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4月份出笋期挖取毛竹春笋和高节竹笋,测定了笋体从基部向顶部0、5、10、15、20、25cm各位段的苯丙氨酸解氨酶（PAL)和过氧化物酶（PO）活性,以及纤维素和木质素含量。竹笋在25℃放置96h自然老化,测定了24、84、72、96h,5、10、15、20、25cm各位段的苯丙氨酸解氨酶和过氧化物酶活性,以及10cm位段24、48、72、96h纤维素和木质素含量的变化。结果表明：PAL和PO活性以及纤维素和木质素的含量从基部向顶部逐渐降低,呈梯形分布,木质化进程是从基部向顶部推进的;竹笋离体后,PAL和PO活性大幅度增高,纤维素和木质素含量大量增加加速了老化进程。讨论了PAL和PO在竹笋老化过程中的活性变化,及其在竹笋老化过程中的作用。 相似文献
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竹笋采后涂膜保鲜对其木质化的影响 总被引：4，自引：0，他引：4
为了给竹笋采后保鲜和竹笋膳食纤维的加工提供理论指导,将采回的毛竹春笋的不同部位在3℃冷藏条件下,进行壳聚糖涂膜保鲜对竹笋中苯丙氨酸解氨酶（PAL）和过氧化物酶（POD）活性以及纤维素和木质素含量影响的研究.结果表明：从顶部到基部,竹笋各区段部位PAL和POD活性逐渐增强,纤维素和木质素含量增大;与对照相比,各种涂膜保鲜处理均显著降低竹笋的PAL和POD活性及纤维素和木质素的生成,加入亚硫酸钠能延缓竹笋的木质化进程. 相似文献
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《林业科学》2019,(12)
【目的】探讨褪黑素处理条件下,高节竹笋采后低温(4℃)贮藏过程中木质素形成、抗氧化酶活性、转录因子基因表达的变化模式,为阐明褪黑素处理对竹笋采后木质化过程的影响及其调控机制提供参考。【方法】以高节竹笋为试验材料,分析低温(4℃)贮藏过程中(0、3、6、9、12天)褪黑素(1. 0 mmol·L-1)处理组和对照组竹笋硬度、黄度、亮度,木质素、纤维素含量,木质素合成相关的苯丙氨酸裂解酶(PAL)、过氧化物酶(POD)活性,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸还原酶(APX)活性以及NAC、MYB转录因子基因表达等指标。【结果】与对照相比,外源褪黑素处理减缓笋体变硬和黄化的速度以及木质素和纤维素的积累速度,显著抑制PAL和POD活性,提高了SOD、CAT和APX活性,有效延缓高节竹笋木质化的发生进程;转录因子MYB20、MYB63、MYB85、SND2和VND7的表达随竹笋采后贮藏时间的延长均受到不同程度的诱导,而MYB42、MYB43、NST1和KNAST7的表达量则有所下降。褪黑素处理一定程度上抑制了MYB20、MYB42和KNAT7的表达,促进了MYB43、MYB63、MYB85和SND2的表达。【结论】外源褪黑素处理有效延缓了高节竹笋采后低温贮藏过程中木质化的发生进程,其机制可能是褪黑素处理降低了木质素生物合成相关酶的活性,提高了抗氧化能力。此外,褪黑素也可能参与竹笋木质化的转录调控过程。 相似文献
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雷竹（Phyllostachys violascens）笋是中国传统的山珍之一，是一种天然绿色食品。但其采后易消耗大量水分和营养而快速老化，在一般条件下难以贮藏。文中首次通过“转录组—代谢组”联合分析揭示了低温贮藏条件下雷竹笋木质化的调控机制，研究表明：与常温贮藏相比，低温可显著抑制采后竹笋中PAL、POD酶活性，降低失水率和总木质素含量，从而将竹笋保鲜时间至少延长20 d。通过“转录组—代谢组”联合分析表明，低温下竹笋木质素前体物质、茉莉酸含量呈上升趋势，并在后期显著富集，说明低温可诱导茉莉酸积累、抑制木质素合成。对低温响应、茉莉酸合成和木质素合成通路关键基因进行筛选，并通过共表达分析发现，低温信号可能通过“低温—木质化”和“低温—茉莉酸—木质化”2种通路共同抑制采后竹笋中木质素合成，延缓其保鲜时间。上述结果可为揭示采后竹笋木质化分子调控通路研究提供了一定依据。 相似文献
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为探索生物保鲜剂处理对采后勃氏甜龙竹笋木质化的影响,以采后勃氏甜龙竹笋为研究材料,剥壳鲜笋用不同浓度茶多酚溶液(0.5%、1.5%、2.5%)处理,并用聚乙烯保鲜袋包装,在4℃下进行贮藏,分析0、2、4、6、8 d贮藏期内,处理组和不添加茶多酚对照组的色差值、木质素、粗纤维、还原糖含量,以及苯丙氨酸解氨酶(PAL)、多酚氧化酶(PPO)、过氧化物酶(POD)、肉桂醇脱氢酶(CAD)、超氧化物歧化酶(SOD)等与木质素合成酶系统相关的关键酶活性指标。结果显示：茶多酚处理减缓了采后勃氏甜龙竹笋黄化的速度、还原糖的降解以及木质素和粗纤维的积累速度,有效延缓了木质化的发生进程,显著抑制了PAL、POD、PPO和CAD活性,提高了SOD活性。研究表明,用茶多酚处理竹笋可将采后勃氏甜龙竹笋的保鲜期延长至8 d,以质量分数为2.5%的浓度配比为最佳,贮藏期间最大程度地保留了勃氏甜龙竹笋的营养成分。 相似文献
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以甜龙竹笋为材料,研究复合生物保鲜剂对甜龙竹笋采后贮藏品质的影响。在前期试验结果的基础上,采用复合生物保鲜剂(2.5%茶多酚+0.05%溶菌酶+1.5%壳聚糖)分别浸泡未剥壳、剥壳、去笋衣处理(3种试验处理)后的竹笋5 min,各试验处理均以超纯水浸泡5 min作为对照,自然阴干后用聚乙烯保鲜袋包装,在4℃下贮藏,分析贮藏0、2、4、6、8、10、12、14 d时笋外观和水分、总糖、纤维素、半纤维素和木质素含量等指标变化。结果显示：随着贮藏时间延长,各处理笋外观色差均有增大的变化趋势;各处理笋的水分和总糖含量均呈现逐渐下降的变化趋势,木质素、纤维素和半纤维素含量则呈逐步增加的趋势;贮藏期间各时期,复合生物保鲜剂处理的笋水分和总糖含量均高于对照组,而纤维素、半纤维素和木质素含量则均显著低于对照组;在3种试验处理中,“复合生物保鲜剂+剥壳”处理的保鲜效果优于其他处理。可见,复合生物保鲜剂能有效地减缓采后甜龙竹笋的木质化进程,以“复合生保鲜剂+剥壳”处理保鲜效果最好。 相似文献
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为研究生物保鲜剂对马蹄笋的保鲜效果,选择9种不同比例的魔芋胶、壳聚糖和柠檬酸的生物保鲜剂对马蹄笋进行浸泡、包装和低温储藏,测定3d和7d时的商品指标和关键酶活性。结果发现,S9(1.5%魔芋胶+2.0%壳聚糖+0.1%柠檬酸)和S1(0.5%魔芋胶+1.0%壳聚糖)保鲜效果最好。前者不仅能够维持绿竹笋在贮藏过程中的感官品质,减少水分散失和提高可食率,在贮藏前期(3d)能明显抑制绿竹笋笋体蛋白质的代谢和POD、PAL的活性,蛋白质含量比对照高55.95%,POD活性降低7.50%,PAL活性降低67.15%;后者在储藏后期(7d)更显著地抑制PPO、POD和PAL的活性,分别比对照降低22.19%、34.56%和47.89%。 相似文献
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《林业实用技术》2016,(3)
本研究运用切顶处理和低温贮藏,研究绿竹笋采后生理变化和保鲜效果。试验结果表明:不同处理绿竹笋PAL活性呈先上升后下降的趋势,以从笋生长点以下2cm处切除,不去壳的处理效果较为理想,其PAL活性最小,为10.932 4u/g·h;从笋生长点以下2cm处切除,去壳的处理在1~20d内的POD活性一致保持在较低水平(28.4912~32.2836u/g·min),能较好地抑制POD活性的变化;从笋生长点以下2cm处切除,不去壳和去壳两个处理对对PPO活性的抑制好于其它处理,蛋白质和感官变化基本一直;从笋生长点以下2cm处切除,不去壳的处理贮藏20d时的可食率最高,为59.94%。 相似文献
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Lewis Clifford E. Burton Glenn W. Monson Warren G. McCormick W. C. 《Agroforestry Systems》1983,1(4):277-297
Agroforestry Systems - Native forages of southern United States are frequently low in nutrients and poorly digestible, while improved pastures are the opposite. Since this area produces rapid... 相似文献
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为研究茂名小良水保站桉树的化学成分,测定了小良5种桉树的8种营养元素的含量,其中K、Ca、Mg、Cu、Fe、Mn、Zn的含量采用火焰原子吸收光谱法进行测定,P含量采用钼酸铵分光光度法测定。结果表明：同一品种桉树同一器官中各营养元素含量比较,四种大量营养元素含量总体表现为K>Ca>Mg>P,四种微量营养元素含量绝大部分植物以Mn含量最高,Cu含量最低;四种大量元素P、K、Ca、Mg含量都表现为叶最大,枝次之,根和干中的含量较小;而四种微量元素Cu、Fe、Mn、Zn在植物各器官含量的高低排序缺乏一致规律;不同种桉树间的营养元素含量差别总体上缺乏一致规律。 相似文献
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In the United States, diseased oaks (Quercus species) exhibit tip blight, branch and stem cankers, and dieback often attributed to Diplodia species or related fungi. Emergence of Diplodia corticola as a pathogen of European oaks, and reports of this fungus in the eastern and western United States, prompted re‐examination of strains from Wisconsin. These had been obtained in the late 1990s and early 2000s and previously identified only as Diplodia species. Nuclear ribosomal ITS sequences were obtained from the Wisconsin strains and analysed with other sequences from GenBank. Wisconsin strains confirmed as D. corticola were from northern red oak (Q. rubra), black oak (Q. velutina), white oak (Q. alba) and bur oak (Q. macrocarpa). Other strains from oaks in Wisconsin were D. mutila and D. seriata. Wound inoculation of northern red, white and bur oak seedlings with D. corticola in a greenhouse resulted in shoot death and stem lesions, from which the pathogen was reisolated. We conclude that D. corticola has been present in the northcentral United States for at least two decades and report two previously unrecognized hosts of this pathogen: white oak and bur oak. The roles of D. corticola, related fungi and influences of other environmental factors in deterioration of oak health in North America merit additional investigation. 相似文献
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Spatial distribution of heavy metals (Cu,Pb, Zn,and Cd) in sediments of a coastal wetlands in eastern Fujian,China 总被引：1，自引：0，他引：1
Lili Zhao Weibin You Haiqing Hu Wei Hong Xiaojuan LIAO Shihong Xiao Ren Wang Jinbiao Cai Xuncheng Fan Yong Tan Dongjin He 《林业研究》2015,(3)
We investigated the spatial distribution (horizontal and vertical concentrations) of copper (Cu), lead (Pb), zinc (Zn), and cadmium (Cd) in five wetland types (mudflat, aquaculture wetland, water area,... 相似文献
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Uluguru forests are globally recognized as important biodiversity hotspots, but anthropogenic pressure threatens their value. This study examined species diver-sity, abundance, and structure of trees i... 相似文献
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We summarized the status of wolves (Canis lupus), elk (Cervis elaphus), and woody browse conditions during the 20th century for the upper Gallatin elk winter range in southwestern Montana, USA. During this period, wolves were present until about the mid-1920s, absent for seven decades, and then returned to the basin in 1996. A chronosequence of photographs, historical reports, and studies indicated willows (Salix spp.) along streams became heavily browsed and eventually suppressed following the removal of wolves, apparently due to unimpeded browsing by elk. However, after wolf establishment in 1996, browsing intensity on willows lessened in some areas and we hypothesized that, at both a landscape and fine scale, browsing pressure reflects terrain configurations influencing predation risk (nonlethal effects), in conjunction with lower elk densities (lethal effects). We measured browsing intensity and heights of Booth willow (S. boothii) along 3000 m reaches of the Gallatin River and a tributary to examine the potential influence of wolf/elk interactions upon willow growth. Where the Gallatin Valley is relatively narrow (high predation risk), willows began releasing in 1999 and by 2002 were relatively tall (150–250 cm). In contrast, willow heights along a wider portion of the Gallatin Valley, along the open landscape of the tributary, and an upland site (all low predation risk) generally remained low (<80 cm). We identified terrain and other features that may contribute to the perceived risk of wolf predation, by elk for a given site. Although alternative mechanisms are discussed, changes in willow communities over time following wolf removal and their subsequent reintroduction were consistent with a top-down trophic cascade model involving nonlethal and possibly lethal effects. If similar top-down effects upon vegetation hold true in other regions of North America and other parts of the world where wolves have been extirpated, wolf recovery may represent a management option for helping to restore riparian plant communities and conserve biodiversity. 相似文献
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广州从化市江埔风水林主要群落类型及其多样性初步研究 总被引：1，自引：1，他引：0
基于广州从化江埔地区的5个群落类型9个400m^2的样地数据,对该地区风水林的植物群落结构及其物种多样性特征进行了初步研究。结果显示：9个风水林群落样方中,共统计有维管植物96种,隶属于48科。群落类型主要有荷木林、藜蒴林、中华锥林、黄桐林和黄樟林,乔木层常见树种为荷木（SchimaSU—perba）、藜蒴（Castanopsisfissa）、中华锥（Castanopsischinensis）、黄桐（Endospermumchinense）、黄樟（Cinnamo—mumparthenoxylon）等;灌草层以罗伞树（Ardisiaquinquegona）、九节（Psychotriaasiatica）、疏花卫矛（Euonymuslaxiflorus）、华山姜（Alpiniachinensis）、半边旗（Pterissemipinnata）等植物为优势种。乔木层多样性指数从大到小依次为荷木林〉中华锥林〉黄桐林〉黄樟林〉藜蒴林,灌草层多样性指数由大到小依次为中华锥林〉黄桐林〉荷木林〉黄樟林〉藜蒴林。藜蒴林群落乔木层和灌草层种类较单一,生物多样性较低。 相似文献
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Seeds of Celtis australis were collected from 13 different sources, ranging from 550 to 1980 masl, in Central Himalaya, India. Significant (p = 0.05) variations were observed for seed traits among provenances. However, among various characters, seed weight exhibited
maximum variation between seed populations compared to other morphological characters. Between provenances, seed weight ranged
from 47.8 to 83.1 g/1000 seed, with mean value of 66.9 ± 10.7 g/1000 seed. Significant (p = 0.01) positive correlation was found between morphological characters of seeds including seed weight and elevational range
of seed source. For one year old seedlings, average shoot and root growth was 61.1 ± 13.3 and 30.5 ± 5.4 cm, respectively,
irrespective of provenance variation. Inter-comparing biomass yield of the seedlings with altitude, average biomass production
was 8.4 ± 2.5, 9.4 ± 3.3 and 12.7 ± 1.7 g/plant, respectively, for low (550–1000 masl), middle (1050–1250 masl) and high (1350–1980 masl)
altitudinal populations. Significant (p = 0.01) positive correlation between growth performance of seedlings and altitude of the seed source was recorded. Across
the provenances, shoots had the highest proportion of total biomass (42.3%), followed by leaves (32.6%) and roots (24.6%).
Among various provenances, Badiyargaon, Agroda, Guptakashi, Jakholi, Gajeli, Srinagar and Palampur populations produced heavier
seedlings and grew faster compared to seedlings of other sources. 相似文献
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A survey was conducted to determine richness of Vascular Endemic Plants of the Uluguru Mountains in Morogoro, Tanzania. Strict and near-endemic species were identified and their habits, habitats and altitudinal ranges were indicated. About 108 strict endemic plant species were identified in the Uluguru Mountains. Most of the endemic species are shrubs followed by herbs, trees and climbers, and are confined to the families Rubiaceae (38 species in 11 general), Orchidaceae (13 species in 7 general) and Balsaminaceae (11 species in 1 genus). The major habitat for endemic species is the montane rain forest on the windward side ranging between 1200 and 2450 m a.s.l. The major areas where the Uluguru endemics are concentrated are the forests of Bondwa/Lupanga followed by Lukwangule/Chenzema and then Bunduki and Mgeta. These areas are therefore the major hotspots for the endemism in the Uluguru Mountains. The information presented in this paper will contribute to the conservation and management of the biodiversity of the Uluguru Mountains. 相似文献