不同砧木伏令夏橙对土壤pH值的适应性

本试验研究了紫色土pH值对枳砧、红桔砧和香橙砧伏令夏橙吸收Fe、叶绿素含量、过氧化物酶活性以及植株生长的影响。结果表明,香橙砧最耐碱;红桔砧其次;枳砧最不耐碱;而耐酸性无大差异。其最适pH依次为6.2、5.7、5.7,pH8时的生长量相当最适pH时的84、50、38％。香橙很有希望在四川作pH>6.5的紫色土柑桔园的砧木。pH4时的生长量依次相当最适pH时的74、71、67％,枳仍是酸性土壤的最优砧木。     

草地贪夜蛾寄主选择性及对其生长发育的影响

旨在为草地贪夜蛾的预测预报、科学防控、适生性分析以及风险评估提供参考依据。以盆栽香蕉苗、玉米苗和草地贪夜蛾3~4龄幼虫作为试材,用室内接虫和田间自然感虫的方法,测定了选择压力和非选择压力条件下草地贪夜蛾对香蕉和玉米的危害指数、草地贪夜蛾发育历期、幼虫存活率、蛹体大小及成虫羽化率。在非选择压力条件下草地贪夜蛾主要选择危害玉米,对香蕉‘桂蕉6号’只是试探取食,接虫7天后对玉米和香蕉危害指数分别是89.05、1.58。在选择压力下草地贪夜蛾幼虫接虫3天后开始取食危害香蕉,接虫后3、5、7天危害指数分别为11.74、16.51、24.76,说明香蕉不是草地贪夜蛾适宜的寄主作物。取食香蕉的草地贪夜蛾幼虫生长缓慢、虫体小,3龄幼虫至化蛹历时9~14天,比取食玉米的草地贪夜蛾长2~4天;成虫羽化历时9~14天,比取食玉米的草地贪夜蛾长4~7天;取食香蕉明显影响草地贪夜蛾生长发育,幼虫存活率为20.0%、化蛹率68.1%、蛹体大小1.25×0.35 cm、蛹重0.13 g、成虫羽化率47.8%,明显低于取食玉米寄主的幼虫存活率为86.7%、化蛹率97.4%、蛹体大小1.57×0.5 cm、蛹重0.21 g、成虫羽化率92.0%。草地贪夜蛾在选择压力下会取食危害香蕉,危害程度相对较轻,能完成世代生活史,但生长发育速度也较慢。香蕉不是草地贪夜蛾适宜的寄主植物,但在香蕉上暴发存在一定的风险。     

Construction of Recombinant Expression Plasmid pYELmleA of mleA Gene and Expression in Saccharomyces cerevisiae

苹果酸-乳酸酶是进行MLF的功能酶。笔者进行酒酒球菌SD-2a的苹果酸-乳酸酶基因重组表达质粒的构建。利用来自重组质粒pLmleA的，mleA基因，以PGK1强启动子和ADH1终止子为调控元件。以大肠杆菌-酵母菌穿梭质粒YEp352为载体，构建了重组表达质粒pYELmleA，并转化酿酒酵母(Saccharomyces cerevisiae)YS58。酵母转化子用含有亮氨酸、组氨酸和色氨酸的YNB平板筛选鉴定。SDS—PAGE检测表明获得的转化子表达了约60KD的目标蛋白。斑点杂交检测表明目的基因mleA转化到受体菌中。获得的转化子在添加了L-苹果酸的培养基中培养4d；取培养液上清用HPLC检测L-苹果酸及L-乳酸含量，采用t检验进行差异显著性分析，结果表明mleA基因进行了功能性的表达，将L-苹果酸转化成L-乳酸，L-苹果酸和L-乳酸含量分别与对照差异极显著和显著，L-乳酸的生成量为1002—1106mg／L。苹果酸的相对降低率为19．16—22．34％。     

清塘净对鱼类等水生生物急性致毒的研究

清塘净对鱼类等水生生物毒性强，毒力降解速度较快，是好的清塘药物。对黄鳝等水生生物９６ｈ的ＬＣ５０及安全质量浓度分别为：黄鳝２．４１ｍｇ／Ｌ和０．２４１ｍｇ／Ｌ；鲤鱼苗０．３８ｍｇ／Ｌ和０．０３８ｍｇ／Ｌ；草鱼苗０．４１ｍｇ／Ｌ和０．０４１ｍｇ／Ｌ；大型蚤０．５２ｍｇ／Ｌ和０．０５２ｍｇ／Ｌ；湖螺２．３３ｍｇ／Ｌ和０．２３３ｍｇ／Ｌ；泥鳅３．０４ｍｇ／Ｌ和０．３０４ｍｇ／Ｌ。     

闽南山地桉树纤维材优良无性系的选择研究

对福建漳州岩溪、天马 2个试验点 1 3个桉树纤维材无性系的生长性状、木材纤维形态和化学组分等性能进行测定与分析 ,并经多性状综合评判 ,选择出具有较高的生长量、生物量和纤维产量 ,适合闽南山地发展的C9、C1 0、EC1、EC3、C6共 5个纤维材优良无性系 ,其中尤以C9、C1 0、EC1三个无性系的各性状为最优。这 5个无性系 ,3a生年平均树高和胸径生长量、每株干材重量和纤维产量分别可达 3 93～ 6 60m、3 83～ 4 97cm ,9 71～ 2 0 48kg·a- 1 和 4 3 6～ 9 5 2kg·a- 1 ,而且木材纤维形态和化学组成等特性良好 ,可进一步扩大繁殖、推广应用。     

油茶产量与其相关因素的研究

本文运用典型相关分析的原理及方法,研究了油茶产量结构因素、叶部因素、树体形态因素、土壤肥力因素等4组因素与油茶产量的相互关系。分析结果表明,这4组因素都与产量有显著相关。依据林分产量——密度数量关系,确定了最适栽培密度,并提出了丰产林分的若干营养生长指标。     

Use of fallout Cs in investigations of overbank sediment deposition on river floodplains

River floodplains have been recognised as important sinks for storing suspended sediment and associated contaminants mobilised from the upstream catchment. However, information on contemporary rates of overbank sedimentation is difficult to obtain using conventional methods. Measurements of the ¹³⁷Cs content of floodplain sediments provide an alternative approach to obtaining; estimates of medium-term rates (ca. 40 years) of overbank sediment deposition. The ¹³⁷Cs approach requires only a single site visit and minimum sample preparation. Furthermore, it is capable of providing information on spatial patterns of sediment deposition on floodplains, which is needed to improve our understanding of the processes involved in overbank flow and sediment deposition. This paper reviews the basis for using ¹³⁷Cs measurements in floodplain sedimentation studies and presents improved procedures for interpreting ¹³⁷Cs profiles in floodplain sediments and for obtaining estimates of sedimentation rates from single measurements of the total. ¹³⁷Cs inventories of bulk sediment cores. The results obtained from a case study undertaken on the floodplain of the River Stour, Dorset, UK, are presented.     

适于FVS的长白落叶松树皮因子

为估算长白落叶松的去皮直径及树皮厚度等,利用小兴安岭南部68株长白落叶松解析木与生物量数据,对带皮胸径与去皮胸径之间、树干材积与木材材积之间、树皮厚度与相对树高之间、树皮因子与树高之间等相关模型进行了研究.结果表明,长白落叶松胸径处去皮直径的最优模型为D1B=0.922DOB(R2=0.99),胸径处树皮因子和树皮调整...     

Extraction of newly immobilized n from an illinois mollisol using aqueous phenol

Studies were conducted on an ¹⁵N-enriched Illinois Mollisol (Flanagan silt loam) to determine the extractability of newly immobilized N with aqueous phenol (45%, v/v). In comparison to mild extradants proposed as indexes of plant available N (i.e. 10 mw NaHCO₃ and hot 10 m CaCl₂), phenol showed the highest selectivity for the immobilized N, both with regard to the amount of biomass N extracted and the magnitude of the extractability ratio (ER). Aqueous phenol was also more selective in removing the immobilized N than reagents used for extraction of soil organic matter (i.e. 150 m Na₄P₂O₇ and 100 m KOH). Results with soils incubated for up to 120 days showed that the amount of ¹⁵N extracted with aqueous phenol fluctuated with time and was related to changes in the soil microbial population, e.g. ER was highest when the bacterial population was maximal. Aqueous phenol shows promise as a selective extradant of potentially-available (labile) organic N in soils.     

河南省新乡市奶牛隐孢子虫感染情况调查

本文应用病原学检查法对新乡市4个奶牛场的102头奶牛进行了隐孢子虫感染情况调查，调查结果：隐孢子虫感染率为20.6%；发病率为5.8% ；不同年龄的奶牛感染情况不同；机体免疫功能较低的奶牛易感染；经鉴定虫种为鼠隐孢子虫（Cryptosporidium muris)。