大豆根腐病菌对大豆幼苗生理生化指标的影响

利用垂直板发芽试验研究了大豆于幼苗期被大豆根腐病菌(Fusarium oxysporum)侵染后幼苗形态建成、总糖含量、可溶性糖含量、丙二醛 (MDA) 含量以及胚根细胞膜透性的动态变化,并对其致病机制和寄主的抗病机理进行了相应的分析.结果表明:大豆根腐病菌(Fusarium oxysporum)在侵染过程中会使大豆侧根原基的产生进程出现滞缓,子叶的营养物质输出受阻,胚根的生长速度减慢,根冠比的动态平衡被破坏,胚根中的总糖含量与对照相比下降,可溶性糖含量、MDA含量升高,细胞膜透性增大.通过分析,认为可溶性糖含量、MDA含量和细胞膜透性可作为抗病育种和药剂调控与保护的研究靶标.     

大豆疫霉根腐病研究进展

从大豆疫霉根腐病病害的起源、生理小种的分化、病害的流行、抗源筛选、抗性机制等方面,综述了国内外该病的研究进展。     

Biocontrol of vascular wilt and corm rot of gladiolus caused by Fusarium oxysporum f. sp. gladioli using plant growth promoting rhizobacterial mixture

Talc-based formulations of plant growth promoting rhizobacterial strain S2BC-2 (Bacillus atrophaeus) and strain mixture, S2BC-2 + TEPF-Sungal (Burkholderia cepacia), inhibitory to the growth of Fusarium oxysporum f. sp. gladioli (FOG), were developed for corm dressing and soil application in gladiolus. In comparison to the individual strain, the strain mixture recorded maximum spike and corm production of 100 and 150%, respectively with less vascular wilt and corm rot incidences of 73.6 and 54.8% reduction over the pathogen control in greenhouse when inoculated with FOG. Reduction in disease incidence under greenhouse conditions occurred through induction of defence gene products such as chitinase, β-1,3-glucanase, peroxidase and polyphenol oxidase. Besides disease suppression, treatment with strain mixture promoted plant growth in terms of enhanced corm and cormel production and flowering. In field experiments, the strain mixture recorded less vascular wilt and corm rot incidences of 48.6 and 46.1% mean reduction over the non-bacterised control, and was almost comparable with that of fungicide (51.5 and 47.1%, respectively). The treatment also recorded increased spike and corm yield with average increases of 58.3 and 27.4%, respectively, relative to the control.     

Effect of environmental C/N ratio on activities of lignin-degrading enzymes produced by Phanerochaete chrysosporium

Lignin-degrading enzymes secreted by white rot fungi play an important role in the degradation of lignin and persistent organic pollutants(POPs).In this study,effect of environmental C/N ratio on the activities of lignin-degrading enzymes,lignin peroxide(Li P)and manganese peroxidase(Mn P),produced by Phanerochaete chrysosporium,a white rot fungus,was investigated.Glucose was used as C source,and ammonium tartrate of different concentrations was used as N source to provide different C/N ratios.Relationships between Li P and Mn P activities and environmental C/N ratio were explored.The results showed that the higher the N source concentration,the faster the mycelium pellets aged.The faster the mycelium dry weight increased,the higher the Li P and Mn P activities.A high C/N ratio was a necessary condition for the secretion of Li P or Mn P.In addition,mycelium dry weight essentially affected enzyme activities.In the 122 C/N ratio and 50 C/N ratio treatments,mycelium dry weight essentially affected Mn P activity and both Li P and Mn P activities,respectively.     

Growing stock variation in different teak （Tectona grandis） forest stands of Mizoram,India

The growing stock assessment of three different teak forest stands （Tuirial： 500 m asl, Sairang： 200 m asl and Phunchawng： 550 m asl） was done in 2006 in Mizoram, India. Five diameter classes were arbitrarily established for knowing the volume attribute data and population structure, viz. a （10-20 cm）, b （20-30 cm）, c （30-40 cm）, d （40-50 cm）, and e （50-60 cm）. Results revealed that the density of the individuals among the studied stands varied from 280 stems/ha to 620 stems/ha. The average diameter of all the individuals ranged between 27.48 cm and 35.43 cm. Similarly, the average height was oscillated between 17.87 m and 22.24 m. The total basal area was recorded between 24.28 m2.ha-1 and 45.80 m2.ha＂l. The maximum and minimum values of total growing stock under all the diameter classes were 669.01 m3.ha-1 and 284.7 m3.ha-1, respectively. The representation of population structure of different stands explained that the perpetuation of this species was ensured for a quite long time.     

漆酶催化活性中心结构及其特性研究进展

漆酶是一种多酚氧化酶，参与木质素的降解或聚合，具有氧化木质素的能力，但不同来源的漆酶其氧化降解木质素的能力相差很大。漆酶的结构决定了漆酶的特性，因而也就决定了漆酶氧化降解木质素的能力。本文综述了近10年来漆酶分子催化活性中心的结构与功能及其特性的研究进展。     

野生大豆接种大豆疫霉根腐病菌后超氧化物歧化酶活性变化

对大豆疫霉菌胁迫下抗感不同野生大豆根、茎、叶中超氧化物歧化酶(superoxide dis-mutase,SOD)活性的变化进行了初步研究。结果表明:接种大豆疫霉根腐病菌后,抗感野生大豆根、茎、叶中SOD活性在病程的大部分阶段多高于相应对照,且总体而言,抗病野生大豆比感病野生大豆SOD活性较相应对照增幅大。     

大豆疫病种子带菌和传病研究

本文对大豆疫病种子带菌和种子传病研究作了详细报道。试验证明，从大豆疫病的感病植株可以获得病英和带菌种子。种子带菌具有传病作用。并阐明了种子带菌规律和病菌在种子里的存在部位。提出了适合植物检疫的种子检验鉴定技术。     

玉米穗腐病导致产量损失的品种和气候因素分析

1986～1990年的研究结果发现,在玉米穗腐病流行年份,抗病和感病玉米自交系的严量损失分别比常年高21％和35％。在气候因素中,日照时数对发病和产量损失影响较大。同一气候条件下感病系比抗病系产量损失大52％～82％。感病品种因穗腐病造成的玉水产量损失比不利的气候因素更为严重。     

林分断面积生长率公式探讨

根据林分生长理论，结合原始调查数据，对林业生产中的3种断面积生长率理论公式Meyer式、Pressler式和张角式的特性作了进一步研究，并对3种方法作了具体验证。研究结果表明：3种断面积生长率计算方法有一定差异，当后期与前期平均断面积比值大于1.30时，Meyer方法计算断面积生长率高于其余两种方法，张角法则和Pressler法则十分接近，但张角法更有理论依据。