Aflatoxin in maize,a multifaceted answer of Aspergillus flavus governed by weather,host-plant and competitor fungi

Aspergillus section Flavi is able to produce aflatoxins (AFs) in vitro down to 0.85 a_w with a potential maximum occurring between 0.95 and 0.99 a_w, while in the field AFs increased significantly with kernel humidity below 0.95 a_w. In order to clarify this apparent discrepancy, a 3-year field trial with artificial inoculation of maize ears with Aspergillus flavus strains was organised. The co-occurrence of Aspergillus section Flavi and Gibberella fujikuroi species complex (Gfsc) was observed. The incidence of A. flavus was significantly influenced by the year and negatively related to Gfsc incidence. In 2012, when the highest temperature and the lowest rain were registered, aflatoxin B₁ (AFB₁) content was the highest and a_w < 0.95 in kernels was measured early throughout the growing season. In 2013 and 2014, the temperature was lower and rain more abundant, and a_w decreased below 0.95 only close to harvest and AFB₁ contamination was limited. The possibility of describing/predicting reasonably well a_w dynamic based on temperature, (degree day) was confirmed. With a_w > 0.95, a positive correlation between AFB₁ production rate and a_w was found, but a negative correlation resulted with a_w < 0.95. Other factors than a_w play a role, but a_w = 0.95 should be considered as an indicator of suitable conditions for rapid aflatoxin accumulation.     

Effects of drought on the morphological and physicochemical characteristics of starch granules in different elite wheat varieties

In this study, scanning electron microscopy (SEM) revealed the formation of pits and pores on the surfaces of starch granules in response to drought stress, with substantially more pronounced effects in the ordinary yield potential wheat cv. Xindong 23 than the excellent yield potential wheat cv. Xindong 20. Drought induced a significant reduction in starch granule sizes in both wheat varieties, though the reduction observed in Xindong 23 was six times more pronounced than that observed for Xindong 20. Amyloglucosidase and α-amylase treatment of starch from wheat grown in drought conditions released significantly more reducing sugars compared with samples from irrigated controls. SEM and confocal laser scanning microscopy (CLSM) revealed that starch granules from the two wheat varieties grown under drought conditions had substantially increased fluorescence after treatment with proteolytic enzymes and staining with methanolic merbromin and 3-(4-carboxybenzoyl) quinoline-2-carboxaldehyde dyes. Analysis of pasting properties showed significant increases of peak viscosity, trough viscosity, break down, and setback following drought stresses. Furthermore, drought induced a significant reduction in the water binding capacity and increased damage to starch only in Xindong 23. These results provide insight into the potential mechanisms through which drought influences the ultrastructures and physicochemical properties of starch in wheat.     

脱乙酰化几丁质的乙酰化程度对诱导油菜抗性的影响

 对甘蓝型油菜“西农长角”发芽 5d的幼苗子叶进行涂抹抗性诱导效应及基机理的影响研究表明 ,脱乙酰化几丁质对抗性的诱导与水扬酸 (SA)相似 ,但乙酰化程度对诱导效果有显著的影响并体现出一定的规律性。苯丙氨酸解氨酶 (PAL)活性随乙酰化程度增加而提高 ;而几丁质酶活性则随乙酰化程度增加而下降 ,只有完全脱乙酰化 (D .A .为 0 % )的 10B和GC能诱导酶活性提高 ,而D .A .为 10 %、2 0 %、30 %的 7B、8B和 9B则表现出抑制作用 ;过氧化物酶(POD)活性都能被诱导而比对照高 ,但乙酰化程度的影响不显著。     

混合动力汽车混合度设计方法研究

提出了并联型混合动力汽车的混合度设计方法,重点讨论混合度设计的约束条件、边值条件及其计算方法。并结合实例说明该混合度的设计方法可合理、有效地确定动力源的功率参数。     

The role of sensitivity to abscisic acid and gibberellin in pre-maturity α-amylase formation in wheat grains

To study the role of abscisic acid (ABA) and gibberellin (GA) sensitivity in regulating pre-maturity α-amylase (PMA) in wheat grains, plants were grown in a glasshouse under cold-shock and ambient conditions. α-amylase activity in response to applied ABA and GA was measured in detached-grains with the embryo removed (in vitro) and in intact-grains attached to the plant (in situ). The in vitro experiment was conducted using Spark (low PMA-susceptible genotype) and Rialto (highly PMA-susceptible genotype), with the aim of defining the time point for GA-sensitivity. The results showed an increase in GA-sensitivity at about 640 degree days after anthesis (DAA) in Rialto. There was no evidence for a change in ABA-sensitivity in either variety. The in situ experiments were conducted using genotypes from a Spark × Rialto doubled haploid population segregating for the Rht-D1a (tall) or Rht-D1b allele and for the presence or absence of 1BS/1RS. For Rht-D1a (tall) or Rht-D1b genotypes with or without 1BS/1RS, the cold-shock significantly increased GA-sensitivity, whereas there was no significant change in ABA-sensitivity. These results show PMA is related to an increase in GA-sensitivity that occurs in the aleurone at around 640 degree DAA, and can be enhanced by environmental factors (e.g. cold-shock).     

互助县现代畜牧业生产发展现状和建议

畜牧业是新农村建设的萤要组成部分,加快农区畜牧业发展对于调整农业产业结构,发展农村经济,增加农民收入,加快新农村建设步伐,实现小康社会具有十分重要的意义。当前,随着社会主义市场经济的深入发展和西部大开发战略的有效实施,互助县畜牧业进入了一个新的发展时期,我们既面临着良好的发展条件和机遇,也面临着新的挑战和问题。为抓住机遇,实现畜牧业发展的新突破,推动新农村建设．提出以下建议和思路,以供参考。     

1981～2010年开平市霾日的变化趋势分析

利用近30年(1981～2010年)开平市霾日的年、季、月和年距平变化趋势进行分析,结果表明30年来开平市霾日呈上升趋势,霾日的年际变化较大;霾日存在明显的季节性,从多到少依次为冬季、秋季、春季、夏季;各月霾日变化是当年10月至次年1月最多,5～8月最少。     

哈密地区雷暴天气变化特征分析

利用1961—2010年哈密地区50年雷暴天气资料,统计分析了雷暴日数的变化特征及时空分布情况,结果表明哈密地区雷暴日数呈逐年下降趋势,尤其近10年下跌趋势很大,在过去的50年中各测站雷暴日数变化速率-0.32～-2.00d/10年。1年中雷暴的活动期在3～10月,活跃期5～8月的平均雷暴日数占全年的90.0%以上。1日中雷暴多发生在正午到前半夜。年雷暴日数的空间分布特征为南部明显少于北部,且雷暴日数随海拔升高而递增。     

内蒙古近30年10℃积温变化特征分析

文中利用内蒙古35个气象观测站整编的1971~2000年资料,研究了内蒙古及其各个生态类型区域的日平均气温稳定通过10℃的初日、终日、初终间日数和积温的空间变化、年际变化、年代际变化趋势。结果表明:内蒙古全区及各区域日平均气温稳定通过10℃的积温变化均呈显著增加趋势,全区范围内平均每十年积温增加95℃,初终间日数增加3.2天。其中,积温增加幅度最大是荒漠化草原区,平均每十年增加156℃;初终间日数增加幅度最大是荒漠化草原区,每十年增加6.9天;初日明显呈提前的趋势,初日在全区范围每十年提前了1.9天;终日呈推迟的趋势,终日在全区范围每十年推迟了1.4天。各区域的初终间日数和积温变化与全区相近,都呈明显的增加趋势。