桉树人工林群落乔木层结构研究

通过对昆明市金殿旅游风景区桉树人工林乔木层结构的调查,结果表明：人工桉树林乔木层树种为单一的直杆桉;样地内直杆桉的胸径和冠幅、胸径和树高成极显著相关性,树高、冠幅和胸径之间有密切联系;树冠系数普遍达到0.12的水平,虽与0.2的水平有一定差距,但一定程度上反映出林地内乔木生长状况不良。     

寄主植物对芒果壮铗普瘿蚊为害的生理效应

研究芒果壮铗普瘿蚊不同程度为害下寄主植物叶片中硝态氮、可溶性糖、可溶性蛋白质、叶绿素含量以及植物保护酶系——超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性的变化.将叶片受害程度划分为4个等级:1～50,51～100,101～200,＞200(每叶片虫瘿数),并以无虫瘿为害的叶片为对照组(CK).结果表明:可溶性糖与硝态氮含量在各个等级之间均没有显著的差异;可溶性蛋白和叶绿素a、叶绿素b含量各为害等级叶片均显著低于CK;而类胡萝卜素含量,高密度为害等级(101～200,＞200)显著高于其他各组及CK.植物保护酶系测定结果显示:CK组活力最低,＞200等级SOD,POD,CAT活力均高于其他各组;其中,51～100与＞200等级SOD活力显著高于其他等级;为害等级量重的(＞200)POD和CAT活力显著高于其他等级;而1～50等级显著低于其他等级.因此,人侵害虫芒果壮铗普瘿蚊的不同为害程度直接影响植物的光合作用及有关营养物质;随着为害等级的加重可导致植物保护酶系的活性增大.     

Performance of Grevillea robusta in plantations and on farms under varying environmental conditions in Rwanda

The growth of Grevillea robusta A. Cunn. ex R.Br. in plantations and on farms was assessed on 67 sites selected at random in the major ecological zones of Rwanda. The following parameters were assessed: diameter at breast height, tree height, altitude above sea level, annual rainfall and temperature, soil pH, soil type, soil fertility, soil depth, spacing and forest type (plantation or farm).

Analyses of variance demonstrated that fertile soil, intercropping and cultivation between trees considerably improved growth performance. However, growth was negatively correlated with altitude, with stands above 2300 m above sea level showing poor growth. In Rwanda with proper management, the species can be grown in plantations and on farms for firewood, poles and sawlogs.     

八棱海棠一年生播种苗苗高年生长规律研究

以八棱海棠1 a生播种苗为研究时象,对其苗高生长规律和苗高与地径、生态因子的关系等进行研究.试验结果证明:Logistic方程可较好地反映苗高生长规律,苗高生长呈现"慢-快-慢-快-慢"的节律,并以此将苗高年生长过程划分为6个生长期.通过苗高生长规律与气象因子的相关分析,证明日平均气温是影响苗高生长的主要气象因子.     

转rolC基因八棱海棠组培苗生物学特性的研究

【目的】通过研究转rolC基因八棱海棠不同株系的转基因拷贝数，在转录水平上的表达丰度，以及转基因组培苗的生物学特性，为进一步深入阐明rolC基因在八棱海棠中的表达机制和培育优良的苹果砧木奠定理论基础。【方法】以通过gus染色和PCR检测的3个转rolC基因八棱海棠株系组培苗为试材。Southern杂交鉴定rolC基因整合拷贝数。Northern杂交鉴定rolC基因在转录水平上的表达丰度。调查转基因植株组培苗在含有不同种类和浓度的植物生长调节剂的培养基上茎段增殖、叶片再生、生根能力等生物学特性；将生根后的组培苗进行炼苗，移入温室4个月后，研究株高、节间数、节间长度、叶面积等生物学特性。【结果】Southern杂交结果表明，rolC基因分别整合进入3个八棱海棠株系基因组，其中株系20a和33a分别获得了1个rolC基因拷贝，株系20b获得了2个rolC基因拷贝。Northern杂交结果表明，3个转基因株系中的rolC基因均在转录水平上得到了表达，且该基因在单拷贝株系的表达丰度高于双拷贝株系。转基因组培苗生物学特性研究结果表明：（1）3个转rolC基因八棱海棠株系茎段增殖系数、叶片再生率、生根所需外源激素浓度均显著低于对照植株，单拷贝株系的以上指标亦显著低于双拷贝株系。（2）3个转基因八棱海棠株系组培苗平均生根数显著高于转基因株系，双拷贝株系显著低于单拷贝株系；根长情况正好相反；对照植株根粗和转基因株系根粗之间均无显著差异。（3）3个转基因八棱海棠株系的株高、节间长度、节间数、叶面积均显著小于对照植株。其中单拷贝株系显著小于双拷贝株系。【结论】rolC基因整合进入3个八棱海棠转基因株系基因组，并分别在转录水平上得到表达。外源rolC基因的表达导致转基因植株体内内源激素含量和植株形态学的改变，且rolC基因的整合拷贝数对它的表达有一定的影响。     

Quantifying the effects of bycatch reduction devices in Queensland''s (Australia) shallow water eastern king prawn (Penaeus plebejus) trawl fishery

This study presents results from an experimental 10-day research charter that was designed to quantify the effects of (a) a turtle excluder device (TED), (b) a radial escape section bycatch reduction device (BRD) and (c) both devices together, on bycatch and prawn catch rates in the Queensland shallow water eastern king prawn (Penaeus plebejus) trawl fishery. The bycatch was comprised of 250 taxa, mainly gurnards, whiting, lizard fish, flathead, dragonets, portunid crabs, turretfish and flounders. The observed mean catch rates of bycatch and marketable eastern king prawns from the standard trawl net (i.e., net with no TED or BRD) used during the charter were 11.06 kg/hectare (ha⁻¹) (S.E. 0.90) swept by the trawl gear and 0.94 kg ha⁻¹, respectively. For the range of depths sampled (20.1–90.7 m), bycatch rates declined significantly at a rate of 0.14 kg ha⁻¹ for every 1 m increase in depth, while prawn catch rates were unaffected. When both the TED and radial escape section BRD were used together, the bycatch rate declined by 24% compared to a standard net, but at a 20% reduction in marketable prawn catch rate. The largest reductions were achieved for stout whiting Sillago robusta (57% reduction) and yellowtail scad Trachurus novaezelandiae (32% reduction). Multidimensional scaling and analysis of similarities revealed that bycatch assemblages differed significantly between depths and latitude, but not between the different combinations of bycatch reduction devices. Despite the lowered prawn catch rates, the reduced bycatch rates are promising, particularly for S. robusta, which is targeted in another fishery. Prawn trawl operators are not permitted to retain S. robusta and the devices examined herein offer the potential to significantly reduce the incidental fishing mortality that this species experiences.     

灰色预测在桉树冻害预报中的应用

本文应用灰色系统理论,选取历年冬季连续30天内≤0℃最大日数为低温指标,建立GM(1,1)模型,对绵阳市大叶桉冻害进行了预测。预测模型为:P(K+1)=25.1239e~(0.3645k)-23.1239后验差检验模型精度为第一级“GOOD”。预测下次灾年将在1999年出现。