Effects of peach branches returning on autotoxins and microbes in soil and tree growth of peaches

Aims This study aimed to investigate the effects of branch returning on the growth of peach (Amygdalus persica "Chunmei/Maotao") saplings, soil enzyme activity, and soil contents of phenolic acids and amygdalin, thereby providing scientific evidence against the application of branch returning for peach trees. Methods One-year-old potted peach tree (Amygdalus persica "Chunmei/Maotao") was used in this study with four agricultural treatments applied, including soil coverage by fragmented peach tree branches (fragment treatment;1.5 and 22.5 g·kg^-1) and applying leachate solutions of peach tree branches to soil (leachate treatment; 1.5 and 22.5 g·kg^-1). No branch addition was used as control (CK). Solid phase extraction, high performance liquid chromatography (HPLC), biological high-throughput sequencing was used to determine the content of autotoxic substances, and microbial community structure in soil. Soil coverage and leachate solution treatments of 30 g and 450 g branches applied to the peach trees were described as 1.5 and 22.5 g·kg^-1, respectively in this paper.Important findings Compared with CK, the phenolic acid and amygdalin contents significantly increased after both fragment and leachate treatments in high quantities (22.5 g·kg^-1). Soil microbial community structure altered in both treatments, with the proportion of fungi (particularly Agaricomycetes, Tubeufia and Cystofilobasidiaceae) increased significantly and bacteria decreased accordingly. Invertase activity in both high-quantity treatments exceeded that in the CK significantly. The activity of catalase and urease was higher at first and then decreased relative to CK under high-quantity fragment and leachate treatments. Specifically, the effect of leachate treatment on enzyme activity was higher than the fragment treatment in the short term. Chlorophyll content, ground diameter (diameter of 5 cm from the ground) growth and net photosynthesis rate of plants were lower in high-quantity fragment and leachate treatments than those in CK, with earlier retardation of new shoot growth. We observed an increase in soil phenolic acids and enzymes in treatments in normal pruning quantity, while no inhibition effect was found on the tree growth. In conclusion, autotoxins (such as phenolic acid and amygdalin) inhibited the growth of peach trees both directly and indirectly through changing soil enzyme activity and microbial community.     

胡杨枝、叶和花芽形态数量变化与个体发育阶段的关系

以同一立地条件下不同径级的胡杨为研究对象,通过野外调查取样和室内分析,探讨胡杨枝、叶和花芽形态数量特征随径级的变化规律及其相互间的关系。结果表明:随着径级的增加,叶形指数、枝条长度、每枝叶片数逐渐减小,叶面积、叶周长、叶柄长、枝条粗度、每枝花芽数、花芽长度和花芽宽度逐渐增加。相关分析表明,枝、叶、花芽形态数量指标均与径级存在极显著正/负相关性;花芽长度、花芽宽度、叶形指数、叶面积、叶周长、叶柄长、枝条粗度、每枝叶片数、每枝花芽数两两间均呈极显著正/负相关,枝条长度与叶形指数、叶面积、叶周长、叶柄长、枝条粗度、每枝叶片数、每枝花芽数间均呈现极显著正/负相关,说明胡杨枝、叶和花芽形态数量不仅随着个体发育阶段而逐渐变化,而且枝、叶和花芽形态数量的变化是协同进行的。方差分析显示,枝条长度、每枝叶片数在4径级开始有显著的减少,枝条粗度则与每枝花芽数、花芽长度和宽度同步从10径级开始呈现"阶梯式"的显著增加,叶形指数和叶柄长度的显著变化也出现在10径级。枝、叶和花芽形态数量表现出明显的阶段性差异与胡杨阶段转变密切相关。     

嵌套式回归建立树木生物量模型

 该文介绍了一种建立树木生物量模型的简单快速方法——嵌套式回归。基本原理是以枝轴为基本单位, 逐级拟合。过程是把枝条分解成枝轴, 从枝轴到枝条, 再到单株, 拟合不同层次或尺度的生物量模型。建立枝轴生物量方程, 估计各级枝轴生物量, 将枝轴生物量(实测值或模拟值)总和起来便得到枝条生物量。由于样本单元之间有包含关系, 实际测定的样本很小, 具有快速实用的特点。检验结果显示, 模型预测值和实测值具有较高的一致性。     

木本植物快速繁殖途径及其增殖效率的影响因素

介绍木本植物快速繁殖的3种途径,即腋芽生枝、器官发生和体细胞胚发生途径。总结了木本植物快速繁殖过程中影响其增殖效率的因素,认为进行木本植物快速繁殖,应扩大取材范围、综合考虑多种因素的作用。     

长白山红松阔叶混交林紫椴枝条的分解实验

研究了长白山北坡椴树（Tilia amurensis）枝条的分散进程,实验结果揭示,分解率是与各实验地的植被类型,海拔,生长季月平均大于5℃的积温等密切相关。其枝条分解的保存率（Y）与分解年龄（x）的相关,可用指数模型：Y＝e^-kx来拟合,在红松阔叶混交林,红松外叶混交林,岳桦去冷杉林及岳桦林中椴树枝条分解常数K分别为－0.168与－0.127,－0.102和－0.094。枝条原重量50％的分解年龄在上述4个森林中分别是4,5,6和7a。实验还指出,在长白山红松阔叶混交林皆伐迹地的实验条件下适当的蔽荫和浇水对分解有正面影响。而且,枝条的分解率主要是以长白山不同海拔植被类型的温度条件而转移,特别是生长季的积温。     

枝条覆盖对平茬花棒生长特征和浅层土壤水分的影响

为了综合评价枝条覆盖对不同立地(平地、丘顶、丘间低地)平茬花棒(Hedysarum scoparium)生长特征和浅层土壤水分的影响,以吉兰泰荒漠-绿洲过渡区平茬花棒为研究对象,于2017年4—10月对覆盖与无覆盖平茬花棒物候期、土壤容积含水量、土壤储水量和生长指标等相关指标进行测定。实验结果表明:(1)枝条覆盖有利于平茬花棒提前萌芽,较无覆盖提前5 d以上。(2)枝条覆盖使不同立地平茬花棒生长初期和生长末期0—100 cm土层平均土壤容积含水量增加20.12%以上,且土壤含水量变异系数随土层深度增加变化减缓;土壤储水量在生长初期和生长末期枝条覆盖较无覆盖增加27%以上。(3)枝条覆盖使平茬花棒株高、新生枝数、基径、冠幅较无覆盖增加10.91%以上,同时其生物量鲜重和干重较无覆盖分别增加4.45%—24.17%和3.78%—18.93%。尤其丘间低地平茬花棒生物量增加效果更加明显(P0.05)。但枝条覆盖不能改变平茬花棒生物量分配格局;(4)枝条覆盖和平茬对花棒生长均具有积极作用,枝条覆盖对丘间低地平茬花棒生长促进作用最好。     

内蒙古高原四种针茅种群年龄与株丛结构的研究

用样带法调查了内蒙古高原4种针茅(StipaL.)的年龄结构,并将其年龄划分为5个阶段:幼苗、幼龄、成年、老龄前期和老龄期。结果表明:幼苗对种群年龄结构和动态有较大的影响,针茅幼苗的存活率通常很低,而成年株丛的存活率较高,株丛的实际寿命很长,老龄株丛在种群中占有较大的比例。4种针茅中大针茅(S.grandisP.Smirn.)和克氏针茅(S.kryloviiRoshev.)的幼苗比例较高,从贝加尔针茅(S.baicalensisRoshev.)群落到小针茅(S.klemenziiRoshev.)群落种群中幼龄和成年株丛比例呈下降的趋势,而老龄株丛比例呈增加的趋势;针茅属植物在株丛水平上的动态主要表现为株丛的破碎与枝条自疏过程,以及株丛生殖枝数量和营养枝生物量的波动,幂函数模型Y=aXb可以对株丛的枝条自疏过程进行定量描述     

栗链蚧生物学特性及其防治试验

栗链蚧Asterolecanium castaneae Russell是危害锥粟的主要蚧虫之一。栗链蚧在福建一年发生2代,以受精的雌虫在栗树枝条上越冬。防治试验表明,选用50%快灭磷1：1000进行喷雾．原液进行涂干或注射效果最好．40%氧化乐果次之。农药混合试验表明．50％快灭磷 40%氧化乐果 80％敌敌畏原液混合进行涂干效果最好。     

黑紫蛱蝶生物学特性的研究

黑紫蛱蝶Sasainia funebris(Leech)一年发生1代,11月份以四龄幼虫在寄主植物枝条上越冬．翌年4月越冬幼虫眠起．6月化蛹,7月中旬为成虫羽化盛期。各虫态历期：卵6．5—7天,幼虫共6龄,计300天左右,蛹12—13天,成虫10—13天。同时,还记述了该蝶各虫态的形态特征、生活习性和天敌情况等。     

大叶黄杨长毛斑蛾的生物学研究

大叶黄杨长毛斑蛾于1990年在山东威海地区首次发现,是为害大叶黄杨的重要害虫,一年发生1代,以卵在枝条上越冬,翌年4月初出现幼虫,5月中旬初开始结茧化蛹,10月底始见成虫,作于1990-1993年对该虫的形态特征,生活史及为害习性进行了观察研究,并提出综合防治措施。