Abstract:Results of experiments in laboratory showed that margosan O possessed strong insecticidal properties and growth regulatory effects on the 3rd instar larvae of the diamondback moth (DBM). The mortality of the larvae and pupae was 84.21%when the 3rd instar larvae of DBM were fed by the leaves of vegetable sprayed with 15 mg/L margosan O. The pupation, emergence and fecundity of DBM were seriously supppressed by margosan O. Experimental results also proved that the LC 50 was 36.90 mg/L and 28.77 mg/L respectively, on resistant strain and susceptible strain of the 3rd instar larvae of DBM.

Abstract:Four fungal diseases of Amla discovered in Guangdong Province were reported in this paper. They are brpwn spot caused by Phyllosticta emblicae C. F. Zhang et P. K. Chi, false anthracnose caused by Kabatiella emblicae C. F. Zhang et P. K. Chi, Peatalotiopsis leaf spot caused by Pestalotiopsis heterocornis (Guba) Y. X. Chen, and powdery mildew caused by Oidium sp. .The first two pathogens were described as new species, and the third was considered to be new in China. Type specimens pf diseases are deposited in the Fungal Collection of South China Agricultural University.

Abstract:The pathogen of wilt disease of poinsettia was identified as Fusarium oxysporum schl. f. sp. euphorbiae Z. D. Jiang et P. K. Chi. f. sp. nov. according to its morphology, cultural character and pathogenicity. This pathogen only attacked poisettia among 14 species of plants on 11 families by the methods of impregnated inoculation and irrigated inoculation. The disease could cause basal stem rotted in the late stage.

Abstract:The results of pot experiments in which Hirschmanniella oryzae was inoculated in rice roots in various population densities showed that the population densities of H. oryzae in rice roots were directly proportional to the initial population density inoculated. But the fresh rice plant mass, the fresh root mass, the number of effective tillers, the one thousand-grains weight and the yield of rice were inversely proportional to that of the initial population density of H. oryzae . The injury level of H. oryxae on rice was 15 nematodes in one gram of rice roots at the end of the maximum tillering stage and could be applied as economic threshhold in the control of H. oryxae with several cultivation measures. The yield of rice was significantly was reduced by H. oryxae and was inversely proportional to the population density of H. oryzae in rice roots in the later tillering stage.

Abstract:苦丁茶是近年来从野生资源中开发出利用的非茶类植物，具适应性广，成材快，经济价值高等特点，并有药用功能，用苦丁茶嫩梢茎切段及带柄叶片作外植体，在含２，４－Ｄ０．５ｍｇ／Ｌ￣４ｍｇ／Ｌ，ＫＴ１ｍｇ／Ｌ，蔗糖３０ｇ／Ｌ，琼脂７ｇ／Ｌ的发言发ＭＳ培养基上，诱导产生愈伤组织，在同样培养基或添加不同附加物的培养基上继代培养，观察比较愈伤组织的增长情况。

Abstract:以６个抗白叶枯病等级不同的品种作６×６双列杂交，按Ｈａｙｍａｎ模型对接种前后过氧化物酶活性变化值作遗传分析。结果表明，在遗传方差中，加性方差占３４３１％，显性方差占４６１７％，上位性方差占１９５０％；广义遗传率ＨＢ２＝９４１６％，狭义遗传率ＨＮ２＝３１３１％；最少加性基因数Ｋ＝４，显性基因数Ｋ′＝１；具超显性遗传，且不同亲本正负效基因分布亦有明显的差异

Abstract:Ten rice quality characters of 172 Cultivars of Guangdong Province were evaluateal by correlation and path analysis methods. The results of correlation analysis showed that the general score assumed significant postive correlation with the vitreousness, gel consistency, rice taste appraisal rate of head rice, rice grain length and rate of brown rice, and significant negative correlation with the rate of chalky grain, rice grain width and amylose content respectively. The results of path analysis showed that the vitreousness made the greatest contribution to the general score, then the ratio of rice grain length to width, rice taste appraisal, amylose content, rate of head rice and gel consistency. The vitreousness had the greatest indirect contribution to the general score through the rate of head rice.

Abstract:The yield potential of rice in Guangdong is great with the improved varieties. It is possible to produce 11 260.5 kg/hm 2 in one season, or 22 521.0 kg/hm 2 in one year with the improved varieties, or 8 677.5 kg/hm 2 with good quality varieties and advanced cultivation techniques includung the improvement of production conditions. The increase of grain self-sufficient rate in Guangdong will depend on the yield increase of single crop, specialy the increase of rice yield in the middle and lower production areas which are nearly two-thirths of the total rice areas in Guangdong.

Abstract:研究了广州地区华南农业大学早季稻实验田在农业管理措施和肥效基本相同的情况下，施用不同肥料对稻田Ｎ２Ｏ排放通量的影响。试验初步表明：早季稻稻田Ｎ２Ｏ排放规律是施纯化肥稻田Ｎ２Ｏ排放集中在施肥后４ｄ￣１８ｄ，施有机肥加化肥稻田Ｎ２Ｏ排放集中在施肥后第５ｄ￣１０ｄ，施猪粪肥几乎无Ｎ２Ｏ排放，施肥期稻田处于灌溉干湿状态有利于Ｎ２Ｏ排放。稻田处于灌溉淹水状态不利于Ｎ２Ｏ排放，稻田表层土壤温度高有利地Ｎ２Ｏ排

Abstract:The soil distribution in Guangdong is characterized by an obvious zonality, showing red soil, latored soil and latosol from north to south. This paper summarizes recent research results on soil element background values and heavy metal environmental capacity in the region, and discusses the differentiation pattern of the environmental background value and critical content of the main zonal soils in Guangdong.

Abstract:Pruning experiments were conducted in five year old mango trees Mangifera indica L. cv. Zihua on Oct. 3, 1993 and repeated on Sept. 20,1994. Results showed that heavy pruned trees flowered 20 days later than light and medium pruned trees, and that full bloom was delayed by 8 days with heavy pruning, but the crop level decreased probably because of delayed accumulation of carbohydrate reserves by strong regrowth after heavy pruning, resulting in a decrease of flowering shoot rate . No fruit quality decrease was observed with heavy pruning. Crop level of heavy pruned trees in 1994/1995 was improved as the result of practicing earlier and less severe pruning.

Abstract:In this paper, study on the ecological characters of the medicinal herb Knoxia valerianoides Thorel et pitard shows that in China ,the distribution of Knoxia valerianoides Thorel et Pitard extend through the tropical zone. South Asia subtropical zone and Central Asia subtropical zone. It is mainly distributed in laterite and red soils which orignated from granite. The limit of vertical distribution gradually ascends as the distribution area extend from east to west. The vegetation of the distribution area is tropical and subtropical evergreen broard-leaved forest. portion of which have evolved into grass-slopes. This medicinal herb is mesophyllous heliophyte, with a peak in its growth phase coinciding with that of the annual rainfall.

Abstract:黄槐决明的叶粉干物质含粗蛋白质２４．７％，粗纤维８．５％，花瓣粉干物质含粗蛋白质１９．１％，粗纤维２０．３％，饲养试验结果表明，９０ｄ龄石歧杂公鸡饲喂含２％，４％，６％黄槐叶粉和３％黄槐花瓣粉的饲粮，鸡的生长和饲料效率和鸡体着色良好，证明黄槐叶及礤花瓣有作为饲料资源开发利用的价值。

Abstract:Based on the ecosystematic characteristics of short rotation eucalypt plantations shown in previous researches, the paper comprehensively analyses and appraises the limiting factors to the productivity of eucalypt plantations-climate, variety, soil, fertilization, managemental measures and investment structure. The purpose of the paper is to identify optimal production programs giving out high output while also preserving eco-environment for the rational management of eucalypt plantations.

Abstract:对火炬松８￣１２年生的２２７个无性系的球果结实量，连续作了３年观察分析，结果表明，无性系间，年度间差异显著或极显著，多数无性系结果量偏低；对无性系果量再选择建成的高一级种子园与供选群体相比，增产达８５％￣１３７％，甚至更高。按球果丰歉波动状态可划分为６种类型，其中以“Ｖ”字类型居多。

Abstract:龙眼的平衡含水率是研究龙眼干燥和在眼干贮藏的重要参数，应用静态法对龙眼进行了不同温度和相对湿度条件下的解吸和吸湿平衡含水主的测定试验，分析了温度和相对湿度对龙眼平衡含水率的影响。比较了不同的平衡含水流率模型对实验数据的拟合精度，发现Ｈａｌｓｅｙ模型较适合于描述龙眼的平衡含水率曲线。

Abstract:The evolution of the Damage between two configurations submitted to the same sequential metropolis dynamics for the Spin-1 lsing model on a square lattice is studied. Using the dynamical finite size scaling techniques the transition temperature for the model is determined and is in contrast with other solutions.