籼稻低温敏核不育系温室筛选与繁殖技术探讨

籼稻低温敏核不育系是适合我国南方稻区应用的两用核不育系类型之一,由于其育性转换临界温度较低(23～24℃),在水稻正常生产季节繁殖比较困难,目前普遍采用的繁殖方法是冷水串灌、海南南繁和温室冬繁等技术.1995～1996年冬春季在广州首次利用温室控温技术冬繁培矮64S获得成功.但1997～1998年冬春季由于遇到罕见的异常低温,升温设施没跟上,穗发育时遭受生理冷害,致使不育系繁殖达不到预期效果.     

水稻两用核不育系繁殖基地计算机选择系统研制与应用

为了解决水稻两用核不育系繁殖产量不高不稳、种子质量差、效益低的问题,利用全国740个气象站点50年的气象资料,应用计算机处理技术,开发了水稻两用核不育系繁殖基地计算机选择系统,并利用该系统筛选最适宜的水稻两用核不育系繁殖基地。该系统以同时满足不育系育性敏感安全期和抽穗扬花安全期光温条件为依据,采用Java语言编制而成。针对不育起点温度为22.0℃、22.5℃、23.0℃、23.5℃和24.0℃的水稻两用核不育系,分别筛选到24、29、20、21和22个安全系数优于海南三亚冬繁的基地,以上5种不育起点温度的水稻两用核不育系在最佳繁殖基地繁种成功概率分别可达83%、93%、100%、100%和100%。2010年,在应用本系统筛选到的云南保山繁种基地进行了不育起点温度为22.0℃的水稻两用核不育系C815S的繁殖,单产达8 437.5 kg hm^-2,创造了我国水稻两用核不育系繁殖产量最高记录,证实采用该计算机系统选择两用不育系繁殖基地是有效的。因此,采用本系统筛选到的繁殖基地进行水稻两用核不育系繁殖,可望解决海南冬季繁殖风险大、产量不高、种子质量差以及冷水串灌繁殖产量不高不稳和效益低下的问题,值得推广应用。     

解决低温敏两系核不育系繁殖问题的策略与实践

为了解决低温敏两系核不育系繁殖中存在的问题,根据云南保山市48年（1953-2000年）的气象资料统计和云南保山市不同年份、不同基地不同不育系繁殖试验。结果表明,云南保山市不育起点温度为22℃的两用核不育系育性敏感期和抽穗杨花期同时满足的概率为83.34%,比海南三亚市高出48.34%;不同不育系在云南保山市繁殖时育性转换顺利,特别是C815S在海拔1560 m的基地大面积繁殖,产量达9133.5 kg/hm2,提出了解决低温敏两系核不育系繁殖问题的策略是建立云南保山市两用核不育系繁殖基地。     

低温水串灌大面积生产培矮64 S原种的探索

采用上坝水库底层低温水串灌取代低气温效应,提高培矮64S大面积原种生产技术.结果表明,处理水的水温满足培矮64S育性转换温度(23.5℃),但随气温的升高,部分时段可能超过培矮64S育性转换温度.同时,处理水温与"冷源"距离有关.距"冷源"越远水温增高的幅度越大.培矮64S夏繁,处理期间每天用低温水串灌19～21 h,其平均结实率仍达47.4%左右,表明采用水库底层低温水串灌是培矮64S大面积原种生产的有效途径,但与其他报道的最高结实率85%相差较远,这可能与本试验大面积无法严格控制条件有关.     

籼型温敏雄性核不育系冷灌繁殖的最适繁殖条件研究

采用不同灌溉时期、灌水深度、水温和持续灌溉天数等处理,研究了籼型温敏核不育水稻培矮64 S、双低S、株1 S、810 S和香125 S的最适繁殖条件。根据不同处理的成穗率、颖花退化程度、花粉育性和自交结实率等结果,提出温敏核不育水稻冷水灌溉繁殖的几个关键技术:①冷水灌溉深度应根据幼穗敏感部位距泥面的高度而变化,培矮64 S等类型不育系在雌雄蕊形成期开始灌冷水,深度为3 cm,随后逐渐深至20 cm,810 S等不育系在花粉母细胞形成期开始灌冷水,深度为7 cm,后逐渐深至15 cm。②冷水灌溉起止时期。培矮64 S等类型不育系在自然对照始穗前20～22 d,即雌雄蕊形成期开始灌冷水,持续时间为18天左右,群体在处理结束后7天左右始穗,13天以内齐穗;810 S等类型不育系在自然对照始穗前15天左右,即花粉母细胞形成期开始灌冷水,持续时间为15天左右,群体在处理结束后4天左右始穗,8天以内齐穗。③各不育系的最适繁殖温度应根据温度梯度试验确定,培矮64 S和株1 S为20.8℃左右,双低S为19.5℃左右,香125 S和810 S为20.8～22.0℃。温度过低对植株生长和幼穗发育产生伤害,过高则影响花粉可育性的恢复。     

不同世代温敏核不育水稻96-5-2S育性对低温的反应

为了探讨水稻光温敏核不育系临界温度遗传稳定性问题，以连续6个世代的温敏核不育水稻96-5-2S（从培矮64S中选育出的新株系）为材料，研究了它们育性对低温的反应差异。结果表明,(1)在它们育性转换敏感期用23.5℃恒温冷水处理10 d(水深20 cm左右)或遇到2～3 d平均日均温22.9～23.1℃(平均日最低温21.7～22.0℃)的自然低温时，所有世代的96-5-2S均表现不育, 自交结实率为0, 花粉可染率为0～0.9%，世代间差异不显著;(2)在它们育性转换敏感期用21℃、22℃恒温冷水处理10 d或遇到4 d平均日均温22.9℃(平均日最低温20.7℃)的自然低温时，所有世代的96-5-2S均表现可育, 自交结实率为0.2%～7.1%,花粉可染率为1.1%～19.5%，世代间存在差异,随繁殖世代增加,花粉可染率与自交结实率有逐渐上升的趋势,当繁殖到第5代时，花粉可染率显著提高，当繁殖到第6代时，自交结实率显著提高。(3)对照培矮64S（05株系）在相同低温条件下，花粉可染率与自交结实率均极显著高于各世代的96-5-2S。以上结果说明, 随繁殖世代增加,96-5-2S的临界温度会发生缓慢的遗传漂移，到第5、6代时，就会在花粉与结实水平上明显表现出来，但不同世代间临界温度的差异小于不同株系（96-5-2S与培矮64S-05株系）间临界温度的差异，据此认为，通过单株选择是降低光温敏核不育系临界温度的重要途径。     

2136S繁殖特性的初步研究

在高海拔低温寡照的贵阳温光条件下,对水稻两用核不育系2136S进行分期播种试验,同时正季在贵阳和春季在海南三亚进行较大群体的2136S的繁种试验,由此探索2136S的繁殖特性．试验结果表明：2136S在21．9～24℃温度范围内,结实率与抽穗前15～24天的5日滑动均温值呈负相关,显著性检验达到极显著水平。在21～22．5℃范围内,其繁殖性较好,自然结实率可达30％～50％。较大群体下繁种,2136S在适宜的繁殖期,如贵阳的秋季和海南的春季,其繁种产量分别可达到2692kg／hm2和3750kg／hm2,可实现简便繁种的目的．     

水稻C815S及其同源株系的育性光温特性

对C815S及其同源株系通过12种人控光温组合处理、短日遮光处理以及分期播种试验,就其育性光温特性、发育感光性以及两者之间的关系进行了研究。结果表明,C815S及其同源株系不育起点温度低,均在23℃以下。在长沙自然长日条件下没有明显不育向可育的转换;在长沙短日条件下,育性出现轻微波动。其育性受光温双因子共同作用,且这种作用的程度与发育感光性强弱似乎存在密切联系。提出了光温敏不育系光温双因子互作量化的光温效应连动假设。这一假设能提供每一光长条件下与之对应的育性转换温度,对光温敏核不育系的选育、制种和繁殖具有实际指导意义。     

温敏核不育水稻育性对低温持续时间的敏感性差异比较研究

培矮64S、810S、株1S、陆18S、729S、139S、康201S、179S、香125S等是一类高温条件下不育、低温条件下可育的高温敏型核不育水稻,它们的临界不育温度为23～24℃左右;go543S是一类高温条件下可育、低温条件下不育的低温敏感核不育水稻,其临界不育温度为29.5℃.分别在自然长日(光长14.2～13.7 h)、高温(日均气温29.0～34.1℃)条     

冷水串灌茭白效应研究

用水库底层冷水串灌茭田后改变了茭白生长的小气候环境,为此,对气温、水温、茭白的经济性状、生育期、经济效益五个方面进行观测和分析。其差异明显,经济效益和社会效益显著提高。     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Variation in forage grasses as hosts of the root-knot nematode Meloidogyne naasi (Franklin) and selection for resistance in ryegrass

Summary Reactions of 13 grasses to Meloidogyne naasi varied with species; ryegrasses, fescues and their hybrids were generally susceptible and cocksfoot and timothy resistant. Marked variation in host resistance levels occurred between genotypes within cultivars.Selection of single plants, followed by tests on replicate tillers, identified resistant and susceptible genotypes in both Italian and perennial ryegrass cultivars. Resistant plants had few nematode-induced galls and fewer females and eggs than susceptibles. There was more or less continuous variation, with many genotypes intermediate between extremes of resistance and susceptibility. Selected resistant and susceptible genotypes are of use in assessing variation in nematode populations and as controls for breeding and selection programmes.     

Current and future strategies in breeding lentil for resistance to biotic and abiotic stresses

Lentil production is limited by lack of moisture and unfavorable temperatures throughout its distribution. Waterlogging and salinity are only locally important. Progress has been made in breeding for tolerance to drought through selection for an appropriate phenology and increased water use efficiency and in breeding for winter hardiness through selection for cold tolerance.The diseases rust, vascular wilt, and Ascochyta blight, caused by Uromyces viciae-fabae, Fusarium oxysporum f. sp. lentis, and Ascochyta fabae f. sp. lentis, respectively, are the key fungal pathogens of lentil. Cultivars with resistance to rust and Ascochyta blight have been released in several countries and resistant sources to vascular wilt are being exploited. Sources of resistance to several other fungal and viral diseases of regional importance are known. In contrast, although the pea leaf weevil (Sitona spp.) and the parasitic weed broomrape (Orobanche spp.), and to a lesser extent the cyst nematode (Heterodera ciceri), are significant yield reducers of lentil, no sources of resistance to these biotic stresses have been found. Directions for future research in lentil on both biotic and abiotic stresses are discussed.     

Present status and future strategy in breeding faba beans (Vicia Faba L.) for resistance to biotic and abiotic stresses

Progress is being made, mainly by ICARDA but also elsewhere, in breeding for resistance to Botrytis, AScochyta, Uromyces, and Orobanche; and some lines have resistance to more than one pathogen. The strategy is to extend multiple resistance but also to seek new and durable forms of resistance. Internationally coordinated programs are needed to maintain the momentum of this work.Tolerance of abiotic stresses leads to types suited to dry or cold environments rather than broad adaptability, but in this cross-pollinated species, the more hybrid vigor expressed by a cultivar, the more it is likely to tolerate various stresses.     

Water Extraction Process of Chinese Herbal Compound Man Gan Ning

[Objectives]To optimize the water extraction process of Chinese Herbal Compound Man Gan Ning and establish a method for its extraction and content determination...