小麦花粉的离体萌发研究

为筛选适合小麦花粉离体萌发的培养基配方,建立有效的离体萌发方法体系,以小麦品种西农1376为材料研究了不同浓度组合的蔗糖和聚乙二醇4000(PEG4000)在小麦花粉离体萌发中的作用,在此基础上又研究了硼酸(H3BO3)、钙离子(Ca2 )以及生理活性类物质维生素B1(VB1)对小麦花粉离体萌发的影响.结果表明:(1)一定浓度的蔗糖、PEG4000、H3BO3、Ca2 对小麦花粉的萌发有明显的促进作用,而VB1对花粉萌发的效果不明显;(2)18%蔗糖 9% PEG4000 2 g/L Ca(NO3)2·4H2O 60 mg/L H3BO3的培养基成分比较适合小麦花粉的离体萌发;(3)在28℃的条件下培养50 min最适合小麦花粉的萌发及观察与统计;(4)在上述培养基和培养条件下直接采用本研究设计的离心管封闭培养方法可使西农1376的花粉萌发率达到70%以上.     

牛角瓜花粉萌发及花粉管生长研究

运用方差分析、多重比较、正交实验和极差分析方法,对牛角瓜花粉的萌发和花粉管生长进行研究,结果表明,培养基内硼酸、硝酸钙、蔗糖、硫酸镁在一定浓度范围内,对花粉萌发及花粉管生长起促进作用,但浓度过高或过低时,则有抑制作用;钾对花粉萌发及花粉管生长影响不显著;蔗糖和硝酸钙对牛角瓜花粉萌发有显著影响,蔗糖和硫酸镁对牛角瓜花粉管生长有显著影响;牛角瓜最适花粉液体培养基为：15% 蔗糖＋350 mg/L Ca(NO3)2?4H2O＋60 mg/L H3BO3＋150 mg/L MgSO4?7H2O;在30～35℃温度条件下,牛角瓜花粉块萌发和花粉管生长最好。     

3份胡椒属种质花粉离体萌发研究

以海南蒟、大叶蒟和球穗胡椒的花粉为材料,研究了不同培养基和采样时间对花粉萌发率的影响。结果表明：3种胡椒种质花粉的最佳萌发条件分别为100 g/L蔗糖＋100 mg/L硼酸+600 mg/L Ca(NO3)2、100 g/L蔗糖＋100 mg/L硼酸＋300 mg/L Ca(NO3)2和100 g/L蔗糖＋200 mg/L硼酸＋300 mg/L Ca(NO3)2。ME3培养基抑制海南蒟和球穗胡椒花粉萌发,蔗糖、硼酸和Ca2+的协同作用可以提高胡椒花粉萌发率,硼酸的浓度需要控制在一定范围内(≤200mg/L     

柱花草花粉活力的测定方法

利用6种常用花粉活力测定方法对柱花草花粉活力进行测定，并筛选出各方法的最佳配方。结果表明：以离体萌发法为最佳，最适培养基：10%蔗糖、10% PEG-6000(聚乙二醇)、0.01% H3BO3、0.03% CaCl2·2H2O、0.01% KNO3，pH 6.5，柱花草花粉在该培养基上30℃条件下培养10 min，萌发率可达84.03%。0.5% I2＋1.5% KI的碘-碘化钾染色效果好，色差明显，较离体萌发法测定值偏高，但差异不显著，可选作简单快速测定法；FDA(荧光素二醋酸脂)染色法、醋酸洋红染色     

大麻花粉萌发的影响因子及花粉储存的初步研究

利用不同蔗糖浓度、硼酸浓度、Ca2 浓度、温度对6个不同熟性的大麻品种的花粉进行萌发研究,结果表明:大麻花粉培养以15%蔗糖 80mg/L硼酸的液体培养基时花粉的萌发率最高,花粉管的生长速度则以硼酸浓度为20mg/L时最快,加入Ca2 则抑制花粉萌发,培养温度25℃最好。花粉储存中,常温下,未干燥的大麻花粉生活力只能保持3d(天);干燥、密封后在1—4℃条件下花粉活力最多可保持30d;干燥、密封后在-20℃条件下,储存120d后的花粉还有较高的萌发率(34%)。     

马铃薯花粉的离体萌发

选出普遍适合马铃薯花粉萌发的液体培养基 :10 %蔗糖 + 0 0 2 %CaCl2 + 0 0 2 %H3BO3+ 0 0 2 %MgSO4 ·7H2 O + 0 0 1%KNO3,在此培养基上花粉的最高萌发率达 78 1%。培养基中加入0 4 %的NaCl能显著提高萌发速度但并无促进萌发的作用 ;5～ 7d的低温预处理能显著提高花粉萌发率和萌发的同步性     

甘蔗花粉离体萌发研究

为筛选适宜栽培种甘蔗花粉离体萌发的培养基配方,建立有效的离体萌发体系,以糖用甘蔗主栽品种ROC22花粉为材料,通过单因素试验探索满足甘蔗花粉离体萌发的基本条件,然后利用L₁₆(4 ⁵)正交试验,寻求甘蔗花粉离体萌发的最适宜培养基配方,在此基础上进一步探讨不同温度对甘蔗花粉萌发的影响。在单因素试验中,培养基以刚好凝固时为最佳。蔗糖、硼酸和硝酸钙在一定范围内对甘蔗花粉萌发起促进作用,超过一定浓度则起抑制作用。硫酸镁作用不稳定,硝酸钾影响较小。正交试验中,蔗糖对甘蔗花粉离体萌发率和花粉管生长速率影响最大,呈显著水平,硼酸次之,硫酸镁影响最小。花粉萌发的适宜温度为30 ℃,萌发率和花粉管长度分别为89.83%和143.03 μm。200 g/L蔗糖+400 mg/L硼酸+100 mg/L硝酸钙+400 mg/L硫酸镁+1 g/L琼脂,在30 ℃下培养花粉萌发率最高,花粉管生长状态良好,这种方法可快速有效鉴定不同甘蔗花粉活力差异。     

大麻花粉萌发的影响因子及花粉储存的初步研究

利用不同蔗糖浓度、硼酸浓度、Ca2 浓度、温度对6个不同熟性的大庥品种的花粉进行萌发研究,结果表明:大麻花粉培养以15%蔗糖 80 mg/L硼酸的液体培养基时花粉的萌发率最高.花粉管的生长速度则以硼酸浓度为20mg/L时最快,加入Ca2 则抑制花粉萌发,培养温度25℃最好.花粉储存中,常温下,未干燥的大麻花粉生活力只能保持3d(天);干燥、密封后在1-4℃条件下花粉活力最多可保持30d;干燥、密封后在-20℃条件下,储存120d后的花粉还有较高的萌发率(34%).     

响应面法优化金银忍冬花粉离体萌发培养基组分

目的以优化金银忍冬花粉离体萌发的培养基组分。方法以盛花期新鲜花粉为材料,采用花粉离体萌发方法,在单因素试验的基础上,通过响应面法优化培养基组分。结果金银忍冬花粉离体萌发的最佳培养基组分为蔗糖质量浓度为400g/L、硼酸质量浓度为127.23mg/L、2,4-D质量浓度为75.00mg/L,在此培养基组分条件下,金银忍冬花粉萌发率的预测值为90.24%,验证萌发率为89.65%。结论利用响应面分析法可得到理论最佳培养基组分,验证结果表明该方法科学、高效。     

不同培养基组分对黄檗花粉离体萌发的影响

以期筛选出黄檗花粉离体萌发最适宜的培养基,以新鲜的黄檗花粉为研究对象,采用花粉离体培养的方法,通过L_9(3~4)正交试验设计,探究蔗糖、硼酸和硝酸钙对黄檗花粉离体萌发的影响。结果表明:蔗糖对黄檗花粉萌发率的影响最大,而对花粉管长度无显著影响;硼酸对花粉管长度的影响最大,而对萌发率无显著影响;硝酸钙对二者均有影响。黄檗花粉离体萌发最适宜的培养基为:10%蔗糖+0.008%硼酸+0.02%硝酸钙。     

Comparative Assessment of the Efficacy of Various Nitrogen Fertilizers

Summary

The efficiency of N fertilizers is usually poor; often less than 50% of the applied N is taken up by the crop. This review focuses on various N fertilizers with respect to the significance of different N loss pathways, namely (i) ammonia volatilization, (ii) dinitrogen and nitrogen oxide emissions, and (iii) nitrate leaching. Further, the significance of biological N immobilization, ammonium fixation and, finally, the impact of nitrate vs. ammonium uptake on crop yield are also discussed. The reviewed literature shows that N fertilizers may differ markedly in their susceptibility to losses. There is, however, considerable scope to improve N efficiency of each N source by proper N management practices.     

Novel food and non-food uses for sorghum and millets

Sorghum and millets have considerable potential in foods and beverages. As they are gluten-free they are suitable for coeliacs. Sorghum is also a potentially important source of nutraceuticals such antioxidant phenolics and cholesterol-lowering waxes. Cakes, cookies, pasta, a parboiled rice-like product and snack foods have been successfully produced from sorghum and, in some cases, millets. Wheat-free sorghum or millet bread remains the main challenge. Additives such as native and pre-gelatinised starches, hydrocolloids, fat, egg and rye pentosans improve bread quality. However, specific volumes are lower than those for wheat bread or gluten-free breads based on pure starches, and in many cases, breads tend to stale faster. Lager and stout beers with sorghum are brewed commercially. Sorghum's high-starch gelatinisation temperature and low beta-amylase activity remain problems with regard to complete substitution of barley malt with sorghum malt . The role of the sorghum endosperm matrix protein and cell wall components in limiting extract is a research focus. Brewing with millets is still at an experimental stage. Sorghum could be important for bioethanol and other bio-industrial products. Bioethanol research has focused on improving the economics of the process through cultivar selection, method development for low-quality grain and pre-processing to recover valuable by-products. Potential by-products such as the kafirin prolamin proteins and the pericarp wax have potential as bioplastic films and coatings for foods, primarily due to their hydrophobicity.     

Evolutionary aspects of the trade-off between seed size and number in crops

Whereas the concept that availability of resources drives seed production is sound in principle, it is incomplete as there are many solutions to the allocation of resources that derive from the trade-off between number and size. This paper examines evolutionary aspects of this trade-off in annual grain crops. The analysis is centred on the working hypotheses that, for a given species and environment, allocation of resources to reproduction involves (H1) high plasticity in seed number, which allows for variable resource availability, and (H2) a relatively narrow range of seed size that results from evolutionary and agronomic selection. Comparisons between crops and fish are used to highlight common evolutionary elements in taxa where parents provide little or no care to their offspring, with the consequence that both number and early survival of offspring, hence fitness of parents, are partially related to embryo size and reserves.

The plasticity of seed number in relation to availability of resources is analysed against the established relationship between offspring number and parent growth rate during critical stages. The notion that seed size is under stabilising selection is analysed against three conditions: (1) mean seed size is conservative for a given species and environment, (2) seed size affects fitness, and (3) seed size is heritable. Databases from published papers were compiled to analyse the relative variability of seed size and number, and the heritability of seed size. Evidence for and against the link between seed size and parental fitness is revised using the Smith–Fretwell model as framework (Am. Nat., 108, 499–506).

The proposal of high plasticity of seed number and narrow variability of seed size resulting from stabilising natural selection is generally consistent with evolutionary and genetic considerations. Agronomic selection may have reinforced natural selection leading to relatively narrow seed size in species such as wheat and soybean, where cultivated types retained high plasticity for seed number. In contrast, selection for one or few inflorescences in crops like sunflower and maize may have morphologically reduced seed number plasticity and increased variability of seed size and its responsiveness to resource availability in relation to their wild ancestors.     

Citrus Flavonoids in Fruit and Traditional Chinese Medicinal Food Ingredients in China

Flavonoids-enriched tissues of citrus such as peel, immature fruit and flower are consumed as culinary seasonings, tea ingredients in China for centuries. This HPLC quantitative study on the five citrus flavonoids, naringin, hesperidin, neohesperidin, sinensetin and nobiletin on a wide range of Chinese citrus fruits and several Traditional Chinese Medicinal food ingredients in East China, revealed a great diversity in flavonoid composition. Huyou peel (C. paradisi cv. Changshanhuyou) was found to be the best naringin (3.25%) and neohesperidin (2.76%) source; C. aurantium, a major ingredient of several citrus-related TCM, is also a suitable source of naringin and neohesperidin, and a good juice source for flavanone glycosides; the peel of Wenzhoumiju (C. unshiu) is one of the richest local species in hesperidin (up to 6.25%); Zaoju (C. subcompressa) has the highest content of nobiletin (0.59%), a polymethoxylated flavone. LC-ES-MS analysis of Zanthoxylum genus for flavonoids revealed for the first time the presence of significant amounts (0.74%) of hesperidin in the root of Liangmianzhen (Z. nitidum (Roxb.) DC), a relative of Sichuan pepper, which is a spice widely used in China.     

Effect of a continuous hot water treatment of potato tubers on seed-borne fungal pathogens

Summary The viability of five pathogens was decreased by treatment with hot water when tested in vitro.Polyscytalum pustulans was most sensitive andRhizoctonia solani least sensitive. Potato tubers were exposed to 55°C for 5 min in a commercial continuous hot water treatment plant using naturally contaminated seed tubers and tubers which had been inoculated by dipping in comminuted cultures. The frequency of eyes colonised byP. pustulans, Helminthosporium solani, andR. solani was reduced to virtually zero and the effect persisted on tubers subsequently stored at 4°C and at 15°C for up to 16 wk. Results withColletotrichum coccodes were inconclusive. Treatment suppressedPenicillium spp. which, however, rapidly recolonised the eyes during storage, leading to higher contamination levels in the treated than in the untreated tubers. With tubers inoculated withPhoma foveata, good control was achieved when the incubation period before treatment was 10 d but not when the period was 42 d.     

Role of Benzoxazinones in Cereals

Summary

Heterocyclic 1,4-benzoxazin-3-ones and related benzox-azolinones are important natural products of the cereal crops maize, wheat and rye. Much research has focused on the role of these compounds as defensive agents against plant diseases and pests. Studies of a wide variety of biological effects on herbivores and nematodes, plant pathogenic fungi and bacteria are reviewed in this article. Phytotoxic activity of the compounds is also considered with respect to allelopathic interaction with higher plants. Recent investigations of molecular aspects of interactions of cyclic hydroxamic acids and related benzoxazo-linones with acceptor organisms have demonstrated different effective detoxification strategies and tolerance mechanisms. This research has greatly advanced our knowledge about the multiple roles that these allelochemicals play in ecological systems.     

Potential of dry fractionation of wheat bran for the development of food ingredients,part I: Influence of ultra-fine grinding

Wheat bran is an undervalued by-product of white flour and has great nutritional potential due to its high content in fibres and bioactive compounds. Micronized bran could be used as a food ingredient to improve the nutritional potential of cereal products, or be used as a starting material for other processes (bioactive compound extraction or bran fractionation). The aim of this work was to find a way to efficiently decrease the particle size of bran. The influence of the grinding temperature (ambient or cryogenic grinding) on the granulometric distribution of particles, their composition, and their microstructure was studied, at lab-scale and pilot-scale. It showed that the intrinsic characteristics of bran (glass transition within intermediate layers at −46 °C) had more influence on its grinding behaviour than the type of grinding device used: the particles size distributions obtained after grinding at lab-scale and pilot-scale were very similar. At both scales, the granulometric curves were narrow for cryogenic grinding, while for ambient grinding they were spread over the whole particle size range. Ultrafine particles were obtained in both ambient and cryogenic conditions. Negative temperatures, by increasing the material’s brittleness, favoured a fast fragmentation of bran: one step of cryogenic grinding allowed a median particle size of nearly 50 μm to be reached, whereas three successive steps of ambient grinding were needed for the same result. On the other hand, ambient temperature favoured the dissociation of the different constituent layers of wheat bran, and produced less composite particles than cryogenic grinding.     

Multiple use of plants: Studies on selenium incorporation in some agricultural species for the production of organic selenium compounds

The technique of spraying plants with inorganic forms of selenium can be employed for phytochemical production of organic selenium compounds. Fractionation of the plant material makes it possible to produce a highly concentrated and well defined selenium supplement with potential use in animal and human nutrition. The fractionation also gives opportunities to combine production of organic selenium compounds with other products, for example plant fibres. Multiple use of plants can contribute to a more efficient utilization of land area (in comparison to monocultures solely adapted to food production). It also gives the opportunity to develop systems suitable for long term fixation of carbon, as long as the plant material is not reoxidised to carbon dioxide. Plant fibres could provide raw material for the production of paper or building materials in combination with the production of organic selenium compounds preferentially accumulated in another fraction of the processed plant.     

Biological factors influencing the transmission of potato leafroll virus by different aphid species

Summary Macrosiphum euphorbiae, collected in the field from potato plants infected with potato leafroll virus (PLRV), transmitted the virus to fewer potato plants in a field trial than did laboratory-rearedMyzus persicae. In the laboratory,M. persicae was the only efficient vector of PLRV fromPhysalis floridana seedlings, potato sprouts or excised leaves toP. floridana. Two clones ofM. euphorbiae and one clone ofAulacorthum solani transmitted PLRV from infected potato plants toNicotiana clevelandii as effeciently asM. persicae but a clone ofAphis gossypii was an inefficient PLRV vector. An isolate of PLRV, whichM. persicae transmitted inefficiently from potato toN. clevelandii, was also transmitted inefficiently byM. euphorbiae andA. solani.