不同采收期对猕猴桃香气成分的影响

采用顶空固相微萃取法(Headspace Solid-Phase Micro-Extractions,HS-SPME),提取美味猕猴桃品种"米良1号"不同采收期果实的香气成分.经气相色谱-质谱联机分析,在10月18日、28日的果实中分别检测出51种、48种香气成分,占各自总峰面积的97.75%和98.36%.果实香气成分主要以酶类、醇类、醛类为主.在两种采收期果实中,除酯类物质呈下降趋势外,醇类、醛类、羧酸类及酮类等香气物质都呈上升趋势.     

Contribution of cultivar,fertilizer and weather to yield variation of winter wheat over three decades: A case study in the North China Plain

Long-term field measured yield data provides good opportunity to assess the impacts of climate and management on crop production. This study used the yield results from a long-term field experiment (1979–2012) at Luancheng Experimental Station in the central part of the North China Plain (NCP) to analyze the seasonal yield variation of winter wheat (Triticum aestivum L.) under the condition of sufficient water supply. The yield change of winter wheat over the last 33 growing seasons was divided into three time periods: the 1980s, the 1990s, and the years of 2001–2012. The grain yield of winter wheat during the 1980s was relative stable. During the 1990s, the annual yield of this crop was continuously increased by 193 kg/ha/year (P < 0.01). While for the past 12 years, yield of winter wheat was maintained at relative higher level, but with larger seasonal yield variation than that back in 1980s. CERES-Wheat model was calibrated and was used to verify the effects of management practices on grain yield. Seven scenarios were simulated with and without improvements in management. The simulated results show that the yield of winter wheat was decreased by 5.3% during 1990s and by 9.2% during the recent 12 seasons, compared with that during 1980s, under the scenario that the yield of winter wheat was solely affected by weather. Seasonal yield variation caused by weather factors was around −39% to 20%, indicating the great effects of weather on yearly yield variation. Yield improvement by cultivars was around 24.7% during 1990s and 52.0% during the recent 12 seasons compared with that during 1980s. The yield improvement by the increase in soil fertility and chemical fertilizer input was 7.4% and 6.8% during the two periods, respectively. The initial higher soil fertility and chemical fertilizer input might be the reasons that the responses of crop production to the further increase in chemical fertilizer were small during the simulation period. Correlation analysis of the grain yield from the field measured data with weather factors showed that sunshine hours and diurnal temperature difference (DTR) were positively, and relative humidity was negatively related to grain yield of winter wheat. The climatic change trends in this area showed that the DTR and sunshine hours were declining. This type of climatic change trend might further negatively affect winter wheat production in the future.     

不同移栽期和采收期对烤烟产量与品质的影响

就9个不同移栽期和采收期组合处理对烤烟产量、品质的影响进行了研究。结果表明,不同移栽期和采收期对烤烟生育期、农艺性状影响不大;但对烤烟经济性状和化学成分影响较大,随着移栽期的推迟,烤烟产值增加;正常时间采收的产值高于推迟采收的产值;不同移栽期和采收期对烤烟化学成分的影响较大,但规律不明显。以延迟14 d移栽＋正常采收处理的综合表现较优。     

基因型对小麦生物产量和籽粒产量的影响

为了解基因型对小麦生物产量和籽粒产量的影响,选取7个不同基因型的小麦品种(系)作为供试材料,对其生物产量、籽粒产量与收获指数的差异进行了比较研究,并对生物产量与籽粒产量及其构成要素的关系作了分析。结果表明:不同基因型小麦的生物产量、籽粒产量和收获指数均存在差异,镇麦168的生物产量居首位,达到1656.3 g/m2,但其收获指数仅为0.45,导致其籽粒产量不高;宁麦13的生物产量较高,收获指数和籽粒产量均为最高。不同基因型小麦的籽粒产量与生物产量呈正相关关系,每穗实粒数、千粒重与生物产量相关不密切。     

摘脱收获复脱分离装置的试验研究

在专用的复脱分离试验装置上,对SG800摘脱机脱穗后的混合物,进行了多因素的性能试验,得出了复脱转筒线速度、凹板栅板间距、脱粒间隙、喂入量等诸因素,与未脱净率、破碎率、夹带损失率、含杂率和功耗等性能指标的相关性及其显著程度,作了因素水平参数组合的初步优选;并测定分析了复脱分离后排出物组成和各性能指标的轴向分布状况;探讨了改善复脱分离性能的途径。     

收获期对寒地青贮玉米营养价值的影响

以青贮玉米龙辐单208为材料,研究了寒地不同收割期对青贮玉米营养价值的影响。试验结果表明,随收获期推后,青贮玉米全株粗蛋白、粗纤维含量呈递减趋势,粗脂肪变化规律不明显。北方寒地青贮玉米适宜收获期为授粉后40～50d。     

草莓采收期维生素C含量的测定

[目的]测定草莓中维生素C含量并确定其最佳采收期。[方法]采用直接碘量法测定不同采收时期的20份草莓中维生素c的含量。[结果]草莓中维生素C的含量随其成熟度的增加而增长,其维生素C含量从草莓绿熟期到釜红期由33．79％升高到46．91％,表明草莓的最佳采收期为全红期,该时期的维生素C含量最高,营养价值最丰富。该试验方法的回收率为95．67％-100．08％,表明碘量法是可以测定水果中维生素C含量的,且该方法具有所需试剂少及操作简单等特点。试验的相对标准偏差为0．59％,精密度偏低。[结论]该研究为增加人们对草莓的保鲜常识以及正确食用草莓补充营养素提供了参考。     

烤烟品系LY1306“上六片”生理采收成熟度对烤烟代谢和品质的影响

为明确洛阳烟区烤烟品系LY1306上六片适宜的一次性采收成熟度,采用田间试验,设置4种采收成熟度处理(M1、M2、M3和M4),研究其对上六片3个叶位(上_1～2片叶、上_3～4片叶和上_5～6片叶)叶绿素相对含量(SPAD值)、叶色相对值、丙二醛(MDA)含量、抗氧化酶活性及碳、氮代谢关键酶活性的影响,并分析烤后烟叶常规化学成分和感官质量的差异。结果表明,随着采收成熟度的提高,上六片3个叶位的超氧化物歧化酶与淀粉酶活性均表现为先升高后下降的变化趋势,在M3处理期达到最大值;过氧化物酶、过氧化氢酶和硝酸还原酶活性逐渐下降,MDA含量逐渐升高,且M3到M4处理阶段变化幅度加大;SPAD值与叶色相对值随着采收成熟度的提高而降低,至M3和M4处理期时,上六片3个叶位的SPAD值均差异不显著,且叶色相对值也趋于稳定;M3处理烤后烟叶的总糖、还原糖含量以及糖碱比均最高,焦甜香味突出,评吸总分最高。总之,建议LY1306在洛阳烟区以M3处理期(上_3～4叶叶面落黄7～8成、主脉全白、支脉2/3变白,叶面皱褶,SPAD值...     

甘蔗生产全程机械化技术

随着甘蔗作物种植面积日益扩大,以传统人工、畜力种植、手工收获为主的生产方式已经不能满足农业发展的需要。该文介绍了甘蔗生产全程机械化所涉及的整地种植机械、田间管理机械和收获机械等,从4个方面提出了发展甘蔗生产全程机械化的保障措施。      

Local perceptions of Matsutake mushroom management, in NW Yunnan China

Matsutake mushrooms are among the most prized and expensive mushrooms on earth. Since the 1980s NW Yunnan Province has become the largest exporter of Matsutake in China, and money from their sale has become crucial to local livelihoods and to the provincial tax base. Amid fears of declining productivity, regulations have been enacted to control Matsutake harvest, though enforcement remains largely in the hands of harvesters themselves. Here, we measure local harvesters’ perceptions of the ecological determinants of mushroom productivity in contrast to that of the outsider conservation community. We interview 122 harvesters in eight villages in Diqing province, NW Yunnan to determine what is perceived to be detrimental to Matsutake yield, how yield can be improved in the future and who harvesters trust for information. Our results indicate that village leaders and forestry officials are overwhelmingly the most trusted sources for information. Mann and Whitney U tests show general consensus among villages, and MRPP analysis shows general consensus within villages. One village showed significantly higher levels of trust in NGOs. Of the 86% of harvesters who had perceived declining productivity trends over the past 10 years, soil disturbance, climate change, and habitat degradation were most often-cited as causal factors. Log-linear analysis showed almost no significant interactions between perceptions and harvester demographics. Environmental protection and reducing soil disturbance were most often-cited as potentially increasing future yields. We suggest that local and outsider knowledge are complimentary in this system, and that forestry officials and village leaders provide the best conduits for management information.