GA3对辽东楤木种子解除休眠中信号分子变化的影响

 研究了GA₃ 对辽东楤木种子在变温(每天高温13～15℃ 12 h, 低温0～4℃ 12 h) 层积条件下解除休眠过程中部分信号分子变化的影响。结果表明: 200 mg/L的GA₃ 丙酮溶液可以极显著促进辽东楤木种子萌发; 显著降低种子内源ABA 含量; 显著提高种子内源GA 含量、CaM含量和NADKase、质膜Ca^{2 +} -ATPase活性, 从而说明了信号分子参与并调节了辽东　木种子休眠解除这一过程。     

黄土高原不同土地利用方式分层植被的盖度差异

[目的] 分析不同土地利用方式黄土高原植被的覆盖状况,为监测该区植被特别是非绿色植被盖度的变化提供数据支持,为遥感估算植被覆盖度(FVC)在土壤侵蚀预测中的应用提供可靠依据。[方法] 选择黄土高原不同土地利用类型的7块植被样地,采用样带法进行逐半月的分层植被盖度调查,分析了绿色植被盖度(f_PV)和非绿色植被盖度(f_NPV)在不同类型以及不同层次结构下的年内变化,为侵蚀过程模型中植被因素的获取提供参数。[结果] ①沙地、草地、人工柠条林地、人工油松林地、黄陵和秦岭的天然林地等6个样地中,植被的年内投影总盖度变化不大。投影f_PV和其所占投影总盖度的比例年内均随时间先逐渐增加,7—9月达到最大值,其后迅速减小。而投影f_NPV随时间的变化趋势与f_PV相反。受耕作制度影响,耕地投影f_PV和f_NPV年内变化剧烈。②7—9月,在黄陵和秦岭的天然林样地,投影f_PV比例可达100%,其他4种样地分别可达60.6%,70.5%,58.8%和84.9%,意味着仅考虑投影f_PV,将忽略占总盖度39.4%,29.5%,41.2%和15.1%的f_NPV的生态效益。③人工柠条、人工油松林地,黄陵、秦岭的天然林地等4种具有明显植被垂直结构的样地中,乔木层、灌木层和地表层的f_PV与f_NPV的年内变化与投影f_PV与f_NPV的变化趋势基本一致;4种样地植被的投影总盖度与地表层总盖度呈线性关系,其相关性可达0.85(R²)。[结论] 黄土高原不同土地利用方式耕地投影f_PV和f_NPV年内变化剧烈,其他样地年内投影f_PV先增加后减小,投影f_NPV与其相反。占总投影盖度的15.1%～41.2%的投影f_NPV,在该区是不可忽略的地被组成。不同层次的f_PV和f_NPV年内变化趋势与投影f_PV和f_NPV一致,地表层总盖度与投影总盖度也存在显著的线性相关性。在区域监测时应重点关注耕地植被盖度的提取季节与地表总盖度。     

耕层厚度对华北高产灌溉农田土壤有机碳储量的影响

针对华北平原长期少免耕可能导致的耕层变浅、变紧的问题,通过人为设置不同耕层厚度试验,采用等质量土壤有机碳库储量和层化比的研究方法,研究了4种耕层厚度（10、20、30、40 cm）水平下0～50 cm土壤有机碳的变化。2 a的田间试验结果表明,不同耕层厚度对土壤有机碳含量有显著差异,与2007年试验开始时相比,土壤有机碳质量分数都不同程度下降,下降幅度为22%～48%。利用等质量计算方法表明20 cm耕层厚度的处理土壤有机碳储量最高。通过层化比的研究表明,随着时间的推移,20 cm的耕层厚度层化比最高,其     

GA3与层积综合处理对打破不同类型野生杏种子休眠的效应

试验以两种类型野生杏(甜仁杏和苦仁杏)种子为试验材料,采用GA3与低温层积相结合的综合性处理方法,研究对打破两种类型野生杏种子休眠的效果,进行发芽率与培根伸长的统计分析.以低温层积处理的作为对照,GA3与低温层积相结合对打破野生甜仁杏种子休眠提高其发芽率及胚根生长有极显著的促进作用,其发芽率与胚根长度最大分别提高到对照的2.9和4.6倍,野生苦仁杏在100 mg/L GA3浸种12 h结合低温层积时其发芽率略有提高,其胚根伸长最大达到对照的2倍.上述结果说明低温和GA3综合处理对打破甜仁杏的休眠有增益效应而对苦仁杏则没有明显的效果.     

层积和激素处理对山楂种子生理生化的影响

为了研究山楂种子的体眠机理,以野生山楂种子为试材,经1个冬季的层积后,用200 mg/L GA3和ABA处理种子,测定层积与激素处理对种子生理生化指标的影响.结果表明,野生山楂种子层积1个冬天不能解除休眠,其休眠程度较深,经GA3处理后,少量种子萌发,但只长子叶,胚芽和胚根没有萌动.层积后山楂种子的细胞膜透性增加,呼吸加强,总糖、还原糖和游离氨基酸含量降低,可溶性蛋白质含量增加.CAT和SOD活性增加.POD和PAL活性降低.GA3处理使种子CAT、SOD、POD和PAL活性均有所降低,而ABA处理除了使SOD活性降低外,对其余各酶的影响与GA3的作用相反.     

Variations in seed germination of Hippophae salicifolia with different presoaking treatments

Mature seeds of H. salicifolia, collected from five provenances (i.e. Hanuman Chatti, Helang, Lata, Rambara and Janggal Chatti) in west Himalaya, India, were treated with stratification (at 4°C for 15, 30 and 60 days) and in different concentrations of GA₃ (5, 10, 20 mM), KNO₃ (50, 100, 200 mM) and Thiourea (50, 100, 200 mM) solution to determine the variations in seed germination. Results reveal that the germination rates of seeds from different provenances under different pre-sowing treatments are significantly increased compared to those in control (24%–30%). The seeds treated with Thiourea (100 mM) have highest germination rate (76%–83% for different seed sources), followed by those (63%–71% for different seed sources) pretreated with stratification (4°C, 30 days). GA3 treatment significantly shortens the mean germination time (MGT) and improves seed germination percentage. Considering the practical applicability and cost effectiveness, thiourea (100 mM) and stratification (at 4°C) treatments for seed germination are recommended for mass multiplication through seeds of H. salicifolia in village/forest nurseries of the west Himalaya, India.     

林层划分方法综述

林层分层是热带林生态学最古老的概念之一, 但对林层分层的定义和测定方法的不同造成了林层分层是否存在及如何划分的争议.作为森林调查的因子, 对林层划分方法的研究具有测树学和群落学双重意义.文中从定性、定量和遥感3个方面综述林层划分的主要方法, 介绍剖面图的绘制、应用及特点, 描述TSTRAT和LMS划分方法的详细步骤, 并通过与FVS和MIDCL等划分方法的对比分析了这4种方法的特点.     

羊柴种子去荚、低温层积处理后萌发特性及HPLC法测定内源激素ABA、IAA含量变化

为了研究羊柴种子自身萌发力对其飞播过程的影响,笔者对羊柴种子去荚处理后含水量、吸水规律、萌发能力以及羊柴种子不同天数低温层积处理后萌发能力进行相关研究,同时对2种处理后内源激素ABA、IAA分别进行生物测定。结果表明：带荚种子含水量为9.16%,去荚种子为8.92%;两者吸水过程均分为急剧吸水期、稳定吸水期、饱和吸水期3个阶段,去荚种子的最大吸水速率为带荚种子的4.79倍,达到饱和期所用时间约为带荚种子的1/2;羊柴种子去荚处理后发芽率、发芽指数最高,分别为81.67%、33.27,为对照组的8.167、38.39倍,带荚种子低温层积处理60天后发芽率、发芽指数次之,为46.67%、4.19;CK组抑制物ABA含量最高,达7921.12 ng/mL,经过80天低温层积处理后ABA含量降至最低,为4590.85 ng/mL。综合去荚处理以及低温层积处理后的发芽率、发芽指数、ABA含量,IAA/ABA比值,最后确定羊柴种子的最适发芽条件为去荚处理以提高其吸水性能或对带荚种子进行60天,4℃的低温层积处理。     

Dormancy release and germination of Echinochloa crus-galli grains in relation to galactomannan-hydrolysing enzyme activity

Echinochloa crus-galli, one of the world's most serious weeds, influences seriously the yield and quality of cereal crop plant.It is well known that E.crus-galli grain is dormant, but its dormant type, as well as its dormancy release and germination in relation to galactomannan-hydrolysing enzyme activity were poorly understood.The cooperation of endo-β-mannanase(EC 3.2.1.78), β-mannosidase(EC 3.2.1.25) and α-galactosidase(EC 3.2.1.22) can hydrolyze the cell walls rich in mannan-based polymers.In the present paper, the mature grains are used as experimental materials, we investigated the water uptake of grains, the effect of removing partial endosperm, after-ripening, stratification and phytohormone on grain germination, and the change in endo-β-mannanase, β-mannosidase and α-galactosidase activities of grains during after-ripening and germination.The results showed that the freshly-collected grains were water-permeable and had only phase I and II of water uptake, while the grains after-ripened for 150 d had an obvious phase III of water uptake.In alternating photoperiod, the germination of grains freshly-collected was zero at 10–35°C, and that of half grains was 11% at 20°C only.The grain germination was notably promoted by after-ripening and stratification, but not by gibberellic acid and 6-benzyladenine at 0.0001–1 mmol L–1.β-Mannosidase activity increased during 0 to 300 d of after-ripening and then decreased.The activity of endo-β-mannanase and α-galactosidase of grains decreased with after-ripening.During grain germination, endo-β-mannanase and β-mannosidase activities obviously increased, while α-galactosidase activity decreased.Our data showed that E.crus-galli grain was a deep physiological dormant, the dormancy release by after-ripening was related to an increasing β-mannosidase activity, and its germination was closely associated with an increasing endo-β-mannanase and β-mannosidase activity; which have provided new knowledge to decrease the harm of E.crus-galli on production of cereal crop plant.     

蝟实种子休眠特性研究

以国家三级保护植物蝟实果实为试验材料,应用扫描电镜和石蜡切片进行了形态解剖观察,通过吸胀和果皮胚乳抑制物测试等方法探讨了休眠原因,并采用硫酸、赤霉素处理及低温层积处理进行了打破休眠的试验。结果表明：(1)蝟实具有坚硬厚实的果皮,机械束缚是休眠的主要原因;(2)胚乳中含有萌发抑制物质,沙藏或赤霉素处理可有效解除其生理休眠;(3)打破蝟实休眠最佳方法为：浓硫酸处理15 min,并用400 mg·L^-1赤霉素处理,或仅用4 ℃沙藏30 d。