Growth, cambial activity and phloem structure in compatible and incompatible peach/plum grafts

Peach (Prunus persica L. Batsch) shoots grafted onto compatible or incompatible clones of rootstocks of myrobolan plum (Prunus cerasifera L. Ehrh. cv. myrobolan) were observed in a greenhouse for 100 days after grafting. The incompatible grafts showed foliar symptoms of incompatibility and reduced shoot growth about 60 days after grafting. Light microscopic studies revealed that cambial activity stopped earlier in the rootstocks, than in the scions, of incompatible grafts. Structural modifications were also observed in the phloem of incompatible grafts. Compared with the compatible graft rootstock, the number of sieve elements differentiated from the cambial zone was reduced in the incompatible graft rootstock, whereas the production of parenchyma cells was not affected. No important ultrastructural alteration was observed in the sieve tubes of the incompatible grafts. However, osmiophilic granulations near the plasma membrane of sieve plates were observed more frequently in the rootstocks of incompatible grafts than in ungrafted myrobolan controls. It is concluded that the external symptoms of incompatibility are not related to massive structural modifications or degeneration of the conducting tissues.     

Growth and the composition and transport of carbohydrate in compatible and incompatible peach/plum grafts

The growth of scions and rootstocks of compatible (Prunus persica L. Batsch cv. Springtime/Prunus cerasifera L. Ehrh. cv. myrobolan P2032) and incompatible (Prunus persica L. Batsch cv. Springtime/Prunus cerasifera L. Ehrh. cv. myrobolan P18) peach/plum grafts were compared. The composition of soluble carbohydrates in phloem and cortical tissues of both peach/plum grafts and ungrafted plums and the translocation of these compounds across the union of grafted plants were examined. Sorbitol and sucrose were the dominant sugars in the phloem and cortical tissues of plum. A cyanogenic glycoside, prunasin, was present in peach tissues in amounts equivalent to those of sorbitol or sucrose, whereas only small amounts of prunasin were detected in plum tissues. The concentration of prunasin was significantly higher in the phloem of the P18 rootstock of the incompatible graft. Sorbitol was the only sugar significantly depleted in rootstock tissues of the incompatible graft when the first foliar symptoms of graft incompatibility became evident. Translocation studies with 1-(14)C-deoxyglucose showed that the relative distribution of radioactivity across the graft union was similar in both compatible and incompatible grafts. However, the total amount of radioactivity translocated across the incompatible graft was less than one-third of that translocated across the compatible graft. The results are consistent with the hypothesis of a progressive poisoning of the root system in the incompatible graft by a compound synthesized in peach foliage. The role of prunasin as a possible candidate is discussed.     

Oxidative stress responses and root lignification induced by Fe deficiency conditions in pear and quince genotypes

We analysed Pyrus communis cv. Conference and Cydonia oblonga BA29, differently tolerant to lime-induced chlorosis, to identify the key mechanisms involved in their different performance under Fe deficiency induced by the absence of Fe (-Fe) or by the presence of bicarbonate (+FeBic). Under our experimental conditions, a decrease in root elongation was observed in BA29 under bicarbonate supply. Superoxide dismutase (SOD) and peroxidase (POD) activities were analysed and the relative isoforms were detected by native electrophoresis. The data obtained for both genotypes under -Fe and for BA29 +FeBic suggest the occurrence of overproduction of reactive oxygen species (ROS) and, at the same time, of a scarce capacity to detoxify them. The detection of ROS (O(2)(-) and H(2)O(2)) through histochemical localization supports these results and suggests that they could account for the modifications of mechanical properties of the cell wall during stress adaptation. On the other hand, in the cv. Conference +FeBic, an increase in non-specific POD activity was detected, confirming its higher level of protection in particular against H(2)O(2) accumulation. Peroxidases involved in lignification were assayed and histochemical analysis was performed. The results suggest that only in BA29 under bicarbonate supply can the presence of ROS in root apoplast be correlated with lignin deposits in external layers and in endodermis as a consequence of the shift of PODs towards a lignification role. We suggest that in BA29 the decrease in root growth could impair mineral nutrition, generating susceptibility to calcareous soils. In the cv. Conference, the allocation of new biomass to the root system could improve soil exploration and consequently Fe uptake.     

Localized graft incompatibility in pear/quince (Pyrus communis/Cydonia oblonga) combinations: multivariate analysis of histological data from 5-month-old grafts

To characterize the structural events associated with incompatibility of graft development, we conducted a histological study of compatible and incompatible pear/pear and pear/quince grafts that had been grown for five months in a greenhouse. Multivariate analysis of histological data describing the structure of the graft union allowed us to discriminate between compatible and incompatible combinations before either macroscopic examination or qualitative microscopic examination differences between graft combinations became evident. The histological variables responsible for the discrimination between incompatible and compatible unions were related to three typical symptoms of graft incompatibility: bark discontinuity, which was the main feature; cambial dysfunction; and accumulation of starch in the scion. Little cell necrosis was observed at the interface of incompatible grafts at the 5-month stage of graft development. Multivariate analysis of histological data provides a new tool for studying early structural events resulting from the graft incompatibility response and for diagnosing early graft incompatibility.     

Modeling internode length and branch characteristics for Pinus radiata in New Zealand

It is recognized that estimation of internode length and maximum branch size is important for the prediction of clearwood in unpruned timber stands, as well as for evaluating the quality and value of logs in general. A review of existing branch models reveals a diversity of approaches as well as a tendency for results to be species specific. Here, a branch model is developed for Pinus radiata in New Zealand, capable of predicting successive internode lengths, the number of branches on each branch cluster, and the size of each branch up to the green crown (GC) at site index age 20. Inputs to the model include tree height and diameter at breast height (dbh) (both at age 20) and basal area per hectare of the top 100 stems. Further optional inputs are an ocular count of the number of branch clusters up to the green crown, and branch factor (BF)—the size of the biggest branch in the first cluster encountered above 6 m. The vertical distributions of internode length and maximum branch diameter are found to reach maxima around 0.3–0.4 of relative height. Internode length and the number of branches per whorl were found to be independent of tree size, site index and stand density. Stems per hectare is not required as an explicit predictor variable but it appears implicitly through tree dbh. Some model output is given and the results are discussed.     

4个桉树无性系愈伤诱导和分化

桉树(Eucalyptus L’Hérit.)是世界三大树种之一,随着生物技术的发展,桉树转基因研究正以前所未有的速度发展,而不同的种、无性系胚性愈伤诱导的难易和植株再生能力的强弱直接影响转基因工程实施的进程。尾巨桉(E.urophylla S.T.Blake×E.grandis W.Hill ex Maiden)无性系DH3229、巨尾桉     

山地梨树容器苗短期培育及栽植技术

通过用塑料容器袋将梨苗装入袋内短期培育成活后,雨季上山栽植成活率达到98%,裸根苗栽植成活率67%,容器苗栽植比裸根苗栽植成活率高31%,栽植成本降低40%。     

梨园橡胶犀金龟发生危害规律及防治技术

橡胶犀金龟在江永县梨园1 a发生1代,以幼虫在有机质丰富的场所越冬,7月下旬—8月上旬发生危害最重。成虫有趋光等习性。幼虫危害梨树根部,成虫危害梨树主干、大根、果实,并引起蚂蚁等病虫发生危害。采取农业、人工、物理、套袋、化学等防治技术,可控制其发生危害。     

花垣县金秋梨引种栽培技术

针对花垣县梨果业发展中存在的问题,进行金秋梨引种栽培示范,取得了明显的社会、经济和生态效益。     

徽州雪梨资源及开发利用

对徽州（今黄山市）特有果树——徽州雪梨的生物学特性，品种，食用药用价值及资源利用现状进行了详细阐述，并提出针对性的建议，为徽州雪梨的合理开发及利用提供参考。     

石家庄地区梨树病虫害发生动态及治理对策

石家庄市辖6区17县(市),是我国的主要梨产区之一。梨栽培历史悠久,现有梨树面积4万hm^2,年产鲜梨8．5亿kg,占河北省梨产量的1／3。品种以鸭梨、雪花梨为主,栽培面积约占本地梨树总面积的近70％,其它品种有黄冠、黄金、酥梨系列,绿宝石、冀密、丰水等。近年来,果品市场持续疲软,梨果价格下跌,收益下降,导致果农的管理投入减少,梨树病虫为害加重;再加上梨树栽培方式的变革,病虫防治手段及农药品种的更新,     

十大花色中原牡丹传统品种核型分化程度

以十大花色的30个中原牡丹传统品种为材料,采用常规制片法观察染色体特征,并根据Stebbins的核型进化理论和分支系统学的编序、赋值方法,对核型的4个重要性状进行了分析,结果表明:30个中原牡丹传统品种均为二倍体(2n=10);且核型类型较原始,以2A型为主;核型以2n=10=6m+2sm+2st为主。‘银粉金鳞’、‘洛阳红’、‘璎珞宝珠’的核型较进化,而‘宫样妆’、‘一品朱衣’和‘赤龙焕彩’较原始。核型参数的重要性排列顺序为臂比均值>核型不对称系数>染色体最长/最短值>臂比大于1.7的比例。花色间的核型差异不显著,相近色系的品种进化程度相近,深色系比浅色系原始。     

库尔勒香梨园土壤氨挥发速率及累积规律

为了掌握库尔勒香梨园土壤氨挥发特征与挥发损失量,以6年树龄库尔勒香梨园为研究对象,采用密闭式集气法对香梨整个生育期的香梨园土壤氨挥发速率及累积量进行研究。结果表明:施肥、灌溉及温度对库尔勒香梨园土壤氨挥发有显著影响。氨挥发速率在一天内的变化,由于温度的影响而具体表现为下午(16:00~20:00)、中午(12:00~16:00)、早上(8:00~12:00)、夜间(20:00~08:00)挥发速率依次降低,并在施肥后的第4天下午(16:00~20:00)时达到最大值0.032 kg/(hm~2·h);氨挥发日累积量在不施肥的情况下随着香梨生育期的推进而逐渐减少,最后趋于平稳。而在4月1日和6月1日对试验样地进行施肥后,氨挥发日累积量明显增加,在4月5日和6月5日分别达到0.411和0.318 kg/(hm~2·d)。在每个月10日对试验样地进行灌水后,氨挥发日累积量明显增加,在5月15日达到最大值0.24 kg/(hm~2·d);氨挥发月累积量在基施肥处理的4月和追施肥处理的6月较大,分别达到9.086和7.619 kg/(hm~2·m)。在香梨整个生育期内,氨挥发累积量达到36.52 kg/hm~2,占总施肥量的12.17%,损失量较大。     

不同温度处理对石斛兰花芽分化和发育的影响

[目的]准确了解石斛兰花芽分化规律,研究不同的温度处理对春石斛兰花芽分化和发育的影响,为石斛兰的花期调控提供技术支持。[方法]采用石蜡切片法观察了石斛兰(Dendrobium Spring Snow)花芽的形态发生和结构发育过程,研究了26/21℃、22/17℃、18/13℃处理条件下花芽分化和发育的差异性。[结果]研究表明:石斛兰花芽分化过程可分为7个时期:休眠期、萌动期、花序原基分化期、花蕾原基分化期、萼片原基分化期、花瓣原基分化期、合蕊柱分化期。在高温26/21℃处理条件下,石斛兰不能进行花芽分化,22/17℃处理条件下,需要56 d才能完成花芽分化,在18/13℃条件下,35 d能够完成花芽分化。[结论]持续足够时间的低温是花芽分化的关键,萌动期是一个对温度高度敏感的时期,此时至少经历2周的低温,能够形成花芽,经历高温,则形成高芽。花芽形成后温度高有利于花芽的发育。     

2种梨砧木叶片光合与气孔形态特征研究

为了探讨梨砧木光合作用与气孔形态特征间的关系及其对环境的适应性,分别以杜梨和豆梨为试材,分析了2种砧木生长量、叶片各光合参数日变化规律和下表皮气孔形态特征的差异情况。观测结果表明:相同环境条件下,杜梨的生长量显著高于豆梨的;两者间净光合速率(Pn)日变化规律的差异显著,其中,杜梨叶片Pn的日变化曲线呈单峰曲线,而豆梨的为双峰曲线,且杜梨的Pn整体大于豆梨的;杜梨的气孔导度(Gs)、蒸腾速率(Tr)在10:00时后均显著大于豆梨的,但杜梨的水分利用效率(WUE)仍维持在较高水平上;豆梨叶片下表皮气孔密度是杜梨的1.5倍;两者气孔长度、气孔开度的日变化规律均相似,但在白天气孔开度的最小值,杜梨出现在14:00时,而豆梨出现在12:00时。相关性分析结果表明:杜梨的WUE与试验环境温度(T)呈显著负相关(P<0.05),而与叶片表面的相对湿度(Hr)呈显著正相关(P<0.05);豆梨的WUE与T呈极显著负相关(P<0.01),而与RH呈显著正相关(P<0.05)。研究结果表明:豆梨气孔对高温、强光等环境的响应较为敏感且强烈,随着每日温度的升高,其气孔闭合现象出现的时间提早,致使光合作用减弱;而杜梨能够保持气孔的正常形态,且杜梨的Gs、Tr均维持在较高水平上,其光合能力较强,并具有较高的水分利用效率,从而表现出更强的环境适应性。     

香榧花芽分化与核酸的关系研究初报

香榧花芽分化与核酸的关系研究初报苏梦云周国璋关键词香榧花芽分化核酸香榧（ＴｏｒｅｙａｇｒａｎｄｉｓＦｏｒｔ．ｅｘＬｉｎｄｌ．）是我国著名的珍稀干果,雌雄异株,一般在４月中下旬开花授粉。由于香榧童期较长（大约需２０ａ左右才开花）,如何促进提早开花结实已...     

培养基成分对梨花粉萌发和花粉管生长的影响

以黄冠梨花粉为试材,研究了不同蔗糖浓度,不同硼酸浓度和不同硝酸钙浓度对黄冠梨花粉萌发和花粉管生长的影响。结果表明：花粉萌发和花粉管生长的适宜蔗糖浓度为100g/L,硼酸浓度为100mg／L,硝酸钙浓度为300mg／L。     

中国水仙花器官愈伤组织诱导、分化及组织学观察

为了建立中国水仙遗传转化体系,为转基因分子育种提供良好受体,以中国水仙‘金盏银台’品种的不同花器官为实验材料,以MS为基本培养基,研究了花药、花梗、子房、花柄愈伤组织诱导情况.对愈伤组织诱导效果较好的花梗和花药培养基中添加不同浓度6-苄基腺嘌呤(6-BA)、硫酸腺嘌呤(Ad)、萘乙酸(NAA)和2,4-二氯苯氧乙酸(2,4-D),筛选出愈伤组织诱导及鳞茎芽再生的最适培养基配方.结果表明:花梗愈伤组织诱导及鳞茎芽分化的最佳培养基为MS+1 g·L-1NaH2P04+0.003 g· L-16-BA+0.001 g· L-1NAA+0.2 g·L-1 Ad+30g· L-1蔗糖,花药愈伤组织诱导及鳞茎芽分化的最佳培养基为MS +0.002 g·L-16-BA +0.001 g·L-1 NAA +30 g·L-1蔗糖;花梗愈伤组织诱导到鳞茎芽分化的时间需要30～35 d,而花药这一过程为80～90 d.对花梗愈伤组织诱导及鳞茎芽分化过程进行组织学观察表明:本研究中产生的小鳞茎是由愈伤组织再分化得来的,表明花梗更有利于作为转基因受体,从而解决了转基因研究过程的一个瓶颈问题.     

刻芽与扭枝对梨不同优系成枝力和成花数的影响

研究刻芽和扭枝对梨不同优系幼树成枝力和成花数的影响,为实现其早果、丰产和省力化栽培提供理论依据。研究方法上采用以6个2年生不同优系为试材,于早春对其主干进行刻芽处理,并对当年发生的侧枝在半木质化时从基部进行扭枝处理,调查统计刻芽后幼树成枝力和扭枝后树体生长和成花状况。研究结果表明,刻芽后,6个优系发枝量分别比对照样本增加了225%、116%、160%、122%、136%、150%,处理样本与对照样本之间差异显著。扭枝对6个优系树高、枝长的影响未达显著性差异,但6个优系均比对照样本的花芽量多,相对而言,杂交优系Ⅳ、Ⅴ、Ⅵ成花量少,平均每株有花芽2个,处理样本与对照样本之间差异显著,花芽量分别是对照样本的7.0倍、1.6倍、4.0倍;杂交优系Ⅰ、Ⅱ、Ⅲ的花芽量多,平均每株有花芽4.4个,处理样本与对照样本之间差异不显著。综上所述,刻芽能显著地提高梨幼树成枝力,西洋梨×东方梨比东方梨×东方梨杂交优系的成枝力高;扭枝对梨幼树的生长发育影响小,但能提高幼树的成花数,尤其对不易成花的含有西洋梨基因的优系效果更加显著。     

Repellent and attractive effects of herbs on insects in pear orchards intercropped with aromatic plants

There is increasing interest in the use of vegetation such as aromatic plants as intercrops to biologically control insect pests in agroecosystems and orchard ecosystems. Understanding the mechanisms underlying the repellent effects of aromatic plants on orchard pests (e.g., scarabaeid pests) can lead to improved application of intercropping cultivation practices in orchards. We tested eight intercropping treatments, each containing a different species of aromatic plant, in a pear orchard, along with a natural grass treatment and a clean tillage (control) treatment. The results showed that intercropping reduced the annual cumulative number and abundance of scarab beetles relative to the control. The annual dynamics of scarab populations were also significantly altered where intercrops were used. However, with the exception of Ichneunmonidae, the natural parasites of scarabs showed no preference for the aromatic plants. A correlation analysis indicated that the reduction in some of the scarab beetle species was related to the abundance of certain specific natural enemy species. In addition, the diversity, evenness and degree of dominance of natural enemy species may have contributed to the decrease in scarab populations. This study shows that intercropped aromatic plants can be applied to control the scarab beetles in orchard ecosystems, but that effects vary across aromatic plant species.