影响市区樟树黄化病的主要因素研究

对合肥市区樟树黄化病与立地条件关系进行了调查研究,并对不同程度的病株叶片营养成分进行了分析,结果表明:樟树黄化原因复杂多样,主要原因是pH值过高导致土壤中的有效铁不能被根系吸收;其他原因如地表水泥覆盖过度、土壤密度过大、污染严重、土壤营养条件不良等因素构成.在土壤矿质元素中,黄化程度与速效K、B、Cu、Zn的含量呈正相关;与有机质、有效Fe、速效N、速效P、Mn等元素含量呈负相关.在樟树叶片营养元素中,速效N、Zn、Fe和Mn含量随着黄化程度的增加而下降;S、Ca、B和Cu的含量随着病害的加重而增加.     

Genetic diversity among coconut varieties for susceptibility to Cape St Paul Wilt Disease

The CSPWD is the Ghanaian form of lethal yellowing disease (LYD) of coconut, caused by a phytoplasma and has been active in Ghana since 1932. The paper updates the results of screening trials conducted with 38 pure and hybrid coconut varieties since 1981. Although no variety was found totally resistant, a wide range of susceptibility level was observed: almost all SGD were still unaffected, while the local WAT had almost totally disappeared, additive values were calculated for the parental varieties and it was shown that, in the average, hybrids are slightly more susceptible than predicted by a purely additive model. According to this genetic model, the SGD × VTT hybrid will be appreciably less susceptible than the MYD × VTT currently being used for replanting devastated farms in Ghana. Our results tend to confirm the general trend that cultivars from the Pacific group (especially the Dwarfs) are less susceptible than the Indo-Atlantic cultivars. Proposals are made to adapt planting material to the risk level. Genetic control can only be efficient if it is considered as a link in a chain of control measures involving the choice of a proper planting site, good management and early eradication of diseased trees.     

土壤中有毒物质对宿根甘蔗苗期黄化的效应研究

为探明宿根甘蔗(Saccharum officinarum L.)发生黄化的原因,遏制黄化现象的蔓延,对宿根甘蔗苗期发生黄化较严重的产地进行实地调查,并采样分析各产地宿根正常苗种植地、宿根黄化苗种植地和新植蔗苗种植地的甘蔗根系、叶片与土壤的各项生理生化指标。结果表明,宿根黄化苗种植地的土壤酚酸含量高于宿根正常苗种植地和新植蔗苗种植地,宿根甘蔗黄化苗的根系细胞严重受损,根系细胞膜透性显著高于宿根甘蔗正常苗和新植蔗苗,根系活力弱;叶片活性铁含量、硝酸还原酶活性和叶绿素含量则低于正常苗和新植苗。说明长期连作导致土壤酚酸类有毒物质大量积累,甘蔗根系中毒,根系受损细胞膜透性增大,大量内容物外渗,死亡的根细胞残体和根系分泌物又加速有毒物质的积累;而植株吸收过量的锰和铝后,降低了甘蔗叶片的硝酸还原酶活性,抑制了甘蔗正常的氮代谢;植株发育不良对新根的萌发和生长也不利,造成植株体内铁锰比例失衡,阻碍宿根甘蔗对铁的吸收与活化,最终宿根甘蔗幼苗因缺铁而出现黄化。     

不同外源激素处理对难落黄烟叶落黄效果及烘烤效果的影响

[目的]解决红花大金元上部叶难落黄、不易烤的问题.[方法]通过进行不同激素处理,研究其落黄、烘烤效果.[结果]喷施乙烯利600～ 800倍液浓度,促进红花大金元品种烟叶上部叶的落黄成熟效果最好,喷施72 h后进行采收最佳;使用乙烯利熏蒸烘烤烟叶,烘烤效果最好,能够有效促进烟叶变黄,缩短烘烤时间,降低燃料和电力消耗量,从而降低烘烤成本.[结论]使用乙烯利喷施或熏蒸烘烤烟叶,难落黄烟叶落黄效果及烘烤效果均较好.     

脐橙果实脐部黄化过程iPAs和ZRs浓度的变化

朋娜和纽荷尔脐橙在脐黄初发期,初生果内源ｉＰＡｓ浓度出现低谷,进入脐黄主要发生期后又上升,但纽荷尔上升较朋娜慢,朋娜次生果内源ｉＰＡｓ浓度明显高于初生果,不出现低谷;纽荷尔次生果内源ｉＰＡｓ浓度随初生果出现低谷,但其浓度仅在脐黄后期高于初生果。朋娜和纽荷尔初生果和次生果内源ＺＲｓ浓度一般在ｉＰＡｓ浓度的１／１０以下,其浓度变化规律与ｉＰＡｓ基本相同。     

番茄抗黄化曲叶病材料引进及评价

为了筛选出抗Ty番茄资源,对引进分离纯化的15份番茄材料进行观测与评价。结果显示,有4份材料表现为高抗,7份材料表现为中抗,3份材料表现为抗,1份材料表现为感。试验结果为聚合优良基因和培育适应福建种植的优良新优品种提供了理论依据。     

烘烤过程中变黄条件对烤烟淀粉代谢的影响

【目的】探讨烘烤过程中变黄条件对烤烟淀粉代谢的影响。【方法】采用河南农业大学设计制造的电热式温、湿度自控烤烟箱对供试烟叶进行烘烤,设置不同的变黄温度、变黄时间和凋萎时间,研究烘烤过程中变黄条件对烤烟淀粉代谢的影响。【结果】随着烘烤的进行,淀粉酶活性迅速升高,变黄时间延长比正常烘烤处理淀粉酶活性达到高峰的时间推迟了12 h,且烤后烟叶淀粉含量低于正常烘烤处理;较高的变黄温度能促使烟叶中的淀粉在烘烤前期快速降解,但后期淀粉降解停滞的时间较早,最终淀粉含量较高;在42℃延长凋萎时间,烤后烟叶淀粉残留量低。淀粉同工酶电泳胶板上明显可见有3条酶带,分别为α-淀粉酶、β-淀粉酶、R-淀粉酶,其中β-淀粉酶活性最高。电泳图谱显示,各同工酶活性0 h时没有差异,24 h时高温处理的活性稍高于低温,36 h时高温变黄比低温变黄酶活性稍低。【结论】烘烤过程中在35~38℃变黄,并在烟叶变黄后延长12 h和在42℃条件下凋萎12 h,有利于淀粉降解和烟叶品质改善。     

Magnesium- und Calcium-Ernährung von Hochlagenfichten —Vergilbungszustand und Reaktion auf unterschiedliche Düngung

Magnesium and calcium nutrition of spruce on high altitude sites — yellowing status and effects of fertilizer application On the ARINUS experimental sites in the Schwarzwald (SW Germany) since 1987 the mineral nutrition of Norway spruce was investigated using various experimental fertilizer treatments. The studies were focused on the nutrient Mg as acute Mg deficiency symptoms were observed at the beginning of the experiments. Treatments with ammonium sulfate, kieserite and dolomitic limestone were carried out to achieve an experimental modification of the Mg supply. In this paper, results on yellowing status, long-term foliar analysis, and data on the binding forms of Mg and Ca in the needles are presented. By application of Mg containing fertilizers the Mg nutrition of the trees could be markedly improved. Thus, deficiency symptoms disappeared. Kieserite application resulted in the fastest response of foliar Mg concentrations. In contrast to Mg, Ca deficiency could not be observed. The results of the (NH₄)₂SO₄ application show that high N input in ecosystems can amplify latent deficiency of mineral elements. Recently on many sites the risk of nutrient imbalances has developed as a consequence of improved N supply due to deposition. Thus, nutritional and site specific aspects should be payed more attention when liming and fertilization measures are planned. A higher percentage of deep rooting tree species as beech and fir could be useful for stabilizing mineral nutrition of forest canopies.     

烘烤和变黄后期变黄程度对烟叶中游离氨基酸含量的影响

就烘烤和变黄后期不同变黄程度对烤后烟叶中游离氨基酸含量的影响进行了研究.结果表明:烘烤能使烟叶中游离氨基酸含量总量大幅度增加,烤后可比烤前增加1.1倍,这种变化主要发生在变黄期,且与变黄后期烟叶变黄程度有关,表现在,随着烟叶变黄程度的提高,多数游离氨基酸和游离氨基酸总量明显提高,但丝氨酸和蛋氨酸含量减少,甘氨酸、半胱氨酸和丙氨酸几乎不受影响.认为烘烤上部烟叶时,应在40～42 ℃耐心烘烤,充分变黄,为定色期香气物质合成提供更多的前体物质.     

Molecular cloning and characterization of disease-resistance gene candidates of the nucleotide binding site (NBS) type from Cocos nucifera L

In this study, degenerate primers were used to amplify nucleotide-binding site (NBS)-type sequences from coconut ecotypes either resistant or susceptible to lethal yellowing. Genomic DNA fragments of approximately 500–700 bp were obtained and sequenced. Phylogenetic analysis of these fragments revealed that they clustered in seven different clades. We also found that all CnRGC sequences were grouped within the non-TIR-NBS-LRR subclass of NBS-LRR genes. The expression analysis revealed changes in expression profiles in response to salicylic acid (SA) and a constitutive expression profile in plants untreated with SA. This is the first large scale analysis of NBS-type sequences in coconut palm.