桃小食心虫Carposina nipponensis(Wals·)辐射不育的细胞遗传学研究

本文研究了亚不育剂量对桃小食心虫Carposina nipponensis(Wals.)染色体的影响及其遗传效应,并对其精子结构变异进行了超微观察。结果表明,正常桃小食心虫染色体结构为漫散着丝点,其数目n=31。最长染色体为4.43±0.49μ,最短为1.54±0.15μ,总长度为96.39±10.75μ,长度变异范围S％=34.76。亚不育剂量(25kR)诱导的染色体变异结果表明,亲代(F。)的辐射损伤可传递到后代,F_1代变异率为83.6％,变异类型主要为“断片”、“桥”,“多着丝点体”等,而且易位染色体数目较多,从而导致F_1高度不育。F_2代畸变率降低,易位染色体数目也较少,育性得到部分恢复。亚不育剂量辐照能使桃小食心虫产生微核。微核测定法可作为衡量桃小食心虫细胞辐射变异的简易指标。 桃小食心虫精子的超微结构与鳞翅目其它昆虫相似,轴丝构型为(9)十9十2。亚不育剂量能使精子产生破裂、空泡、微核,轴丝构型异常,轴丝和线粒体衍生体数目及形态发生变化等,并在F_1代得到加强。     

苏丹兰Ⅱ号染料标记人工饲养玉米螟的研究及应用

用含万分之一浓度的苏丹兰Ⅱ生物染料的饲料喂饲玉米螟幼虫,能使幼虫和成虫均带天兰色,标记的颜色均匀、鲜明、易于分辨,并且对玉米螟的主要生物学特性无影响。尤其是标记玉米螟雌蛾所产的卵仍带标记天兰色,这在昆虫的染色技术中,尚未见报道。运用此标记法已成功地测定玉米螟成虫的一次迁飞距离和扩散能力,估测田间野生玉米螟数量和消长规律等。此技术经济、安全、方便、很有实用价值,为生物染料应用于标记昆虫开辟了新的途径。     

苹果不套袋栽培模式下桃小食心虫发生动态及性信息素诱杀防治效果

为明确苹果不套袋栽培模式下桃小食心虫的发生动态、危害情况及性信息素的诱杀防治效果,本研究采用性信息素监测和诱杀的方法,在烟台、威海、泰安3个苹果产区对不套袋栽培苹果园桃小食心虫的发生动态及蛀果率进行了调查,并在泰安地区进行性信息素诱杀结合常规药剂(35%氯虫苯甲酰胺水分散粒剂)开展桃小食心虫的防治试验。结果表明,2016年烟台、威海、泰安3个地区田间桃小食心虫成虫发生始末期均为5月中下旬到10月上旬,6~9月是桃小食心虫群体数量发生的高峰期,其中,田间共出现2次比较明显的高峰,桃小食心虫发生动态趋势、成虫发蛾高峰期和持续时间在2种栽培模式下的差异不显著。3个苹果产区不套袋栽培苹果园的桃小食心虫性信息素诱捕器全年诱捕数量为2 148~5 384头·诱芯~(-1),显著高于套袋栽培苹果园的911~1 235头·诱芯~(-1);且不套袋栽培苹果园的桃小食心虫蛀果率为6.13%~8.63%,显著高于套袋栽培苹果园的0.38%~0.50%。在成虫发生期,7月初和9月初性信息素诱杀处理对桃小食心虫的防效分别为63.70%和78.19%,低于常规药剂防治处理的66.62%和80.94%;而性信息素诱杀结合常规药剂处理对桃小食心虫的防效分别为95.86%和96.85%,显著高于性信息素诱杀和常规药剂防治单独使用的效果。本研究为探明苹果不套袋栽培模式下桃小食心虫发生为害规律提供了重要参考,也为开展桃小食心虫的绿色防控提供了理论依据。     

辐射不育小菜蛾的扩散能力

采用(32)~p标记法研究了辐射不育小菜蛾的扩散能力。试验表明,10天内,不育小菜蛾有94％扩散在40m范围内,极个别可达120m,而在这10天中,后3天的诱捕虫数平均每天仅占总诱捕虫数的0.5％,说明辐射不育小菜蛾的扩散有一定期限,3天内扩散范围约700m~2。     

辐照处理大豆食心虫不育的研究

本文对辐射不育技术防治大豆食心虫的有关问题进行了研究。１．人工饲养：改变光周期，打破滞育，每天光照１８ｈ处理，羽化率最高，滞育期由原来１０个月之久，降低到１个月左右，由１年只发生１代，到可以连续多代饲养，繁殖１代只需４０～４２ｄ；并筛选出较好的人工饲料配方，采用黄豆芽饲养初孵幼虫，成活率较高，发育正常。２．确立了辐照时期以羽化前２天的老熟蛹期为宜，辐照剂量以１２０Ｇｙ为宜，处理后羽化的成虫，活动正常，所产的卵不孵化，可达到绝育。３．田间防治试验：用上述剂量辐照处理老熟蛹，羽化出的成虫释放到种有大豆的纱笼里，防治效果可达８８．１％～９９．０％，虫食率由１０．１％下降到０．１％～１．３％；释放于田间，防治效呆为８６．５６％，虫食率由１１．４２％下降到１．５５％。由此证明，辐射不育技术为防治大豆食心虫开辟了一条新途径     

辐射不育技术防治柑桔大实蝇的效果

在贵州省惠水县中联桔园(500亩)中,1987年和1989年分别释放56272头和95320头辐射不育柑桔大实蝇,释放比分别为12.5:1和45:1,使柑桔大实蝇虫果率由常年的5—8％下降到0.005％,防治效果十分显著。测得柑桔大实蝇可飞翔扩散1500米远。     

辐照对桃小食心虫脱果幼虫羽化率的影响

桃小食心虫(Carposina sasakii Matsmura)是广受关注的检疫性害虫,为比较不同射线的辐照效应以及不同种群对辐照的耐受能力,采用60Coγ射线、5MeV X射线和6MeV X射线对老熟幼虫进行辐照处理,剂量为60、80、100、120、140和160 Gy,剂量率为2.55~5.5 Gy·min-1。辐照后经室内饲养,分析羽化率结果表明,随着剂量的增加羽化率显著降低,100%阻止羽化的剂量为160Gy。相同剂量辐照时,不同射线处理苹果种群老熟幼虫的校正死亡率间无显著性差异。相同剂量60Coγ射线处理苹果种群(第13代和第20代)和山楂种群(第6代)的老熟幼虫,校正死亡率也无显著性差异。使用POLO软件进行机率值分析,预测检疫辐照处理中普遍使用的最低吸收剂量ED99和ED99.9968,阻止成虫羽化的剂量值非常接近(ED99=152.4~159.2 Gy;ED99.9968=195.2~208.7 Gy)。由此说明,不同辐照源阻止桃小食心虫老熟幼虫羽化的生物学效应相同,不同种群对辐照的耐受性相同,继代饲养后辐照耐受性未发生变化。由于老熟幼虫为水果中最耐受的虫态,可建议采用200Gy作为桃小食心虫幼虫检疫处理的最低吸收剂量。     

电子束处理对玉米象繁殖力的影响

本研究用电子加速器辐照处理玉米象成虫以及隐藏于小麦籽粒中的玉米象卵、幼虫和蛹 ,研究不同发育阶段玉米象辐照后的繁殖力。结果表明 ,高于 1 80Gy的辐照处理的成虫不能产生后代 ,辐照处理具有明显的当代延迟发育效果 ;高于 1 80Gy剂量辐照处理玉米象的蛹 ,羽化出的成虫不能产生下一代成虫 ;高于 90Gy以上的辐照处理玉米象的幼虫和卵 ,其羽化出的成虫不能产生下一代的成虫。 1 80Gy辐照可以作为阻止不同虫态玉米象的继续繁殖下一代的有效剂量。     

辐照棉铃虫成虫田间扩散能力的研究

３００ Ｇｙ γ射线辐照棉铃虫（ Ｈｅｌｉｃｏｖｅｒｐａ ａｒ ｍ ｉｇｅｒａ Ｈｕｂｎｅｒ） 成虫（ 棉田第１ 代） 在田间的扩散试验表明：释放的标记虫约９７ ％ 集中在离释放点半径７２０ ｍ 的范围内。最远平均扩散距离为６１５ ｍ 。棉铃虫扩散密度与扩散距离呈倒数相关,符合模型 Ｎ ＝－ ０８３ ＋ １６４７３４／ ｘ 。野生棉铃虫有向嫩绿寄主植物扩散的趋势。     

辐射不育野蚕雄蛾田间扩散能力的研究

采用糖醋液和活雌蛾的方法诱集回收野蚕雄蛾,研究辐射不育野蚕雄蛾的田间扩散能力。试验表明,该回收方法可以使田间释放的野蚕雄蛾的回收率达１２．６％－１３．５％,不育野蚕雄蛾在２４ｈ内,９０．８％扩散在距释放中心半径内１５ｍ的圆周内,覆盖面积达７００ｍ＾２。据此,在用辐射不育法田间防治野蚕时,１ｈｍ＾２桑地只需设立３０个释放点就可满足防治的需要,达到较好的防治效果。     

辐照亚洲玉米螟F-1雄虫在田间的扩散能力和对性诱剂的反应能力

用亚洲玉米螟性诱剂田间诱捕释放的１００Ｇｙ、１５０Ｇｙ和２００Ｇｙ辐照的Ｆ１雄虫和正常雄虫。试验表明,部分辐照的Ｆ１雄虫丧失了飞翔扩散能力或对性诱剂的反应能力,但在距释放点５５０ｍ处诱捕到的Ｆ１雄蛾数与诱捕总数之比与正常雄蛾无显著差异。     

Assessing the potential use of two portable chlorophyll meters in diagnosing the nutritional status of plants

The SPAD-502 and the FieldScout CM 1000 chlorophyll meters were compared in their performance in diagnosing the nutritional status of plants. Leaves of a wide range of greenness were used to push the sensitivity of the tools to their limits. Both devices showed high reproducibility when used by different operators. The SPAD-readings were well-correlated with leaf nitrogen (N) concentrations, since leaves from heavily fertilized plants were not included in the sample population. The FieldScout-readings showed a marked saturation curve with the leaf N concentration, thus it cannot be used as a reliable N nutritional status index. The results also showed that the use of SPAD-502 in the diagnosis of the nutritional status of an orchard requires the establishment of specific critical concentrations for cultivars and sampling dates. The SPAD-502 appeared to have potential in the diagnosis of the nutritional status of the orchard for nutrients other than N.     

Temporal Variations in Primary,Secondary, and Micronutrient Contents in Soil of Litchi Orchard

Litchi is one of the important subtropical fruit crops in the state of Jharkhand, occupying around 33,000 ha with production of about 165,000 metric tons. Considering the importance of soil analysis in litchi crops, the present investigation was carried out in an established orchard (begun in 1979) at the Horticulture and Agroforestry Research Program, Indian Council of Agriculture Research Complex for Eastern Region, Plandu (Ranchi), Jharkhand, India, to study the nutrient concentrations in soils of litchi and the interrelationships among available nutrient concentrations present in soil, and crop productivity in order to develop a sound fertilizer management program. Periodic collection of soil samples from the established orchard was carried out on the second week of every month during 2006–2007. Analysis of soil samples were carried out for macro- and micronutrients in soil. Mean soil nutrient contents for nitrogen (N), phosphorus (P), and potassium (K) were 232 kg ha^?1, 53 kg ha^?1, and 420 kg ha^?1, respectively. The greatest contents of N and K were observed at full canopy distance, whereas for that for P was at one-third and two-thirds the canopy distance. Mean soil nutrient contents were 1.52 C mol (P⁺) kg^?1, 1.11 C mol (P⁺) kg^?1, and 23 ppm for calcium (Ca), magnesium (Mg), and sulfur (S), respectively. The greatest contents of Ca and Mg were observed at one-third the canopy distance whereas that for S was at two-thirds the canopy distance. However, mean soil nutrient contents were 1.03, 53, 65, and 1.42 ppm for copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn), respectively. The greatest content of Fe was observed at two-thirds the canopy distance whereas that for Cu was at one-third the canopy distance. The greatest Mn content was observed for both two-thirds and full canopy distance whereas Zn contents had no significant differences among the canopy distances. However, soil sampling at two-thirds canopy distance from the trunk was observed to be ideal for soil analysis.     

Comparison of understorey biological nitrogen fixation and biomass production in grassed‐down conventional and organic apple orchards in Canterbury,New Zealand

Abstract

In a previous study, the understorey biomass production and biological nitrogen (N) fixation of a grassed‐down organic apple orchard were presented. The aim of this paper is to report the results of a similar study of two conventional orchards in a nearby location and to compare the present results with those of the organic orchard. Biological N₂ fixation was determined in the field using the ¹⁵N isotopic dilution technique and the experiments were conducted over a two‐year period. Present results showed that substantial amounts of N (112 to 143 kg N ha^‐1.2 years^‐1) were fixed in the understorey of the conventional orchard and these were not significantly different from those of the organic orchard. However, the N₂ fixation was sustained in the conventional, but not in the organic orchards in the second year, probably due to regular additions of fertilizers in the conventional orchards. In both orchards, N₂ fixation was better correlated with clover than total dry matter yield. Seasonal effects found were highest N₂ fixation and biomass production occurring during late spring and early summer and lowest during winter. Climatic factors were investigated in one of the conventional orchards and it was found that seasonal effects were related to a combination of temperature and moisture deficit effects.     

Effect of long term addition of composts and poultry manure on soil quality of citrus orchards in Southern Italy

A 6-year study was conducted in an organically managed orange orchard located in Sicily (Southern Italy) to assess the effect of compost and organic fertiliser utilisation on soil quality. Adopting a randomised-block experimental design with three replicates, four treatments were carried out. In treatments 1 and 2, two different composts (C1 from distillery by-products and C2 from livestock waste) were applied. The plots of treatment 3 were fertilised using dried poultry manure. The control treatment was fertilised by mineral/synthetic fertilisers. In order to verify the hypothesis that composts and organic fertilisers improve soil fertility, soil quality was evaluated by selecting dynamic soil parameters, as indicators linked to C and N cycles. Total organic C, total N, C/N ratio, humified fraction, isoelectric focussing (IEF) of extracted organic matter, microbial biomass C, potentially mineralisable N under anaerobic conditions, potentially mineralisable C, C mineralisation quotient and metabolic quotient were determined for each sample. Moreover, the Community Level Physiological Profile (by Biolog technique) was defined, calculating derived functional biodiversity and versatility indexes. Parameters related to IEF and potentially mineralisable C showed significant differences among the treatments. Moreover, total C, total N and humification parameters tended to increase, while no differences were observed in biodiversity indexes. On these findings, it was concluded that composts and poultry manure only weakly affected soil properties, though they increased soil potentially available nutritive elements to crops.     

Marking springtails (Folsomia candida) with rubidium

Marking springtails is a basic tool to evaluate their fundamental ecological phenomena. Rb marking is based on the fact that enriched rubidium in an organism can be tracked trough the experiment. Our goal was to improve the rubidium-marking technique in Folsomia candida (Willem) for both microcosm and field experiments. We investigated four methodological problems of this technique, in particular, we determined the required Rb concentration in the diet to reach marking level, measured the period when labeling could be detected under two different feeding conditions, and we estimated the effects of Rb on springtails' growth. Because marked and unmarked animals are always mixed in the course of recapture we also measured the levels of contamination between labeled springtails and those in the control groups. For introducing rubidium, we fed animals with Rb-treated Baker's yeast. Rubidium-chloride labeling persisted in springtails for 27 days during which the Rb-levels in marked animals remained distinguishable from those in unmarked ones. Rb-elimination rate depended highly on the feeding conditions, with Rb-elimination being faster when food was in excess. The fitted exponential model to Rb-elimination suggested that Rb-labeling may be used for 46 and 103 days for experiments with and without food respectively. We found no effect on Collembola growth at low Rb-levels (1.2 μg Rb/g dry yeast) but at higher concentration growth was reduced. We found that contamination occurred when springtails were stored together in glycerin, however the unmarked sample with the highest Rb content was still just 4.8% of the lowest marked sample. These results provide a basis for mark-release-recapture and other studies using Rb marking on springtails.