场供应品种和调节供应,同时还将获得巨大的经济效益。通过正交试验对切分西红柿进行了微波处理常温保鲜的试验研究,得出了真空包装的切分西红柿在微波短时处理后只达到巴氏杀菌的低温杀菌温度,却得到能长期贮存的品质优良的样品的结果;确定了这种方法的最佳处理参数,其最佳参数为0.12%维生素C处理时间为54s;对样品进行图像处理,得到色彩直方图和色彩均值,用确切的数值说明保鲜方法的保鲜作用;分析包装对西红柿保鲜的影响作用,认为切分西红柿应采用避光包装保存     

A comparison of soil and water properties in organic and conventional farming systems in England

Organic farming and improvements to agricultural sustainability are often seen as synonymous. However, an extensive European review demonstrated that in practice this is not always true. This study aims to compare the status of soil and water properties between separate fields managed in either an organic or a conventional manner. Soil samples were collected from 16 pairs of farms, throughout England, with both arable and grass fields within each pair on similar soil type. Chemical (nutrients, pesticides, herbicides) and physical (aggregate stability, field capacity, shear strength, soil organic matter, infiltration rates) soil properties were measured in four main soil texture classes in organic and conventional fields. The physical soil properties varied significantly between the different classes of texture and land use. The heavier textured soils have significantly higher soil organic carbon (SOC), aggregate stability and shear strength. The coarse‐textured soils have significantly lower field capacity moisture contents. The grassland has a significantly higher level of SOC, field capacity moisture content, aggregate stability and soil shear strength. However, there were no significant differences between organic and conventional treatments for any of the soil physical properties measured. There were fewer traces of agrochemicals in the soil water from the organic fields compared with the conventionally managed fields. The conventional arable fields had higher levels of total inorganic nitrogen than the other land uses and treatments. There was evidence to show that infiltration rates were significantly higher on organically managed grassland soils (7.6 mm/h) than conventionally managed grassland (2.5 mm/h) with lower stocking rates. The results suggest that improved grassland management, whether organic or conventional, could reduce predicted runoff by 28%.     

喷施保铃剂与杀虫剂种子处理技术配套使用对棉花生长发育及产量的影响

本研究表明，叶面喷施保铃剂与常规拌种剂（６０％甲拌磷乳油＋５０％林丹胶悬剂）配套使用，表现出显著的防虫壮苗、促进生长、保铃增产的正联合作用。较单一的种子处理果枝数分别增加１３．５％和１．４％；现蕾数增加５１％和１４％；单株成铃数提高２９．４％和１７．３％，产量提高２９．３％和３１．４％。较空白对照处理保铃增产效果更加显著     

仙人掌原汁护色工艺研究

以新鲜“米邦塔”仙人掌茎片为原料,利用正交试验对仙人掌原汁的最佳护色条件和工艺进行了研究。结果表明:在85-90℃下,仙人掌在0．35 g/L醋酸铜溶液中热烫12 min后,再用1．0g／LL-抗坏血酸和0.3 g／L柠檬酸进行协同护色,护色效果最好。     

PBAT全生物降解地膜在辽西半干旱区的降解及残留特性

为明确全生物降解地膜在辽西半干旱区农田中的降解特性,以普通地膜(CPF)为对照,设置2年田间试验,结合扫描电镜(SEM)和傅里叶红外光谱(FTIR),测定PBAT全生物降解地膜(BPF)的降解及残留指标。结果表明:全生物降解地膜从玉米苗期(40 d左右)开始出现降解,拔节时地膜降解已进入破裂期,抽穗之后进入崩解期。随着覆盖年限的增加,地膜残留量也相应增加,普通地膜和全生物降解地膜表层残膜累积量分别增加165%和47%,残片总数分别增加80%和21%;2种地膜残留量均随土层加深而减少,但伴随覆膜年限增加,深层土壤中残膜占残膜总量比例呈增加趋势,其中,普通地膜比例由8.2%增至12.4%,全生物降解地膜由2.9%增至3.7%。通过2年覆盖,表层土壤中普通地膜和全生物降解地膜的残片数分别为277万和236万片/hm²,残膜质量分别为73.6和57.6 kg/hm²,与普通地膜相比,PBAT全生物降解地膜可实现自身降解,有效减少农田残留,以其替代普通地膜应用于辽西半干旱区玉米覆盖栽培具有可行性。     

Effects of the nitrification inhibitor nitrapyrin and tillage practices on yield-scaled nitrous oxide emission from a maize field in Iran

Nitrification inhibitors can effectively decrease nitrification rates and nitrous oxide(N₂O)emission while increasing crop yield under certain conditions.However,there is no information available on the effects of nitrification inhibitors and tillage practices on N₂O emissions from maize cropping in Iran.To study how tillage practices and nitrapyrin(a nitrification inhibitor)affect N₂O emission,a split factorial experiment using a completely randomized block design with three replications was carried out in Northeast Iran,which has a cold semiarid climate.Two main plots were created with conventional tillage and minimum tillage levels,and two nitrogen(N)fertilizer(urea)management systems(with and without nitrapyrin application)were created as subplots.Tillage level did not have any significant effect on soil ammonium(NH₄⁺)and nitrate(NO₃^-)concentrations,cumulative amount and yield-scaled N₂O emission,and aboveground biomass of maize,whereas nitrapyrin application showed significant effect.Nitrapyrin application significantly reduced the cumulative amount of N₂O emission by 41%and 32%in conventional tillage and minimum tillage practices,respectively.A reduction in soil NO₃^-concentration by nitrapyrin was also observed.The average yield-scaled N₂O emission was 13.6 g N₂O-N kg^-1N uptake in both tillage systems without nitrapyrin application and was significantly reduced to 7.9 and 8.2 g N₂O-N kg^-1N uptake upon the application of nitrapyrin in minimum tillage and conventional tillage practices,respectively.Additionally,nitrapyrin application increased maize biomass yield by 4%and 13%in the minimum tillage and conventional tillage systems,respectively.Our results indicate that nitrapyrin has a potential role in reducing N₂O emission from agricultural systems where urea fertilizers are broadcasted,which is common in Iran due to the practice of traditional farming.     

减氮密植模式下常规粳稻产量形成特征

以常规粳稻南粳9108和南粳5718为试材,探讨了减氮密植对常规粳稻产量形成特征的影响。结果表明,南粳9108和南粳5718在T1处理（较常规栽培减氮10%、增密15%）下的产量与CK（常规高产栽培）条件下基本持平,在T2（较常规栽培减氮20%、增密30%）和T3（较常规栽培减氮30%、增密45%）处理下的产量则较CK显著下降;T1处理下参试品种的有效穗数和每穗粒数与CK相当,T2和T3处理的有效穗数、每穗粒数、群体颖花量与CK相比显著下降,结实率和千粒重亦低于T1处理和CK。本研究表明,适宜减氮密植处理可以实现常规粳稻节氮、高产栽培。     

Effects of residue management on nitrogen losses in surface and sub-surface water from sugarcane fields

The effect of three sugarcane (Saccharum officinarum L.) residue-management plans on nitrogen losses in surface runoff and sub-surface leachate was studied for 3 years. The three management plans evaluated were conventional burning (CB), compost application with burning (COMB), and remaining green cane trash blanketing (GCTB) treatment. In the CB treatment, sugarcane residue was burned after harvest. The COMB treatment consisted of compost applied at ‘off bar’ with sugarcane residue burned immediately after harvest. Compost was applied in the amount of 13.4 Mg ha^?1 annually. Surface runoff was collected with automatic refrigerated samplers and sub-surface leachate was collected with pan lysimeters over a period of 3 years. Total nitrogen (TN), NO₃/NO₂–N, and NH₄–N were measured. The mean losses of nitrogen (TN, NO₃/NO₂–N, and NH₄–N) from the COMB treatment after the burning procedure (post-harvest, years 2 and 3) were on average 2.7 times higher than those before harvest and burning (pre-harvest, year 1). Mean leaching losses of NO₃/NO₂–N were 0.36, 0.82, and 0.10 kg ha^?1 for the CB, COMB, and GCTB treatment, respectively. The losses of NO₃/NO₂–N from the GCTB treatment in surface runoff and sub-surface leachate were significantly reduced compared to the CB and COMB treatment.     

Impact of direct drilling and conventional tillage on seasonal changes of soil water content in Chromic Haploxerert (south-west Spain)

A continuous monitoring of spatial and temporal variability of soil water content was studied under two soil management systems: direct drilling (DD) and conventional tillage (CT), during four consecutive seasons. The soil water content was read at different soil depths using multisensor capacitance probes in each soil-management treatment. During the first season (2003–2004), soil water content dynamics for both treatments were similar during the rainy season, although the DD plot was able to retain more water in the soil profile, and during the maximum evapotranspirative period faster soil water depletion took place in the CT plot. The 2004–2005 season registered a high evapotranspiration rate (1741 mm) with low rainfall (228 mm), promoting a low soil water recharge for both treatments. The 2005–2006 season registered an increase in rainfall, promoting a greater recovery of the soil water reserve in DD than CC plot. Finally, during the 2006–2007 season with an evapotranspiration rate ET₀ and rainfall of 1504 and 560 mm, respectively, DD retained more soil water content, mainly in the deeper zones, with progressive soil water depletion during the maximum evapotranspirative period in comparison to CT. Thus, DD was demonstrated to be a promising soil management technique for improving the soil water content.     

Maize growth and yield as affected by wheat residues and irrigation management in a no-tillage system

Determining the proper rate of wheat residues incorporation into the soil under a wheat–maize double cropping system is an important issue in southern parts of Iran, where these two irrigated crops are consecutively grown. A 2-year experiment (2010–2011) was conducted to evaluate the effect of wheat residue incorporation rates (25%, 50% and 75%) and irrigation intervals (12, 16 and 20 days) on yield and growth of maize under no-tillage system compared to control without residue and under conventional tillage (CT) at the College of Agriculture, Shiraz University, Shiraz, Iran. The experiment was conducted as a split plot arranged in randomized complete block design with three replications. The results showed that increased irrigation intervals reduced the plant height (14.6%), leaf-area index (12.9%), rows (10.1%) and grains per ear (29.8%), thousand grain weight (6.9%), grain (33.8%) and biological yield (24.2) and harvest index (23.2%). Water deficit had no significant effect on soil organic matter and carbon-to-nitrogen ratio. Under 12 and 20 days irrigation intervals, the highest grain yields were obtained with 12.7 and 8.6 t ha^?1 in CT and 25% residue incorporation into soil, respectively. Therefore, according to the results of this 2-year study, realized incorporation of 25% wheat residue soil covering percentage is recommended for this area with limited water resources.