Forage Quality Components in Grazing-Type Lucerne (Medicago sativa L. complex)

Much is now known about the morphological attributes of the lucerne plant that contribute to improved tolerance to grazing. With the aim of developing grazing-tolerant varieties, a range of genotypes were preliminarily selected for the presence of desirable attributes, and categorized into four morphological models based on their top-growth morphology and vigour. Little is known about the implications for forage quality of selection of non-conventional, grazing-type lucerne. This investigation was undertaken to study aspects of the quality (crude protein, fibre, and lignin content; nutritive value; plant leafiness) of the selected material, with particular reference to the morphological models identified in the first phase and to flower colour, which has taxonomic importance within the species. The results indicate that selection of grazing-type cultivars would not produce detrimental effects in terms of forage quality relative to common, hay-type lucerne. Plants with yellow or variegated flowers, often corresponding to rhizomatous types, were characterized by high leaf percentage, which resulted in high-quality features.     

Root Morphology of Maize and Its Relationship to Root Lodging

Crown root traits of maize ( Zea mays L.) such as number and diameter are the most easily accessible root traits. Their impact on root lodging resistance is little documented. We evaluated 28 flint x dent hybrids at one location for 2 years for crown root traits and for lengths of internodes. Plants were grown at normal and at supraoptimal density. A maximum number of crown roots was observed at the fifth and sixth nodes, above ground internodes 8-10 had maximum lengths. After a cool wet year maximum internode length or numbers of roots per node were found at higher tiers. A supraoptimal plant density caused an increase in lengths and a decrease in root numbers at upper internode and node levels. Crown root morphology and histology were studied at normal plant density in one growing season. From the lowest to the highest node level, root diameters increased steadily, whereas the number of late (large) metaxylem vessels in crown roots showed a strong increase at upper nodes. The diameters of metaxylem vessels increased already strongly at lower node tiers. All data were correlated with the root lodging counts from 42 hybrid tests in northern and southern Germany. In the warm year, at normal plant density, length of internodes 6 and 8 were correlated significantly positively with root lodging in about 25 % of all cases. Number of metaxylem vessels in roots at node 6 were significantly negatively correlated with root lodging in more than 20 % of all cases. Specific morphological and histological traits seem to indicate root lodging. However, their expression depends to a great extent on environment which lessens their value for selection.     

磷胁迫对不同基因型甜菜根系形态及根分泌物的影响

选用了三种不同抗磷胁迫能力的基因型甜菜种质材料‘品14’、‘品17’和‘品20’,通过液培和沙培法对低磷胁迫下甜菜根长、根冠比、根系H+及有机酸分泌等形态和生理特性进行了研究。结果表明：（1）磷胁迫对甜菜根系的形态特征影响显著,与正常磷营养水平比,各基因型甜菜的根系长度和根冠比均有显著增加（p<0.05）,其中抗磷胁迫能力最强的‘品20’增加幅度显著高于其他两个基因型;（2）甜菜根系主要分泌草酸、乳酸、马来酸及反丁烯二酸,其中大部分为草酸和乳酸,在低磷胁迫下,只有抗磷胁迫能力最强的‘品20’此两种酸的分泌达到显著增加水平;（3）不同基因型甜菜受磷胁迫后,近根区生长环境变化各异,其中抗磷胁迫能力最强的‘品20’H+的分泌量的增幅显著高于其他两个基因型。     

水稻籽粒维生素E及组分在品种间的变异与分布

维生素E是人与动物必须从食物中摄取的微量营养元素之一,根据侧链的饱和度可将其分为生育酚和三烯生育酚,水稻种子中均含二者。本研究利用反相高效液相色谱法测定了18份籼稻和16份粳稻品种糙米中维生素E各异构体的含量。结果表明,种子中各异构体的含量在籼稻与粳稻间存在显著差异,粳稻种子中的生育酚和维生素E含量一般要高于籼稻;籼稻种子中三烯生育酚与生育酚的比值(1.61)极显著高于粳稻(0.95),籼稻中以γ-三烯生育酚为主,而粳稻中主要含α-生育酚。水稻种子中同种类型异构体(即α-型间或γ-型间)含量间具有显著正相关,但γ-型与α-型异构体间呈显著负相关。这些数据为进一步研究水稻种子中维生素E的代谢调控和营养品质改良提供了有益的表型数据。     

济南市紫花苜蓿害虫和天敌种类及其发生动态的研究

为了控制紫花苜蓿害虫的危害,提高紫花苜蓿的产量和质量。2011年5-8月,本研究系统调查了济南唐王紫花苜蓿害虫和天敌昆虫的种类,分析了主要害虫及天敌的发生动态。结果表明：紫花苜蓿昆虫种类繁多,共7目14科32种,其中主要害虫有蚜虫、蓟马、叶蝉、盲蝽,主要天敌有草蛉、瓢甲、食蚜蝇等。蚜虫5-6月份危害严重,7-8月份少量发生;蓟马在紫花苜蓿的整个生长季节均有发生;叶蝉和盲蝽的发生有2个高峰期,分别在6月中旬和7月中旬。本研究为控制紫花苜蓿害虫提供直接、客观依据。     

Effect of Split Nitrogen Application on Growth and Yield of Wheat (T. aestivum L.) Genotypes with Different N-Assimilation Potential

A field experiment was conducted with different nitrogen regimes to assess the growth and yield performance of wheat genotypes which differ in nitrate assimilation potential. Genotypic differences in biomass accumulation were observed at different growth stages. The nitrogen treatment had little effect on biomass accumulation at early stages of growth, while at later stages of growth there was enhanced biomass accumulation when N was applied in more than two splits. On an average, genotypes with high nitrate reductase activity (the 'HNR' genotypes) accumulated 14.2 % more biomass than the genotypes with low nitrate reductase activity ('LNR' genotypes) when an extra dose (40 kg N ha⁻¹) of nitrogen was given at the time of anthesis. The application of nitrogen in more than two splits increased grain yield of both 'HNR' and 'LNR' genotypes mainly by increasing grain weight per ear. The application of an extra dose of nitrogen (40 kg N ha⁻¹) at the time of anthesis increased grain yield of 'HNR' genotypes by 38.5 % as compared to 'LNR' genotypes.     

红菜苔种子大小和种皮颜色对种子质量及苔产量的影响

该试验就红菜苔种子大小和种皮颜色对种子发芽势、发芽率、简化活力指数以及红菜苔植株的熟性、株平均苔数、单株苔重、单位面积苔产量的影响进行了研究。结果表明：（１）大粒种子的简化活力指数、株平均苔数苔重及单位面积的苔产量均显著或及显著高于小粒种子，而且，大粒种子植株现蕾比小粒种子早４－５天。但种子大小对发芽势、发芽率无影响。（２）深褐色种子的发芽势、发芽率、简化活力指数均显著或及显著高于深红色和灰褐色程     

Effect of Leaf Sugar and Starch Concentrations on Apparent Photosynthesis in Alfalfa

Rates of apparent photosynthesis (AP), dark respiration, photorespiration, mesophyll resistance, and concentrations of soluble starch, sugars, chlorophyll and nitrogen were measured in alfalfa leaves ( Medicago sativa L.) grown under high or low light levels in an attempt to evaluate the effect of nonstructural carbohydrate concentration on net CO₂ assimilation.
Leaf N and chlorophyll levels of high light plants exceeded those of low-light plants. Constant light increased both starch and sugar levels in low-light plants, but had little effect on high-light plants. Rates of AP declined in low-light plants upon transfer to constant light conditions, apparently due to increases in stomatal and mesophyll resistance. Leaf starch levels were negatively correlated (P > 0.05) with rates of AP and positively correlated with mesophyll resistance in both groups of plants but leaf sugar content was not correlated with either AP or mesophyll resistance.
Starch and sugar levels of high-light plants declined substantially upon transfer to constant darkness, while low-light plants were less affected. Rates of AP declined in both groups of plants due to increases in both mesophyll and stomatal resistances. Neither sugar nor starch levels were correlated with AP or mesophyll conductance in this treatment.
The data support the hypothesis of feedback inhibition of photosynthesis, mediated through an increase in mesophyll resistance, which is associated with high levels of starch in the leaves.     

不同遗传体系基因效应对水稻籽粒碳氮代谢的影响

选用6个不同类型的水稻品种（系）,按完全双列杂交设计（6×5）配成一套亲本、F1和F2 3个世代的遗传材料。采用包括种子、细胞质、母体植株三套遗传体系的种子性状遗传模型和统计分析方法,分析了稻米可溶性糖含量、全氮含量、糖氮比3个性状的遗传特点。遗传方差分析结果表明,可溶性糖含量和全氮含量两性状的表现同时受到种子、细胞质、母体植株三套遗传体系的控制,其中可溶性糖含量和主要受制于二倍体母体植株核基因的显性效应;全氮含量、糖氮比主要受制于种子核基因的显性效应。遗传率和选择响应分析结果表明,可溶性糖含量、糖氮比的遗传率较小,对其进行选择不易奏效;全氮含量以直接狭义遗传率为主,采用单粒选择易取得较好效果。     

不同纬度地区光温生态对水稻光、温敏不育性的选择压研究

对不同纬度地区广州(23°08＇N)、福州(26°05＇N)、长沙(28°12＇N)、杭州(30°19＇N)、南京(32°N)和沈阳(41°49＇N)的光温生态对光、温敏不育性的选择压作了初步分析。结果表明,在不考虑温度因素的前提下,对光敏不育的选择压从南到北渐增,而对光敏可育的选择压渐减,在不考虑日长的前提下,对温敏不育的选择压除沈阳外,其余5个地点差异不大,对长日低温不育和短日高温可育光敏型不育系的选择压,在分析的6个地点中,没有一个是非常具备的。通过对各地育成的101份不育系的育性转换光温反应型的分类,分析了在不同生态选择压下的育种成效。讨论了改单一环境下选择为多点多环境下选择和在人工控制选择压下进行有目的的选择的重要性。     

Effect of Variety and Seeding Rate on Establishment and Productivity of Alfalfa Sown in Autumn

Five alfalfa varieties (var.) were sown on 26 September, 1983 near Aleppo on clay or heavy clay soils, classified as Vertisols (FAO-system) or Chromoxerertic (Calcic) Rhodoxeralf (USDA-system). Irrigation was applied after planting to ensure uniform germination. Thereafter the study was conducted under supplementary irrigation. The parameters measured to estimate fresh weight (FW) and dry matter (DM) yields; plant height, ground cover and regrowth after cutting, indicated that winter-active var. ( Moapa 69, CUF 101 and Aleppo local ) resulted in better productivity than semi-dormant ( Paravivo ) and dormant ( Lebanon local ) varieties. The 2-years mean average FW yields were 70.2, 68.2, 65.2, 57.1 and 36.9 t/ha, or 16.2, 16.0, 15.5, 13.1 and 8.9 t/ha DM respectively. Forage yields were similar among the 12, 16 and 20 kg/ha seeding rates, indicating little justification for high seeding rates under good establishment conditions, even if a seeding-year yield is desired. In general, seeding rate had also no effect on plant population, which was reduced with time and towards the end of the tested period it became nearly similar and counted 137, 132 and 134 plants/m² according to the seeding rates respectively. Alfalfa yields were positively correlated with plant height, ground cover and regrowth after cutting. The highest yielding combination for FW and DM yields in Moapa 69 with 12 kg/ha seeding rate.     

Responses of Root Nodule Formation and Nitrogen Fixation Activity to Nitrate in a Split-Root System in Peanut (Arachis hypogaea L.)

Peanut is an important constituent of crop rotation systems with various vegetable crops, which need large amounts of inorganic nitrogen. Nitrate inhibits nodule formation and nitrogen fixation of the peanut plants in these cropping systems. To elucidate this nitrate-induced inhibition, an experimental method using a split-root system was designed and the inhibitory level of nitrate (14 m M ) was applied to half of the roots for 5 or 30 days in pot experiments. In the application of nitrate for 5 days, the dry weight, the nitrogen content, and both the number and the fresh weight of nodules for each half of the roots were unaffected by the nitrate applied to the other half. However, the nitrate induced significantly lower nitrogenase activity in the applied half. In the application for 30 days, nitrate induced a significantly higher nitrogen content in the applied half of the roots, and the inhibitory effect on nodulation and nodule development was observed not only in the applied half but also in the other half. Thus, the inhibitory effect of long-term nitrate application on the nodulation and nitrogenase activity of peanut may be systemic, but that of short-term nitrate application, in which external nitrate may regulate nitrogen fixation, may not be systemic.     

西藏拉萨市‘白燕2号’与箭筈豌豆不同混播比较研究

为了提高西藏高寒牧区饲草产量,缓解草畜矛盾。在西藏拉萨研究了‘白燕2号’与箭筈豌豆不同混播比例草地,在适宜刈割时期牧草养分比较研究。结果表明,各混播比例间的产草量、粗蛋白、粗脂肪、粗纤维、粗灰分、Ca和P含量差异显著,混播可显著提高产草量和牧草品质;且随着箭筈豌豆比例的增加,粗蛋白含量随之增加,最高为单播箭筈豌豆达到22.58%。各混播比例以H4为佳,鲜草产量达到7.71 kg/m2、粗蛋白含量达到13.66%、粗脂肪含量达到1.99%、粗纤维含量达到35.99%、粗灰分含量达到6.77%、Ca:P为5.36。在西藏气候适宜的地区可将‘白燕2号’与箭筈豌豆按此比例（箭筈豌豆40%+‘白燕2号’60%）混播推广以改善饲草品质。