Effects of plant height and row spacing on kenaf forage potential with multiple harvests

Kenaf (Hibiscus cannabinus L.) forage potential can be enhanced through its regrowth capacity and higher production in narrow rows. A field experiment was conducted in Matamoros, Coahuila, Mexico, during 2 growing seasons (2004 and 2005) to study the effects of plant height and row spacing on kenaf forage potential with multiple harvests. This study evaluated the effects of (1) 2 plant heights at cutting (1.0-1.2 m and 1.8-2.0 m) and (2) 4 inter row spacings (0.19, 0.38, 0.57 and 0.76 m) using a 2 x 4 factorial arrangement of treatments in a completely randomized block design with 4 replications. Dry matter (DM) and crude protein (CP) yields, DM partitioning, neutral detergent fiber (NDF) and CP concentrations were determined. Heights at cutting × row spacing interactions were not significant for the monitored variables (p>0.05). Kenaf response to treatments was only relevant for main effects (p≤0.05). Row spacing and plant height affected DM and CP yields (p≤0.05), whereas only plant height affected chemical composition and DM partitioning (p≤0.05). Dry matter (17.0%-26.0%), and CP (12.4%-15.6%) yields were higher (p≤0.05) when plant heights had reached 1.8 to 2.0 m. Row spacing reduction from 0.76 m to 0.38 and 0.19 m increased DM yield (20.4-33.4%) and CP yield (24.2-38.5%) (p≤0.05). Kenaf forage potential increases when planted in narrow rows and harvested 2 or 3 times during the growing season.     

Occurrence of cotton aphids (Aphis gossypii) and lady beetles (Hamonia axyridis) on Hibiscus syriacus Linne: Are the aphids a pest of cucurbits?

Populations of cotton aphid on Hibiscus syriacus increased rapidly from 17 to 24 May 2007, and then decreased as its predator, the lady beetle Hamonia axyridis, increased in number. There was a 10 day time lag between peak populations of aphids and lady beetles. The infestation of aphids on H. syriacus produced some damage, but H. syriacus recovered soon after the lady beetles arrived. Cotton aphid clones from H. syriacus were transferred to other summer host plants: to five different vegetables on two dates, and to cucumber on three dates. Apart from one case where reproduction occurred on eggplant, most H. syriacus aphid clones did not survive on the vegetables. The cotton aphid on H. syriancus was prey and a food source for H. axyridis and acted to conserve natural enemies.     

Transformation parameters enhancing T-DNA expression in kenaf (Hibiscus cannabinus)

Kenaf(Hibiscus cannabinus)is a fast growing annual with tremendous potential as a source of fiber for ropes, textiles and paper. Kenaf is an environmentally friendly crop; however, commercial production of kenaf is hindered by weed competition at the seedling stage. Herbicide resistant kenaf cultivars would reduce seedling weed competion and make growing kenaf more profitable. Factors that are important in establishing a transformation system for kenaf were examined. The influence of Agrobacterium strain, temperature, host tissue wounding, acetosyringone, virG/virE genes and host cell division on T-DNA expression in the kenaf shoot apex were investigated. Three Agrobacterium strains were tested, and A. tumefaciens LBA4404 significantly (α=0.05) yielded a high number of shoots surviving on selection medium; no shoots survived with EHA101S or Z707S. There was no significant difference (α=0.05) in transient T-DNA expression between 28 °C and 25 °C; however, shoots did not survive 16 °C or 19 °C co-cultivation temperatures. Shoot apex survival was increased significantly (α=0.05) when virulence genes and a cytokinin, TDZ, were combined. Sonicated shoots showed an increase in transient expression and shoot survival. Optimal conditions for shoot apex T-DNA transfer and expression were sonication for 5 s, co-cultivation with LBA4404 containingvirG/virEat room temperature, and 200 μmol/L acetosyringone.     

悬浮培养玫瑰茄细胞的生长行为及动力学方程的建立

以培养多年的玫瑰茄（Hibiscus sabdariffaL.)白色细胞株为材料,在以3％蔗糖为碳源,植物生长调节剂为4．5μmol/L2,4-D（2,4－二氯苯氧乙酸）,2．3μmol/L Kt（Kinetin,细胞激动素）的悬浮培养条件下,研究了玫瑰茄细胞的生长及泛醌积累动态、培养液PH值的变化以及培养过程中玫瑰茄细胞对碳源、氮源、磷源的消耗动态,并以此数据建立了悬浮培养玫瑰茄细胞的生长、蔗糖消耗、泛醌形成的非结构动力学模型,经验证表明,模型与实际情况有较高的拟合度。     

四种杀虫剂对棉蚜药效试验的初报

采用浸渍法 ,室内测定了 4种杀虫剂对越冬寄主木槿上棉蚜的毒力 ,这几种药剂的防治效果均良好 ,其毒力 (LC50 )为阿维菌素 >吡虫啉 >甲氰菊酯 >氰戊菊酯。建议在棉蚜的越冬寄主上集中防治     

A-seco-oleane-type triterpenes from Phomopsis sp. (strain HKI0458) isolated from the mangrove plant Hibiscus tiliaceus

From the fermentation broth of an unidentified Phomopsis sp. (strain HKI0458) isolated from the mangrove plant Hibiscus tiliaceus, four A-seco-oleane-type triterpenes, namely 3,4-seco-olean-11,13-dien-4,15alpha, 22beta,24-tetraol-3-oic acid (1), 3,4-seco-olean-11,13-dien-4,7beta,22beta,24-tetraol-3-oic acid (2), 3,4-seco- olean-13-en-4,7,15,22,24-pentaol-3-oic acid (3), and 3,4-seco-olean-13-en-4,15,22,24-tetraol-3-oic acid (4) were obtained. Their structures were elucidated by extensive spectroscopic (UV, IR, FABMS, and 2D NMR) data analyses.     

拟南芥植物硫肽激素基因在玫瑰茄细胞中的表达

利用玫瑰茄愈伤组织遗传转化体系,通过根癌农杆菌将AtPSK2基因导入玫瑰茄细胞,并获得了功能性表达。研究结果表明,所获得的转基因玫瑰茄细胞系的临界植板细胞密度和临界起始细胞密度分别降低了60%和50%,悬浮细胞培养周期由16d缩短到12d,转化愈伤组织的比生长速率比对照提高了75%,转基因玫瑰茄细胞和愈伤组织中的花黄素含量与对照相比没有发生明显变化。本研究所获得的转基因玫瑰茄细胞系不仅为花青苷和花黄素等次生代谢产物高产细胞株的选育提供出发材料,而且为PSK-α作用机理的深入研究提供一个有用的模型。     

NaCl胁迫对海滨木槿抗氧化系统和渗透调节的影响

以盐生植物海滨木槿为材料,不同浓度NaCl胁迫对其抗氧化酶活性、抗氧化物质和渗透调节物质含量的影响进行分析。结果显示:随着NaCl浓度的升高,海滨木槿叶片中超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)、过氧化物酶(POD)、谷胱甘肽还原酶(GR)和谷胱甘肽转硫酶(GST)的活性先升高后降低,而过氧化氢酶(CAT)的活性呈持续下降趋势,但它们达到最高活性时的NaCl浓度不同;各处理的丙二醛(MDA)含量先下降后升高,但始终低于对照;抗氧化物质抗坏血酸(AsA)和谷胱甘肽(GSH)的含量均高于对照,且在200 mmol.L-1时达到最高;各处理渗透调节物质可溶性糖和脯氨酸(Pro)的含量均较对照增加且升幅较大。研究表明,海滨木槿在NaCl胁迫下具有较强的活性氧清除能力和渗透调节能力,从而表现出较强的耐盐性。     

Origin and diversification of Hibiscus glaber, species endemic to the oceanic Bonin Islands, revealed by chloroplast DNA polymorphism

Abstract Two woody Hibiscus species co-occur in the Bonin Islands of the northwestern Pacific Ocean: Hibiscus glaber Matsum. is endemic to the islands, and its putative ancestral species, Hibiscus tiliaceus L., is widely distributed in coastal areas of the tropics and subtropics. To infer isolating mechanisms that led to speciation of H. glaber and the processes that resulted in co-occurrence of the two closely related species on the Bonin Islands, we conducted molecular phylogenetic analyses on chloroplast DNA (cpDNA) sequences. Materials collected from a wide area of the Pacific and Indian Oceans were used, and two closely related species, Hibiscus hamabo Siebold Zucc. and Hibiscus macrophyllus Roxb., were also included in the analyses. The constructed tree suggested that H. glaber has been derived from H. tiliaceus, and that most of the modern Bonin populations of H. tiliaceus did not share most recent ancestry with H. glaber. Geographic isolation appears to be the most important mechanism in the speciation of H. glaber. The co-occurrence of the two species can be attributed to multiple migrations of different lineages into the islands. While a wide and overlapping geographical distribution of haplotypes was found in H. tiliaceus, localized geographical distribution of haplotypes was detected in H. glaber. It is hypothesized that a shift to inland habitats may have affected the mode of seed dispersal from ocean currents to gravity and hence resulted in geographical structuring of H. glaber haplotypes.     

Genetic diversity of Hibiscus tiliaceus (Malvaceae) in China assessed using AFLP markers

Amplified fragment length polymorphism (AFLP) markers were used to investigate the genetic variations within and among nine natural populations of Hibiscus tiliaceus in China. DNA from 145 individuals was amplified with eight primer pairs. No polymorphisms were found among the 20 samples of a marginal population of recent origin probably due to a founder effect. Across the other 125 individuals, 501 of 566 bands (88.5%) were polymorphic, and 125 unique AFLP phenotypes were observed. Estimates of genetic diversity agreed with life history traits of H. tiliaceus and geographical distribution. AMOVA analysis revealed that most genetic diversity resided within populations (84.8%), which corresponded to results reported for outcrossing plants. The indirect estimate of gene flow based on phiST was moderate (Nm=1.395). Long-distance dispersal of floating seeds and local environments may play an important role in shaping the genetic diversity of the population and the genetic structure of this species.