不同紫花苜蓿品种在河西走廊盐碱地的适应性研究

通过田间试验测定不同紫花苜蓿品种的株高、分枝数、茎叶比、生物量、出苗率和越冬率,评价16个紫花苜蓿品种在河西走廊盐碱地的适应性,遴选出适宜河西走廊盐碱地种植的紫花苜蓿品种。结果表明:参试的16个紫花苜蓿品种,骑士T、SR4030和巨能的出苗率较高,甘农3号的出苗率最低;16个紫花苜蓿品种间株高差异不显著(P0.05);BR4010、WL343HQ、阿迪娜、亮苜2号和WL363HQ的分枝数显著大于标靶和金皇后的分枝数;岩石和德宝的叶茎比显著高于金皇后和骑士3的叶茎比;德宝、亮苜2号和骑士T的产量大于其他品种;亮苜2号和骑士3的越冬率显著高于甘农3号和SR4030的越冬率;阿迪娜和WL343HQ的倒伏率最小,骑士T和标靶的倒伏率最大。以株高、分枝数、茎叶比、生物量、出苗率和越冬率为变量因子,通过聚类分析将16个紫花苜蓿品种聚为6类,综合评判结果认为,亮苜2号、骑士T、德宝适宜种植于河西走廊盐碱地。     

生草栽培果园根系生长动态研究

通过对金太阳杏生草(紫花苜蓿)栽培与生长动态的研究表明,金太阳杏新根在1年中有2次明显的生长高峰,1次是在3～4月,占全年的37%以上,第二次在6月中下旬至7月上旬。而紫花苜蓿主要在7月中旬以后,两者在时间尺度也存在有差异,根据金太阳杏新根周年变化特点,掌握2个时期,即3月中旬和6月上中旬。     

角倍蚜瘿内世代生物学及角倍生长的初步研究

角倍蚜Schlechtendalia chinensis(Bell)在盐肤木Rhus chinensis Mill.上所形成的倍子(即角倍)约占全国五倍子总量的80％,经济价值很大。该倍蚜的生活周期属异寄主全周期型,虫型多样,生活习性复杂。在其生活年史中,春季有翅孤雌蚜(春迁蚜),迁飞到第一害主盐肤木上产雌雄性蚜,经一月左右(一般在夏初),雌蚜生殖,产下的干母爬到嫩叶上取     

不同保存方法对角倍蚜性蚜数量和存活率的影响

比较了不同类型虫袋和填充物对角倍春迁蚜产性蚜数量和存活率的影响,结果表明:采用柱状虫袋填充玉米苞皮及对玉米苞皮进行浸泡处理可以提高性蚜的数量和雌蚜/干母的存活数;与传统的三角纸袋填充棕丝相比较,柱状虫袋填充浸泡玉米苞皮的雌蚜数、雌蚜/干母存活数、雄蚜数和性蚜总数分别增加了107.6%、229.1%、71.1%和87.5%,雌蚜/干母存活率提高了21.1%。虫袋内的雌蚜数、雄蚜数和性蚜总数与春迁蚜数呈显著负相关;雌蚜数和雌蚜/干母存活数与雄蚜数、性蚜总数和雌雄性比分别呈极显著正相关。角倍产区的环境因子明显影响春迁蚜的羽化期,但对春迁蚜产性蚜的数量没有明显影响。     

Resistance against oxidative stress in leaves of young beech trees grown in model ecosystems with different soil qualities, elevated CO2, and lachnid infestation

Summary The aim of the present study was to investigate whether the resistance of beech foliage(Fagus sylvatica) against oxidative stress was affected by soil quality, nitrogen or CO₂ fertilisation, or lachnid infestation(Phyllaphis fagi). For this purpose young beech trees were grown for four years in reconstructed calcareous or acidic forest soils in open top chambers under ambient or elevated CO₂ concentrations with two levels of nitrogen fertilisation. At harvest lachnid colonisation was observed, preferentially on leaves from trees in calcareous soil and on leaves from trees fertilised with the high nitrogen level. General leaf characteristics such as pigment concentrations, dry mass, and leaf mass ber area were not affected by the soil type, nitrogen fertilisation or CO₂ regime. Leaves colonised with lachnids displayed slightly increased leaf mass per area. When the stress resistance was challenged by exposure to paraquat — a herbicide inducing oxidative stress — leaves from trees grown on calcareous soil maintained significantly longer membrane integrity and, thus, were better protected against stress than leaves from trees on acidic soil. Other experimental variables had negligible or no effects on the resistance against oxidative stress.      

Quality and decomposition of black locust (Robinia pseudoacacia) and alfalfa (Medicago sativa) mulch for temperate alley cropping systems

Black locust and alfalfa mulch quality were characterized over a 9-week period of decomposition. Both mulch materials were harvested with a forage harvester. The black locust material was harvested from trees annually coppiced for four years, the alfalfa from a preflorescent second cutting. Two identical, adjacent experiments were conducted, one on each mulch source. A randomized complete block design was used with four replications for this single factor experiment. Fifty grams fresh weight of both mulch types were placed in litter bags, made of 98% shade cloth, a woven plastic with holes approximately 1×0.5 mm. The treatments included two placements of the mulch material, surface and buried. Sampling took place on weeks 0, 1, 3, 6, and 9.The incorporation of mulch materials appears to accelerate dry weight loss. From an initial dry weight of 44.25 g, the buried black locust mulch averaged 4.58 g, while the surface mulch averaged 7.41 g by week 6. The alfalfa mulch initially weighed 40.99g, with buried mulch averaging 1.75 g and surface mulch averaging 4.08 g by week 9.Carbon concentration of alfalfa mulch increased with time in both mulch placements from 43.6% to 57.6% and 51.8% in surface and buried mulch, respectively. Black locust, with an initial carbon concentration of 46.9% increased to 55.9% for the buried mulch and to 53.89% in surface mulch. Nitrogen concentrations increased as well in buried mulch. Lignin concentrations increased dramatically over time for both species of mulch. Black locust lignin concentrations rose from 13.11% to 51.0% (buried) and 32.9% (surface); alfalfa mulch lignin concentrations rose from 6.67% to 31.4% (buried) and 47.7% (surface).     

进境美国苜蓿草中苜蓿黄萎病菌的检疫鉴定

从一批进境的美国苜蓿草样品中分离得到了一株与苜蓿黄萎病菌(Verticillium albo-atrum)相似的分离物M1。该分离物原始菌落为白色,边缘规则呈圆形,菌丝较致密,气生菌丝较少,苜蓿组织块不被菌丝覆盖,菌落生长速度为小于2.5 mm/d;M1在PDA上进行纯培养,前6d内,菌落为白色圆形,容易产生分子孢子轮枝状分生孢子梗,7d后菌落中央表面因产生休眠菌丝开始变成黑褐色至黑色,20d后菌落的表面和背面大部分均变黑色,仍不产生微菌核和厚垣孢子。M1的DNA用V.albo-atrum特异引物Vaa1/Vaa2进行检测,PCR扩增后得到预期330 bp的产物片段,产物序列与V.albo-atrum相应序列的相似性为100%。该分离物接种苜蓿草根部,15d后引起苜蓿黄萎病的典型症状。根据分离物的形态特征、PCR检测结果、PCR产物序列分析,以及致病性测定结果,将进境美国苜蓿草样品中的分离物M1鉴定为苜蓿黄萎病菌。     

10个小麦品种（材料）对麦长管蚜的室内苗期抗蚜性*

［目的］ 明确不同小麦品种对麦长管蚜(Sitobion avenae)的室内苗期抗性。［方法］ 在温室内采用每株小麦接种1头蚜虫的方法,测定了麦长管蚜在来源于3个国家的10个小麦品种上的发育历期（DD）、相对日均体重增长量（MRGR）和成虫日均产仔数（Rm）,以此来确定不同小麦品种（材料）的抗蚜性。［结果］ 应用多元方差分析,多目标综合判别及聚类分析等方法分析表明,麦长管蚜在‘Ww2730’、‘98 10 30’、‘Astron’上的适应性最差,这几个品种对其抗性最好,是可以利用的抗性品种（材料）;‘98 10 35’、‘98 10 32’次之;‘Batis’对麦长管蚜的适应性最好,抗性最差;‘186Tm’,‘Xanthus’,‘Amigo’对麦长管蚜适应性较好,与作为对照的‘小偃 22’一样,抗性处在中间水平。［结论］ 研究结果可以为进一步的抗蚜育种提供依据。     

Biology,incidence and host susceptibility of Pineus boerneri (Hemiptera: Adelgidae) in Colombian pine plantations

Adelgids (Hemiptera) in the genus Pineus have been reported as introduced insect pests causing serious losses to Pinus plantations worldwide. In 2008, Pineus boerneri was recorded for the first time in Colombia, with infestations noted on Pinus kesiya, P. tecunumanii, P. maximinoi and P. oocarpa. The lack of information on this insect in Colombia prompted investigations of its life cycle and infestation levels as well as host susceptibility of the main Pinus species planted in Colombia. In addition, the possibility of using a Ceraeochrysa species, an already established predator of adelgids in Colombia, for biological control was considered. Results showed that Pineus boerneri in Colombia has an anholocyclic life cycle comprised of four instars with a complete duration of between 49 and 97 d. Infestations were higher in the middle and upper part of trees. Pinus kesiya and P. maximinoi had the highest levels of susceptibility in field as well as in greenhouse trials. A survey of naturally infested trees showed P. tecunumanii to be moderately susceptible, whereas P. patula and P. oocarpa had low levels of susceptibility in a greenhouse trial but were not susceptible in the field. Investigations considering the impact of predation of Ceraeochrysa species showed a high predation rate of up to 140 P. boerneri consumed per day by a single Ceraeochrysa individual. Other predators of P. boerneri were recorded but were not sufficiently common to warrant detailed study.