影响甜柿坐果率因素试验研究初报

为解决甜柿坐果率低的问题,采取了人工授粉、花期喷施赤霉素和主干环剥等技术措施。结果表明:人工授粉、花期喷施赤霉素和主干环剥与对照比较分别高24.28%,17.15%,13.87%,均能显著提高甜柿的坐果率。虽然花期喷施赤霉素和主干环剥的平均单果重显著小于对照,但甜柿单位面积产量与对照相比仍有显著提高。     

施用不同浓度萘乙酸对文冠果坐果率的影响

为了提高文冠果的坐果率,在木垒县新户乡新沟村果园选取15棵文冠果树,每棵树随机选取1个样枝,进行不同浓度萘乙酸的喷施试验。所有样枝分为5个试验组,其中1个为对照组。在文冠果盛花期,在4组试验枝条喷施体积分数分别为10×10-6、30×10-6、50×10-6、70×10-6的萘乙酸溶液。试验结果表明,与未喷施萘乙酸样枝对比,喷施萘乙酸有提高坐果率的作用,萘乙酸体积分数为50×10-6时文冠果坐果率最高。     

环剥与环割处理对冬枣生长结果及果实品质的影响

以8年生冬枣为试材,研究不同时期环剥与环割对冬枣生长结果及果实品质的影响,旨在为改进枣树的栽培技术和提高枣树的产量与枣果质量提供理论依据。结果表明:主干环剥及主枝环割适宜在盛花期即开花30%~50%时进行,可明显提高冬枣果实及花序坐果率,提高产量;环剥与环割后果实的维生素C、总酸、总糖和可溶性固形物含量提高;环剥处理后的枣果总糖含量较环割处理高,硬度较环割处理低,果实品质更好;盛花后期即开花60%~80%进行环剥与环割,可提高枣果纵横径及单果质量,促使果实膨大,所以在栽培中可结合盛花期进行环剥、环割后,在盛花后期根据树势情况进行2次环剥、环割处理;木质化枣吊的坐果率、可溶性固形物含量、平均纵横径和单果质量均高于脱落性枣吊,说明在生产中应注意培养木质化枣吊,这是提升枣果产量及品质的有效方法。     

外源激素与配比施肥对文冠果坐果率的影响

2015年5月,在辽宁省建平县选取30年生的文冠果(Xanthoceras sorbifolium)花枝,在花期喷施不同浓度的不同外源激素,2016年4月喷施外源激素和不同配比施肥,试验对其坐果率的影响。结果表明,在文冠果盛花期,分别喷施浓度为20 mg·kg-1的2,4-二氯苯氧乙酸(2,4-D)和200 mg·kg-1的赤霉素(GA_3)能显著地提高文冠果的坐果率,且坐果率达到最高,分别为83.44%和84.58%。在配比施肥试验中,N,P,K比例水平为2:1:2,结合喷施200 mg·kg-1的GA_3的处理,其平均坐果率达到最高值,为93.16%;在配比施肥试验的14个处理中,5个处理的平均坐果率较高,达81.57%~93.16%。     

物理绞扎等技术对沙漠戈壁冬枣坐果率的影响

通过对民勤县沙漠戈壁不同树龄冬枣(Ziziphus jujuba cv. Dongzao)树采取主干主枝物理绞扎、环剥等方法,试验分析研究绞扎、环剥2种方法对提高沙漠戈壁冬枣坐果率的影响。试验结果表明:在戈壁沙区,对2年生冬枣幼树促进坐果宜采取主干绞扎方法,不宜用主干环剥方法,主干环剥会引起树体早衰,用工较多;对4年生冬枣树采取环剥和绞扎技对促进坐果均有效果,但环剥比绞扎效果更好,主枝环剥效果较主干环剥效果更好。     

提高设施栽培大石早生李果实品质的初步研究

采用叶面喷肥、疏果、套袋、铺反光膜等不同方法,对设施栽培条件下大石早生李果实品质进行了研究。结果表明:疏果对果实的单果重、可溶性固形物、Vc、还原糖含量分别提高了30.2%、1.3个百分点、10.6%、0.337个百分点。与对照相比,差异达极显著水平;叶面喷施美果灵,使果实的可溶性固形物、还原糖含量分别提高了1.1和0.209个百分点,使Vc含量提高了26.2%。与对照相比,差异达显著水平;铺反光膜使大石早生李果皮的花青素高于对照11.9%～62.1%,且差异达极显著水平。     

提高枣坐果率的几个方法

枣树开花量大、落花落果重。据报道 ,金丝小枣在乐陵产区的自然坐果率只是 0 .2 4%～ 1.6 %。所以为提高坐果率 ,在生产中除加强肥水、合理修剪保证光照之外 ,还可采用以下方法。1.枣头摘心　于 6月份枣花开放至坐果期 ,在枣头长 1/ 3处摘心。注意不宜过早 ,以免刺激营养生长。2 .开甲 (即环状剥皮 )　开甲适期为盛花期 ,从距地面 30ｃｍ处开始 ,环剥位置每年上移 4～ 5ｃｍ。环剥宽度依生长势不同而异 :弱树 2～ 3ｍｍ、中庸树 3～ 4ｍｍ、壮树 4～ 5ｍｍ。若甲口过宽 ,可涂泥或绑缚塑料薄膜以促进甲口愈合。3.生长调节剂　盛花初期喷洒 10…     

不同化学疏花剂对桃坐果率和果实品质的影响

【目的】筛选适宜的桃化学疏花剂及其浓度,探究不同种类和浓度的化学疏花剂对桃坐果率及果实品质的影响。【方法】以3年生晚熟桃'秋甜'为试验对象,于盛花期喷施不同浓度的NAA、6-BA、石硫合剂3种化学疏花剂,以喷清水和自然坐果分别为对照,在果实采收时调查不同处理的坐果率和果实品质,研究不同处理对桃坐果率和果实品质的影响。调查的果实品质指标包括平均单果质量、果实纵径、果实横径、可溶性固形物含量、可溶性糖含量、可滴定酸含量等。【结果】与对照相比,喷施不同种类和浓度的化学疏花剂,'秋甜'桃坐果率均明显下降,且与NAA、6-BA、石硫合剂浓度呈负相关,即随其浓度的增加,坐果率明显下降。从保证产量和疏花疏果效果方面综合考虑,盛花期喷施20 mg/L NAA、0.2 g/L 6-BA或相对密度1.001 4 g/cm~3的石硫合剂效果较好,坐果率分别为24.04%、27.95%、26.63%。与对照相比,喷施不同种类和浓度的化学疏花剂均明显提高了平均单果质量。其中,以喷施相对密度1.002 8 g/cm~3的石硫合剂、20 mg/L的NAA、0.2 g/L的6-BA的平均单果质量较高,分别为388.54、384.56、380.12 g,且与其他处理差异显著。各处理均提高了可溶性糖含量,喷施20 mg/L NAA、0.2 g/L 6-BA或相对密度1.002 1 g/cm3的石硫合剂显著提高了可溶性固形物含量。喷施20、30 mg/L NAA或0.1、0.2 g/L 6-BA提高了可滴定酸含量。【结论】盛花期喷施20 mg/L NAA、0.2 g/L 6-BA对'秋甜'桃有较好的疏花效果,并且能提高果实品质。     

不同处理对巴旦杏坐果的影响

以“鹰嘴”巴旦杏为试材,在盛花期进行了喷施营养元素和生长调节剂对提高坐果率的研究。结果表明:不同浓度的处理中,硫酸锌和硼砂的浓度均以0.6%处理效果最好,坐果率分别比对照提高9.0%和4.67%;赤霉素和2,4-D浓度以40 m g/L和20 m g/L处理效果最好,坐果率分别比对照提高7.67%和8.33%。     

日光温室杏树栽培化学保果技术研究

研究了在盛花期人工点授的基础上进行化学保果技术,结果表明,盛花期喷施0.3%磷酸二氢钾+5%蔗糖+0.3%硼砂+花粉(>0.01g/L)可显著提高杏树的坐果率、单果重及株产量。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。