酒泉胡杨林的数量分类和排序

本文应用ＴＷＩＮＳＰＡＮ等级分类和ＰＣＡ，ＤＣＡ排序技术对甘肃酒泉地区的天然胡扬林分进行了分类和排序，并将排序的结果与环境因子之间进行了回归分析。结果表明，（１）甘肃酒泉地区的胡杨天然林分可以被划分为４个类型，这四个类型在生长更新状况及生境条件方面存在着较显著的差异，而在林分的龄级结构上并无显著区别．（２）酒泉地区胡杨生长的主要限制因子是地下水位，水矿化度，土壤总盐量及ＣＬ￣－含量，ＰＨ值不是影响胡杨林生长的主要限制因子。而气候因子对酒泉地区胡杨林的影响并不大。     

额济纳胡杨林生长规律及生物生产力的研究

本文利用34块胡杨林标准地获得的林分数量及质量指标,对额济纳胡杨林的生长规律和生物生产力及其与生态因子之间的关系进行了研究。结果表明胡杨生长具有明显的阶段性,不同的生态因子对胡杨的生物生产力具有不同的影响。     

黑河下游胡杨林耗水规律研究

2003年5-10月,对黑河下游额济纳绿洲中一块25年生的胡杨林耗水进行了研究,结果表明通过标准木的标准比导率和树木胸径和边材面积的相关模型,可以比较准确地推算出林分的蒸腾耗水量。胡杨林的蒸腾耗水量具有明显的季节差异;胡杨幼林在生长季节耗水量为213.4mm。林分的生长状况主要受地下水位和土壤含水量的影响。     

酒泉绿洲天然胡杨林主要生长季对全球气候变化的响应

利用酒泉绿洲胡杨林分布区所辖4个气象站点1955-2010年的平均气温观测资料,采用气候倾向率、ArcGIS反距离加权差值、Mann-Kendall非参数统计检验等方法,对该区天然胡杨林主要生长季的时空变化特征及其对全球气候变化的响应进行分析。结果表明：近56 a来,研究区胡杨有生长期初日提前,终日推后,年生长期延长以及叶黄初日推后的趋势,且提前和推后幅度自20世纪90年代以来变化明显。空间分析表明：胡杨林主要生长季变化有一定规律性,生长期初日提前幅度依次为：鼎新＞玉门＞瓜州＞敦煌;生长期终日推迟的幅度为：鼎新＞玉门＞敦煌＞瓜州;年生长期延长的幅度为：鼎新＞玉门＞敦煌＞瓜州;叶黄期初日推迟幅度依次为：鼎新＞敦煌＞玉门＞瓜州。Mann-Kendall突变表明：研究区胡杨的生长期初日、终日以及叶黄期初日均存在多个突变,且突变年份多滞后气温突变年份。由此可见,研究区胡杨对气候变化响应较为敏感。     

不同时间尺度环境因子对黑河下游胡杨(Populus euphratica)径向生长的影响

本研究以黑河下游额济纳旗成熟的河岸胡杨林为对象,分析不同年龄胡杨(Populus euphratica)的年轮宽度序列与不同时间尺度环境因子的关系。结果表明:①在年尺度上,气温是影响胡杨径向生长的主要因子,但不同年龄胡杨对气温的响应有所不同。②在季节尺度上,休眠季气温越高越有利于壮龄胡杨的径向生长,而生长季气温越高越不利于老龄胡杨的径向生长。③在月尺度上,前一年3月和当年9月的平均气温越高,对壮龄胡杨的径向生长越有利,而当年10月平均气温越高,对老龄胡杨的径向生长越不利;前一年7月径流量的增加对老龄胡杨的径向生长有利,而当年2月径流量的增加对壮龄胡杨径向生长有利。综上所述,在季节和年等相对较长的时间尺度上,气温是影响胡杨径向生长量的主要因素,随着时间尺度的缩小,胡杨对环境因子的响应更为细化,并且表现出一定的滞后效应。径流量作为重要的环境因子在月尺度上才突显出来,前一年7月和当年2月的径流补给对胡杨径向生长有极大的促进作用。因此,在黑河统一调度管理过程中,可通过适度调增2月和7月洪水的下泄量来满足胡杨径向生长对水分的需求。     

旱梯田果园间作对土壤和果树的影响

连续三年研究结果表明，旱梯田果园间作，在干旱时段降低土壤水分（8．3％－33．8％），湿润时段增加土壤水分（9．2％－40．8％），不同间作物种类增减程度有差异；使土壤生物活性增强，NO3－N含量降低，NH4－N仅洋芋处理增高显著；间作物根重与果树很重及地上部生长成反比；间作均影响果树生长，以牧草无芒雀，百脉根抑制最强大，大豆一花生－草水樨次之，洋芋－谷子－糜子影响最小，且经济效益好，可作为该地区同类果园间作的参考模式。     

小麦雪霉叶枯病产量损失研究

人工接种试验结果表明，雪腐格氏霉引起小麦成株期叶枯、鞘枯和穗腐。鞘枯使小麦穗粒重减少０．８％～３２．９％，千粒重降低９．５％～１６．９％；穗腐使小麦穗粒重减少９．６％～３９．８％，千粒重降低７．８％～１７．９％；鞘枯－穗腐复合症状使穗粒重减少１０．２％～６５．２％，千粒重下降９．５％～１４．８％，叶斑－鞘枯－穗腐使粒重减少１１．７％～５１．５％，千粒重下降１２．１％～１８．３％。     

克·多·酮种衣剂的分析方法研究

本文用气相色谱２％ＯＶ－１玻璃柱，ＦＩＤ检测器，１６０～２００℃程序升温分析测定了１７％克·多·酮种衣剂中的克百威和三唑酮；用薄层－紫外法测定了多菌灵的含量。克百威、三唑酮和多菌灵的变异系数分别为１．３６％，２．１３％和０．９６％，平均回收率分别为９７．８％，９８．９％和９８．５％。     

塔里木河下游阿拉干断面胡杨林空间分布特征及其影响因素

通过小尺度生态监测与遥感数据分析获取塔里木河下游荒漠河岸林现状信息,集中对阿拉干断面设立的100hm2长期监测样方内的胡杨树进行了详细的调查,对该断面胡杨林空间分布特征及其影响因素进行了分析。研究结果表明：塔里木河下游的胡杨具有伴河生长的特性;随着离河距离的增加,胡杨株数呈递减趋势;大部分胡杨主要分布在离河道200m范...     

额济纳胡杨林生态效益评价及保护对策探讨

胡杨是古地中海残遗植物种 ,胡杨林生态系统在绿洲演替与发展的不同阶段发挥着主要作用。额济纳胡杨林是我国第二大胡杨林 ,是维系额济纳绿洲存在的重要天然屏障。本文通过对胡杨林生态效益的评价 ,提出胡杨林不仅在生态系统方面有重要作用 ,而且对当地及周边地区的经济、社会发展也有不可替代的作用。并对当前胡杨林存在的问题 ,利用保护生物学和恢复生态学加以研究 ,为胡杨林的保护提出一些措施。     

4种剂型噻虫胺对柑橘木虱的田间防治效果

2018年-2019年,采用田间小区试验评价了噻虫胺4种剂型(30％悬浮剂、18％包埋颗粒剂、13.5％壳聚糖微球和0.5％颗粒剂)及2种施用方式(喷雾和沟施)对柑橘木虱的防治效果.结果 表明:叶面喷施30％噻虫胺悬浮剂60 mg/kg处理对幼年树及成年树上柑橘木虱的控制效果好且持效期约30 d,而药后46～96 d的...     

Causes of incipient rot and rot in regrowth Eucalyptus diversicolor (karri) trees

Eucalyptus diversicolor (karri) is the second most important commercial timber tree in Western Australia. Sawlogs from regrowth trees often have a discoloration in the heartwood that is more abundant than in sawlogs from mature trees. Other symptoms in regrowth logs include white rot, white pocket rot and brown rot. Fungal isolations and pathogenicity tests were conducted to determine whether this discoloration was incipient rot, and if so, what caused it and which rot(s) would eventually develop. A combined sample of 329 discs from recently felled trees and freshly cut scantling had discoloration in 48%, white rot in 14%, white pocket rot in 12% and brown rot in 4% of pieces of wood. Hymenochaete semistupposa was isolated from 22% of discoloured wood and 39% of white pocket rot samples. Stereum hirsutum was isolated from 4% of discoloured wood and 13% of white rot samples. Koch's postulates in regrowth karri trees showed that H. semistupposa caused extensive discoloration, with white pocket rot developing in the heartwood within 4 years, while S. hirsutum caused extensive discoloration, with white rot developing in both the heartwood and sapwood within 2 years. It was concluded that the discoloration was incipient rot, which would eventually develop into either white rot or white pocket rot.     

Enhancement of Postharvest Disease Resistance in Ya Li Pear (Pyrus bretschneideri) Fruit by Salicylic Acid Sprays on the Trees during Fruit Growth

The Ya Li pear (Pyrus bretschneideri) trees were sprayed three times with 2.5 mM salicylic acid (SA) around 30, 60 and 90 days after full flowering. The fruit were harvested at commercial maturity (about 120 days after full flowering), inoculated with Penicillium expansum, and incubated at 20 °C, 95–100% RH. The results showed that resistance to the pathogen of the mature pear fruit was remarkably enhanced by the SA sprays. Disease incidence in the SA-treated fruit was 58.0% or 26.5%, and lesion diameter on SA-treated fruit was 58.4% or 29.0% lower than that in/on fruit without SA treatment (control) on day 12 or 17 after incubation, respectively. The SA spray applied to the trees around 30 days after full flowering notably enhanced accumulation of hydrogen peroxide in the young fruit. Meanwhile, activities of defense enzymes, including peroxidase, phenylalanine ammonia-lyase (PAL), chitinase or β-1,3-glucanase in the young fruit from SA-treated trees was 29.5%, 60.0%, 24.4% or 35.7% higher than that in the control fruit 4 days after the SA spraying. Furthermore, after harvest, activities of PAL, chitinase and β-1,3-glucanase were still significantly higher in the mature pear fruit from the trees sprayed three times with SA than those of the control fruit. Activities of the antioxidant enzymes including catalase and ascorbate peroxidase in the young fruit were significantly reduced by SA spraying. However, the activity of another antioxidant enzyme, glutathione reductase in the young fruit was significantly enhanced by SA spraying. These results suggest that enzymes exerting their functions in different ways may be coordinately regulated by SA in the pear fruit. Our study indicates that treatment of SA sprays on the trees may provide further protection against postharvest disease of Ya Li pear fruit in practice and could be used as an alternative and economical approach to reduce application of chemical fungicides.     

Rate, placement and timing of aldicarb applications to control Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), in oranges

BACKGROUND: The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is a cosmopolitan insect pest of citrus and vectors the bacterium Candidatus Liberibacter asiaticus, a suspected causal organism of citrus greening or ‘huanglongbing’ disease. Aldicarb 150 g kg^?1 GR (Temik^® 15 G) was evaluated at three rates, two placements and three timings for ACP control in orange trees. RESULTS: Application of aldicarb at 5.6, 2.8 and 1.4 kg AI ha^?1 in March 2006 reduced adults by 58–66%, 45–46% and 25–37% respectively compared with untreated controls in two separate trials. No difference was observed in placement (one versus two sides of the tree) or tree size (8 years old versus 12 years old). Application at 5.6 kg ha^?1 in January 2007 reduced adults by 86% and shoot infestation by 77% in spring, and was generally better than the November and especially February applications. Even more striking results were evident on adults caged on treated plants for 25 days in March. Spiders and ladybeetles were equally abundant in treated and untreated trees. CONCLUSION: Aldicarb application at 5.6 kg ha^?1 to the bed side of mature citrus trees 2–3 months before spring growth can suppress ACP through spring without a direct effect on principal psyllid natural enemies. Copyright © 2008 Society of Chemical Industry     

Maturation and Seasonal Discharge Pattern of Ascospores of Anisogramma anomala

ABSTRACT Maturation and release of ascospores of Anisogramma anomala were monitored over a 6-year period (1988 to 1995) in European hazelnut orchards located in western Oregon. Perithecia of A. anomala were dissected from stromata collected monthly from September to May to determine spore maturation. Spore maturation began in late summer; by January, >90% of the spores were morphologically mature. Similarly, both the number of mature ascospores per perithecium and the proportion of ascospores that germinated increased through autumn. After January, the number of spores per perithecium declined until May, when few viable spores remained. Each of the 6 years, rain catch-type spore traps were placed under cankers in diseased trees from 15 September to 30 June. Based on spore collection periods of 1 to 4 weeks, three patterns for the seasonal release of A. anomala ascospores were observed: in the 1988-1989 season, >80% of the seasonal ascospore release occurred between September and January; in the 1989-1990 season, 32 to 42% of the seasonal ascospore release occurred after mid-April; and in the other 4 years, monthly releases of ascospores were relatively uniform over the 9-month seasonal period. Timing and amount of precipitation were the most important variables accounting for the differences among the yearly patterns of ascospore release. Over all years and sites, the cumulative proportion of total ascospores collected in each orchard was highly correlated (R(2) = 0.90) with cumulative precipitation. This relationship was confirmed in mist chamber experiments. A regression model was developed relating cumulative ascospore release to cumulative hours of precipitation. The model provides an estimate of the proportion of ascospores remaining to be released after budbreak, which coincides with the period of highest susceptibility to infection.     

梨叶叶龄与梨黑星病菌侵染发病的关系

田间试验结果表明，鸭梨叶片在生长发育期抗病性差，易感染黑星病；发育成熟后，抗病性逐渐增强。自然条件下，受叶片抗病性和孢子着落量的综合影响，鸭梨成熟叶片很少感染黑星病。鸭梨叶片从展叶到发育成熟，在梨树生长发育前期（盛花期后60d内）约需40d，后期（盛花期60d后）约需30d。正处在生长发育期的鸭梨叶片受侵染，潜育期为18－25d，发病后，病斑大，产孢期短；成熟叶片受侵染，潜育期多在40d以上，发病后，病斑小，产孢期长。梨树生长前期梨黑星病的流行主要由于大部分叶片正处在生长发育期抗病性较差；后期果实发病则主要源于成熟叶片内长期潜育和长期产孢的黑星病菌。     

Canker and wood rot pathogens present in young lemon orchards in south-west Arizona

Canker and wood rots are economically important preharvest diseases of lemons in south-western Arizona, where commercial lemon production is concentrated. However, the aetiology and epidemiology of canker and wood rots are not well understood. This study comprised a large survey of canker and wood rot incidence and severity in Arizona and the characterization of fungal species associated with the disease. A total of 5431 trees with ages ranging from 1 to 20 years old in 10 lemon orchards were surveyed from 2018 to 2020. Our survey results revealed that canker and wood rot occurred in all 10 lemon orchards studied. Canker and brown rots of twigs, branches, and trunks were the most prevalent symptoms of affected trees ranging from 1 to 20 years old. In contrast, canker and white rots of twigs and branches were observed mostly on 1- to 5-year-old trees. Disease incidence for both diseases was less than 2% on 1- and 2-year-old trees. Brown rot increased significantly in older trees, ranging from 62.9% to 100%. Fungi were isolated from canker and wood rot samples and identified based on morphological characters and DNA sequences. Fomitopsis meliae and Hypoxylon macrocarpum were the primary canker and wood rot pathogens isolated from the surveyed orchards, at frequencies of 89% and 11%, respectively. In pathogenicity tests, both fungi were capable of causing canker and wood rots on lemon cv. Lisbon branches and the necrotic length caused by F. meliae was twofold greater than that caused by H. macrocarpum.     

The problem of Pitymys voles in orchards in central and southern Italy1

Voles of the genus Pitymys have in recent years caused serious damage in orchards (apple, citrus) in central and southern Italy. They gnaw the roots and base of the trunk of young and mature trees, killing them in a few days. The outbreaks can be related to certain recent changes in cultural practice, especially the introduction of overhead irrigation. Results are presented for control trials by trapping or by chlorophacinone baiting.     

Verticillium wilt of almond in California 1

Wilt of almond due to Verticillium dahliae, also known as‘black heart', is an occasionally serious disease problem in orchards in California (US). Verticillium wilt is most severe on trees 2–6-year-old, and symptoms lessen as trees mature. Usually only a few trees in a young orchard are affected, though sometimes many young trees die. Severe economic losses of 9000-11 000 USD per ha resulting from verticillium wilt in almond orchards have been recorded. Foliar symptoms may be difficult to discern after trees are 5–6-year-old. Unlike previous reports of new infections arising each year, recent research indicates that infections may perennate in vascular tissue of primary scaffolds and trunks. Some differences in tree damage are apparent among scion cultivars. Pre-plant fumigation with methyl bromide and/or chloropicrin is not reliably effective for prevention of verticillium wilt. Solarization has been effective when applied prior to or at planting. Post-plant therapeutic treatments are not consistently effective.     

苗圃毛白杨由锈病引起的生长量损失估计

1983—1985年,通过定株系统观测,对毛白杨幼苗由锈病造成的生长量损失做了数理分析,提出3个数学模型,可试用于计算不同病情(x)对单株胸径增长量(y)的影响,并可做为研究防治苗圃锈病的经济效益和防治指标的参考。用于1年生养干苗的模型为:y_1=0.2998e~(-0.08481x) 用于2年生养干苗的模型为:y_2=0.4208e~(-0.0457x2) 用于3年生养干苗的模型为:y_3=0.7913e~(-1.0282x3)