Dynamics of the Cumulation of Macroelements – Phosphorus, Potassium, Calcium and Magnesium During Development to Maturity of Soybean Seed

Dynamics of the cumulation of phosphorus, potassium, calcium and magnesium in developing seed of four soybean genotypes under the defined climatic conditions in the course of three years was observed. Samples were being taken at weekly intervals from the point at which the grain reached a size suitable to be analyzed up to the full maturity of the seed. By analyzing the results it was found out that the intense cumulation of the minerals tested took place during the stages III and IV of the seed development, that is, in the course of intense cumulation of dry matter and the most expressive metabolic activity in the seed. Investigation of the impact of climatic conditions provides evidence that cumulation of the tested macroelements has been favourably influenced by increased precipitation along with moderate air temperatures within the seed developing period. The highest content of the minerals found with the cultivar Maksimirka independently of the year investigated reveals that mineral cumulation in soybean seed is affected by the cultivar and genetic particularity.     

Analysis of Growth and Productivity of Indian Mustard (Brassica juncea) in Relation to FYM, Nitrogen and Source of Fertilizer

A field experiment was conducted during the winter seasons of 1992–93 and 1993–94 at Anand to study the effect of FYM, nitrogen and source of fertilizer on growth and yield of mustard [ Brassica juncea (L.) Czernj & Cosson]. The results showed significant variation in leaf area index (LAI), crop growth rate (CGR), dry matter production and seed yield. The direct effect of farmyard manure (FYM) was conspicuous in improving the growth of mustard. FYM application at 10 tonnes ha⁻¹ significantly increased the LAI, CGR and dry matter accumulation per plant at almost all the stages during first year study (1992–93) and in pooled analysis. Similarly, nitrogen application registered maximum LAI, CGR at 75 kg level and RGR and NAR at 50 kg level at almost all the during both years. Sulphur carrying source (Ammonium sulphate plus single super phosphate) increased all stages growth characters. Maximum dry matter accumulation per plant and seed yield were recorded with highest levels of FYM (20 tonnes ha⁻¹), N (75 kg ha⁻¹) and source having S. Seed yield was strongly associated with LAI and dry matter accumulation per plant at all the stages.     

加快淮北地区杂交粳稻发展的几个问题

回顾了淮北地区十多年来杂交粳稻示范推广的发展过程，分析了影响杂交粳稻发展的主要原因，并论述了加快该地区杂交粳稻发展的几个主要问题。     

Leaf, floret and seed infection of wheat by Pyrenophora semeniperda

Infection processes of Pyrenophora semeniperda on seedling and adult wheat leaves and wheat ears were investigated. Almost 100% germination of conidia occurred on seedling leaves, compared with 20–30% on adult leaves. Appressoria formed over the anticlinal epidermal cell walls and haloes always accompanied infection. Sometimes papillae formed within the leaves as a resistance mechanism. Infection hyphae ramified through the intercellular spaces of the mesophyll resulting in cellular disruption. The infection processes on floral tissues were similar to those observed on leaves; however, no infection occurred on anther, stigmatic or stylar tissues. Infection of ovarian tissue occurred both with and without appressoria formation. Hyphae grew mainly in the epidermal layers and appeared unable to breach the integumental layer as no growth was observed in endosperm or embryo tissues. The optimum dew period temperature for conidial germination was 23·6°C, compared with 19·9°C for lesion development, 20·4°C for the production of infection structures on seedling leaves and 23·7°C for floret infection. Leaf disease development occurred in a logistic manner in response to dew period, with maximum infection observed after 21 h compared with > 48 h in seeds. An initial dark phase during the dew period was necessary for infection and temperature after the dew period had an effect, with significantly more numerous and larger lesions being formed at 15°C compared with 30°C. Seedling leaves were found to be more susceptible than older leaves, under both field and controlled environment conditions. Infection of wheat seeds following inoculation of ears, or after harvest burial of inoculated disease-free seeds, was demonstrated. In the latter, 3-week-old seedlings were slightly stunted, whereas older plants were unaffected. The apparent unimportance of this plant pathogen as a cause of leaf disease in relation to its poor adaptation to dew periods and dew period temperature is discussed, along with the importance of its seed borne characteristics.     

鹰嘴豆籽粒贮藏蛋白双向电泳的研究

以鹰嘴豆为材料,通过对样品制备、电泳条件的优化,建立其籽粒贮藏蛋白的双向电泳技术,并通过电泳图谱的分析,了解贮藏蛋白等电点和相对分子质量的分布情况．结果表明,经考马斯亮蓝染色获得贮藏蛋白斑点约380个,等电点范围在pH4．0～8．0,其中大部分集中在pH6．0～7．0;鹰嘴豆籽粒贮藏蛋白质的相对分子质量为11000．120000,表现出2个分布峰,一个在30000～40000,另一个在50000～60000;鹰嘴豆与大豆籽粒贮藏蛋白的分子质量和等电点分布基本相似．     

双斑东方鲀三倍体育苗生产性研究

采用温度休克方法诱导双斑东方鲀三倍体,在水温18-20℃条件下,卵受精后5分钟用40℃的水处理双斑东方鲀受精卵10分钟,三倍体诱导率100％,孵化率相对诱导量达25％;育苗采用前期室内工厂化培育与后期土池培育相结合方法,培育出全为三倍体(体长3 cm以上)苗种5．8万尾,对应孵出苗量,成活率为34．6％。     

黄土高原亚高山草地退化对土壤种子库的影响

本试验对黄土高原亚高山草地不同退化程度下土壤种子库的物种组成、种子密度、分布特征以及影响因素进行了研究.结果表明,研究区地上植物有31种,分属于14科、25属;种子库植物有32种,分属于14科、31属;种子库的83.45％ 都分布于浅层土壤中(0～5 cm).随着草地退化程度的加重,地上植被和地下种子库中多年生植物的比...     

种子超干贮藏对紫花苜蓿前期生长和生理特性的影响

采用硅胶室温干燥法对陇东紫花苜蓿（Medicago sativa L. cv. Longdong）种子进行超干处理,使其含水量由9.03%（CK）分别降至7.09%～4.59%共八个不同含水量水平,用铝箔纸密封,常温下贮藏1年后,采用沙培盆栽试验,研究种子超干贮藏对苜蓿生长和生理的影响。结果表明,超干贮藏后,紫花苜蓿种子的出苗数、植株的株高比CK显著提高,MDA含量显著降低。播种第30天时,含水量为6.36%～4.59%处理种子的出苗数较CK提高25%～50%;播种第60天时,种子含水量为6.36%～5.46%处理的植株株高较CK提高11.02%～15.68%,各超干处理种子的植株MDA含量仅为CK的44.92%～70.29%;所有处理植株的根体积、地上干重、地下干重和可溶性糖含量仅为CK的55.36%～89.29%、63.06%～88.05%、50.71%～76.69%和63.35%～97.86%;除4.59%含水量处理的叶片数和5.18%含水量处理的根瘤数与CK比差异不显著,其它各处理的单株叶片数与根瘤数均显著低于CK,其中各超干处理的根瘤数仅为CK的63.00%～92.56%。说明超干贮藏能够提高苜蓿种子的出苗数、植株的株高和耐受性,但降低了植株的生物量及根体积,并影响了叶片生长及根瘤的形成。     

Analysis of the seed dispersal patterns of wild soybean as a reference for vegetation management around genetically modified soybean fields

There are concerns that genetically modified soybean might threaten the genetic diversity of the wild soybean populations that are distributed in East Asia because genetically modified soybean has no crossing barrier with wild soybean. A simple and effective method to prevent hybridization via pollen flow is spatial separation between the two species because their hybridization occurs only when they grow in close proximity. Therefore, the invasiveness of wild soybean needs to be known in order to secure the appropriate distances. As wild soybean seeds are dispersed mechanically by pod dehiscence, an experiment was conducted in which white sheets were placed on the ground, concentric circles were drawn around the parent plants, and the number of dispersed seeds within each 0.5 m‐wide zone were counted. About 40% of the produced seeds were dispersed and the number of dispersed seeds gradually declined as the distance from the parent plants increased. The model that explained the relationship between the number and distance of the dispersed seeds was produced by using a generalized linear model procedure. More than 95, 99, and 99.9% of the produced seeds stayed within 3.5, 5.0, and 6.5 m after natural pod dehiscence. Knowing these values is useful for evaluating the level of invasive risk by mechanical seed dispersal. The goal of the work is to efficiently and deliberately prevent hybridization by isolating genetically modified soybean fields and wild soybean populations by vegetation management, including weeding and setting up specific‐width buffer zones.     

Integration of soil, crop and weed management in low-external-input farming systems

Greater adoption and refinement of low-external-input (LEI) farming systems have been proposed as ways to ameliorate economic, environmental and health problems associated with conventional farming systems. Organic soil amendments and crop diversification are basic components of LEI systems. Weed scientists can improve the use of these practices for weed management by improving knowledge of four relevant ecological mechanisms. First, multispecies crop rotations, intercrops and cover crops may reduce opportunities for weed growth and regeneration through resource competition and niche disruption. Secondly, weed species appear to be more susceptible to phytotoxic effects of crop residues and other organic soil amendments than crop species, possibly because of differences in seed mass. Thirdly, delayed patterns of N availability in LEI systems may favour large-seeded crops over small-seeded weeds. Finally, additions of organic materials can change the incidence and severity of soil-borne diseases affecting weeds and crops. Our research on LEI sweetcorn and potato production systems in central and northern Maine (USA) suggests that these mechanisms can reduce weed density and growth while maintaining crop yields. Low-external-input farming systems will advance most quickly through the application of interdisciplinary research focused on these and other ecological mechanisms.