一种新型的桃树栽培模式——草地桃园

桃三李四梨五年,这是传统果业生产中大冠稀植传统模式下的一种技术写照,一般桃树丰产期都得5-6年或更长,这对于当前农民致富的迫切愿望来说,传统模式是难以实现短、平、快脱贫效果的。再加上变化莫测的市场与人们对果品高品质的要求,桃农们急盼一种投产丰产期早,品种能随市场转的新型栽培模式的出现。源于美国的草地桃园就能实现这一切要求,它可以使桃树栽培做到当年栽当年或次年就丰产,而且能实现品种的快速更新,能够生产出糖度更高色泽更艳的优质果品,能够使果园管理变得更简易、劳动力成本更低,这就是桃的新型栽培模式———草地桃园。     

Response of Corn to Banded Zinc Sulfate Fertilizer in Fields with Variable Soil pH

Abstract

There are soil series that contain free calcium carbonate (CaCO₃) within fields where the surrounding pHs of the soil series are slightly acid. The objective was to study corn (Zea mays L.) grain yield response to zinc (Zn) fertilizer on different soil series within fields. The study was conducted at 12 sites between 1998 and 2000. Treatments were 0 and 5.6 kg Zn ha^?1 applied in bands to field‐length strips of corn and replicated four times. Multiple soil series were identified at each site, and treatment pairs were located within them. Grain yields, whole plant (V6 to V10 growth stage), and grain Zn content and uptake were measured. The most common result was no response to Zn application. However, significant yield decreases occurred on some soils as a result of Zn application in two situations: on soils with high soil‐test Zn or on soils with low soil‐test Zn and high pH.     

Increasing urea-N efficiency in transplanted lowland rice by urea solution band placement

Alternative N fertiliser management strategies are needed to increase N-use efficiency in wetland rice (Oryza sativa L.). In the wet season of 1993–1994, field experiments were conducted to evaluate the band placement of urea solution in comparison with broadcast prilled urea, neem-coated urea, or point-placement of urea supergranules. Both grain yield and N-use efficiency were higher with band placement of urea solution (50 or 100 kg N ha^-1) compared to a conventional split application of prilled urea at 100 kg N ha^-1. The total ¹⁵N recovery was 58.7 and 51.7% with band placement of urea solution at 50 and 100 kg N ha^-1, respectively, compared with 47.8% for neem-coated urea and 28.5% for a conventional split application of prilled urea. Current address: Training Division, KVK, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India Pin 641 003     

放牧条件下柴达木绒山羊畜群结构优化与设计

在完成柴达木绒山羊生长发育测定,调查生产现状和产品市场的基础上,建立畜群结构优化分析模型,规划求解后,得出最佳畜群结构,并对现有的不合理环节提出指导意见,有利于在有限的资源条件下,充分发挥品种特性,实现经济利益的最大化.     

Starter fertilizer to spring barley and spring wheat in south-east Norway: Effects on growth and nutrient uptake

Abstract

Field experiments were carried out on three representative soils, to evaluate the effect of various starter fertilizers, together with different rates of band placed phosphorus (P), on nutrient uptake and yield of spring barley (Hordeum vulgare L.) and spring wheat (Triticum aestivum L.). The starter fertilizers were placed in the immediate vicinity of the seed, while the band placed P was placed at about 5 cm below the seeds and spaced at 25 cm between alternate seed rows. As starter fertilizer, monoammonium phosphate (MAP), calcium nitrate (CAN), ammonium nitrate (AN) and triple superphosphate (P20) were compared. In both species, effects of starter fertilizer on P uptake were most marked early in the growing season. At GS 13 application of 20 kg P ha^?1 as MAP increased the P uptake by 50% in barley and by 35% in wheat, compared to no seed-placed nutrients. For grain, the increase in P content was 8% for both species. The higher P uptake at GS 13 was supported by observations of higher plant vigour in the treatments with either P20 or MAP as starter fertilizer. The use of N only as starter fertilizer did not increase the vigour of the plants. Band placement of P also gave more vigorous plants in spring barley. The grain yield increased on the silty clay loam and on the silt soil when starter fertilizer was applied, especially with the use of MAP. Smaller and non-significant yield differences were found when starter fertilizer was used on the loam soil. No delay or reduction of emergence was observed with starter fertilizer. Therefore, on soils where root growth or nutrient uptake becomes limited during the first weeks after sowing, application of starter fertilizer is recommended in Norway for both spring barley and spring wheat. Crops grown on silty soils seem to have an especially high demand for easily available P given as starter fertilizer.     

RAPD标记与新扬州鸡生长性能的相关性研究

本研究对新扬州鸡进行RAPD分析 ,评定其遗传多态性。从 2 1个引物中筛选出OPAY0 2、OPAY1 3和OPAY1 7,并根据其多态性组合对周龄增重的影响 ,探索RAPD标记与新扬州鸡早期生长和屠宰性能的关系。结果表明被检测到的新扬州鸡中 70个DNA条带 ,分子量大小在 0 .38kb～ 2 .98kb之间 ,平均条带共享率为 0 .80 37,OPAY0 2引物对 5 6日龄平均增重、日增重、屠体重、半净膛重、全净膛重均存在显著的遗传效应     

电泳技术鉴定黄瓜种子纯度的应用研究

本试验以经济价值较高，易发生混杂的黄瓜种子为材料，于１９９５－１９９７年采用蛋白质电泳技术对黄瓜的十个品种进行了分析，结果表明：通过蛋白质电泳谱带可将试验中的十个品种明显区分开。     

Trees as large-scale natural phononic crystals: Simulation and experimental verification

Urban trees are usually planted on a periodic layout in the spatial configuration. We regard urban trees as large-scale natural phononic crystals. The entire forest is reduced to a reasonable “tree-soil” unit cell based on the phononic crystal theory and finite element method by COMSOL software is used to obtain the dispersion curves. The Rayleigh wave band gaps of phononic trees are distinguished by the sound cone method. The influences of soil elastic modulus and tree height on band gaps are investigated. A three-dimensional simulation model and experiment test are applied to validate the effect of phononic trees on vibration control. The numerical frequency reduction zones coincide exactly with the theoretical band gaps. Increasing soil stiffness results in a higher-frequency and wider band gap. An increasing tree height is beneficial to obtain low-frequency band gaps. A periodically arranged plantation that Rayleigh wave band gaps at frequency ≤60 Hz could be designed. This study opens up a new theoretical basis for the quantitative analyses of urban trees to the ground vibration mitigation at a certain frequency range.     

云南鲁甸M_S6.5地震灾区滑坡提取方法研究

[目的]利用遥感技术快速准确的提取地震灾区滑坡。[方法]以鲁甸地震灾区为研究区,分别运用高分一号和Landsat8卫星OLI多光谱影像数据。[结果]利用面向对象影像分类以及波段运算等技术,结合震前、震后影像,对灾区滑坡进行提取,在此基础上总结了地震次生灾害的关键技术和工作流程。[结论]以Landsat8卫星影像为数据源,进行波段运算,能较好的提取地震次生灾害。     

香猪等五品种猪的C—带和银染带的分析和比较

本文分析和比较了香猪、北京黑、长白、长北和社长北杂种的C-带和银染带。指出了家猪有可能存在Lin所没有揭示的异染质。得出了它们的NORs平均值分别为3.96、3.88、2.03、2.95和3.00。NORs联合率平均值为3.00％,但香猪高达7.31％。对香猪的结果分析表明,香猪具有以下细胞学特征:(1)染色体Y长;(2)染色体Y长臂C-带浅染;(3)D组染色体C-带具有极大的多态性;(4)染色体2～4之一的长臂有时出现C-带;(5)染色体NORs联合率高。