Genetic variation for seed dormancy in Cuphea laminuligera and Cuphea lanceolata

Summary Various Cuphea species are adapted to temperate climates and characterized by caprylic, capric, and lauric acid-rich seed oils. These fatty acids are solely commercially available from palm kernel and coconut oils; thus, there is considerable interest in Cuphea as an alternative source of these fatty acids. Cuphea is a genus of undomesticated species characterized by seed dormancy and seed shedding. Our goal is to eliminate these domestication barriers in a few species with agronomic potential. Our objective was to survey existing Cuphea laminuligera and C. lanceolata germplasm for genetic variation for seed dormancy (germination percentage after a certain seed storage period). Recurrent half-sib family selection was practiced in various open-pollinated and synthetic populations. Half-sib family seed were evaluated for germination percentages at 26° C after various seed storage periods. There was significant genetic variation among families in every population. Additive genetic variance, half-sib family-mean heritability, and expected selection response magnitudes depended on the length of the seed storage period within a given population. Estimates of these parameters were significantly greater for longer seed storage periods within a population. Heritability estimates ranged from 0.00 to 0.79. Expected half-sib family selection responses ranged from 0.0 to 23.9%. Our study demonstrated there is substantial genetic variation for seed dormancy in C. laminuligera and C. lanceolata.     

Effects of harvest management on growth dynamics, forage and seed yield in berseem clover

Berseem clover (Trifolium alexandrinum L.) is an annual forage crop widely grown in Mediterranean environments. However, there is little information available on the patterns of accumulation and partitioning of assimilate in berseem and how this varies with harvest management, plant ontogeny or is influenced by genotype. Field experiments were conducted in Foggia (Italy) during three growing seasons (1991–92, 1992–93 and 1993–94), with the aim of evaluating the effects of different harvest managements on growth dynamics, forage yield and seed yield of one population of Egyptian (cv. ‘Giza 10’) as well as Italian (cv. ‘Sacromonte’) origin. Cutting treatments were applied at three different plant ages: sixth internode elongation (A), early flowering (B), and uncut control (C). The growth and development of the shoot and root systems were followed by destructive harvests made at about 5-day intervals during 9 weeks in spring in all treatments. Seasonal growth pattern, determined as dry matter accumulation, forage yield and seed production were greatly influenced by harvest management. The maximum value (20.5 g per plant on average) of dry weight was reached at about 250 days after sowing for treatment C. Defoliation induced a decrease of crown and root dry matter, however, as shown by the allometric relationships, the growth of roots and shoots was closely correlated and in most cases, shoot growth was higher than root growth and stem relative growth rate (RGR) was higher than leaf RGR. Berseem clover is a defoliation-tolerant species because after cutting, regrowth was accompanied by higher values of leaf-stem ratio (LSR), RGR and stem elongation rate (SER) than in control plants. The highest value for total forage yield (1.6 Kg m⁻²) and seed yield (60.5 g m⁻²) were obtained in treatment B and A, respectively. Plants cut at the sixth internode elongation showed a good seed yield and a small decrease (15%) in total forage yield as regards treatment B. Therefore, treatment A appeared the most favourable for obtaining double utilization (forage and seed yield) in a berseem crop. Berseem plants were greatly influenced by harvest treatments applied, but the response did not vary according to the genetic characteristics of the two cultivars examined.     

小麦不同粒位、粒重及其种子活力研究

对4个小麦品种各粒位上的粒重及种子活力进行了研究。结果表明：各粒位的粒重差异显著，其大小在麦穗上的分布具有明显的区域性。穗中下部小穗的第1、2花位籽粒最大（43.9mg)，上部小穗及中部高位小花所结籽粒最小（26.2mg），除种子大小影响种子活力外，粒重相同的种子，位于下部小穗上的籽粒具有较高的种子活力。     

镧对油菜种子透性及种子活力的影响

本文以油菜种子为材料,研究了稀土镧对油菜种子透性和种子活力的影响。在０．０５－２．００ｍｏｌ／Ｌ水平,Ｌａ＾３＋降低种子细胞内的电解质,Ｋ＾＋,Ｃａ＾２＋和Ｎａ＾＋的相对外渗量,并表现为随Ｌａ＾３＋浓度的增加而下降。低于０．１ｍｏｌ／Ｌ降低糖的相对外渗量,高于此浓度糖的相对外渗量升高。     

蝴蝶兰成花差异基因的筛选与分析

为探明蝴蝶兰花芽分化调控的内在分子机制,以及花芽分化过程中的关键基因,本研究以蝴蝶兰不同分化时期的花芽进行转录组测序,筛选调控植株成花转变的关键基因并进行实时荧光定量PCR(qRT-PCR)验证.测序共得到44.42 Gb的原始数据,分别注释到7个公共数据库(Swiss-Prot,Nr,KEGG,KOG,Pfam,eg...     

开花期低温胁迫对四川攀西稻区水稻开花结实的影响

以3种籼稻品种和3种粳稻品种为试验材料, 利用人工气候室在开花期进行低温胁迫处理, 研究了低温胁迫对攀西稻区籼、粳稻开花和结实及两者间关系的影响。结果表明, 开花期低温胁迫下籼稻和粳稻的开花习性、花药和花粉特性和结实表现不同。常规粳稻开花对低温有较高的耐冷性。低温胁迫下籼稻品种(组合)花药体积、花药开裂率、可育花粉率、柱头着花粉数和柱头花粉萌发率较对照降低幅度均比粳稻品种(组合)大; 籼稻品种(组合)各产量构成因素较对照降低幅度比粳稻品种(组合)大。相关分析表明, 结实与水稻花药和花粉主要性状有密切关系。开花期低温胁迫影响花药和花粉发育成熟, 使花药不能正常开裂、散粉不足, 可育花粉率和柱头花粉萌发率降低, 直接影响受精结实, 成为结实率降低的主要原因之一。     

甜玉米种子活力低下原因及其种子处理方法

综述有关甜玉米种子活力低下的生理、遗传和环境等因素的研究进展，种子引发，包衣和有机溶剂渗入等种子处理方法对提高甜玉米种子活力和田间出苗率的效果及其应用前景。     

Recurrent Mass Selection for Reduced Seed Dormancy in Cuphea lanceolata and Cuphea laminuligera

Seed dormancy is a domestication barrier in certain Cuphea species. Between and within species variation has been observed for seed dormancy in agronomically promising Cuphea species, e.g., C. laminuligera Koehne and C lanceolata Ait. In tins note, we report on progress made in reducing seed dormancy through recurrent mass selection in the C. lanceolata population LN43 and LN78. The germination percentages of unselected LA12 and LN43 populations increased from 0.0 % to greater than 95.0 % following an after-ripening period of 20 weeks. We observed no germination percentage differences between unselected and selected LN43 populations following two cycles of selection. In contrast, there were highly significant differences between the unselected and selected populations of LA12 following two cycles of selection. The germination percentages of cycle zero (C₀) and cycle two (C₂) populations after-ripened 10 weeks were 10.7 and 92.7 %, respectively. After one cycle of selection in the C. Lanceolata population LN78, the germination percentage of seed after-ripened 10 weeks had increased from 1.3 % for the C_o population to 28.7 % for the C₀ population. In summary, mass selection greatly reduced seed dormancy in LA12 and LN78, but had no effect in LN43.     

过量表达中国水仙(Narcissus tazetta var.chinensis)NTAG1基因促进拟南芥早花和衰老

中国水仙有金盏银盘和玉玲珑两个品种,玉玲珑由于雄蕊瓣化而形成重瓣花,而目前人们对这种重瓣花的分子机理不清楚.根据重瓣花多与C类花器官特性基因相关,本文通过RT-PCR方法分别克隆和分析了两种花型水仙品中的AGAMOUS同源基因NTAG1基因,序列分析表明,两种水仙中该基因序列完全相同,RT-PCR半定量分析它们的表达模...     

驼绒藜属牧草种子生理学特性的研究--营养成分、植物激素与种子活力相关性分析

本论文对驼绒藜属植物种子的生理学特性进行了研究,包括种子的活力、种子的营养成分、激素水平等内容,同时对种子的劣变机理进行了探讨.驼绒藜属牧草种子在营养成分及激素含量上存在种间、生态型间及株龄间的差异,相关分析表明,种子含糖量及内源激素与种子活力相关性均不显著,种子氮、磷含量与种子活力有显著的相关性.对驼绒藜属植物种子短命和劣变原因的初步分析,认为是由遗传和环境两方面的原因所至,一是由于驼绒藜植物属于高数量低营养种子类型,种子自然寿命较短;二是由于种子发育过程中自然环境恶劣,造成种子营养不良,发育程度较差;三是由于贮藏条件不适宜,尤其是含水量较高,造成种子劣变加速.     

采种季节和设施对矮生菜豆种子产量和质量的影响

以SG259和Provider两个矮生菜豆品种为材料，分春秋两季在不同设施下进行了采种试验。结果表明，采种季节、采种设施以及品种对矮生菜豆的生育期、单株分技数、单株结荚数、种子产量、种子千粒重以及发芽势和发芽率均有明显的影响。在杭州的气候条件下，Provider的种子产量和质量明显优于SG259；秋季采种时的种子质量优于春季采种。春季采种时，无论是种子产量或是种子质量均以温室采种较为理想；秋季采种时温室的优势不是非常明显。根据本试验结果，从种子产量、质量以及生产成本考虑，杭州地区矮生菜豆原种的繁殖宜在秋季露地进行。     

Production and use of maize seed for sowing in Bolívar,Ecuador

In the province of Bolívar in the Andean region 212 farmers, six salesmen and 14 technicians, involved in maize production, were interviewed. The majority of the farmers interviewed were small-holders; 64% of the farmers had a farm size of less than 4.5 ha. Maize is the most important crop and is often grown in association with beans. Most maize, 96%, is soft maize meant for human consumption. The cultivars grown are open pollinated ones. One cultivar, ‘Guagal’, was grown extensively. A few others, among which an improved version of Guagal were of some importance. In the production of maize the farmers consider damage due to insects, wind (lodging), diseases, drought and hail, the low prices for their surplus maize and the high costs of fertilizers, chemicals, sowing seed and labour as the most important constraints. The seed for sowing the next crop mainly came from seed kept from the last harvest. Farmers indicated that they select from the harvested ears the healthy looking larger ones. Kernel type also was a selection criterion. Selection for plant type in the field was rarely done. Of the farmers 71% stored the maize as kernels while 29% stored the seed kept on the ears. The storage was predominantly done somewhere in the house in plastic (56%) or cloth bags (14%), in a pile (13%), just on the floor (4%) or in cans (4%). Some farmers still had seed left from the last sowing and were willing to give a sample for testing. From 32 such samples the quality was assessed by INIAP, the Ecuadorean governmental research and breeding organisation. The samples were consistently of a low quality. Especially the vigour of the seedlings was poor and most of the seeds were infected or contaminated by fungi. In the region a few salesmen offer maize seed for sale of cultivar Guagal at prices affordable by the farmer. Of improved cultivars the prices were higher than most farmers are willing to pay. The technicians considered good seed quality and good maintenance of the cultivars effective methods in obtaining better yields. Many farmers do not have access to seed of INIAP and are not familiar with the improved cultivars.     

对玉米杂交制种花期不遇的原因、花期预测及花期调节的探讨

是指母本吐丝期与父本抽雄散粉期相遇不良或不能相遇，影响母本授粉结实，造成制种减产甚至失败的情况。     

杂交水稻种子生理特点与耐贮藏性研究

与常规水稻相比，杂交水稻种子具有明显的生理优势。具体表现在杂交水稻种子脱氢酶，细胞色素氧化酶和淀粉酶活性强。且杂交水稻种子胚乳中具有α－淀粉酶，而常规水稻种子乳中不具有此种酶。杂交水稻种子萌发速率和活力指数也比常规水稻大。但杂交水稻种子耐贮藏性较差。本文对杂交裟发物生量特点与耐茂５怀的关系进行了讨论。     

Effect of drought stress on content and composition of seed alkaloids in narrow-leafed lupin, Lupinus angustifolius L.

The effect of drought stress at three growth stages on seed alkaloid content in two sweet (W26 and Polonez) and one bitter variety (Zubr) of spring sown Lupinus angustifolius L. was investigated in a lysimeter experiment on sandy soil in Denmark. Full irrigation resulted in medium alkaloid content. Drought stress during the vegetative phase increased alkaloid content to 0.094, 0.192 and 2.55% of seed dry matter, respectively. At the flowering stage alkaloid content decreased to 0.070, 0.152 and 1.99%, while drought stress during pod-filling increased alkaloid content for the determinate variety W26 to 0.097%, but decreased it to 0.161 and 1.98% for the two indeterminate varieties Polonez and Zubr, respectively. Drought during either flowering or pod-filling resulted in an increased mean seed weight and a reduced number of seed per square metre. Alkaloid content was negatively correlated to seed weight. The alkaloid composition differed for the three genotypes, and was affected by drought treatment. Compared to the bitter variety the sweet varieties were characterized by reduced concentrations of lupanin, 13-hydroxylupanin and angustifolin, whereas spartein, isolupanin and isoangustifolin were little affected.     

菜用大豆品种花荚粒形成的初步研究

通过对24个菜用大豆品种花荚及籽粒形成的比较,认为不同熟期类型品种间发育规律存在差异。早熟品种较晚熟品种花、荚形成发育快,时间短,脱落也快。籽粒形成主要集中在三个时期：籽粒重在中后期,荚皮重在中前期,荚重在中期。中期的生殖生长是籽粒形成的基础,也是影响产量的关键。因此在江苏徐淮地区的生态条件下,鼓粒前的花荚期长短是选择菜用大豆品种生育指标的重要因素。菜用大豆鼓粒前的花荚期以20d左右为宜。     

Influence of flower and flowering characteristics on seed yield in diploid and tetraploid red clover

Tetraploid red clover (Trifolium pratense L.) often produces insufficient seed to be economically interesting. Numerous studies have identified poor pollination due to long corolla tubes as its cause, but other studies disagree. Therefore, we investigated seed yield, corolla tube length and flowering traits in 244 plants from five diploid and five tetraploid cultivars during 2 years. Tetraploids produced fewer seeds, fewer flower heads and fewer seeds per head, but an equal number of flowers per head when compared to diploids. Although corolla tubes were longer in tetraploid than in diploid red clover (P < 0.001), no correlation between corolla tube length and seed yield was detected. Therefore, the corolla tube length is likely neither the main nor only cause of low seed yield in tetraploid red clover. Instead, three putative causes for low seed yield were identified: tetraploids produced less inflorescences per plant, possessed a lower degree of determinacy and had markedly less seeds per head when compared to diploids. Possible causes for such differences include lower pollen viability and higher rates of embryo abortion.     

甘蓝型油菜开花相关基因的鉴定及进化与表达分析

开花是开花植物繁衍后代的前提,控制开花时间对农作物获得高产稳产具有重要影响。然而,关于甘蓝型油菜基因组水平上开花相关基因的信息报道较少。本研究对甘蓝型油菜开花相关的基因进行了鉴定、特征分析、进化与表达模式分析。结果表明,基因组水平上共鉴定到甘蓝型油菜1173个开花相关基因,这些基因分为9类,且不均匀地分布在染色体上;与白菜(AA,2n=20)和甘蓝(CC,2n=18)相比,甘蓝型油菜(AACC,2n=38)经过自然杂交和染色体加倍后,使开花相关基因的数目显著扩增;选择压力分析表明,糖代谢信号途径的基因比自发途径的开花相关基因受到的选择压力更大;仍有一些开花相关基因在拟南芥和油菜基因组内非常保守。甘蓝型油菜基因数目的扩增和功能分化导致其开花调控机制更加复杂,本研究为油菜开花途径提供更多的信息,也为阐明拟南芥和油菜开花基因的进化关系指明了方向。     

玉米雄性不育化制种优质高产技术研究

玉米雄性不育化制种与常规玉米制种相比,具有免除人工去雄、降低生产成本、提高种子质量等优点,最大限度地发挥杂种优势。根据玉米雄性不育化制种特点,研究了恢复型玉米雄性不育杂交种ST501亲本的特征特性以及影响不育化制种质量及产量的各项因素,从亲本质量、花期调整、合理密植、科学施肥、病虫害防治、人工辅助授粉、适时收获等环节,提出了产量4500~5250公斤/公顷优质高产制种配套技术。     

PEG处理对提高谷子种子活力方法的研究

本文以中等活力的谷子种子为材料,研究了PEG的不同分子量、不同浓度和不同处理时间对种子活力的影响。结果表明：（1）PEG可明显改善谷子种子细胞膜造性,显著提高种子发芽力和活力;（2）PEG分子量越大,活力提高越多,而低浓度、短时间的PEG处理,即可达到显著提高种子活力的目的;（3）用PEG10000、5％的PEG溶液处理谷子种子1天,其发芽势、发芽率、发芽指数和电导率分别比对照提高43．3％、32．2％、51．8％和-49．9％。