荔蝽的综合防治研究

１９９０～１９９３年间，在桂西南的左江、桃城、浪湾和武鸣４个华侨农场的荔枝龙眼果园中，进行了荔蝽的发生情况调查和综合防治研究。结果表明：（１）在试区内荔蝽每年发生一代，主要以成虫在高大的龙眼树上越冬。越冬成虫在早春气温达１５℃以上时开始活动、交尾产卵，３月下旬至４月下旬为产卵盛期，卵期９～２３ｄ不等，３～５月为种群数量最大的时期，因此荔枝龙眼的春梢、花和幼果受害严重。（２）荔蝽的主要天敌是蝽卵跳小蜂和平腹小蜂，在５月中下旬调查，保护区内这两种寄生蜂的总寄生率可高达９８．２９％，明显的控制了荔蝽的继续繁殖为害。（３）荔蝽的综合防治方案，应根据果园的生态结构，因时因地制宜，协调运用农业防治、人工防治、生物防治和化学防治等方法，着重抓好荔蝽越冬期和荔枝龙眼春梢、花果时期的防治工作。     

生长调节剂的不同配比对龙眼控梢促花效应的研究

采用“311－B”最优混合设计进行田间试验，研究多效唑、乙烯利、细胞分裂素三种生长调节剂的不同配比在龙眼控梢和促花上的效应，通过建立龙眼控梢（y^a)、促花（y^b)三元二次回归模型来寻求出三种生长调节剂在龙眼控梢、促花上的最佳浓度和配比。由回归分析结果得出，在试验条件，多效唑、乙烯利、细胞分裂素对龙眼控梢的最佳浓度和配比分别为：400.00mg/L、150.00mg/L、2.50mg/L，对龙眼促花的最佳浓度和配比分别为：494.97mg/L、185.61mg/L、0.969mg/L。     

四种钻蛀性龙眼梢、果害虫的空间分布及种群动态

在福建省农业科学院果树所资源圃，从1999到2000年对荔枝尖细蛾（Conopomorpha litchielle Bradly)、荔枝蒂蛀虫（Conopomorpha sineusis Bradly)、龙眼亥麦蛾（Hypitima longae Yang et Chen)和桃蛀螟（Dichocrocis punctiferalis Guenee)4种钻蛀性龙眼梢、果害虫的空间分布和种群动态进行调查,结果表明，4种害虫均在向南方位分布较多；荔枝尖细蛾幼虫在5、6、10月以第1代、第2代和第8代分别在龙眼枝梢上形成3个高峰期；荔枝蒂蛀虫幼虫在8、9月以第5、6、7代分别在龙眼枝梢和果穗上形成高峰期；龙眼亥麦蛾在6、7月份以第2代在枝梢和果穗上形成高峰期；桃蛀螟在8、9月份以第3、4代在龙眼成熟期数量最多。     

龙眼不同品种各营养器官多糖含量分析

分析比较了龙眼各营养器官之间、同品种不同结果母枝类型间、同品种不同植株之间、不同龙眼品种之间的多糖含量。结果表明:龙眼各营养器官皆含有多糖成分,且差异显著,依次为叶(4.575%)>新梢(1.928%)>枝条(1.644%)>根(0.918%);同一营养器官仅在不同成熟期的部分龙眼品种间多糖含量存在显著差异。     

广西荔枝龙眼冬季暖害气象指标及其时空分布研究

利用广西玉林市荔枝龙眼冬季暖害观测记录资料以及观测点同期气象资料，确定了荔枝龙眼冬季暖害气象指标；分析了广西荔枝龙眼冬季暖害的时空分布特征，并进一步提出了防御对策。     

5种龙眼梢、果害虫的时间、空间、营养生态位研究

研究了为害龙眼梢、果的5种害虫(龙眼亥麦蛾、荔枝尖细蛾、荔枝蒂蛀虫、龙眼角颊木虱、荔枝蝽)的时间、空间、营养上的一维生态位宽度和重叠,在此基础上,建立了5种龙眼梢、果害虫的时间-空间-营养三维生态位,分析了5种龙眼梢、果害虫对资源的利用相似程度.并讨论了生态位在害虫预测预报和防治上的指导作用.     

广西龙眼真菌性病害种类调查初报

根据近几年的调查，共发现广西龙眼真菌性病害14种，其中桂圆拟茎点霉菌Phomopsis guiyuan、龙眼拟茎点霉菌Phomopsis longanae、龙眼壳二孢菌Ascochyta longan、细莲格孢菌Alternaria alternata为广西首次报道，而文中描述的龙眼盘二孢菌Marssonina dimocarpi和龙眼叶点霉菌Phyllosticta dimocarpi为新种，龙眼顶多毛孢菌Bartalinia bischofiae为国内新记录种。假链格孢菌Nimbya sp．尚需进一步鉴定。     

有机复合肥对龙眼秋梢及果实品质的效应

试验探讨不同类型复合肥对龙眼秋梢及果实品质的影响,结果表明:①活力素复混肥料对秋梢及夏延秋梢的质量,表现良好的效应,与进口复合肥比较无显著的差异,可以取代进口复合肥,减少外汇支出;②活力素复混肥料对提高龙眼果实品质有极显著的作用,可作为龙眼施肥的主要肥料;③在较低用量的活力素复合肥料的基础上,增施神力钾王,能显著地提高龙眼果实的单果重。     

龙眼荔枝大幅度减产的气象原因分析及对策

树体、花序受寒（冻）害和花期高温干旱,是导致１９９６年广西龙眼荔枝大幅度减产的主要气象原因。在辐射天气条件下,若最低气温＜０℃,地面最低温＜－２℃时,幼苗和嫩梢发生不同程度的霜害;最低气温≤－２℃、地面最低温≤－４℃时,分枝和幼树主干发生霜害;最低气温≤－４℃时,大分枝甚至主干被冻死。在平流天气条件下,若全冬（１２～３月）＜１２℃的有害积寒＞８０℃·ｄ、最强一次平流积寒＞４５℃·ｄ,花序和嫩梢易受寒害死亡。花期高温干旱,使授粉受精不良,是导致果实严重败育的主要原因。针对上述问题提出了相应对策。     

龙眼钙、镁营养元素诊断技术的研究

通过对4个果园中产量高、中、低三个等级龙眼的土壤和植株养分分析，结合龙眼产量测定，探讨龙眼钙、镁营养元素的营养诊断指标。以交换性钙和交换性镁作土壤钙、镁营养元素诊断的诊断形态，以1月份时中上部老熟秋梢（结果母枝）第2位叶的全量钙、镁作为龙眼植株钙、镁营养元素的诊断形态，分别拟定出了土壤、植株钙和镁营养的诊断指标。     

龙眼鲜果剥壳力学特性

该研究试验测定龙眼鲜果的力学特性。对龙眼鲜果的压缩试验结果表明,其抗挤压能力,在各方向上具有良好的一致性,可以将其简化为各向同性、厚度均匀的薄壳球体;基于薄壳理论的分析结果表明,采用一对法向集中力,有利于龙眼果壳的均匀破裂;在对果壳进行拉伸试验过程中发现,龙眼果实沿纵向和横向的结合力都大于蒂部,由此可以推断,采用对辊摩擦法可以实现龙眼鲜果壳的剥离,为设计龙眼鲜果剥壳去核机械提供了重要依据。     

The influence of the physical attributes of a spruce shoot on momentum transfer

The drag force on fourteen three-prong spruce shoots (Picea rubens) was measured over a range of wind tunnel velocities. The boundary layer resistance to momentum transfer was found to be influenced by the shoot orientation, inclination, and flexibility. Momentum transfer was also influenced by shoot needle density; however, this influence was a function of the shoot orientation. For wind velocities below about 2.0 m s^?1, these factors did not greatly influence the momentum transfer to the shoots. For wind velocities above about 2.0 m s^?1 the momentum transfer decreased with; (1) decreasing inclination of the shoot to the airflow, (2) decreasing shoot flexibility, and (3) orientating the shoot so that the densely-needled side of the shoot faced the wind. A pair of empirical equations were derived relating momentum transfer to wind velocity.     

The effects of ryegrass roots and shoots on loess erosion under simulated rainfall

Numerous studies have demonstrated that vegetation coverage is very important to control soil erosion by water. However, the combined impacts of plant roots and shoots on soil erosion by water and the relative contributions of the roots and shoots are not clearly understood. Four rainfall simulation experiments with the rainfall intensity at 1.5 mm min^− 1 were conducted at an interval of 5 weeks to investigate the effects of ryegrass (Lolium perenne L.) shoots and roots on soil erosion and runoff reductions. Ten ryegrass planted pans and four fallow pans were prepared for the experiments. The first rainfall simulation experiment was conducted after ryegrass had been planted for 12 weeks. It showed that compared with the runoffs in the fallow pans, the runoff in the planted pans decreased 25% and 70% in the 12th week and the 27th week, respectively; and the sediment decrements amounted up to 95% in the 27th week. The results also indicated that the shoot effect on runoff reduction, accounting for over 50% except in the 27th week when the shoot affect also accounted for 44%, was relatively greater than the root effect. However, the roots contributed more to soil loss reduction than the shoots, and in particular accounted for 90% of soil loss reduction at the 27th week. Both the soil erosion rate and average infiltration rate were linearly correlated with root surface area density in cm² root surface area per unit soil volume. Ryegrass planting could improve soil physical properties, especially soil aggregate stability, which increased from 33.1% in the 12th week to 38.5% in the 27th week. The study results are probably useful in evaluating the effects of plant shoots and roots on soil erosion control.     

EDTA对铅污染土壤上芥菜生长及铅积累特性的影响

采用盆栽实验研究了EDTA对Pb污染土壤上芥菜生长及Pb积累特性的影响。结果表明,单独Pb处理对芥菜生物量没有明显的影响,但高Pb处理(2000mg kg-1 Pb)芥菜地上部含水量显著降低;Pb处理芥菜体内Pb含量随土壤Pb浓度的增加而明显增加,根系Pb含量高于地上部Pb含量;3mmol kg-1 EDTA处理能促进土壤Pb溶解,增加土壤有效Pb含量,影响芥菜的正常生长,芥菜地上部生物量下降,高Pb浓度处理比低Pb浓度处理更明显;EDTA处理14天芥菜地上部和根系Pb积累量都比不加EDTA的对照明显增加,地上部Pb总量增加到对照的13.1～80倍;EDTA处理芥菜地上部与根系Pb含量的比值上升,表明EDTA处理促进Pb向地上部运输,这种促进作用因土壤Pb浓度的不同而略有差异。     

Effect of Glomus etunicatum inoculation on aluminum,phosphorus, calcium,and magnesium uptake of two barley genotypes with different aluminum tolerance

Abstract

This study was conducted to evaluate the effect of vesicular‐arbuscular mycorrhizal (VAM) fungus Glomus etunicatum on growth, absorption, and distribution of calcium (Ca), magnesium (Mg), phosphorus (P), and aluminum (Al) in one Al‐tolerant and one Al‐sensitive barley cultivar. The plants were grown in sand daily irrigated with nutrient solution containing 0 or 600 μM Al at pH 4.8. Significant interaction (P=0.05) among variety, mycorrhiza, and aluminum (VxMxAl) were noted for both shoot and root dry matter (DM); shoot concentration and content of Al, P, Ca, and Mg; root concentration of Al, P, and Mg; and root content of Al, P, Ca, and Mg. With VAM inoculation: i) root colonization degree was about 50% in all treatment, ii) shoot DM yield increased between 30 and 70%, iii) Al concentration and content decrease down to a half both in shoots and roots of sensitive barley, iv) Ca concentration in shoots of sensitive barley showed a high increase at 600 μM Al, and v) P concentration and content in shoots of both varieties increased significantly.     

Genotypic Difference in Arsenic and Cadmium Accumulation by Rice Seedlings Grown in Hydroponics

Genotypic differences in arsenic (As) and cadmium (Cd) uptake and their translocation within rice seedlings grown in solution culture were investigated. Arsenic uptake and its translocation differed significantly between eight cultivars. The largest shoot and root As concentrations were found in cultivar ‘TN1’ and ‘ZYQ8’, while cultivar ‘JX-17’ had the lowest As concentration. Arsenic concentration in shoot or root of ‘JX-17’ was about 50% of that in cultivar ‘ZYQ8’. Specific Arsenic uptake (SAU) was found significantly different between rice cultivars, which was about 2-fold higher of ‘ZYQ8’ than that of ‘JX-17’. The Cd accumulation also differed significantly between cultivars. Rice cultivar ‘JX-17’ had the highest ability in Cd uptake, but the lowest ability in Cd translocation from root to shoot. The transfer factor (TF) of Cd had an important effect on Cd accumulation by rice seedlings. Arsenic can competitively inhibit P uptake by rice seedlings, P concentrations in shoots, or roots treated with As were significantly lower than those without As addition. However, the concentrations of P and As were positively correlated within these genotypes. The Cd immobilization by cell wall was an important mechanism for Cd detoxification. The cell wall bound 21–44% of total Cd in shoots and 25–59% of total Cd in roots of these tested genotypes. The genotypic differences in As and Cd uptake and translocation within rice seedlings provide the possibility of selecting and breeding genotypes and /or cultivars with reduced levels of As and Cd in rice grains.     

Gradient differences in soil metal solubility and uptake by shoots and roots of wheat (T. aestivum)

The aim of this research was to identify and quantify gaps in currents methods and models for predicting the plant availability of selected nutrient and contaminant metals (Cu, Ni, Zn, Cd) in soil. This study investigated relationships between the relative solubility of Cu, Ni, Zn, and Cd determined by six extraction methods with short-term uptake by shoots and roots of wheat (Triticum aestivum). For Cu, Ni, and Cd, relationships between solubility and plant uptake were found to be different for shoots and roots, with Cu and Ni solubility being more closely correlated with root uptake compared with shoot uptake. Correlation coefficients for Cd concentrations in shoot and root tissue for all six solubility methods were poor (r ²?<?0.5), while corresponding results for Zn explained more than 50 % of shoot variation but less than 50 % of root variation. Soil Cu solubility explained up to 85 % of variation in root uptake compared with 42–55 % for shoot uptake. These results clearly demonstrated that purely chemical and passive diffusion mechanisms were inadequate predictors of Cd uptake by shoots and roots, together with Cu uptake by shoots. Thus further attempts at refining soil metal bioavailability assays based solely on chemical extraction without consideration of plant responses are unlikely to improve prediction of plant uptake.     

The mutual interference of spruce canopy structural elements

The drag force on fourteen three-prong spruce shoots (Picea rubens) has been measured in a wind tunnel in velocities ranging from 0.4 to 4.5 m s^?1. The influence of wind velocity and shoot needle density on momentum transfer and the mutual interference to momentum transfer are evaluated.The influence of the shoot needle density (ranging from 0.6 to 1.7) on momentum transfer is velocity dependent. The shoot needle density does not influence the momentum transfer to the shoot when the wind velocity is less than about 1.5 m s^?1. However, a slight trend of increased momentum transfer to the shoot with decreased shoot needle density was found for wind velocities between 1.5 and 4.5 m s^?1. This trend is not statistically significant.The shelter factor, a measure of the mutual interference to momentum transfer to the shoot structure, is shown to be dependent on the model used to describe the flow around and through the shoot. This suggests that any apparent velocity dependence of the shelter factor may actually be due to a change in flow conditions. It is concluded that: (1) the needles are the vegetative component involved in mutual interference within the shoot for wind speeds between 0.4 and 1.5 ms^?1, and (2) the shoots themselves are the vegetative component involved in mutual interference within a shoot array for wind speeds between 1.5 and 4.5 ms^?1. The shelter factor at the low wind speeds is estimated to be 2.1 The shelter factor at the higher wind speeds should be based on interference between shoots and not between needles within a single shoot.     

荔枝瘿螨的为害及其防治方法

荔枝瘿螨在南宁地区每年出现二个虫口高峰,第一个高峰在5～6月;第二个高峰在9～10月。其为害引起落花、落果,着果率降低,被害枝着果率仅为健枝的42.4%,受害果重量减少10%～16%。新梢未萌发之前,螨体大部分集中在被害梢毛瘿内,其中又以鲜褐色毛毡螨量最多,其次为褐色毛毡。过冬瘿螨多群集在被害的夏梢及秋梢毛毡上。当新梢萌发刚露白时,瘿螨即从被害梢毛毡转移至新芽上。基于这一习性,在荔枝树未发新芽前剪除害梢是防治该螨的有效方法,较适合于幼树。药剂防治最好在新梢萌发时进行。