Runner formation on strawberry plants in autumn and winter

Summary The present experiments with runner plants of the strawberry variety Deutsch Evern are part of an investigation carried out to determine the conditions under which runners are produced in autumn and winter. This information is necessary to produce runners on mother plants of strawberry selections which are tested for viruses during these seasons.In this paper the influence of increasing the light intensity during the day or the intensity of the additional light, or both, on runner production under a 16 hr day was studied at 17°, 20° and 23°C.It was found that at 20° and 23°C more runners were produced by increasing the light intensity during the day or the intensity of the additional light, or both. But increasing the light intensity produced the best results at 23°C. At that temperature there was a decline in runner production in December and January, if only the light intensity during the day or the intensity of the additional light had been increased. This was hardly the case when both light intensities had been increased.     

Heterosis in brussels sprouts,especially with reference to cold resistance

Summary Experiments on heterosis in Brussels sprouts are described. The plants obtained after inbreeding showed reduced vigour and gave sprouts of poor quality. The heterosis cross yielded sprouts of a better quality than the original varieties. After the severe winter 1953–1954, it was observed that a heterosis effect for cold resistance also exists. These results are discussed and interpreted according to Jones' dominance hypothesis.

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Samenvatting Proefnemingen over heterosis bij spruitkool zijn beschreven. De door inteelt verkregen planten hadden minder groeikracht en leverden spruiten van slechte kwaliteit. De heterosis-kruising gaf spruiten van betere kwaliteit dan de oorspronkelijke rassen.Na de strenge winter 1953–'54 kon worden vastgesteld, dat een heterosis-effect voor kouderesistentie bestaat. Deze resultaten worden besproken en verklaard met behulp van de dominantiekoppelingstheorie van Jones.

     

Problems of heat spot in fragaria vesca L. when indexing strawberry selections for viruses

Summary In view of the available labour the testing of strawberry selections for viruses by runner grafting is carried out in autumn and winter. In order to obtain sufficient runners on the test plants these tests were carried out at a constant temperature of 23°C. At this temperature, however, the indicator plants (Fragaria vesca) developed heat spot. The symptoms are reminiscent of virus-infection, which makes it difficult to decide whether the test plant carries a virus or not.It was found that heat spot symptoms became less distinct at a constant temperature of 17°C, and were absent on newly developed leaves. Consequently the indicator plants were transferred to 17°C after 2 successful unions had been obtained at 23°C. In this way it was possible to obtain a reliable impression of the state of health of the test plant.     

Influence of the temperature on runner production in five strawberry varieties

Summary The object of the present experiments was to ascertain whether there are differences in runner production between the strawberry varieties Deutsch Evern, Oberschlesien, Auchincruive Climax, Jucunda and Madame Moutot. To this end runner plants of these varieties were grown at 4 constant temperatures, viz. 17°, 20°, 23° and 26°C, in a natural day.It was found that runners were produced at all 4 temperatures. However, there were differences between the varieties in the number of runners produced.As the temperature became higher the number of runners increased, except in the variety Madame Moutot, which has a lower optimum temperature for runner production than the other varieties tested.Both the degree and duration of runner production were affected by temperature.     

基于生物量的冬小麦越冬前植株地上部形态结构模型

越冬前植株地上部形态建成是冬小麦株型构建和可视化的重要基础。为定量分析冬小麦越冬前植株地上部形态结构参数与器官生物量的关系,以济麦22、泰农18和鲁原502为材料,于2013-2014和2014-2015年度开展了品种和施氮试验。利用2013-2014年度越冬前植株地上部形态结构参数和器官生物量等数据构建了冬小麦越冬前植株地上部形态结构模型。经2014-2015年度数据检验,除叶鞘长和叶弦长模型精度略低外,叶长、最大叶宽、叶切角和叶弦角模型精度均较高,所建模型可较好地模拟不同品种与各施氮水平冬小麦越冬前植株地上部形态结构。     

Using tube rhizotrons to measure variation in depth penetration rate among modern North-European winter wheat (Triticum aestivum L.) cultivars

Deeper plant root systems are desired for improved water and nitrogen uptake in leaching environments. However, phenotyping for deep roots requires methods that enable plants to develop deep roots under realistic conditions. Winter cereals raise further complications as early growth occurs under low light and temperature during autumn and winter—conditions not met in standard glasshouse facilities. This study used tube rhizotrons of 2 m length, positioned outdoor under a rainout shelter to screen for depth penetration rates (DPR) of roots. Rooting depths of 1 to 1.5 m were achieved with 23 widely grown North European winter wheat cultivars in two autumn/winter and two summer experiments and nine of the cultivars were represented in two or more experiments. Heritability of DPR of roots was only consistent in autumn/winter experiments (27 %) signifying the importance of phenotyping in relevant seasons and environments. Depth penetration rate of roots varied significantly within the tested cultivars, from 1.39 (±0.35) mm °C^?1 day^?1 for cv. Tuareg to 2.07 (±0.34) mm °C^?1 day^?1, for cv. Mercedes. This study documented consistent differences of DPR among North-European winter wheat cultivars in long tube rhizotrons under semi-natural conditions, which may form part of future phenotyping facilities for deep rooting traits.     

Dry matter and nitrogen accumulation and residues of oil and protein crops

Oil and protein crops are of growing importance in cropping systems. This study was carried out to compare oil crops of linseed, rapeseed, sunflower and protein crops of faba bean and white lupin for grain production, residual plant dry matter and nitrogen. Two field experiments with either oil or protein crops were conducted in 1993 and 1994, respectively. Total dry matter production, grain yield, residues, N concentrations and mineral N in the soil were measured. Dry matter production and distribution as well as N uptake and residues varied greatly among species and between years. In 1993, oil crops gave up to 3 t ha⁻¹ grain and 16 t ha⁻¹ residues with sunflower, while in 1994 up to 5 and 11 t ha⁻¹, respectively, were recorded with winter rape. Protein crops showed an opposite reaction in years. Nitrogen uptake and residual N amounts were correlated with dry matter production. Plant residues of oil crops contained 20–140 kg N ha⁻¹; those of protein crops up to 80 kg N ha⁻¹. Despite the variation of residual plant N the variability of mineral N in the soil at harvest was hardly influenced by crops and amounted to only 20–50 kg NO⁻₃-N ha⁻¹.     

Influence of genotype and culture conditions on the production of embryos from anthers of tetraploid wheat (Triticum turgidum)

Summary Anther culture of 10 tetraploid wheat (Triticum turgidum) genotypes and two backcross lines representing a wide range of genetic variation was studied in a randomized block design with three replications. Each replication consisted of 2 pots with 3 plants. The day length was 16h and temperature 25° C/15°C for day/night in a controlled greenhouse where the anther donor plants were grown. Two different treatments were used for anther culture. The first one was potato 2 medium (Chuang et al., 1978) modified by adding 0.5 mg/l glutamine and solidified by gelrite (4g/l) (Henry & De Buyser, 1981). Cultures were incubated in light (15 E m^–2 S^–1) at 26°C at 16h day length. The second medium was described by Fadel & Wenzel (1990), differing from the first by the nature of the sugar (maltose) and consistency of the medium (semiliquid by ficoll). Anther cultures were incubated in the dark at 28°C. The study of about 1300 anthers per genotype and treatment showed that both genotype and treatment affected embryo formation of tetraploid wheat. The backcross lines exhibited significant differences for androgenic abilities when compared to their common parent. Most of the genotypes were medium dependent for androgenesis and revealed significant interactions with the two treatments. Five green plantlets were regenerated and fertile doubled haploid plants were obtained from three out of the 12 studied genotypes.     

Simultaneous selection of segregating two-row winter barley material in England and Italy

Summary Independent but simultaneous selection by two breeding teams of the same segregating two-row winter barley material at Cambridge, England and Fiorenzuola, Italy was carried out over the years 1978–1982 with the objective of comparing the individual selection of the two breeding teams and assessing the adaptation of the surviving selections. Visual selection in the generations F₃ to F₅ did not result in any clear cut compartmentalisation of the material and both teams were as likely to select from families previously selected only by the other team as from families they had themselves previously selected. Lines with specific adaptation to each site as well as lines well adapted to both sites were identified from yield trials carried out in F₅ and F₆. The former showed only a very small yield advantage over lines with general adaptation to both sites.     

Development of highly sprouting tolerant wheat germplasm with reduced germination at low temperature

The development of sprouting tolerant spring and winter wheat varieties that retain dormancy in cool, wet conditions is a long-term objective in Hokkaido, Japan. A highly tolerant spring dwarf line, “OS21-5”, derived from “Tordo” × “Zenkoji”, was used to develop transgressive spring, “OS38” and “OS74”; and winter, “OW77”, “OW104” and “OW93” wheats. More recently, winter lines with improved agronomic performance, though still deficient in quality and scab resistance, have been identified. In general, germination percentage of mature grain at 10 ^°C was closely related to the mean temperature experienced during the 5 days prior to maturity (dough–yellow ripening stage) and to the capacity to maintain a high amylograph paste viscosity. Dormancy at 10 ^°C appeared to be determined by a combination of genotype and variation in sensitivity to temperature during the later stages of ripening. Genotypes such as “OS38” and ‘OWl04’ were both highly tolerant to germination at 10 ^°C and insensitive to temperature during ripening. By comparison, most of the other cultivars showed a similar, intermediate sensitivity to ripening temperature, and dormancy decreased as ripening temperature increased. Dormancy of‘RL4137’ at maturity, and to a lesser extent ‘Gifukomugi’ and ‘KKI354’, was very sensitive to ripening temperature and useful levels of dormancy only developed under cool ripening temperatures, mean temperature < 18–20 ^°C.     

The breeding of scab-resistant frame cucumbers in the Netherlands

Summary Scab caused by the fungus Cladosporium cucumerinum, may cause serious damage to frame cucumbers. Bulbosan (trichlorotrinitrobenzene) is an effective chemical means of control. Between 1945 and 1954 this German fungicide could not be supplied, and, as a result, the need for resistant varieties became very great.Before 1920 scab-resistance in pickling cucumbers was already known to Dutch growers. Selection started around 1920 on the initiative of W. G. v. d. Kroft and resulted in scab-resistant pickling cucumbers of which Baarlose Nietplekker VI is still widely grown. In 1948 G. W. v. d. Helm (Exp. Garden at Sloten) started breeding a scab-resistant yellow slicing cucumber destined for gardeners in the neigh-bourhood of Amsterdam. The resistant variety Highmoor was used as one parent. In 1954 the yellow variety Vios and the white variety Mabro were introduced. In 1952 G. W. v. d. Helm at the Exp. Garden Sloten, and J. M. Andeweg at the Institute of Horticultural Plant Breeding, Wageningen, simultaneously started breeding green scab-resistant frame cucumbers, using Highmoor as the resistant parent. In 1955 the experimental garden at Sloten introduced the scab-resistant green slicing cucumbers Amato and Proso, while in 1956 the Institute of Horticultural Plant Breeding introduced the scab-resistant green slicing cucumber Esvier. In 1953 seed of 2 first-backcross populations was supplied by the Institute to seed growers. At present intensive breeding for scab-resistance is also being carried out by a number of Dutch seed growers.Scab-resistance depends on one dominant gene; and young plants can readily be tested for resistance. Consequently a backcross scheme can easily be carried out. Rapid breeding is possible because at least 2 cultures can be carried out yearly. If necessary, cuttings of promising plants can be taken. Before and after artificial pollination the flowers can be tied up with raffia. It is simpler, however, to pinch the flowers with a special stainless clip as originally used for grafting cucumbers.The uniform fruit colour of the Dutch green frame slicing cucumbers is a recessive character; the fruit length of the Dutch varieties is dominant.     

An evaluation of seed and seedling drought tolerance screening tests in wheat

Summary A series of experiments was performed in order to evaluate the significance of seed germination and seedling growth in osmotic media as screening methods for drought tolerance.Ten spring wheat (Triticum aestivum L. em Thell.) and one durum wheat (Triticum durum Desf.) were tested under controlled environments, using polyethylene glycol-6000 (PEG) solutions as the moisture stress inducing media.Tolerance in the rate of endosperm utilization, under stress, prior to the onset of germination varied among cultivars.Germination rate or injury to germination at various concentrations of PEG differed significantly among cultivars. Cultivar rating with respect to injury to germination changed with stress levels. Injury to germination did not correlate with endosperm utilization rate in PEG or in water.Germinating seedlings were tolerant to extreme desiccation up to the stage of emergence of the first leaf from the coleoptile.Growth of photosynthesizing seedlings was monitored as they were carried through an increasing concentration gradient of PEG solutions, ranging from –5.9 to –11.3 bars of water potential. Cultivars significantly differed in seedling growth tolerance to increasing levels of water stress. Seedling growth tolerance across cultivars was not correlated with their germination responses under srress.It is concluded that tolerance to water stress in growing seedlings can be screened for by using PEG-containing nutrient solutions. It can not be predicted from germination tests in osmotica.Work was done under a US-Israel Binational Science Foundation (BSF) Grant no. 1654/78.Contribution from Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel, No. 192-E, 1979 series.     

全球变暖下1951—2014年北京地区的季节变化

为了深入了解气候变暖背景下北京季节变化特征,利用1951—2014 年北京观象台逐日气温资料,采用相关分析和突变检测等方法,研究了北京四季开始日期和四季长度的变化特征及其与气温变化的联系。结果表明：（1）北京春季、夏季、秋季和冬季的常年平均开始日期分别为4月3日、5月26日、9 月16 日和11 月3 日。1951—2014 年北京入春和入夏日期显著提前,入秋和入冬日期显著推迟。（2）北京冬季最长,其次为夏季和春季,秋季最短。1951—2014 年北京地区夏季显著延长,而冬季显著变短。夏季显著变长是受夏季开始日期显著提前和秋季开始日期显著推迟共同影响;冬季显著缩短则是受春季开始日期显著提前和冬季开始日期推迟共同影响。（3）1951—2014 年北京年平均气温呈显著升高趋势,线性变化率为0.35℃/10 a。北京气温变化对气候季节变化有显著影响,气温升高,则春季和夏季开始日期提前,而秋季开始日期推迟,夏季延长。（4）北京四季开始日期和四季长度在1990 年前后均发生了显著突变。在全球变暖背景下,北京气温、四季开始日期和四季长度均对气候变暖存在非均衡响应。     

A century of Nordic barley breeding—Effects on early vigour root and shoot growth, straw length, harvest index and grain weight

In cereals early vigour has been identified as an important trait affecting drought tolerance, nutrient uptake, weed competitive ability and yield. To further study how this trait has changed following years of barley (Hordeum vulgare L.) breeding for improved yield, landraces and cultivars from Sweden and Denmark were analysed for seedling root and shoot growth in hydroponics. The Swedish and Danish materials, 35 and 39 cultivars, respectively, represented the gene pool used during one hundred years of barley breeding. Besides seedling growth characteristics, straw length, harvest index and 1000-grain weight were studied in field trials over two years in Sweden, Norway and Latvia. From 1890 to 2005 straw length has decreased from 110 cm to 60–70 cm and harvest index has improved from 0.42 to 0.55, with highly significant linear relationships with year of introduction (r = −0.87 and r = 0.89, p < 0.001, for straw length and HI, respectively). Other traits like 1000-grain weight, heading and maturity date have been less affected. Seedling root weight has also decreased by 33.9 and 25% in Swedish and Danish germplasms, respectively. The decrease in shoot weight is similar to that of the root biomass. Seedling root length (longest seminal root) has decreased by about 10%, while specific root length (mm root mg⁻¹ root dry matter) has increased by 28.6 and 19.0% in Swedish and Danish cultivars, respectively, indicating the development of finer roots in modern cultivars. There are indications that during recent years the deceasing trends have been broken by the introduction of new high yielding cultivars with improved seedling growth. In line with this there are also significant positive relationships between both seminal root length (r = 0.60–0.84, p < 0.05–0.001) and root weight (r = 0.62–0.78, p < 0.05–0.001) and grain yield from official variety trials carried out in Sweden in 1995–1999 and in Sweden and Denmark in 1999–2005. Reasons for the previously decreasing trends and the new trend in modern cultivars are discussed as well as the possibility of using hydroponics for selection.     

Cold tolerance in beans (Phaseolus spp.) as analyzed by their exotherms

Summary Cold tolerance of common bean (Phaseolus vulgaris L.), runner bean (P. coccineus L.) and several bean lines was evaluated under artificial conditions. Seedlings were exposed to –6°C gradually, then to –12°C rapidly in the growth chamber with copper-constantan thermocouples attached to various parts of the plant. Seedling freezing curves with exotherms were then analyzed. Three basic parameters were measured: time required for exotherm to appear, temperature of the appearance of the exotherm and temperature rise caused by the exotherm. Exotherm appearance in beans was related to freezing injury and death of the seedlings. Exotherms of the common bean variety Bush Blue Lake 92 seedling recorded at the stem, primary leaf base, tip and petiole and true leaf appeared at the same time, however their shape was different. Exotherms of stem appeared at higher temperature than those of primary leaves. Their shapes always followed the same pattern. Beans with cold tolerance were found to produce exotherms later than susceptible ones. Exposing 3 weeks old bean seedlings to 12°C delayed the time of exotherm appearance in the cold susceptible cultivar Bush Blue Lake 92. Some plants survived 2 hours exposure to –6°C in the growth chamber.     

1962—2013年山东临沂四季变化特征分析

为了反映气候变暖对临沂季节变化的影响,以便更好地服务于当地应季农业生产、防灾减灾等方面,根据气候季节划分国家标准,利用临沂市气象局所辖10个台站1962—2013年逐日气温资料,分析了临沂地区近52年来四季开始日期和四季长度的变化特征。结果表明：临沂市春季起始日明显提前,秋、冬季起始日均有不同程度的推迟,且这种变化在20世纪90年代到21世纪初最为明显,而夏季起始日变化趋势则不明显。四季长度的变化表现为,春、夏季略呈延长趋势,冬季则呈现明显缩短趋势,秋季变化趋势不明显。四季长度的突变多发生在20世纪80年代末到90年代初,且在80年代后,春、夏季长度呈增加趋势,冬季长度则持续缩短,尤其是1998年以后冬季缩短更为明显。四季长度均存在3年、6年、9年的周期,其中春季以3年周期最为明显,夏、秋、冬季则以6年的周期最为显著,另外春、夏、秋季长度还存在12年左右的周期,冬季长度存在30年左右的周期。     

Variation of PGM and IDH isozymes for identification of alfalfa varieties

Growth habit, heading date and Vrn genotypewere examined for wheat landraces cultivated in China,Korea and Japan, to study their ecogeographicaldifferentiation in east Asia. Spring type landracesaccounted for 43.6% of the whole, and the frequencyvaried between the localities, being closely relatedto the degree of winter coldness. Spring typelandraces mainly adapted to north and south Chinawhere average January temperature is under –7 ^°Cand over 4 ^°C, respectively. On the contrary,winter type adapted to areas of average Januarytemperature from –7 ^°C to 4 ^°C. As toheading date, significant difference was not observedbetween spring and winter type landraces but betweenlocalities, and those cultivated in north China weresignificantly later in heading. It is thereforeindicated that spring type mainly adapts to areaswhere wheat is sown in spring to avoid frost injury,and where winter temperature is not low enough tovernalize winter type wheat. Genetic analysis forspring type landraces showed that the relativefrequency of four Vrn genes was different witheach other. Vrn3 was most widely and frequentlyfound among the four genes, followed by Vrn1 andVrn2. Only seven landraces proved to be thecarrier of Vrn4. The frequency was alsodifferent between localities. Genotype with Vrn1plus other dominant gene(s) adapted to spring sowingto avoid severely cold winter in north China, whilegenotype with only Vrn3 adapted to winter sowingin south China and southwest Japan. It is thereforeconcluded that at least three ecotypes, differing ingrowth habit and Vrn genotype, areallopatrically distributed in east Asia, as a resultof adaptation to winter coldness in each locality.     

Intergenotypic competition and border effect in bread wheat and barley

Summary A coordinated series of experiments aimed to estimate border effect and intergenotypic competition was carried out on bread wheat and barley in Italy and Germany. The performance of the varieties grown in alternate rows 14–17 cm apart proved to be strictly dependent on the bordering variety. The varieties grown in adjacent plots consisting of eight rows showed significant border effects: the two external rows yielded up to 40% more than the two innermost, and the two 30 cm end hills facing the alleys yielded 29% more than the central part of the plot. Is has been suggested that in variety trials the first 30–40 cm at both ends of each plot should be removed mechanically. In spite of the border effect detected in the outer rows of the plots, the varieties similarly exploited the extra space available at the borders, and the space of 30 cm left between adjacent plots seems to be sufficient to dilute the intergenotypic competition at plot level to an extent only marginally affecting variety performance.In conclusion, grain yield based on whole plot (8 rows, 6–10 m²) appears to provide a good estimate of true yield, providing that it is based on the actual area of the plot, including the uncropped strip between adjacent plots. By contrast, the reduction of plot size to 1–3 rows is not feasible without introducing considerable bias into the estimation of the yield potential of the varieties.Abbreviations WW winter wheat - WB winter barley - SB spring barley     

Overcoming self-incompatibility in Ipomoea cairica by IAA

Summary Ipomoea cairica Sweet (Convolvulaceae) exhibits sporophytic self-incompatibility. This has partially been overcome under in vitro conditions, by treating the pollen and/or stigma with 10^-5–10^-1M indole-3-acetic acid (IAA), the optimum being 10^-2M. The self-pollen. which otherwise does not even stick to stigma. germinates after self-pollination provided only one or both the partners are treated. The pollen tubes not only penetrate stigmatic papillae but also traverse the whole length of the style, at least in optimum experimental combinations.     

Genetic control of spikelet number per ear with particular reference to rate of spikelet initiation in hexaploid wheat,Triticum aestivum L.em.Thell.Thell.

Summary Inheritance of spikelet number per ear and rate of spikelet initiation in wheat (Triticum aestivum L. em. Thell.) was studied in the land race spring wheats, 8–23 and 8–27 from Afghanistan, under controlled temperature and photoperiod. Spikelet number per ear was found to be under simple genetic control with dominance for high spikelet number. It is suggested that the gene determining spikelet number does so by determining the rate of spikelet initiation.