辽宁省玉米育种的回顾与思考

讨论了辽宁省玉米育种目标的变化、育种技术方法的变化与进步,回顾了杂交种的选育、种质创新与自交系选育取得的重要成就。介绍了农家品种、综合种、品种间杂交种的鉴选与应用,分析了杂交种的选育和应用、自交系的选育和种质创新、理论研究。就辽宁省玉米育种现状从种质、育种方法、目标和品种审定进行了阐述。     

引入美国种质对我国玉米育种的影响

我国育种者从美国商业杂交种中分离了许多二环系,逐渐形成了PA(Reid)和PB(non-Reid)两大种质群,并利用这些二环系改良国内种质,取得了明显成效。PA种质是目前我国玉米育种利用的主要A类种质,在很大程度上稳定了我国玉米育种的杂种优势模式。而PB种质在引入抗病、耐逆基因的同时,倾向于破坏我国玉米杂种优势模式的稳定性和集中性,瓦解了我国的玉米杂种优势模式,同时也造成对热带种质的盲目利用,使得玉米育种的技术路线和杂种优势模式变得复杂化。目前直接对商业杂交种的分离选系在很大程度上造成育种思路与杂种优势模式的混乱。正确利用国外商业杂交种选育二环系和改良种质,对于制定今后玉米育种的技术路线和指导产品创新具有重要的实践意义。     

美国玉米带群体与西班牙玉米群体的杂种优势模式

美国玉米带群体与西班牙玉米群体的杂种优势模式Ｊ．Ｓｉｎｏｂａｓ等玉米育种的方向是选育高配合力的自交系，这些自交系用于生产农民种植的商品杂交种。杂交种的杂种优势表达主要依赖于通过自交方式获得的这些自交系的群体间的遗传差异。Ｓｐｒａｇｕｅ（１９８４）把瑞...     

黑龙江省玉米育种研究回顾与展望

系统阐述了黑龙江省玉米育种五十年在农家品种、综合种、品种间杂交种的鉴选与应用。讨论了杂交种的选育和应用、自交系的选育和基础材料的创造、基础理论研究、专用玉米育种方面的发展历程与研究进展,回顾了育种目标的变化发展、育种技术方法的变化与进步、杂交种的选育推广、种质创新与自交系的选育取得的重要成就,对黑龙江省玉米育种未来发展提出建议和展望。     

玉米育种的策略

1 认识玉米育种的特殊性 玉米的天然异花授粉习性与遗传基础的杂合性,以及因此产生的利用自交系间F_1代的杂种优势的育种程序,形成了玉米育种的特殊性。 (1)育种过程较长。它包含分离筛选自交系和组配鉴定杂交种两个步骤。要使众多杂合的基因位点,经过自交分离和选择获得大多数有利基因位点达到纯合或基本纯合的自交系,通常需要6～8代。要对杂交种的生产力和适应性作出较为准确的鉴定,一般需要3～4年。     

多抗、高产、稳产、优质、高配合力玉米自交系育种的途径与方法探讨

本文通过总结分析多抗、高产、稳产、高配合力、优质育种目标的复杂性(所需聚合的基因对数很多)、必要性(竞争的综合目标不能简化降低)、迫切性(竞争形势要求育种速度必须很快),提出较简便、准确、可行的玉米杂交种竞争杂种优势评估与玉米自交系和杂交种的高产稳产性综合评价方法,进而提出切实可行的玉米自交系和杂交种的高产稳产性育种途径与方法。     

玉米品种兴达1号的选育与栽培要点

玉米育种是以利用杂种优势为主,从具有优良农艺性状、一般配合力和特殊配合力高的自交系为原材料进行选育。就玉米杂交种而言,一般5～7年更换1次。近几年甘肃省玉米育种工作者通过育种攻关,选育出了几个适应不同生态区种植的品种,但适用范围小,推广面积上不去,跟不上全省玉米生产发展的需要。     

玉米优异核心种质资源多基因矮生系5003及其姊妹系5005创制

玉米优异核心种质5003及其姊妹系5005是我国第一个自主选育的多基因控制的矮源资源。5003(5005)及其衍生自交系适应性广、抗逆性强、配合力高,与国内外主要种质类群均有明显杂种优势,构成了新的矮生杂种优势群。从20世纪80年代至今,全国各地育种单位育成含有5003(5005)种质的优良自交系25个,配出年推广面积超过10万hm2以上的玉米杂交种有38个,累计推广面积达1.08亿hm2。     

耐旱丰产玉米育种的探讨

本文依据自己的育种实践,对耐旱丰产玉米育种的几个问题进行了讨论。认为玉米的耐旱性和丰产性在适当的选择环境下,运用相应的选择方法是可以有机结合在一起的;在育种实践中,田间相对萎蔫度、ASI、RI(修)是评价材料耐旱性的有效方法。发现目前广泛应用的骨干系中不乏玉米耐旱基因。认为水旱平行交替环境是选育耐旱、高配自交系的必要条件。并对耐旱丰产玉米杂交种的性状特点进行了研究。     

用RFLPs和有关杂交种资料预测玉米单交种的表现

用ＲＦＬＰｓ和有关杂交种资料预测玉米单交种的表现ＲｅｘＢｅｒｎａｒｄｏ商用玉米杂交种是典型的自交系间杂交种。这些系来自相对互补的杂种优势组。遗憾的是，育种者不能评价来自不同杂种优势组的自交系间所有可能的单交组合，大量可能的杂交组合经常受限制。例如，安...     

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.