滩羊尿对典型草原三种草地植物生长的短期作用特性

研究了不同尿液浓度和土壤含水量下，羊尿对典型草原植物茵陈蒿、委陵菜和狗尾草生长的短期作用特性。结果表明，不同施尿量施尿后1个月，狗尾草对羊尿沉积的响应为高尿液浓度负效应，低尿液浓度正效应；茵陈蒿和委陵菜为负效应。土壤含水量越高，羊尿对其分蘖（枝）的负效应越低。不同尿液浓度下，三种植物对羊尿响应的负效应顺序为茵陈蒿〉委陵菜〉狗尾草；且其分蘖（枝）对羊尿和土壤水分互作反应的正效应顺序为狗尾草〉委陵菜〉茵陈蒿。具体放牧过程中，可通过家畜适时饮水降低尿液浓度，以降低畜尿对草地的负效应。     

多年生黑麦草高频再生体系的建立及优化

从外植体预处理方式、基本培养基、激素浓度等方面着手,对多年生黑麦草愈伤组织诱导、继代、不定芽分化及再生过程中的影响因素进行了研究,提高了再生频率。结果如下：切取胚端半粒种子,经75%乙醇处理1min,0.1%HgCl处理15min,在经无菌水清洗4～6次后接种方式较好;愈伤组织诱导培养基以MS＋2,4—D 8.0 mg/L（或另添加甘露醇25 g/L）为佳;愈伤组织接种于MS＋2,4—D 8.0mg/L＋甘露醇25 g/L上进行1～2次继代后于NB＋6—BA2.0 mg/L上进行分化;不定芽转接至MS＋6—BA2.0 mg/L上进行扩繁或于1/2MS＋NAA0.5mg/L＋IAA0.5mg/L上进行生根。     

放牧强度、植被结构与草地生态环境的关系

本文综述了放牧对草地植物组成及植物生物量的影响、不同放牧方式和强度对家畜和草地的影响、高寒草甸地区人工草地建植和利用的研究进展。为了保护草地植物多样性及获得较高草地生产量,应使草地承受适当的放牧压力。     

羊草与灰色赖草杂种F1再生体系的建立

对羊草(Leymus chinensis)与灰色赖草(Leymus cinereus)杂种F1幼穗进行离体培养,建立了杂种F1植株再生体系.结果表明:不含任何激素的MS培养基是最佳的分化培养基,分化成苗率为66%;2,4-D对愈伤组织的诱导及其质地的改造有重要作用;3.0 mg/L 2,4-D MS培养基愈伤组织诱导率最高,为68%;2.0 mg/L 2、4-D MS诱导的愈伤组织胚性最强;诱导率与分化率没有直线对应关系;再生体系的建立为杂种F1育性恢复的研究奠定了基础.     

Effect of indole-acetic acid (IAA) on the development of symptoms caused by <Emphasis Type="Italic">Pythium ultimum</Emphasis> on tomato plants

The effect of indole-acetic acid (IAA) on the development of symptoms caused by Pythium ultimum on tomato plants was investigated using different bioassays. Application of IAA (5 μg ml⁻¹) on tomato seedlings inoculated with P. ultimum did not affect their emergence suggesting that IAA did not affect the severity of Pythium damping-off. However, IAA was shown to influence the development of P. ultimum symptoms on tomato plantlets. Low concentrations of IAA (0–0.1 μg ml⁻¹) within the rhizosphere of plantlets increased the severity of the symptoms caused by P. ultimum, while higher concentrations (10 μg ml⁻¹), applied either by drenching to the growing medium or by spraying on the shoot, reduced the symptoms caused by this pathogen. In addition, the study demonstrated that P. ultimum produces IAA in liquid culture amended with L-tryptophan, tryptamine or tryptophol (200 μg ml⁻¹) and in unamended culture.     

几种药剂防治白萝卜蚜虫、烟粉虱试验效果

为探索防治白萝卜蚜虫、烟粉虱安全高效的药剂,减少农药用量,降低残留,使生产的白萝卜符合出口国要求,我们选择了几种药剂防治白萝卜蚜虫、烟粉虱的药剂,进行了田间试验。试验表明,在蚜虫、烟粉虱混合发生初期,用10%吡虫啉可湿性粉剂15g/667m2,其药后5d、7d对蚜虫校正防效达到97.8%、95.8%;用1%除虫菊素-苦参碱微囊悬浮剂75mL/667m2,其药后5d、7d对烟粉虱校正防效达到73.9%、78.2%,在生产上应每隔7d用药1次,连用2次。以上2种药剂对白萝卜安全且有较好的防治效果。     

小麦叶疫病检疫研究

介绍了１９９２￣１９９５年间小麦叶疫病检疫研究的主要结果。研究证实我国局部地区已有叶疫病发生,分离得到了１１个小麦链格孢菌株,并研究了其生物学特性,确定了小麦链格孢的鉴定条件和鉴别标准,发现分生孢子链长度和分枝状况是区分类似种类的主要特征。提出了病株诊断方法和种子带菌的快速检验方法,后者包括吸水纸培养检验法和ＧＬＵＺＡ鉴别性培养基培养检验法,根据研究结果和国外发病动态,提出了有关检疫对策的建议。     

植物凝集素对桃蚜生长发育的影响

通过实验 ,研究了来自三种不同植物的植物凝集素 (ConA、STA和WGA)对桃蚜生长发育的影响 ,发现这三种植物凝集素对桃蚜均有一定的拒食性 ,并且对桃蚜的蜜露分泌量、平均相对生长速率以及存活率均有一定的影响 ,其中以STA的影响最为显著 ,WGA次之 ,ConA为最弱     

Reduced inter-row distance improves yield and competition against weeds in a semi-dwarf durum wheat variety

Weed and nutrient management in cropping systems of semi-arid areas is a major constraint to cereal yield. Where the use of herbicides is banned or discouraged, the competitive ability of a crop is crucial to reduce weed growth and diffusion. Genotypic differences in the competitive abilities of crops are an important trait to reduce weeds, especially for plant height. However, there is contrasting information about the interactions of other management practices and genotypic traits on wheat yield and competitive ability against weeds and weed growth. The present study investigated yield and quality of durum wheat (Triticum durum Desf.) and weed growth and composition for two wheat cultivars with contrasting competitive abilities against weeds. Wheat was grown under three spatial arrangements (5-cm, 15-cm, 25-cm inter-row distance) and three sowing densities, and broadleaf weeds were either removed or not. The sowing rate did not affect the yield of these wheat cultivars or the weed growth. Reduced inter-row distance dramatically reduced weed biomass for both wheat cultivars, and increased wheat yield and nitrogen uptake in the low-competitive, high-yielding, semi-dwarf cv. ‘PR22D89’, when both weed free and with weeds. These results have direct implications for weed and nutrient management in low-input and organic cropping systems.