多巴胺引发对盐胁迫下水稻种子萌发及幼苗生长的影响

【目的】探讨多巴胺(Dopamine,DA)引发对盐胁迫下水稻种子萌发及幼苗生长的影响。【方法】 以新疆自育水稻品种新稻17号为研究对象,分别用0（纯水）、0.1、0.5、1、1.5 mg/L的DA溶液(分别用S0、S0.1、S0.5、S1、S1.5表示)引发种子,采用浓度为100 mmol/L的NaCl溶液模拟盐胁迫,以未引发无盐胁迫处理作为对照1(CK),未引发有盐胁迫处理作为对照2(S-CK),研究多巴胺引发对盐胁迫下水稻种子萌发、幼苗生长及生理特性的影响。【结果】与CK相比,盐胁迫下(S-CK)水稻种子的萌发受到明显抑制且萌发速率降低,幼苗长势弱。引发处理不同程度缓解了盐胁迫对种子萌发的抑制,提高发芽率(13.3%~25.8%)和发芽速率,促进幼苗生长;可溶性糖和脯氨酸含量增加(16.4%~51.8%和6.5%~31.2%),超氧化物歧化酶 (28.9%~72.7%)、过氧化物酶 (15.0%~60.1%)和过氧化氢酶 (35.1%~133.0%)活性显著提高,丙二醛 (7.1%~26.8%)含量明显降低。表明对种子进行引发处理,通过增强盐胁迫下水稻种子活力,提高幼苗渗透调节物质含量和抗氧化酶活性,降低丙二醛含量,增强了水稻种子及幼苗的耐盐性,其中1.0 mg/L的多巴胺溶液(S1)引发效果优于水引发(S0)。【结论】对于新疆自育水稻品种新稻17而言,1.0 mg/L多巴胺溶液引发能够有效提高其对盐胁迫的抵抗能力,促进种子萌发和幼苗生长。     

Quality of guayule seeds separated by physical attributes

Guayule (Parthenium argentatum Gray) is being developed as a new commercial crop to be grown in arid and semiarid regions. Guayule stands are presently established using transplants; however, establishment by direct-seeding would reduce costs and make production more economical. A major difficulty in field establishment by direct-seeding is the variation in the quality of guayule seeds. Guayule seeds vary greatly in color, size, and weight, which are the attributes believed to be associated with the observed germination differences among and within seed lots. To determine the importance of these attributes, guayule seeds from different seed lots were separated by size (diameter) and color, each separation class was weighed and then seed quality determined by germination percentage and rate. X-ray analysis was used to distinguish filled from unfilled seeds, and this was related to the germination results. In six guayule breeding lines (N565, 11591, AZ-2, AZ-3, AZ-4, and AZ-5), the highest quality seeds were darker (opaque-black and gray), small to medium in diameter (1.4–1.6 mm), and were heavier (a greater proportion of filled seeds). Color appeared to be a more efficient separator for seed quality than seed size; however, separation by size may be acceptable on a large scale and still provide higher quality and more uniform seed lots.     

Seed priming and in situ moisture conservation measures in increasing adaptive capacity of rain-fed upland rice to moisture stress at Eastern Himalayan Region of India

In the uplands of Eastern Himalayan Region (EHR) of India, dry-seeded rain-fed rice occupies considerable area. However, productivity of rice in this region is very low and is mainly due to frequent occurrence of intermittent soil moisture stress, weed infestation, and poor crop establishment. Keeping this in view, a field experiment on rain-fed direct-seeded rice was conducted during two consecutive years 2011 and 2012 at the EHR of India (27° 95′N latitude and 94° 76′E longitude, 662 m above MSL) to evaluate the effect of seed priming (SP) with different durations (0, 12, 18, and 24 h) and in situ furrows at various row intervals as moisture conservation measures (MCM) on seed germination, plant stand, profile moisture recharge, rice productivity, water and energy use efficiency, and harvest monetary benefits. Results revealed that SP for 24 h duration significantly (p < 0.05) improved the seed germination and crop stand, rice grain yield by 30–36 %, water use efficiency by 29–36 %, and energy productivity by 15–22 %. In situ furrows at regular and alternate row intervals also registered 1.89–3.2-fold increase in profile moisture recharge, 20–34 % higher rice productivity, 23–33 % improvement in water use efficiency, and 6–16 % increase in energy productivity over without MCM. Seed priming helped in improving seed germination, seedling establishment, and plant stand, while MCM was useful in mid-season rainfall capture and profile moisture recharge during intermittent moisture stress for better plant growth. However, adoption of in situ furrows (regular and alternate row intervals) as MCM increased the cost of cultivation by 13–27 % over normal practices but was compensated by the significant increase in grain yield, water use efficiency, benefit:cost ratios, and farmers’ profit.     

小麦对直播稻田千金子的化感作用及化感物质分离鉴定

 研究了小麦茎根水提取液对直播稻田千金子的化感作用，并分离鉴定了化感物质。结果表明：扬麦158和扬麦10号不同生育期的水提取液对千金子种子萌发均有抑制作用，但对幼苗生长无抑制作用；对水稻种子萌发及幼苗生长均无抑制作用；利用室内生测及GC MS分析鉴定抑制千金子种子萌发的化感物质为有机酸，对千金子种子萌发的抑制率达94.90%，有机酸的主要成分为棕榈酸、油酸、亚油酸、硬脂酸及肉豆蔻酸。     

Comparative efficacy of surface drying and re-drying seed priming in rice: changes in emergence, seedling growth and associated metabolic events

In seed priming, seeds are soaked in a solution of low water potential and dried back to their original weight. This study was conducted to evaluate the comparative performance of different seed priming treatments and to investigate whether re-drying is essential or not? Seeds of fine grain aromatic rice (Oryza sativa L.) cultivar Super-Basmati were subjected to hardening, osmohardening with CaCl₂ and KCl (ψ _s ?1.25 MPa) each for 24 h (one cycle), and hydropriming and ascorbate priming (10 mg L^?1) for 48 h. Seeds were primed in two sets. In one set after each treatment, seeds were given three surface washings with distilled water and dried back near to original moisture contents with forced air. In the other case, after surface washings with distilled water, seeds were surface dried using blotting paper and sown immediately. All the priming treatments improved the emergence, seedling growth and reserve metabolism. Use of surface drying was more effective for rice seed invigoration, as evident from earlier and synchronized seedling emergence. Moreover, shoot and root length, seedling dry weight, root score, α-amylase activity, soluble sugars and dehydrogenase activity were also improved, although germination percentage and leaf score were similar from both strategies. Results suggested that surface drying, rather than re-drying close to original weight, was more effective, while among the treatments, osmohardening with CaCl₂ was the most effective. Increasing rice production with judicious use of water is need of the day, and aerobic rice cultivation is an attractive alternative for this purpose. However, poor and erratic stand establishment is one of the major hindrances in its wide scale adoption. In this regard, seed priming techniques are pragmatic approaches to achieve proper stand establishment in the new rice culture. They help in improving seedling density per unit area under optimal and adverse soil conditions and may be opted to improve the performance of aerobic rice.     

大田越冬水稻种子的筛选鉴定

连续阴雨与早春低温是影响我国南方水稻生产的主要不利气候因素,常导致水稻烂芽和烂种。本研究通过在自然条件下筛选大田中越冬后而能够在翌年发芽成长为植株的方式,以期获得成苗率高、烂芽烂种率低的种质资源。结果表明,172份种质在自然条件下经历冬季后,绝大部分种质的种子腐烂,仅Kasalath和日本晴种子在大田越冬后能发芽生长。这两种常规水稻种子大田越冬特性的发掘,将为培育降低烂芽烂种率的优良品种提供宝贵种质资源。     

壮芽灵浸种对德香4103直播群体结构和产量的影响

大田直播条件下,研究了壮芽灵浸种对三系杂交水稻德香4103群体结构和产量的影响。结果表明：（1）壮芽灵浸种可以显著提高稻种的发芽势,但发芽率提高不显著;（2）壮芽灵浸种可以缩短从始苗到全苗的时间2 d,在播种量相同的条件下,基本苗和出苗率得到显著提高,基本苗从56.67万株/hm^2提高到68.89万株/hm^2,出苗率从75％提高到91％;（3）壮芽灵浸种可以显著提高群体最高苗数和成穗率,最高苗从573.33万/hm^2提高到612.22万/hm^2,成穗率从44％提高到47％;（4）壮芽灵浸种后有效穗数、结实率、千粒重显著提高,增产达7.70％。     

Development of Rice “Seed-Mats” Consisting of Hardened Seeds with a Cover of Soil for the Rice Transplanter

Conventional seedling mats for rice transplanters in Japan are heavy to carry, and much labor is required to collect, wash and store the nursery boxes. In addition, seeding time overlaps with the labor peak in spring. To reduce such labor, we developed a “seed-mat” consisting of hardened rice seeds (Oryza sativa L.) glued onto a molded rice-hull mat with a cover of soil glued on. Seed hardening, which is done by soaking seeds in water at 15ºC for 5 d followed by drying, and heating of the seeds at 50ºC for 5 or 7 d, reduced the time to 50% germination (T₅₀). In dormant seeds, the heating before the hardening enhanced the effect of the hardening more than the heating after the hardening. Seed hardening increased the dry weight of the shoots from the seed-mats. Covering the mat with soil also increased the percentage of seedling emergence, shoot length, number of leaves and shoot dry weight of the seed-mats. The hardened seeds maintained short T₅₀ and 95% or higher germination for 120 d at room temperature. In the seed-mat, the hardened seeds maintained 95% or higher seedling emergence for 208 d. In conclusion, superior seed-mats could be produced using the procedure involving both seed hardening and cover of soil. The seed-mats can be prepared in winter and stored until seedling-raising period in spring. By the seed-mats, seedling mats can be prepared for the rice transplanter without using nursery boxes, which take up storage space and require much labor.     

Seed characterization and direct sowing of native grass species as a management tool

There is insufficient information about germination, seed biology and seedling establishment of native grass species of the cerrado (Brazilian savannah) to recommend their use in restoration of disturbed areas. We evaluated the production, percentage of fertile seeds, germination, seedling growth and establishment in the field of eighteen native grass species and one exotic invasive species (Melinis minutiflora) and also the effects of different storage periods on germination. The percentage of fertile seeds varied from 6·0 to 94·2% among native species. Ten species produced a minimum of 800 fertile seeds per gram. Germination rate was in the range of 11·0 to 98·8%. Storage for 1 year reduced the germination rate in one species, did not affect germination of three species and increased germination (by 2–10 times) in 14 species. After 2 years of storage, six species showed reductions in germination. Three different patterns of resource allocation were observed and might provide mechanisms for increasing seedling establishment under different environmental conditions. In the field, only two species flowered in the first year after sowing and an additional eight in the second year of observation. Melinis minutiflora is an aggressive species with more than three times the fertile seed production of native species (2820 seeds per gram), high germination rate (55%) and a high number of germinable seeds (1551 per gram). Despite the wide variation in seed characteristics and the delay in flowering, it is concluded that most native grass species can be used in projects aiming at the restoration and management of degraded areas.     

Evaluation of alternative tillage and crop establishment methods in a rice–wheat rotation in North Western IGP

The rice–wheat rotation covering 13.5 million ha in the Indo-Gangetic Plains is vital for food security. Its sustainability is at risk as the current production practices are inadequate resulting in high cost of cultivation and inefficient use of inputs (i.e. water, labor and energy). In a field study, we evaluated resource conserving and cost-saving alternative tillage and crop establishment options with an aim to improve system productivity and efficiency. Treatments included transplanting and direct-seeding of rice after reduced and no-tillage, followed by wheat after no-tillage. Conventional-tilled (puddled) transplanted rice followed by conventional-tilled wheat was included as a current practice. Rice yields of transplanted rice were similar irrespective of tillage/puddling. However, both dry and wet direct-seeded rice yielded 0.45–0.61 Mg ha⁻¹ lower than puddled transplanted rice. Wheat yield after no-tillage was either higher or equivalent to conventional practice. Wheat provided more economic return (US $35 ha⁻¹) than rice. No-till wheat was 6% more profitable than the conventional practice (T1). Rice transplanting with or without puddling had similar water application but dry direct-seeded rice had 10–12% lower and wet direct-seeded rice 20–24% higher. Machine labor without tillage was lower by maximum of 51 and 43% in rice and wheat, respectively. Similarly, human labor was also 9–16% lower in no-till rice compared to other practices. Two years results consistently showed $35 more net income when rice was transplanted without puddling than that of conventional practice. Direct-seeded/un-tilled rice had variable response in 2 years; US $16 more in year 1 and similar in year 2 to the puddled transplanted rice. Direct-seeded or transplanted rice after no-tillage can be more efficient and profitable alternatives to current practice (puddled transplanted rice), however, require further refinement in areas of cultivar development for no-till direct-seeding condition, nutrient, water and weed management to harness maximal potential.     

杂交水稻种子的裂颖及其危害

杂交水稻种子存在较严重的裂颖现象,这是不育系的一种遗传特性。裂颖种子不耐储藏,随储藏时间的延长,裂颖种子的生活力迅速衰退,发芽率和发芽势降低,秧苗素质差,并严重影响自然混合种子群体的发芽及幼苗生长。选育闭颖能力强的不育系,改进制种技术,强化种子选种,采用多起多落浸种和旱育秧等措施可防治或减轻裂颖种子的危害。     

Effects of light, hydropriming and abiotic stress on seed germination, and shoot and root growth of pyrethrum (Tanacetum cinerariifolium)

Poor germination and seedling establishment are major problems in arid and semi-arid environments, and these characteristics are considered to be important factors in later plant growth and yield. Laboratory experiments were conducted on freshly harvested pyrethrum (Tanacetum cinerariifolium) seeds to investigate the effects of light (influenced by the seeding method) and seed hydropriming on germination, and shoot and root growth at 25 °C. Exposure to light could reduce germination from 52% to 22% and increase the mean germination time (MGT) from 7 to 12 days. The responses of hydroprimed and unprimed seeds to salt and drought stress were determined at osmotic potentials of 0 (distilled water), −0.3, −0.6, −0.9, −1.2 MPa in NaCl and PEG6000. Seed germination and seedling growth were inhibited by increasing salt and drought stress. The germination percentage of unprimed seeds was reduced from 52% to 16% in −1.2 MPa NaCl, and no seeds germinated at osmotic potentials ≤−0.9 MPa PEG. Both shoot and root growth were inhibited at osmotic potentials ≤−0.9 MPa NaCl and ≤−0.6 MPa PEG. Hydropriming shortened the delay of MGT at all osmotic potentials, and improved the germination percentage in distilled water (from 52% to 59%) and resistance to salt stress with nearly double germination (from 16% to 29%) at the highest salt concentration. When non-germinated seeds were transferred to distilled water after 20 days of incubation in total up to 12-15% of NaCl and 25-27% of PEG stressed seeds did not recover. These results show that the inhibition of the germination and seedling growth at the same osmotic potential of NaCl and PEG resulted from drought stress rather than salt toxicity, and that hydropriming is an effective tool to improve the quality of pyrethrum seeds.     

Improvement of seedling establishment under flood condition by seed coating with molybdenum compounds for wheat and barley

Wheat and barley are often cultivated also in paddy fields in winter in Japan. The drainage of paddy fields is often poor. The seedling establishment of wheat and barley is more prone to become poor if it rains heavily after sowing. The flooding damage on seedling establishment is thought to be caused by many factors. The generation of sulfide ions in flooded and reduced soil is thought to be one factor of the flooding damage. In this study, the effect of seed coating with molybdenum compounds, which suppress the generation of sulfide ions, on the flooding damage of wheat and barley seedling establishment. Two poorly soluble molybdenum compounds were coated on wheat or barley seeds at different amounts. Coated seeds were sown in soil and soon flooded for 2 d at 20 °C. When seeds were not coated with molybdenum compounds, rates of seedling establishment were no more than 32%. However, when any molybdenum compounds of .05–.5 mol-Mo kg^?1 were coated, seedling establishment was significantly improved and rates of seedling establishment were no less than 54%. However, when sown seed were not flooded, the establishment rates of the seeds, which were coated with a molybdenum compound of no less than .1 or .2 mol-Mo kg-1, were significantly decreased. Accordingly, coating of molybdenum compounds could improve the seedling establishment of coated seeds under flooded condition, but might impair the seedling establishment of coated seeds under unflooded condition.     

木霉T2-16发酵产物对杂交水稻种子活力和秧苗素质的影响

应用木霉T2-16菌株在改良后的GPF培养基中发酵培养的产物,对5个杂交水稻组合进行浸种处理.结果表明:该发酵产物能提高种子活力,表现为促进种子的提早萌发、提高种子的活力指数和降低种子的相对电导率.两优培九盆栽试验显示,经木霉T2-16发酵产物浸种处理后,秧苗根系及地上部生物量增加,根系活力增强,幼苗叶片中叶绿素和可溶性蛋白含量提高,与抗病性有关的酶活性增强.显示木霉发酵产物在提高杂交水稻种子活力和培育壮苗、提高秧苗抗病性方面具有促进作用.     

植物生长调节剂对毛萼紫薇种子萌发及幼苗生长的影响

自然条件下毛萼紫薇Lagerstroemia balansae结实率很高,但自然萌发率和成苗率极低。适合的植物生长调节剂处理种子,能够有效打破种子休眠、有效促进幼苗生长。本研究采用TTC染色法测定毛萼紫薇种子的生活力,比较5种植物生长调节剂GA3、TDZ、IAA、6-BA和NAA处理下毛萼紫薇种子的发芽率、发芽势及对幼苗生长的影响。结果表明:(1)毛萼紫薇种子生活力较低;(2)200 mg/L GA3处理的种子发芽势,发芽率较高,幼苗长势良好;其次是0.02 mg/L的TDZ处理,再次是200 mg/L IAA的处理;(3)1~20 mg/L的6-BA和NAA处理对毛萼紫薇种子的萌发无促进作用。上述结果表明:GA3、TDZ、IAA能有效促进毛萼紫薇种子的萌发及幼苗生长。     

Multiple effects of two drivers of agricultural change,labour shortage and water scarcity,on rice pest profiles in tropical Asia

The effects of shortage of agricultural labour, represented by direct-seeding technologies replacing transplanting, and of water scarcity, represented by limited water supply, on rice pests (pathogens, weeds, insects) were studied. The analysis was based on a field characterisation data set covering six sites in tropical Asia and several cropping seasons. Two-way ANOVAs and MANOVA were, respectively, used to test the effects of the two factors on individual rice pest injuries, and on the profile of injuries that an individual rice crop experiences over a cropping season. Fourteen injuries were considered, which individually were significantly (P < 0.05) influenced by crop establishment (nine injuries), by water management (11 injuries), or their interaction (nine injuries). Multiple analysis of variance indicated that rice injury profiles, regionally, are altered by both factors. The results suggested that injuries caused by some pests would be enhanced (e.g., brown spot, planthoppers) or reduced (e.g., stem rot, sheath blight, rice whorl maggot) by crop establishment shifting from transplanting to direct-seeding. Water shortages, proxied in our data by poor water management, would favour some injuries (e.g., sheath rot, brown spot, neck blast, whiteheads) or suppress others (e.g., stem rot, sheath blight). Very strong increases in weed infestation were observed with both direct-seeding and poor water management. The results are discussed with respect to pest management in rice.     

Morphological and physiological traits of seeds and seedlings in two rice cultivars with contrasting early vigor

Early vigor is important for crop establishment in rice. This study was conducted to determine the seed and seedling traits in relation to early vigor in rice. Laboratory tests and pot experiments were carried out in 2013 and 2014. Morphological and physiological traits of seeds and seedlings were compared between two contrasting rice cultivars, Yuxiangyouzhan with superior early vigor and Huanghuazhan with general early vigor. For seed traits, Yuxiangyouzhan had lower seed hull weight but higher seed amylose content, seed amylase activity, and plumule–radicle ratio than Huanghuazhan, and consequently, Yuxiangyouzhan had about 10% higher germination percentage and velocity and 37% longer plumule than Huanghuazhan. For seedling traits, leaf area, specific leaf weight, leaf chlorophyll and soluble protein contents, leaf net photosynthetic rate, and shoot–root ratio were higher in Yuxiangyouzhan than in Huanghuazhan, and as a result, seedling shoot biomass was 23–32% higher in Yuxiangyouzhan than in Huanghuazhan. These results indicate that Yuxiangyouzhan has both superior seed and seedling vigor. The former is attributed to the low mechanical strength of seed hull, high conversion efficiency of seed reserve, and high mobilization of seed reserve to plumule, while the latter is due to large leaf area, high leaf photosynthetic capacity, and high partitioning of dry matter to shoot. This study enriches the physiological understanding of superior early vigor in rice.     

丹东杂草稻种子的耐冻能力和低温发芽特性研究

为了解丹东杂草稻种子冬季在野外能存活的原因,将丹东杂草稻和对照品种越光的干种子在水中浸不同时间,后在-20℃下处理7 d,在25℃下发芽。对照品种越光在浸种1 h后冷冻处理,其种子的发芽率从98％降为4％,浸种时间延长到1.5 h已不能成苗,而丹东杂草稻种子在1 h浸种处理后,其发芽基本不受影响,甚至在3 h浸种处理后成苗率仍达2.3％。在不同低温下发芽试验中发现丹东杂草稻在11℃能发芽,杂草稻的发芽临界温度要比对照越光低。讨论了杂草稻种子抗冻的潜在价值。      

高温处理对不同状态水稻种子发芽率的影响

以2个早籼稻品种的超干种子、干种子、鲜种子、湿种子、露白种子为材料,研究了高温处理对不同状态水稻种子发芽率的影响。结果表明,水稻不同种子状态耐受高温能力存在极显著差异,从强到弱依次为超干种子干种子鲜种子湿种子露白种子;水温对种子发芽率的影响比气温更显著;处理温度超过一定范围,发芽率随着温度升高和时间延长极显著下降;不同品种高温处理后的种子发芽率表现相同规律趋势,但也存在极显著个体差异;种子水分制约种子耐受高温能力,种子水分含量越高,耐受高温能力越弱。     

NADPH Oxidases Act as Key Enzyme on Germination and Seedling Growth in Barley (Hordeum vulgare L.)

Reactive oxygen species (ROS) play an important role in seed germination. Although hydrogen peroxide (H₂O₂), a type of ROS, enhances the germination rate of various plant seeds, little is known about the mechanism. NADPH oxidases catalyze the production of superoxide anion (O₂^-) that is one of the ROS and the enzymes regulate plant development. We, therefore, investigated the role of NADPH oxidases in seed germination and seedling growth in barley (Hordeum vulgare L.). The production of O₂^- was observed both in embryo and aleurone layers in barley seeds treated with distilled water (DW). However, it was suppressed in seeds treated with diphenylene iodonium (DPI) chloride, NADPH oxidase inhibitor. Moreover, DPI markedly delayed germination and remarkably suppressed α-amylase activity in barley seeds, indicating the importance of NADPH oxidases in germination of barley seeds. The gene expression and the enzyme activity of NADPH oxidases gradually increased after imbibition, and the enzyme activities were closely correlated with seedling growth after imbibition. Besides, DPI markedly suppressed the seedling growth. These results indicated that NADPH oxidases perform a crucial function in germination and seedling growth in barley. These facts clearly reveal that O₂^- produced by NADPH oxidases after imbibition regulates seed germination and seedling growth in barley.