Ca2+、PEG预处理对干旱胁迫下小麦幼苗某些酶活性的影响

本文结果表明，Ｃａ＾２＋、ＰＥＧ预处理小麦种子具有提高其幼苗ＲＷＣ及ＳＯＤ、ＣＡＴ、ＰＯＤ的活性和降低膜透性的效应，在干旱胁迫下植株生长抑制减轻。随着干旱胁迫的加强、ＳＯＤ、ＣＡＴ、ＰＯＤ活性迅速上升并始终维持较高水平，具体表现为浸种处理ＰＥＧ〉Ｃａ＾２＋〈Ｈ２Ｏ；ＲＷＣ表现为ＰＥＧ〉Ｃａ＾２＋〉Ｈ２Ｏ，植株生长抑制程度表现为ＰＥＧ〈Ｃａ＾２＋〈Ｈ２Ｏ。解除干旱胁迫后，Ｃａ＾２＋，ＰＥＧ浸种处理的     

Crops use-efficiency of nitrogen from manures permitted in organic farming

The current increase in the organic agriculture segment has created a new market for fertilisers permitted for use in organic farming. Off-farm N sources for organic farming are scarce, considering the restriction on the use of chemical fertilisers. Thus, when some products are permitted in organic agriculture, commercial opportunities become available. In this study we compare the performances of Vegethumus (Veg) and Phenix (Phe), two manures that are permitted in organic farming, with several other manures, ammonium nitrate (AN) and control treatments. A 3-year field trial and a pot experiment were carried out in order to estimate dry matter yield, N uptake, and N nutritional status of the crops, as well as soil N availability, the latter was assessed by using anion exchange membranes inserted into the soil. Apparent N recovery (ANR) values in the field trial were 6.3% and 58.2% in Veg and AN plots, respectively, after the application of 380 kg N/ha in the previous five growing seasons. In the pot experiment, the ANR of Veg and Phe, the organic amendments permitted in organic farming, were 5.0% and 13.6%, while Beiraadubo (Bei) and Nutrisoil (Nut) had ANR of 27.2% and 42.0%. The poor results of the amendments permitted in organic farming, in light of their high prices suggest that their use must be carefully considered by farmer in their fertilization strategies.     

Resistance to turnip mosaic virus in white cabbage

Summary Resistance in white cabbage to external necrosis caused by turnip mosaic virus had a significant genetic component. Estimates of heritability ranged from 41% to 48%. Resistance to internal necrosis was determined by unknown environmental factors with no significant genetical component. Although correlation between external and internal symptoms was poor in general, plants which had no external symptoms at harvest did not develop internal symptoms during storage. It is proposed that selection for lack of external symptoms will also produce lines resistant to internal symptoms.     

多效农艺营养纸膜对番茄和黄瓜生育的影响

采用多效农艺营养纸膜覆盖栽培番茄、黄瓜对其生育与开花结实，土壤养分含量及微生物含量进行了调查。结果表明，营养纸膜覆盖的的比地膜覆盖的土壤有机质含量增加，植株的Ｔ／Ｒ值降低，促进了植株的生长和开花结实，而且土壤中的病原菌也得到很好的控制。     

土壤干旱胁迫对玉米叶片水分状况、膜透性及酶抗氧化系统的影响

A simulation experiment on the responses of maize （Zea mays L.） from the third leaf stage to maturity for different soil water levels （well-watered, moderately stressed, and severely stressed） was conducted by controlling irrigation and using a mobile rain shelter in a neutral loam, meadow soil to determine the effects on leaf water status, membrane permeability and enzymatic antioxidant system for different growth stages. The results indicated that drought stress relied on drought intensity and duration, with more severe drought stress creating more serious effects on maize. Compared with wellwatered conditions, during the silking and blister stages moderate stress did not significantly change the relative water content （RWC） and did change significantly the relative conductivity （RC） （P 〈 0.05） of the leaves; however, severe stress did significantly decrease （P 〈 0.01） the leaf RWC and increase （P 〈 0.01） membrane permeability （leaf relative conductivity）. Furthermore, under severe drought stress antioxidant enzyme activities declined significantly （P 〈 0.01） in later stages, namely for superoxide dismutase （SOD） the tasseling and blister stages, for peroxidase （POD） the milk stage, and for catalase （CAT） during the tasseling, blister, and milk stages. Meanwhile, membrane lipid peroxidation （measured as malondialdehyde content） significantly increased （P 〈 0.01） in all stages.     

涝害和高温下棉花苗期的生长生理代谢特征

雨涝和高温是长江中下游地区限制棉花生长的2种主要气象灾害,且夏季伴随发生概率大,目前尚不清楚高温胁迫下棉花苗期对涝害的响应特征。2013年利用桶栽试验,在棉花苗期设置不同涝害(受涝0、3、6、9 d)和高温(高温0、3 d)水平,分析棉株关键形态生长特征、倒4叶叶绿素荧光特性及膜脂保护性酶活性。结果表明,受涝天数不超过3 d进行连续高温处理对棉花形态生长特征无显著影响;受涝时间3 d遭遇高温胁迫,进一步限制了棉花株高和叶面积生长,干物质量减少,根/冠比降低,且这些参数在高温胁迫下低于不受涝处理的时间普遍比自然温度条件下提早3 d。受涝过程伴随高温加剧降低了根系活力,进一步减少了叶绿素a、叶绿素b含量及PS II最大光化学量子产量和潜在光化学转换效率,而对叶绿素a/叶绿素b影响普遍不明显。在自然温度条件下,叶片和根系超氧物歧化酶、过氧化物酶活性随受涝天数的延长而降低,丙二醛含量则变化相反。涝害和高温复合胁迫下,叶片超氧物歧化酶和过氧化物酶活性先升高后降低,在受涝3 d最高,受涝9 d最低;叶片和根系丙二醛含量急剧增加,表明受涝过程中遭遇高温天气加剧了棉株细胞膜的受损程度。从对棉花生长的影响程度来看,涝害居首位,高温胁迫次之,且二者交互作用在叶绿素、PS II潜在光化学转换效率及叶片超氧物歧化酶、过氧化物酶和丙二醛上表现显著。研究可为长江中下游平原湖区棉苗抗逆栽培及棉田排水管理提供科学参考。     

鲜榨苹果汁陶瓷膜超滤澄清与除菌的中试试验研究

该研究应用膜孔径为100 nm的陶瓷膜错流超滤中试系统(MEMBRALOX^?，Pall)对果胶酶酶解后的鲜榨苹果原汁进行了过滤澄清与除菌效果研究。结果表明，100 nm陶瓷膜错流超滤的最佳操作条件为：跨膜压力为0.85×10⁵ Pa，温度为50℃，膜面流速为5 m/s；以0.5%次氯酸钠和4% NaOH溶液作为清洗剂，膜通量的恢复率可以达到98%。过滤后果汁中的悬浮颗粒和引起浊度升高的大分子胶体物质大部分被滤除，而果汁的各项质量指标如pH值、总酸、糖度等却未发生     

基于图像处理与人工神经网络的小麦颗粒外观品质评价方法

综合利用计算机视觉、图像处理、人工神经网络技术，实现小麦品质评价自动化。通过比较不同背景，发现在黑色毛面纸板背景下，使用数码像机获得容易处理的小麦图像。应用分水岭算法自主开发了图像分割处理软件，分割小麦图像并识别提取出完整的小麦颗粒，针对每个小麦颗粒，计算了其12个形态学特征、12个色泽参数等图像特征参数。利用所提取的24个小麦图像特征参数，采用人工神经网络BP算法建立起小麦粒径外观品质评价模型，并应用于小麦的品质识别，取得了良好的试验结果。多次建模运算证明，该方法具有较好的稳定性，对小麦粒径外观品质评价的平均识别准确率可达93%。     

利用改善液培养牛卵母细胞和早期胚胎的研究

在基础液 M199配制的培养液中,加入牛卵泡内的颗料细胞,置39℃、5%的 CO_2培养箱中培养72 h 后回收过滤液(简称改善液)。用这种不同浓度和保存时间的改善液,在体外成熟培养牛卵母细胞和胚胎时分别代替培养液和培养液加颗粒细胞制作的单层细胞培养体系。结果表明:(1)在基础液 M199中分别加入0%、25%、50%、75%、100%改善液和对照纽,其分裂率(78.7%～83.0%)组间均无差异(P>0.05);受精卵在体外培养至囊胚率,其中0%改善液组为30.4%,与对照组46.5%有显著差异(P<0.01);囊胚孵化率0%和25%改善液组分别为57.1%和57.9%,与对照组76.6%有显著差异(P<0.01)。(2)改善液保存时间为0 d,-4℃ 5～7 d,-20℃180 d 和对照组,分裂率(80.5%～86.3%)组间均无差异(P>0.05);受精卵在体外培养至囊胚率和囊胚孵化率,其中-20℃保存180 d 组分别为31.1%和54.5%,与对照组46.1%和72.0%有差异(P<0.05)。     

行间耕播机弹性可覆土镇压轮性能有限元仿真分析及试验

为提高播种机的播种及镇压性能,解决播种作业中覆土后即时镇压的难题,结合橡胶类材料的变形理论与轮胎力学的研究基础,建立基于种沟沟型的理论模型,并设计出一种具有覆土功能的弹性镇压轮,镇压轮横截面由顶端连通的两个腔室组成,通过镇压轮侧缘与种沟接触产生的挤压力以同时实现覆土和镇压作业。利用ABAQUS软件对镇压轮进行有限元仿真分析,考察其覆土及镇压性能,通过有限元仿真分析证实该模型可行有效。通过与双圆盘覆土器和传统橡胶镇压轮的田间对比试验测得,该文所设计的弹性可覆土镇压轮作业后种子平均覆土深度为34 mm,变异系数为15.68%,镇压后种子上方距离地表5 cm的土壤紧实度为33.5 k Pa,变异系数为13.97%,应用双圆盘覆土器和传统橡胶镇压轮作业后种子平均覆土深度为35.3 mm,变异系数为17.51%,镇压后种子上方距离地表5 cm的土壤紧实度为26.5 k Pa,变异系数为15.32%,田间对比试验证实弹性可覆土镇压轮和双圆盘覆土器均可满足玉米播种作业对覆土深度的要求,但弹性可覆土镇压轮对土壤的镇压强度大于传统橡胶镇压轮,同时由覆土深度变异系数和镇压强度变异系数可以看出,弹性可覆土镇压轮在作业过程中的覆土深度稳定性和镇压强度稳定性均优于双圆盘覆土器和传统橡胶镇压轮。