Effects of temperature,vapour pressure deficit and radiation on infectivity of conidia ofBotrytis cinerea and on susceptibility of gerbera petals

The effect of vapour pressure deficit, temperature and radiation on the postharvest susceptibility of gerbera flowers toB. cinerea, on the water relations of gerbera flowers and on the lesion formation after conidial infection ofB. cinerea was studied. The temperature range in whichB. cinerea could germinate and growin vitro is 5–30 °C. In climate chamber experiments flowers had more lesions ofB. cinerea at temperatures of 20 and 25 °C than at 10 and 15°C. At 15, 20 and 25°C the infectivity ofB. cinerea conidia was negatively affected during a storage-period of 7 days. At a vapour pressure deficit (VPD) of 200 Pa significantly more conidia ofB. cinerea were infective than at 800 Pa. At a VPD of 800 Pa the susceptibility of gerbera flowers forB. cinerea was not significantly different than at 200 Pa. High radiation levels in glasshouses in spring and summer negatively influenced the infectivity of conidia ofB. cinerea on the flower surface, but did not affect the susceptibility of gerbera flowers forB. cinerea. In spring and early summer conidia lost their infectivity at high radiation levels, high temperatures and high levels of VPD. In summer gerbera flowers could be more susceptible toB. cinerea because of high temperatures in glasshouses, but the negative effect of radiation on the conidia ofB. cinerea seemed to overrule the temperature effect. Thus, the numbers of lesions in spring and summer can be low compared with the numbers in other seasons, although the numbers ofB. cinerea colonies on spore traps can be high. The effect of temperature on the susceptibility of gerbera flowers can probably be explained by changes of water status in the petals. At higher temperatures the number of lesions and the turgor (=water potential—osmotic potential) in the petals increased. Temperatures <10°C during lesion formation (RH>95% and VPD<50 Pa) had a temporary negative effect on the number of lesions. After 3 days of incubation the numbers of lesions were about equal (30 lesions/cm²) from 5 to 20°C. At 30°C no lesion formation was observed even after 3 days.     

某类高阶非线性偏微分方程组弱解的正则性

本文研究一类2k阶非线性偏微分方程组之解的正则性,没有假定通常的椭圆性条件而只假定所谓"无穷远处"的椭圆性条件,证明了解的k-1阶导数为李普希兹连续的.     

宁夏南部山区抗旱应灾农业技术体系的探讨

通过分析宁夏南部山区干旱气候规律及其对农业的胁迫效应，指出干旱灾害是宁南农业生产力水平低而不稳的重要原因；加强与气候条件相适应的农业技术的研究和改进，是宁南农业持续稳定发展的重要基础。结合多年来的旱地农业科技攻关研究工作，在对单项农业技术进行组装集成的基础上，建立了包括工程措施、生物措施、农艺措施、化学措施等四大措施紧密结合的宁南山区抗旱应灾农业技术体系，探讨了宁南山区抗旱应灾的主要技术策略。对于广大旱农地区提高农业系统防旱抗旱能力，实现农业高产稳产具有普遍指导意义。     

关中平原小麦产量对气候变化区域响应的评价模型研究

根据关中地区宝鸡、西安、渭南与咸阳 4地 (市 )的 1 949～ 1 999年的逐年小麦单产记录序列以及 4地 (市 )的气象观测站点自建站以来至 2 0 0 0年近 5 0年的气象记录序列 ,对关中地区小麦产量与年均温、年降水作相关分析 ;探讨了关中地区小麦单产对气候变化区域响应的评价模型。结果发现 :关中平原气候具有暖干化趋势 ;随着气温变暖 ,小麦产量增加幅度减小 ;小麦产量对降水波动的响应比对气温波动的响应显著。     

渭河阶地全新世土壤粒度成分高分辨率研究

通过对渭河阶地全新世土壤的野外考察和粒度成分的高分辨率分析研究，揭示了该区域褐色土的成壤作用过程与季风气候变化的关系。研究表明渭河第二级阶地褐色土形成在全新世气候最适宜期（8500－3100a B.P.），从8500a B.P.开始该土壤开始发育，老官台文化兴起。从3100a B.P.开始的气候干旱化和沙尘暴堆积形成了黄土L。层。西周时期对应于该干旱期的初期。     

民勤绿洲生态气候资源及其利用

民勤绿洲边缘 ,光照丰富、温差大 ,有利于农产品质量的提高。但是水资源缺乏 ,地下水位急剧下降和土地沙化是民勤绿洲农业生产的首要问题。如何充分利用现有生态资源 ,并充分提高其利用率是摆在我们面前的一个主要课题。只有通过引进优良品种 ,调整农业种植结构 ,大力推广节水灌溉技术 ,才是解决上述问题的有效途径     

环境条件和微生物对灭线磷降解的影响

环境条件和微生物影响灭线磷在土壤中的降解。随着土壤含水量和温度的增加,灭线磷的降解速度加快;微生物对灭线磷的降解有显著影响,30℃、含水量为40%条件下,未灭菌土中灭线磷的半衰期为16.6 d,灭菌土中灭线磷的半衰期为31.6 d;有机质对灭线磷的降解也有显著影响,有机质含量高,有利于灭线磷的降解;灭线磷在碱性土壤中的降解快于在酸性土壤中;30℃、含水量为40%条件下,灭线磷在3种土壤中的降解速度为:东北黑土＞广东红土＞山东砂壤土。     

Effect of air temperature, rain and drought on hot water weed control

The influence of rain and drought before, and air temperature during, weed control with hot water was studied in laboratory experiments on the test weed Sinapis alba (white mustard). The plants were grown in a greenhouse and treated outdoors. There was no difference in weed control effect when S. alba plants at the four‐leaf stage were treated at the air temperatures 7°C and 18^°C. The effective energy dose for a 90% fresh weight reduction was 465 kJ m^?2 for both air temperatures. Weed control of S. alba at the four‐ to six‐leaf stage in rainfall above the rainwater run‐off level increased the required effective energy dose by 20% (i.e. 120 kJ m^?2) compared with dry plants. A short period of drought just before treatment on S. alba at the two‐ to four‐leaf stage increased the plant fresh weight reduction, which was 22% at low energy dose (190 kJ m^?2) and 44% at high energy dose (360 kJ m^?2). Hot water weed control should thus be carried out when the plants are drought stressed and avoided when the plants are wet. The air temperature seems to be of little importance in the range 7–18^°C.     

分蘖洋葱的特性及高效栽培技术研究

分蘖洋葱最突出的特性是分蘖性强，生长快，分蘖的多少直接影响分蘖洋葱的产量。试验表明：12-20℃条件最适宜其生长，良好的土壤营养和适宜的环境有利于分蘖洋葱的分蘖生长，获得高产、优质商品。     

马杜霉素发酵法生产工艺的研究

马杜霉素是一种应用广泛的兽用抗球虫抗生素.以马杜霉拉放线菌(Actinomadura Yumanense sp.)ZU-M3为生产菌株,通过摇瓶实验获得较适宜的发酵条件:发酵培养基含葡萄糖7%,豆饼粉1.2%,玉米浆1.2%,NaCl 0.3%,CaCO3 0.1%,K2HPO3 0.03%,Fe2(SO4)3 0.01%,初始pH为6.6,发酵温度为34 ℃.用3L发酵罐做放大试验,通气速率为0.12 m3/h,搅拌速率600 r/min,发酵8 d 菌液发酵单位达到8 336 μg/mL.该研究结果对于大规模的工业化生产具有指导意义.