科尔沁沙地外来入侵植物光梗蒺藜草的种子库分布格局

在通辽市科尔沁区的固定沙地,半流动沙地采用相邻样方法观测光梗蒺藜草已萌发种子和未萌发种子在不同埋深中的分布,发现在固定沙地中,光梗蒺藜草种子分布在埋深较浅处(0～3cm),集中分布在0～1cm;在半流动沙地中,光梗蒺藜草种子分布较为分散,在1～15cm埋深处均有分布,在埋深0～5cm处种子数量较多。固定和半流动沙地中光梗蒺藜草种子随着埋深增加出苗率也随之增加,可达到100%。负二项式法和方差/均值比率(分布系数)法一致的验证了光梗蒺藜草苗和土壤种子库的种子种群分布格局为集群分布。光梗蒺藜草自然散布距离很短,是造成其种群集聚分布格局的原因。     

稻田耳叶水苋发生规律及生物学特性研究

为明确上海地区稻田新优势杂草耳叶水苋的发生规律,对上海地区稻田中耳叶水苋的发生情况进行了田间调查和定点观察,并在室内研究了其生物学特性。结果表明,耳叶水苋发生周期长,有两个明显的发生高峰,分别为水稻播种后第1周和第3周。水稻播种后45 d,耳叶水苋种群数量达到最大,随后,种群数量逐渐下降。耳叶水苋的种子在23～27 ℃条件下发芽最好。作为一种水生杂草,其种子在土壤含水量40％～60％的湿润或饱和状态下,发芽率较高,且耳叶水苋的种子对水层具有较好的适应能力,即使处于10 cm水层下也可以正常萌发。耳叶水苋种子极小,其顶土能力较差,覆盖0.5 cm土层能有效抑制其出苗。     

外来入侵生物烟粉虱的生物学特性及种群数量消长规律研究

根据2005～2010年应用塑料黄板涂抹机油系统诱集烟粉虱成虫以及烟粉虱的饲养观察结果表明,烟粉虱在临海地区年可发生11代;其越冬的临界温度为旬平均气温8.5℃。随着寄主植物的生长,成虫逐渐向上部叶片转移,并形成植株自上而下为成虫(初产卵)、若虫和蛹壳(伪蛹)的虫态垂直分布状态。其全年种群数量消长主要呈双峰型曲线变化,其中夏峰期一般在5月中旬至9月上旬;秋峰期一般在10月中旬至11月下旬。影响种群数量消长的主要因素有种群基数、气候条件、耕作制度和洪涝淹没等。其中关键在于气温条件,即烟粉虱虫口密度(M)随气温(T℃)的变化而变化,其线性关系模型为M=0.607T-4.064 5,n=36;r=0.682 6**;其曲线关系模型为M=0.007 1T2+0.351 3T-2.218 8,n=36;r=0.684 6**。当旬平均气温在8～10℃时种群处存活临界状态;当旬平均气温在10～20℃时种群数量处低密度状态,并呈低位运行;当旬平均气温处20℃以上种群数量增速较快,并随气温升高而升高;当旬平均气温处30℃以上时种群数量有所回落,并出现相对低谷期。随后种群数量又回升成峰,并对秋季蔬菜产生较重为害。     

苘麻不同种群的种子萌发特性

为揭示农田恶性杂草苘麻种子的休眠萌发机制, 探寻基于休眠调控的绿色防控途径, 采用60℃温水浸种30 min+30℃恒温培养的方法测定了不同种群苘麻 Abutilon theophrasti 种子的萌发率?萌发势与萌发指数?结果表明, 供试的18个种群中, 种群XJ01?JL04和JL01的萌发率分别为89.95%?89.18%和87.77%, 显著高于其他种群; 而种群HB01的萌发率最低, 仅为41.50%?测定了萌发差异较大的种群JL01和HB01种子的萌发关键期指标, 发现JL01种群在温水浸种后培养2 h的吸胀数量?10 h破皮数量和20 h露白数量, 显著高于HB01种群, 其种子数量分别是HB01种群的1.37?1.76和2.96倍?通过进一步比较8个种群种子的萌发吸胀?破皮与露白数量指标, 证实苘麻不同种群种子存在显著休眠萌发差异, 其原因可能是由于母体生活环境不同所致?     

棉田棉蚜种群动态及瓢虫对棉蚜种群数量的影响

根据新疆尉犁县4种棉花品种的棉田调查,利用棉蚜数量和时间进行回归分析,探讨其种群动态,应用棉蚜数量和瓢虫数量进行相关分析,研究棉田棉蚜种群与瓢虫种群的关系。结果表明,在不同品种的棉田中,棉蚜种群数量基本呈指数规律上升与下降。在尉犁县孔雀农场的中棉35和军棉1棉田中,从2001年5月31日至6月28日棉蚜种群数量呈指数增长,从6月28日至7月26日棉蚜种群数量呈指数下降。在尉犁县达西村的抗虫棉9和新陆中11棉田中,棉蚜种群数量开始发生和发生高峰期均比中棉35和军棉1推迟1周左右,其中抗虫棉9棉田的棉蚜发生高峰期数量最多,而新陆中11棉田的棉蚜发生期数量最少。在不同品种的棉田中,瓢虫是棉田棉蚜的主要天敌,对棉蚜起控制作用,它与棉蚜种群数量呈显著的跟随关系,发生期比棉蚜滞后1周左右。     

二化螟种群数量变动规律研究

根据临海市１９７４～１９９８年二化螟发生危害的测报调查资料,分析水稻二化螟的种群数量构成及其变化特点,阐述水稻二化螟种群数量的消长规律及相关特征,明确造成二化螟种群数量上升的主要原因是种群基数增加,越冬场所扩大,耕作制度变化、机械收割推广和冬季气温上升等     

辣椒开花对西花蓟马种群的影响

为揭示寄主植物开花与否对西花蓟马种群增长的作用,研究了辣椒是否有花对不同密度下西花蓟马种群数量的影响。结果显示,开花辣椒上的西花蓟马种群数量明显高于无花辣椒,在接入30头/株密度下,7 d、14 d、21 d和28 d 4个时间段开花辣椒上西花蓟马种群数量分别是未开花的2.3倍、1.5倍、1.8倍和2.5倍;15头/株密度下,开花辣椒上种群数量是未开花的2.0倍、1.3倍、1.5倍和1.7倍。结果表明,开花的辣椒植株对西花蓟马种群数量的增长有明显的促进作用。     

广东海岛南澳县桔小实蝇种群动态

2009～2011年在广东省汕头市南澳县使用桔小实蝇诱剂监测桔小实蝇种群动态数量。研究结果表明:南澳县桔小实蝇为害极为严重,南澳县一年四季均有桔小实蝇的发生为害,一般情况下,高峰期在每年6～9月;受温度、雨量和监测点周围生态环境等因素的影响,同一监测点每年桔小实蝇种群出现高峰的数量有明显差异。     

柠条种子小蜂在不同柠条寄主上的种群动态

2017年6月－7月, 系统调查了树锦鸡儿、甘蒙锦鸡儿、荒漠锦鸡儿和中间锦鸡儿4种植物上第一代柠条种子小蜂种群动态及寄主荚果发育进程。结果表明, 不同寄主植物上的柠条种子小蜂幼虫、蛹、成虫数量有显著性差异, 密度大小依次为: 树锦鸡儿＞中间锦鸡儿＞甘蒙锦鸡儿＞荒漠锦鸡儿。在发生时间动态上, 柠条种子小蜂幼虫、蛹和成虫的数量基本呈现先逐渐上升后下降的趋势, 4种寄主植物上不同虫态的柠条种子小蜂高峰期出现时间各不相同。甘蒙锦鸡儿上的小蜂出现最早, 6月17日幼虫达到高峰期; 中间锦鸡儿上的小蜂出现最晚, 7月2日幼虫高峰期, 7月14日成虫高峰期; 树锦鸡儿与荒漠锦鸡儿居中。柠条种子小蜂发育进程与锦鸡儿植物的荚果发育进程吻合。本文讨论了柠条种子小蜂种群动态与寄主植物的关系, 明确了柠条种子小蜂发生和达到高峰的时间, 为柠条种子小蜂预测预报和综合治理提供依据。     

浙江台州西兰花小菜蛾种群数量运动规律研究

于2001～2011年应用性诱剂监测方法对小菜蛾种群数量运动规律及季节性消长规律进行了长期定点系统监测研究。结果表明,西兰花小菜蛾种群运动态势在监测的11年中呈螺旋式下降,年度大发生频率约30%;生长季节其发生消长随西兰花生育期推进而逐渐加重,全季主要有两个发生盛期,第1个盛期在西兰花的莲座生长期和花蕾生长期,发生频率47%,第2个盛期在结球采收期,发生频率40%;气温(T)对小菜蛾种群数量(M)发生存在极显著相关关系,其关系模型为:M=0.221T+0.0457或M=-0.034T2+1.4912T-9.4889。     

不同贮藏条件对大赖草种子萌发的影响

将野外观测与室内实验相结合,研究不同贮藏条件对大赖草种子萌发的影响。结果表明：室内干藏与野外埋藏于地表的种子随贮藏时间的延长,种子萌发率呈现缓慢升高后逐渐降低的趋势,说明大赖草种子存在着后熟现象;埋藏5 cm深度的种子,埋藏2、7、8个月时,种子自然萌发率分别为5.15%、7.52%和94%,剩余种子在室内条件下萌发率大于95%。而埋藏于原生境的种子埋藏2个月无萌发现象,埋藏8个月自然萌发率为90%;说明大赖草的种子在土壤中属于瞬间种子库;黑暗有利于大赖草种子的萌发。不同贮藏条件下大赖草种子的含水量表现为：埋藏5 cm深度>埋藏于地表>室内干藏,大赖草种子萌发的最低含水量为19.5%。在自然生境中,野外埋藏的种子被动物搬运的占12%～90%,平均达44.5%,致使土壤中种子数量锐减。因此,大赖草种子在土壤种子库中数量匮乏;自然生境中干旱少雨、水分缺少,导致种子萌发后易“闪苗”。这些因素是大赖草有性繁殖更新率低的主要原因。     

The influence of reduced cultivations and direct drilling on the long-term decline of a population of Avena fatua L. in spring barley

Changes in the numbers of Avena fatua seed, incorporated into soil, were monitored in four successive spring barley crops which were harvested early for silage to prevent seed shedding. In the first year there were four times as many seedlings after tine cultivation compared with ploughing, but this was reversed in the second year as re-ploughing brought up dormant seeds and gave more seedlings than tine cultivation. Only 11–14% of the sown seeds produced seedlings during the 4 years. When the seeds were first buried to 25 cm by ploughing, and the barley was direct drilled without cultivation, only 0.4% emerged as seedlings. Few viable seeds remained in the soil after 4 years whether the soil was cultivated annually or not but seed numbers decreased more rapidly with tine cultivation than with ploughing. A few of the deeply buried seeds persisted where the land was direct drilled without cultivation.     

东北稻区稻田杂草稻控制措施的探讨

东北稻区自生杂草稻在目前常用的稻田除草剂常规剂量处理下株防效为0,种子埋深10 cm以下才能控制其萌发出土,灌水深度10 cm对种子发芽没有明显的抑制作用.在秋季灌水条件下越冬的种子冻死率为100％,而在干燥态土壤中多数种子可安全越冬.     

3种保水措施影响下的风沙土水盐及地温特征

对塔克拉玛干沙漠腹地不同保水措施(覆膜、覆沙、喷施Guilspare)和裸地(对照)土壤水分、盐分分布及耕作层温度的变化特征进行了分析.结果表明:夏季采取保水措施能够抑制土壤蒸发,提高土壤的蓄水保墒能力.同时,还能起到抑制土壤盐分表聚的作用,明显地改变了风沙土水盐空间分布,降低表层盐分被淋溶至林木根系层的概率.保水措施...     

Dormancy cycle and viability of buried seeds of Papaver rhoeas

Seeds of three Spanish Papaver rhoeas populations (two resistant to both tribenuron‐methyl and 2,4‐dichlorophenoxyacetic acid and one susceptible to both herbicides) were buried at 2, 8 and 20 cm depth in Lleida (Catalonia, Spain). At various intervals up to 77 months they were exhumed and tested for germination in an agar medium and for viability in a tetrazolium test. A similar annual dormancy cycle was found for each population in 3 years. Maximum germination occurred between September and December. Practically no seeds germinated between February and May. Burial depth influenced the germination cycle in the first 16 months after burial, and higher germination was found to occur in the seeds that were buried at 2 or 8 cm, but no consistent effect was observed thereafter. In a second study, burial depth had no effect on the loss of dormancy of P. rhoeas seeds in the first 2 months after burial. Viability of the buried seeds decreased slowly throughout the 77‐month experimental period and, at the end of this period, it was 53, 72 and 61% for seeds buried 2, 8 and 20 cm respectively. No significant differences were observed between the three populations.     

江苏省江都市黑褐色谷壳杂草稻种子库调查

江苏省江都市稻田黑褐色谷壳杂草稻种子主要集中在表层土壤,即0～2 cm的土层内,占黑褐色谷壳杂草稻种子数量的92.65%。在土壤种子库中,黑褐色谷壳杂草稻数量在严重危害田块是黄色谷壳稻的17.9倍,中等危害田块为1.58倍,轻度危害田块仅0.17倍。     

Environmental and physiological factors affecting the fate of seeds of yarrow (Achillea millefolium L.) in arable land in New Zealand

Yarrow (Achillea millefolium L.) has arisen as a problem weed in arable land in New Zealand. A spring-sown yarrow population of 58 plants m^?2 produced approximately 243000 seeds. These were capable of immediate germination in the autumn, but virtually no germination occurred in the winter and up to 80–100% at other times of the year. Seeds are positively photoblastic, but a considerable percentage of seed (>30%) may germinate in the dark after chilling, coat pricking, exposure to high nitrate concentrations or to alternating temperatures. Seed buried at 32 cm in undisturbed soil lost viability slowly over 4 years while seed in the top 8 cm lost viability almost completely within 2 years.     

Effect of growth medium, Striga seed burial distance and depth on efficacy of Fusarium isolates to control Striga hermonthica in Burkina Faso

Striga hermonthica is a destructive parasite of cereal crops in the semi‐arid tropical zone. Two greenhouse experiments were conducted at Kamboinsé, Burkina Faso, to investigate the effect of inoculum substrate and location of Striga seeds on the ability of 14 indigenous Fusarium isolates to control the parasite. In Expt 1, Fusarium isolates reduced emerged Striga number, Striga vigour and dry biomass. As a result, sorghum dry biomass and grain yield were enhanced. Inoculum substrate did not influence the ability of Fusarium isolates to control Striga. In Expt 2, Fusarium isolates, substrate and their interaction significantly influenced germination of Striga seeds at both 35 and 50 days after sowing. Isolates grown on compost were more effective at reducing germination of Striga seeds than those grown on chopped sorghum straw. The per cent germination of seeds 50 days after sowing, buried at 5 cm depth, was significantly lower than that of seeds buried at 10 cm. At 10 cm depth, Fusarium isolates still reduced Striga seed germination with respect to the control; horizontal planting distance, 5 or 10 cm from sorghum hills, had no effect.     

Effects of the seed weight and burial depth on the seed behavior of common ragweed (Ambrosia artemisiifolia)

Common ragweed (Ambrosia artemisiifolia L.) is one of the annual plants that were described recently as invasive weeds in Europe. This species is described as an invasive plant that produces seeds that are highly variable. Its production of variably sized seeds is regarded as promoting its spread in different environments. Experiments were carried out to determine the influence of the seed weight and temperature on germination and the influence of the seed weight and burial depth on seedling emergence. The seeds were divided into a number of classes of weight and the seed weight effect on germination was evaluated by Petri dish assays. In another experiment, the seeds were buried at different depths in a clay soil/sand mix to estimate the burial effect on germination and seedling emergence. The germination level of A. artemisiifolia was high overall, between 76.8% and 94.2%. The seed germination was modified by temperature but it was not influenced by the seed weight. The amounts of germination and seedling emergence were greater for the seeds on the soil surface and decreased with an increasing burial depth, from 2 to 8 cm. No germination or emergence was observed for the seeds that were buried at 10 and 12 cm. The lightest seeds were more sensitive to burial. A greater level of seedling emergence for those seeds that were placed near the soil surface could explain the success of this species in open habitats, where the probability of deeper burial is low. After high seed production, the management of A. artemisiifolia in fields could be partly achieved through soil tillage, burying seeds below 10 cm, and not carrying out deep soil tillage the following year.