HEAD EMERGENCE IN FORAGE GRASSES IN RELATION TO FEBRUARY–MAY TEMPERATURES AND THE PREDICTING OF EARLY OR LATE SPRINGS

The date of the spring appearance of inflorescences in herbage plants has been studied at the Welsh Plant Breeding Station, Aberystwyth (Lat. 52"N.), and data collected between 1926–64 examined for Lolium, Dactytis and Phleum . The seasonal variation in mean date of emergence showed a range in perennial ryegrass of 14 to 29 days, in Italian ryegrass 14 to 20. in cocksfoot 18 to 25, and in timothy 14 to 19 days. Inflorescence initiation under field conditions is a response to increasing photoperiod, but the rate of development and the date of appearance is controlled by the weather, especially temperature. There is a negative correlation between accumulated temperature and head emergence. The mean emergence date provides a good index of the year by year heading sequence of the different cuuivars. A study of the air and soil temperatures between February and May showed that the accumulated temperature above 42°F for March, and the number of times that the soil temperature at 4 in. deep reached and exceeded 42^T provide a means for predicting the degree of earliness or lateness of spring in relation to head emergence in grasses.
Observations on the phenology of flowering plants and especially fruit trees can also be used for prediction. This second method is simpler and more direct and it has the further advantage of providing a slightly earlier forecast.     

CLASSIFICATION OF STARCH- AND FRUCTOSAN-ACCUMULATING GRASSES AS C-3 OR C-4 SPECIES BY CARBON ISOTOPE ANALYSIS

Type of nonstructural polysaccharide, starch or fmctosan, accumulated in the lower intemodes of grass shoots was not completely consistent with carbon isotope determinations and does not appear to he dependent on the type of photo-synthetic pathway that prevails.     

THE SEASONAL PATTERN OF DRY-MATTER PRODUCTION OF GRASSES IN THE NORTH PENNINES

The seasonal pattern of DM prodaction of Lolium perenne, Cynosurus cristatus. Anthoxanthum odoratum. Festuca ovina and Agrostis stolonifera. cnt to 3 cm at 6-week intervals was studied on five sites, ranging from 49 to 303 m above sea level, in north-west Lancashire. Total annual production declined from a mean of 704 g/m² on the lowest site, to 553 g/m² on the highest, largely as a result of a severe depression in the spring peak of production, i.e. from 6.7 to 2.5 g/m² per day. Later in the year, the daily rate of DM production was similar on all sites. Species varied in their response to increased altitude; Lolium was worst affected by this and Festuca least. The significance of these results, and possible reasons for the decline in spring production are discussed.     

东北地区栽培大豆品种资源分类探讨

资源研究的目的是利用，资源分类也应围绕这一中心。据此，本研究栽培大豆品种资源的栽培区，栽培型，单株粒重，百粒重，生育期，抗病性（花叶病毒，霜霉病，灰斑病，孢囊线虫１号，３号），抗虫性（食心虫），株高，油分，蛋白质，叶形，花以及茸毛色，把东北三省（黑龙江，吉林，辽宁）１７７８份栽培大豆品种资源划分为１个区，１个型，５类，２５群，９９亚群，１６６３个类型。提出了栽培大豆品种资源分类的基本模式及今后的发     

SEASONAL PATTERNS OF DIGESTIBLE ORGANIC MATTER AND PROTEIN PRODUCTION FROM GRASSES IN THE NORTH PENNINES

The seasonal pattern of digestible organic matter (DOM) and crude-protein production of Lolium perenne, Cynosurus cristatus, Anthoxanthum odoratum, Festuca ovina and Agrostis stolonifera cut to 3 cm at 6-week intervals was studied at five sites ranging from 49 to 303 m above sea level in north-west Lancashire for the years 1969–70. DOM production declined from 482 g/m² on the lowest site to 220 g/m² on the highest; similarly protein production declined from 142 g/m² to 73 g/m². Small but significant differences in the percentage of crude protein occurred only ia 1970, whereas DOM as a percentage of DM in the various species differed considerably between sites in both years. The significance of the results and the seasonal fluctuations in production are discussed.     

SWARD GROWTH IN RELATION TO PATTERN OF DEFOLIATION

It is suggested that the growth of a grass sward may be affected by heterogeneity of plant height. An initial test of this possibility was made by cutting a stand of Dactylis glomerata in such a way as to produce adjacent areas of tall and short herbage. This pattern was obtained by using three different cutting treatments, two of which gave yields which were greater than predicted from controls. The results are discussed in relation to alternative methods of harvesting grass.     

马铃薯不同品种淀粉积累生理基础研究——淀粉积累与磷酸化酶、蔗糖转化酶的关系

本试验以高淀粉品种晋薯２号、中淀粉品种内薯３号、低淀粉品种紫花白为材料，对不同生育时期块茎淀粉含量、淀粉积累速度与淀粉磷酸化酶、蔗糖转化酶活性的关系进行了研究，其结果表明：全生育期３个品种淀粉磷酸化酶活性均呈单峰曲线变化；不同生育时期，各品种淀粉含量与淀粉磷酸化酶活性无明显规律性；不同生育时期，各品种淀粉积累速度与淀粉磷酸化酶活性呈正相关。淀粉含量和温度是影响淀粉磷酸化酶活性的两个重要因素，而温度又起主导作用。全生育期，３个品种的蔗糖转化酶均呈苗期为最高，中期显著下降，后期略有回升的变化趋势；不同生育时期，各品种淀粉含量与蔗糖转化酶活性均呈显著负相关；不同生育时期，各品种淀粉积累速度与蔗糖转化酶活性亦呈负相关。因此，蔗糖转化酶活性可作为马铃薯高淀粉育种早期选择的重要生理指标。     

大豆硝酸还原酶活力与硝态氮含量的关系

大豆植株主茎硝酸盐含量从基部向上逐渐增加,营养生长期和开花盛期,近幼生茎下段茎节间硝态氮含量较高,结荚期以后幼生茎段硝态氮含量较高。大豆品种间硝态氮含量和硝酸还原酶活力有明显的差异。吉林20号硝态氮含量和硝酸还原酶活力较高,而大白眉较低。大豆品种间内源基质硝酸还原酶活力差异和外源基质硝酸还原酶活力差异结果是一致的。内源基质硝酸还原酶活力和外源基质硝酸还原酶活力都与幼生茎段硝态氮含量呈显著正相关。     

A COMPARISON OF LEAF AND TILLER GROWTH IN SEVEN PERENNIAL GRASSES AS INFLUENCED BY NITROGEN AND TEMPERATURE

Leaf and tiller development along the main shoot of cocksfoot, ryegrass, timothy, Hordeum bulbosum , meadow fescue, S170 tall fescue and an Algerian tall fescue are described. Comparisons between plants grown at two levels of applied nitrogen, and in a heated and an unheated glasshouse, from January to April, 1961, showed that timothy, cocksfoot and, to a lesser extent, H. bulbosum and ryegrass, generally developed leaves faster than the fescues. Numbers of live leaves per shoot, and numbers of actively-elongating leaves per shoot declined in a similar varietal order. Despite this, the large leaves of the fescues resulted in their having a leaf area per main shoot equal to, or exceeding that of, the other grasses for most of the experiment. In general, rate of leaf appearance, number of live leaves, number of actively-elongating leaves and leaf length were increased by a high level of N and high temperature, but high tesnperature reduced leaf width and, in some instances, tiller numbers.     

细胞壁羟脯氨酸的含量与大豆灰斑病抗性关系的研究

大豆植株在正常生长条件下,细胞壁中羟脯氨酸的含量是处于相对稳定的,当大豆受到灰斑病菌的侵染时,细胞壁中羟脯氨酸的含量相应的增加,在抗灰斑病的大豆品种中,细胞壁中羟脯氨酸含量的积累不论是在积累的速率和积累的量上的均较感病品种更加明显。这一结果表明,大豆细胞壁中羟脯氨酸这种含量上的变化与大豆对灰斑病的抗性作用是密切相关的。     

CLIMATIC FACTORS IN RELATION TO GROWTH AND SURVIVAL OF PASTURE PLANTS

The distribution of natural and cultivated grasslands in relation to climate and the use of various indices and diagrams in studies of crops and climate are discussed. Attempts to establish simple linear relationships between yield and weather components have been disappointing. Studies involving light, theoretical considerations of productivity, adaptation of herbage plants in relation to climatic origin, etc. have proved more useful. Problems involved in extending the work conducted under controlled conditions to the field, are stressed. Particularly important is a better characterization of the environment prevailing in and immediately above swards of different types. The importance of winter survival in Britain is discussed.     

大豆对SMV数量(程度)抗性的综合分级方法研究

选用63个不同抗性类型的代表品种,进行接种大豆花叶病毒病,分析了品种发病率、病级、潜育期和病害扩展速度4个数量抗性组分的遗传变异特点,以4个组分为基础指标,对63个品种的程度抗性进行了聚类分析.发现在距离约为0.38时,63个品种被分成免疫、高抗、中抗、中间、中感和高感6种类型,在聚类分析的基础上建立了各抗性级别的判别函数;另外,利用发病率、病级和接种至最大病情的天数构建了度量数量抗性强弱的综合病情指数(SDI),提出各抗性级别的临界标准;并对同一批材料聚类和判别分析分级结果与综合病情指数分级结果进行了比较,结果显示两种方法可取得类似的分级效果,而综合病情指数是对感病对照的相对统计量,不受时间、地点和批次的限制,便于不同环境下品种抗性的鉴定以及品种间抗性的比较,且简单易行.因此,综合病情指数可作为对SMV数量抗性鉴定的分级指标.     

ANIMAL PREFERENCE IN RELATION TO THE CHEMICAL COMPOSITION AND DIGESTIBILITY OF VARIETIES OF COCKSFOOT

Assessments of animal preference (measured as mean % herbage removed) were made on varieties of cocksfoot in Yorkshire and in Scotland, and parallel chemical analyses were carried out. A similar range of varieties were examined at progressive stages of spring growth at Cambridge. In vitro digestibility tests were made also. In the Yorkshire trials, a significant positive relationship was established between soluble carbohydrates and animal preference and a negative correlation between fibre and animal preference. In Scotland, the relationship between soluble carbohydrate and animal preference was less pronounced. Animal preference in the spring was for the early varieties which have thick and succulent stems up to the stage of ear emergence. In the aftermath animal preferences were less marked.
In trials at Cambridge, the early varieties, notably Scotia, were higher than the late varieties both in digestibility and in soluble carbohydrates. This tendency was also present in Scotland but was less pronounced.     

大豆根系性状和磷效率的遗传规律研究

选用两个磷效率差异明显的大豆品种,在营养液(磷浓度为0,50 μM KH2PO4)和田间(土壤有效磷含量26 mg/kg)进行根系性状的遗传研究.结果表明:两个基因型的根系性状存在显著差异,F1代的总根长和磷效率都表现出明显的超亲优势,其超亲优势率分别为68%和56%;这些性状F2代的为连续变异,表现出多基因控制的特征,且都存在明显的超亲分离个体.遗传模型分析结果表明,这些性状一般都为两对主基因加多个微效基因控制,而且除根平均直径外(水培中无主基因存在),总根长和根体积的遗传模型在大田和短期营养液条件下基本一致.产量及生物产量与总根长、总表面积、平均直径、根体积和磷效率都呈极显著正相关,表明通过这两个性状也可以对根系和磷效率进行间接选择.大田试验各根系性状和磷吸收效率的遗传力都较高,因此在育种过程中对这些性状进行早代选择是可行的.     

PEDOMETER MEASUREMENTS OF THE DISTANCE WALKED BY GRAZING SHEEP IN RELATION TO WEATHER

During the winter months of 1963 and 1964, mature non–pregnant Clun Forest ewes at pasture were equipped with pedometers to study the value of these instruments for measuring distances walked, and to investigate the importance of weather on the distances travelled. Approximately 80 periods were recorded, each of about 24 hours. The accuracy of the measurements was checked by using a rangemeter and it was found that the reliabihty of pedometer records must be assessed on the animal from which they are obtained. The individual characteristics of the pedometers and/or the sheep gave rise to inaccurate records from about 50% of the instruments studied.
Multiple regression analysis of data for each of the three sheep which provided suitable records revealed that, in dry weather, the average distance walked per hour of recording period increased signiJBcantly with mean air temperature in one case and with hours of bright sunshine in another. Wind–speed effects were unimportant. The distance walked by all three sheep increased significantly with hours of daylight per recording period, and this was the only variable found to affect distance walked in wet weather. Differences between average distances walked per hour under dry–and wet–conditions were non–significant.
It is concluded that for measuring the distances walked by sheep, the disadvantages of the pedometer outweigh its advantages.     

世界不同纬度与海拔大豆蛋白质和脂肪分布概势

本文研究了国际大豆品种试验9年的结果,表明大豆蛋白质含量显著地受地理纬度变化和年度变化的影响,脂肪含量显著地受海拔的影响。世界高脂肪和高蛋白质含量区域均在南、北纬11°—20°59′之间。但前者分布在低于海拔500m的低平地区,后者分布在海拔500—1000m的地区。     

A STUDY OF SEED DEVELOPMENT AND YIELD IN TIMOTHY AS RELATED TO DATE OF HARVEST

Studies of seed development and yield were conducted on three Aberystwyth varieties of timothy. The stages of seed development are described, as are their correlation with the external appearance of the head. Evidence is presented to support the suggestion that the latitude in the dale of harvest is greater than has hitherto been accepted. Population studies of seed crops have revealed that the abundant small heads (less than 4 cms. in length) contribute very little to the yield. The partition of the yield amongst the different inflorescence age-groups is given for each variety and methods of judging crop ripeness are discussed.