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951.
M. A-M. Mahir M. Fortass L. Bos 《European journal of plant pathology / European Foundation for Plant Pathology》1992,98(4):237-252
A virus, isolated from faba bean (Vicia faba) obtained from Algeria, was readily recognized as a tobravirus by its particle sizes and morphology. Pea (Pisum sativum) and French bean (Phaseolus vulgaris) characteristically reacted to the isolate like pea early-browning virus (PEBV), but faba bean,Antirrhinum majus, Nicotiana rustica, andN. tabacum reacted with line-pattern symptoms which were unusually brilliant on theNicotiana species. In electronmicroscope decoration tests, the isolate did not react with an antiserum to the Dutch type strain of PEBV, but with one to the broad bean yellow band (BBYB) serotype from Italy. It resembles this serotype in reaction on faba bean, but seems to differ appreciably onN. rustica, N. tabacum, andPetunia hybrida. It is described as a deviant isolate of the BBYB serotype of PEBV.All thirteen faba-bean genotypes tested were found to be susceptible to the Algerian isolate and two Dutch type strain isolates of the virus, and to react with erratic line-pattern symptoms to the Algerian isolate only. All ten genotypes of chickpea (Cicer arietinum) tested reacted hypersensitively, and four out of ten genotypes of lentil (Lens culinaris) were susceptible to the virus but reacted differentially to the three isolates. Seed transmission of PEBV, including the new isolate, in faba bean is confirmed (9% for the Algerian isolate, and over 45% for one of the Dutch type strain isolates), and seed transmission of the virus in a non-legume (N. rustica, 4%) is herewith first reported. This is the first report on the occurrence of the BBYB serotype of PEBV outside Italy, and of PEBV outside Morocco in North Africa. 相似文献
952.
953.
Bistra Atanassova 《Euphytica》1999,107(1):13-21
Data and findings concerning the development of an effective male sterility system (as already applied in the practice of
producing tomato hybrid seed) through the use of the positional sterility (ps 2) gene are reported. Undesirable selfing and
the necessity of emasculation are discussed as the two main disadvantages that limit the use of ps 2-sterile seed parents
in tomato hybrid seed production. The following specific characteristics in the performance of ps 2-lines were evaluated:
1) the percentage of selfing in the ps 2-lines varies within and between the years of growing, being forever lowest during
the period of hybrid seed production; 2) the percentage of selfed seeds when using a ps 2-line as seed parent in producing
hybrid seed is significantly lower than the percentage of selfing, observed on this same line; 3) the ps 2-gene expressivity
varies depending on the genotype. This enables the breeding of ps 2-lines exhibiting very low percentage of selfing; 4) stamen
emasculation at anthesis (as applied in ps 2-lines) is significantly easier and more rapid than emasculation in floral buds.
The easy maintenance of the sterile lines – by artificial selfing it is possible to produce 100% ps 2 progeny – and the high
yield of hybrid seed obtained are discussed as important advantages in using this type of sterility in tomato hybrid seed
production.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
954.
饵料对稚幼参生长变色的影响 总被引:5,自引:0,他引:5
报告了藻粉,浮泥,人工配合饵料,混合饵料对稚幼长岛县牝一海水育苗场变色的影响。经3个胸月的投喂试验。结果:人工配合饵料组稚幼参体长,体重增长较快,纯藻粉组,浮泥组投喂效果都较差。藻粉中添加部分“海丰”牌饲料预混剂和30%的浮泥,对稚参有明显的助长作用,日均增长,增重是纯藻粉组的2倍以上,且明显快于人工配合饵料组。 相似文献
955.
Impact of Mastitis Control Measures on Milk Production and Mastitis Indicators in Smallholder Dairy Farms in Kiambu District,Kenya 总被引:1,自引:1,他引:0
Bovine mastitis and mastitis control were investigated on smallholder farms in central Kenya. After an initial observational study, a clinical trial to assess the impact of three different mastitis control strategies – (1) improved udder hygiene, (2) treatment of subclinical cases, and (3) a combination of these – was conducted on 100 randomly selected farms with 332 lactating cows. Before the implementation of control measures, the milk yield was low (mean 6.5 kg/day; median 6 kg/day) and somatic cell counts (SCC) were high, with 80% and 43% of cows having milk with SCC greater than 250×103 cells/ml and 600×103 cells/ml, respectively. Infectious pathogens were also commonly isolated, with 63% of cows being positive for pathogenic bacteria. Neither intervention strategy alone had any effect on mastitis indicators or milk yield. In combination, the measures had some impact, lowering the prevalence of contagious pathogens by 18%, but this was not reflected in a significantly increased milk yield, lowered SCC or reduced incidence of clinical mastitis. 相似文献
956.
A. F. Ibrahim A. N. Sharaan A. W. El Wakil 《Journal of Agronomy and Crop Science》1991,167(3):170-175
Two promising selected land races of safflower ( Carthamns tinctorious L.) designated as line 11 and line 13, together with the local variety Giza 1 , were examined under three levels of moisture depletions, i.e. 40, 60 and 80 % ASMD at Fayoum, Middle Egypt during 1986/87 and 1987/88 seasons. In both growing seasons, the second irrigation treatment i.e. 60 % ASMD gave the highest means for growth characters as well as seed yield and most of its components. Seed oil content per cent exhibited an increased as soil moisture depletion increased with no significant difference between entries. Safflower entries showed clear differences in some yield components which compensate each other and resulted in no significant difference in seed yield per hectar.
Consumptive use of water by safflower plants increased as the available soil moisture around the root zone increased. No significant differences were found in water consumed by safflower entries used in all experiments.
In the two experimental seasons, the best water use efficiency (WUE) for seed production was obtained also from the second treatment (60 % ASMD). The line 11 gave the best WUE. 相似文献
Consumptive use of water by safflower plants increased as the available soil moisture around the root zone increased. No significant differences were found in water consumed by safflower entries used in all experiments.
In the two experimental seasons, the best water use efficiency (WUE) for seed production was obtained also from the second treatment (60 % ASMD). The line 11 gave the best WUE. 相似文献
957.
静电处理林木种子适宜参数选择的初探 总被引:1,自引:0,他引:1
本文采用技术经济学中加乘混合综合评价方法,对刺槐、紫穗槐种子的15种静电处理进行了综合评价,并应用数理统计学中方差分析和t-检验方法,对两树种的适宜处理参数进行了筛选,结果表明,静电处理刺槐的适宜处理参数为:-100×5,-100×10,-100×20,-100×40。-150×5,-150×10,-150×20,-150×40,-200×5(kV/m×min);静电处理紫穗槐的适宜处理参数为:-100×5,-100×10(kV/m·min)。在静电处理参数两个组分中,场强起主导作用,时间次之。因此,在实际应用中时间选用可以短些。 相似文献
958.
Two series of field trials were performed at three sites in Schleswig-Holstein between 1981 and 1988 to inquire into the yield structure of European winter types of Vicia faba L. and to compare their yield potential with that of spring types. Due to low winter survival, 6 winter types could be evaluated only in 4 environments in dependence of 1–3 sowing times (series α: seed rate 30/m2) and 1 winter type in 5 environments in dependence of 3 sowing times and 3 seed rates (series β: seed rate 15, 30, 45/m2). Seed yield of winter type averaged 410 g/m2 (D.M.) surpassing spring types by about 14 %. Environments caused a considerable variation in yield (275–620 g/m2) and in each yield component of winter types, while sowing dates and seed rates hardly affected the components seeds/pod and seed weight, which displayed stable genotypic rank orders. Compensative forces among the components plants/m2, tillers/plant and pods/tiller, were established. Plant densities of less than 10/m2 in spring, generally led to seed yield below 350 g/m2. Variation between 15–30 plants/m2 due to environments, sowing times or seed rates were frequently not fully compensated by tillering of plants, but often variation of the thus formed yield potential was reduced by pod set of tillers resulting in 210–270 pods/m2. The direction of correlations of pods/tillers with tillers/plant and plants/m2 differed due to experimental conditions whereas negative correlations between pods/tiller and tillers/ m2 were generally evident. Tillering was significantly influenced by the sowing time, though the increase because of early sowing was often covered by compensative effects of different plant densities. A genotypic capability to produce reproductive tillers was demonstrated using an approach which considered different plant densities and compensative forces. Neither a genotypic capability of tillers to set pods nor direct effects of environments or sowing time on pod set were established. 相似文献
959.
960.
使用芳氧基乙酸万酯类化合物AoBe处理不同生育期春小麦,在低浓度条件下有促进幼苗生长、提高田间出苗率、刺激增产等生理作用,在高浓度条件下有抑制生长和致死作用。可见,AoBe具有植物生长调节剂的基本作用特性。AoBe刺激增产作用的适宜处理时期和浓度范围是:浸种和挑旗期为0.01ppm,分蘖期为0.1ppm,拔节期为1 ppm,抽穗期为100ppm左右。以0.01ppm浸种和0.1ppm在分蘖期喷施为最佳组合。1000ppm处理春小麦种子则表现为致死作用。 相似文献