激素浸种对薄壳山核桃种子萌发的影响及其种子吸胀过程中SOD和POD活性变化

薄壳山核桃﹝Carya illinoinensis ( Wangenh.) K. Koch﹞为胡桃科( Juglandaceae)山核桃属( Carya Nutt.)植物,又名美国山核桃、长山核桃,是世界上著名的经济树种之一[1-2]。目前,主要采用本砧嫁接的方法培育薄壳山核桃良种嫁接苗,而培育优质实生苗作为砧木是该技术的关键环节之一,因此,了解其种子萌发特性极为重要。目前,对薄壳山核桃种子萌发特性的研究主要集中在植物激素催芽方面[3-5],而有关激素催芽过程中的适宜浸泡天数、种子吸胀过程中相关的酶活性变化等问题尚不明确。     

Proline and Oxidative Metabolism in Young Pecan Trees Associated with Sulphate Accumulation

Pecan [Carya illinoinensis (Wangenh.) K. Koch.] is a deciduous tree whose fruits (nuts) are of high economic value and offer excellent nutritional benefits. However, soils high in sulphates can limit its growth and development. Working with 5-year-old trees of ‘Western Schley’ pecan grown in soils high in sulphates, the levels of proline and oxidative metabolism were recorded in the leaflets. Results showed that different levels of visible leaflet damage (‘sufficiency’, ‘low’, ‘moderate’ or ‘severe’) were associated with different levels of leaflet sulphates (mg kg⁻¹): ‘sufficiency’ (≤40), ‘low’ (41–60), ‘moderate’ (61–80) and ‘severe’ (80–100). ‘Severe’ sulphate damage was associated with significant reductions in chlorophyll (TChl) (17.04 μg g⁻¹), relative water content (RWC) (50%) and leaf area (LA), and with increases in the concentrations of total carotenoids (TC) and proline (Prl). Increases were also observed in the activities of the oxidative metabolism enzymes: superoxide dismutase (SOD) (1.82 units min⁻¹ g⁻¹), catalase (CAT) (2.86 μmol H₂O₂ min⁻¹ g⁻¹) and antioxidant capacity (AC) (87% DPPH inhibition). However, guaiacol peroxidase (GP) showed a reduction (2.97 nmol GSH min⁻¹ g⁻¹). An inverse relationship was found between the sulphate concentration in the leaflets with respect to the evaluated parameters of TChl, TC, RWC, LA, AC, and GP. Proline synthesis and antioxidant enzymatic activity indicate salt stress in pecan leaflets in orchards irrigated with deep-well water high in sulphates.     

Host‐associated genetic differentiation in pecan leaf phylloxera

Host‐associated differentiation (HAD) is the formation of genetically distinct host‐associated populations. One of the genotypic signatures of HAD is that populations exhibit stronger differentiation by host‐plant species than by geographic isolation. HAD, as a mechanism promoting ecological speciation, has been invoked to explain phytophagous insect diversity. Two traits proposed to promote HAD are endophagy and parthenogenesis. Using amplified fragment length polymorphisms (AFLPs), we tested for the presence of HAD in pecan leaf phylloxera, Phylloxera notabilis Pergande (Hemiptera: Phylloxeridae), an endophagous, gall inducing, and cyclically parthenogenetic insect on sympatric pecan and water hickory at a geographic mesoscale. This species shows strong HAD. Whereas the effect of collecting site was significant, accounting for 7.3% of molecular variation, host‐plant species identity accounted for 63.5%. In addition, a choice test indicated that pecan leaf phylloxera originating from water hickory showed weak but significant preference for leaflets of the natal host, whereas pecan leaf phylloxera originating from pecan did not. This is the first such study of a species of arboreal Phylloxeridae, a poorly known insect group. This is also the first endophage and the second parthenogen shared by these two hickory species to show evidence of HAD. This hickory system could be a good parthenogen‐rich counterpoint to the goldenrod system in the study of HAD in insect communities.     

蜘蛛病原真菌一新种

虫壳属一新种大别山虫壳（Ｔｏｒｒｕｂｉｅｌａｄａｂｉｅｓｈａｎｅｎｓｉｓ）及其同时在蛛体上并存的无性型大别山球束梗孢（Ｇｉｂｅｌｕｌａｄａｂｉｅｓｈａｎｅｎｓｉｓ）。子囊壳表生至浅埋生,孔口黄色,子囊孢子弹射后呈波浪形弯曲。次生子囊孢子长柱形,９．４～１５．１×０．７～１．２μｍ。孢梗束单个或两个,白色,在其２／３处仍有分生孢子梗。分生孢子梗长２７～４４μｍ,光滑。分生孢子纺锤形,３．２～４．０×１．１～１．８μｍ。具糙梗孢式的共无性型方式,分生孢子线形,１１．０～２０．０×０．７～１．１μｍ。列出了该属已知种的检索表,并分别命以中名     

山核桃林集约经营过程中土壤有机碳和微生物功能多样性的变化

研究集约经营时间为5、10、15、20 a山核桃林的土壤有机碳和微生物功能多样性的演变规律.结果表明: 天然混交林改造为山核桃纯林并经强度经营后,林地土壤有机碳(TOC)、微生物生物量碳(MBC)、水溶性有机碳(WSOC)含量显著下降,但有机碳库的稳定性增强.与天然山核桃 阔叶混交林(0 a)相比,经过5 a的强度经营,TOC、MBC、WSOC含量分别下降28.4%、34.1%和53.3%,20 a后分别下降38.6%、48.9%和64.1%,土壤有机碳组分中的芳香碳、酚基碳和羰基碳比例提高,芳香度提高了23.0%.山核桃的强度经营降低了土壤微生物功能多样性,0、5 a与10、15、20 a土壤微生物活性的平均颜色变化率(AWCD)值差异显著,Shannon指数(H)和均匀度指数(E)在0、5 a与15、20 a间差异显著.林地土壤TOC、WSOC、MBC、AWCD、H和E等6个指标两两之间均显著相关.     

New fossil fruits of Carya (Juglandaceae) from the latest Miocene to earliest Pliocene in Tennessee,eastern United States

Fossil fruits including nuts and associated husk valves of a new species of Carya (Juglandaceae) are described from the latest Miocene to earliest Pliocene in northeastern Tennessee, eastern United States. The husk valves are elliptic, 1.2–4.5 mm thick, with a convex exterior face and a concave interior face; the nuts are globose to ovoid in shape, smooth and longitudinally ribbed on exterior surface, with a short protruding apex and a slightly 4-angled base; inner ribs, lacunae and primary septa are well-developed, while secondary septa are absent or weakly developed. The combination of these carpological characteristics clearly shows a close resemblance to the genus Carya in Juglandaceae. Detailed comparisons of carpological morphology and anatomy indicate that the present fossil taxon is different from both living and most other fossil species of the genus, and therefore warrants the designation of a new fossil species, Carya tennesseensis Huang et al., sp. nov. Carya tennesseensis displays a carpological similarity to C. ventricosa from the late Oligocene to early Pliocene in Europe, suggesting a potential species exchange of the genus between Europe and southeastern North America during the late Neogene. The new fossil species represents one of the few fruit fossil species of Carya from its modern distribution range in southeastern North America. It provides crucial information for better understanding the rapid diversification of the genus from the late Miocene to early Pliocene, and the origin and establishment of today's Carya biodiversity in this region.     

76株薄壳山核桃实生单株的果实品质差异及综合评价

对南京地区种植的76株薄壳山核桃〔Carya illinoinensis(Wangenh.)K.Koch〕实生单株的8项果实性状和种仁中5种脂肪酸含量的差异以及各指标的相关性进行分析,并筛选出单项性状优良的单株;在此基础上,结合主成分分析结果,对供试76株单株的果实品质进行综合评价.结果显示:8项果实性状(包括坚果质量、种仁鲜质量、坚果壳厚度、坚果纵径、坚果横径、果形指数、出仁率和含油率)以及种仁中5种脂肪酸(包括棕榈酸、硬脂酸、油酸、亚油酸和亚麻酸)的含量均有较大变异,变异系数为663%~2899%,其中,出仁率的变异系数最小,亚麻酸含量的变异系数最大,8项果实性状的变异系数总体上小于5种脂肪酸含量的变异系数.部分果实性状间极显著或显著正相关,少数果实性状间极显著或显著负相关,而5种脂肪酸含量间均极显著正相关,但脂肪酸含量与果实性状间总体上无显著相关性.主成分分析结果表明:在8项果实性状中,与坚果大小有关的性状较为重要;而5种脂肪酸含量均同等重要.对果实性状和脂肪酸含量的主成分分析结果显示:第1主成分的决定指标包括含油率以及棕榈酸、硬脂酸、油酸、亚油酸和亚麻酸的含量,第2主成分的决定指标包括坚果质量、种仁鲜质量、坚果壳厚度和坚果横径,说明薄壳山核桃果实评价的首要指标为种仁中脂肪酸含量,其次为果实大小.在利用坚果质量、种仁鲜质量、坚果壳厚度、出仁率、含油率、果形指数、油酸含量和不饱和脂肪酸含量8个单项指标优选单株的基础上,结合主成分分析结果,71号单株的综合得分较高,其种仁鲜质量、含油率以及油酸和不饱和脂肪酸的含量均较高,可作为优良品种选育的首选候选单株.根据上述研究结果,建议在薄壳山核桃不同育种目标的优良品种选育工作中,将主成分分析法作为单项性状筛选法的有效补充方法.     

AFLP analysis of variation in pecan somatic embryos

Before somatic embryogenesis can be applied, the genetic fidelity of cultures needs to be determined. Problematic of tissue-cultured woody species is the extensive evaluation time needed for assessments. The development of methods whereby plants could be rapidly screened for potential tissue culture-derived genetic changes would be very valuable. We evaluated the applicability of AFLP (amplified fragment length polymorphism) analysis for the assessment of genetic variability in somatic embryos of pecan [Carya illinoinensis (Wangenh.) C. Koch] and made comparisons between and within embryogenic culture lines. AFLP readily detected differences between culture lines, with 368 polymorphic loci identified. Individual culture lines generally produced somatic embryos with similar overall banding patterns. Embryos derived from the same culture line generally grouped together in a phenogram generated by UPGMA (unweighted pair-group method, arithmetic average) analysis. However, a few somatic embryos exhibited higher levels of polymorphism and failed to group with others regenerated from the same line. The relation between the detected within-line differences and their contribution to phenotypic variation is yet to be determined. Received: 9 September 1998 / Revision received: 12 November 1998 / Accepted: 8 December 1998     

生草栽培对山核桃林地土壤养分及微生物多样性的影响

高强度经营导致山核桃林地土壤性质改变,设置了白三叶、黑麦草、油菜、紫云英、自然杂草和清耕(对照)6个处理,以3次重复,随机排列的2年田间试验,研究了不同生草栽培对山核桃林地土壤养分和微生物多样性的影响。结果表明:与清耕相比,生草栽培均能改善土壤养分状况,除全钾外,白三叶和紫云英处理较其他处理能显著提高土壤养分含量,其余几个处理间差异不明显;生草栽培显著提高了土壤微生物生物量碳(MBC)含量,白三叶、黑麦草、紫云英、油菜和自然杂草处理分别较清耕提高了169.6%、159.7%、144.1%、138.6%和58.6%,差异达显著水平(P0.05)。6种不同处理的土壤微生物活性(AWCD)、微生物Shannon指数和均匀度指数均存在明显差异。不同处理的土壤AWCD为白三叶紫云英油菜自然杂草黑麦草清耕;白三叶处理的土壤微生物Shannon指数高于其他处理;白三叶、紫云英和油菜处理的土壤微生物均匀度指数显著高于其他处理。相关性分析表明,土壤微生物活性、微生物Shannon指数和均匀度指数两两之间均达到极显著差异(P0.01),三者与土壤各养分指标之间未达显著差异,但表现为正相关关系。白三叶、紫云英和油菜对改善土壤微生物特性效果较好。     

不同修剪措施对薄壳山核桃枝条生长及枝条和叶片碳氮代谢物积累的影响

以薄壳山核桃品种‘马罕’（Caryaillinoensis‘Mahan’）的5年生嫁接苗为实验材料,研究枝条短截（1/4、1/3和1/2短截）以及枝条和主干的环剥和环割对其枝条生长及枝条和叶片中碳氮代谢物积累的影响。结果显示：经不同程度短截处理后,枝条萌芽率均显著高于对照（未经任何修剪）,新枝的数量、长度和直径也均不同程度高于对照,而比叶质量及叶绿素含量总体上与对照无显著差异;经1/2和1/3短截处理后,长度0-10cm和30cm以上的新枝比例明显提高;枝条和叶片中可溶性糖含量和C/N比均高于对照、全N含量均低于对照,枝条中淀粉含量低于对照而叶片中淀粉含量高于对照。经枝条环剥和环割处理后,枝条萌芽率和比叶质量均高于对照但无显著差异,枝条平均长度增长量和叶绿素含量均显著低于对照、枝条平均直径增长量均显著高于对照;枝条和叶片中可溶性糖和淀粉含量以及C/N比均高于对照,全N含量均低于对照。经主干环剥和环割处理后,枝条的萌芽率和平均直径增长量以及比叶质量均显著高于对照,枝条平均长度增长量和叶绿素含量均显著低于对照;枝条和叶片中可溶性糖和淀粉含量以及C/N比均高于对照,枝条中全N含量高于对照而叶片中全N含量则低于对照。此外,品种‘马罕’的结果枝长度为0-30cm,其中长度0-10cm的结果枝数量最多。研究结果表明：不同短截措施均能提高薄壳山核桃的萌芽率、促进新枝伸长和增粗;而枝条和主干的环剥和环割处理对枝条萌芽率无明显促进作用,但有利于枝条增粗;不同修剪措施总体上有利于其叶片及枝条中碳水化合物的合成和积累。总体上,1/3短截及枝条和主干的适度环剥可促进品种‘马罕’结果枝的形成。