Studies on Essential Oil Composition in Leaves of Torreya grandis cv. ‘Merrillii' and Chemotaxonomy

The chemical components of different genera and species of Taxaceac have been analyzed in order to provide the data for discussion of the systematic position of this family. A characteristic component kayaflavone from the leaves of Torreya grandis cv. ‘Merrillii' has been reported in our previous paper. Recently we have obtained also a new diterpene torreyagrandate from the leaves of this species. The present paper deals with our preliminary study on essential oil composition of the leaves in the same species. 26 components have been identified. Three of them, limonene, α-pinene and δ-3-carene, are the main ones, with their contents being 44.24%, 20.75% and 4% respectively. The essential oilalso contains torreyol which is a characteristiccomponent in this species.     

Establishment of an Index to Appraise Cold-resistant Breeding for Citrus in Early Stage

Cold-resistance of citrus protoplasm and field plants in 5 different varieties was studied. The relative analysis between cold resistance of citrus protoplasts and that of field plants indicates that the cold resistance of citrus protoplasm can be considered as an index of cold resistance of field plants.     

Optimization of Electrofusion Parameters and Interspecific Somatic Hybrid Regeneration in Citrus

This study was primarily attempted to optimize the electrofusion parameters using protoplasts isolated from cell suspension cultures of "Page" tangelo ( Citrus reticulata Blanco x C. paradisi Macf) and mesophyll protoplasts of rough lemon ( Citrus jambhiri Lush) as fusion partners. It was shown that the binuclear heterokaryons frequency reached 15% with the following parameters: alternate current (AC) 125 V/cm, AC time 60 s, direct current (DC) 1 250 V/cm, DC pulse width 50 μs, DC pulse interval O. 5 s, No. of DC pulse 3. Considering the fact that different types of protoplasts have different specific weights, higher frequency of the binuclear heterokaryons was obtained by controlling the centrifugation time after fusion. The fusion products regenerated into plantlets after 3 to 4 months of culture. Chromosome counting of the root tips and morphological observation of the regenerants verified that 78% were tetraploids and the rest were diploids with the leaf morphology of mesophyll parent. Peroxidase (POX) isozyme and RAPD analysis indicated that interspecific somatic hybrids were obtained and an autotetraploid plant of mesophyll parent type was also verified.     

Somatic embryogenesis and plant regeneration from pistil thin cell layers of Citrus

 Callus induction, somatic embryogenesis and plant regeneration were obtained in six different citrus species [Citrus deliciosa Ten. (cv 'Avana'), C.limon (L.) Burm. (cv 'Berna'), C.madurensis Lour. (cv 'CNR P9'), C.medica L. (cv 'Cedro di Trabia'), C.tardiva Hort. ex Tan. (cv 'CNR P6'), C.sinensis (L.) Osb. (cv 'Ugdulena 7')] from cultures of pistil transverse thin cell layer explants [(t)TCL]. Explants were cultured on three different media: the nutrients and vitamins of Murashige and Skoog medium alone (MS) or MS supplemented with either 500 mg l^–1 malt extract (MS I) or 500 mg l^–1 malt extract and 13.3 μM 6-benzylaminopurine (MS II). Sucrose (146 mM) was used as the carbon source. Somatic embryos were visible 2–5 months after culture initiation. The different genotypes showed a different embryogenic frequency from stigma, style and ovary (t)TCL explants. All of the cultivars regenerated somatic embryos. Percentages of style (t)TCL explants producing somatic embryos ranged from 0% (C.deliciosa, C.madurensis, C.sinensis and C.tardiva on the three different media) to 5.2% (C.limon on MS II). Embryo formation in stigma (t)TCL explants ranged from 0% (C.madurensis on MS and MS I, C.sinensis on MS, C.deliciosa and C.tardiva on the three different media) to 42.4% (C.limon on MS II). Embryo formation in ovary (t)TCL explants ranged from 0% (C.deliciosa on MS, C.limon, C.medica, and C.sinensis on the three different media) to 9.3% (C.tardiva on MS I). After about 12 weeks somatic embryos developed into plantlets at a high frequency. Received: 22 September 1998 / Revision received: 6 November 1998 / Accepted: 23 November 1998     

脐橙与柠檬种间细胞电融合再生杂种植株

‘纽荷尔’脐橙（Ｃｉｔｒｕｓｓｉｎｅｎｓｉｓ（Ｌ．）Ｏｓｂｅｃｋ）胚性细胞悬浮原生质体与‘尤力克’柠檬（Ｃｉｔｒｕｓｌｉｍｏｎ（Ｌ．）Ｂｕｒｍ．ｆ）叶肉原生质体经电场诱导融合,培养８个月,首批再生了１棵植株,形态学观察,染色体计数及ＲＡＰＤ分析证明异源四倍体体细胞杂种,该杂种的获得为三倍体无籽柠檬品种培育提供了杂交亲本。     

单性结实和自花结实柑橘果实发育过程中IAA、ZR和GA3含量的变化

对单性结实的龟井温州蜜柑(以下简称龟井)和自花结实的鄂柑1号橘(以下简称鄂柑1号)果实发育过程中不同部位的IAA、ZR和GA₃的含量变化进行了测定。结果表明:(1)两品种果皮IAA含量呈相似的变化趋势,均于果实增大期间出现明显高峰,但鄂柑1号的IAA高峰值显著较高;二者果皮ZR含量动态却相反,增大期间龟井果皮ZR的含量相对较高且趋上升,而鄂柑1号却趋下降;二者果皮GA₃含量均于增大期间出现类似的上升过程,之后均趋下降。(2)龟井果肉IAA、ZR和GA₃含量前期均较高,此后均明显下降并居较低水平;而鄂柑1号果肉IAA和GA₃均于增大期间出现明显的上升且含量明显高于龟井,而ZR含量与龟井一样呈下降趋势,但ZR的含量更低。(3)鄂柑1号种子的IAA、ZR和GA₃在花后72d均相对较高,之后急剧回落至相对较低的稳定水平。     

葡萄实生树阶段转变过程中的内源多胺含量变化

用高效液相色谱法测定二年生巨峰葡萄自然实生树不同节位叶片、芽、韧皮部中内源多胺含量的结果表明,随着节位的升高,在3种组织中的腐胺(Put)和亚精胺(Spd)含量增加,21～25节腐胺增加幅度最大,自21节起亚精胺含量陡增;21～25节叶片中的精胺(Spm)含量出现高峰.说明21节左右可能是童性消失进入生殖生长期的临界点.     

The shelf life and effectiveness of granular formulations of Metschnikowia pulcherrima and Pichia guilliermondii yeast isolates that control postharvest decay of citrus fruit

Our overall objectives were to prepare commercially acceptable formulations of the postharvest biological control yeasts, Metschnikowia pulcherrima and Pichia guilliermondii, which have a long storage life and to determine the effectiveness of these formulations to control postharvest green and blue moulds on citrus fruit. Yeasts, grown on a cane molasses-based medium, were combined with talc or kaolin carriers and various adjuvants and the viability of yeast in 12 formulations was determined over a 6 month period. Formulation no. 11, containing talc, sodium alginate, sucrose, and yeast extract, for both yeasts had a significantly higher viable yeast cell content over a 6 month storage period. Among the formulations, three formulations (formulations no. 5, 6, and 11) were selected for additional in vivo testing because they had higher levels of viability amongst yeast cell populations during storage and were easier to resuspend remained in suspension more easily. These formulations were tested on Satsuma mandarin and grapefruit to control green and blue moulds. Formulations no. 5, 6, and 11 for both yeasts effectively controlled green mould, while only formulation no. 11 with either yeast isolate M. pulcherrima (isolate M1/1) or P. guilliermondii (isolate P1/3) effectively controlled both blue and green moulds.     

Proximity to forest edge does not affect crop production despite pollen limitation

A decline in pollination function has been linked to agriculture expansion and intensification. In northwest Argentina, pollinator visits to grapefruit, a self-compatible but pollinator-dependent crop, decline by approximately 50% at 1km from forest edges. We evaluated whether this decrease in visitation also reduces the pollination service in this crop. We analysed the quantity and quality of pollen deposited on stigmas, and associated limitation of fruit production at increasing distances (edge: 10, 100, 500 and 1000m) from the remnants of Yungas forest. We also examined the quantitative and qualitative efficiency of honeybees as pollen vectors. Pollen receipt and pollen tubes in styles decreased with increasing distance from forest edge; however, this decline did not affect fruit production. Supplementation of natural pollen with self- and cross-pollen revealed that both pollen quantity and quality limited fruit production. Despite pollen limitation, honeybees cannot raise fruit production because they often do not deposit sufficient high-quality pollen per visit to elicit fruit development. However, declines in visitation frequency well below seven visits during a flower's lifespan could decrease production beyond current yields. In this context, the preservation of forest remnants, which act as pollinator sources, could contribute to resilience in crop production. Like wild plants, pollen limitation of the yield among animal-pollinated crops may be common and indicative not only of pollinator scarcity, but also of poor pollination quality, whereby pollinator efficiency, rather than just abundance, can play a broader role than previously appreciated.