Anatomical Characteristics of the Formation of Crown Root Primordia in Unelongated Stems of Wheat

Abstract

Anatomical observations were conducted to clarify some characteristics of the crown root primordia (CRP) formation in wheat stems. Unelongated portions of main stems were sampled from the plant at 3.2 and 7.2 plant age in leaf number, which were adopted as indexes because of the similarity to rice plants. Then, serial cross sections were made to investigate the position of CRP in the unelongated stem taking into consideration the running of vascular bundles in the stem. CRP were formed just outside tissues of the peripheral cylinder of longitudinal vascular bundles. The positions of CRP were not successive along the stem axis. They showed no definite relation to the running of vascular bundles. Diameters of CRP at the upper portion of the stems were larger than those at the lower portion. The positions of CRP along the stem axis were not distinguishable into nodal and internodal position. CRP and emerged CRs were not classified by the well-known ‘nodal root’ or ‘shoot unit root’, or the ‘unit’, which have been applied recently to rice plants. Further studies are necessary to clarify the factors controlling CRP formation anatomically and quantitatively.     

Radiation effects on potential number of grains per spike and biomass partitioning in two- and six-rowed near isogenic barley lines

The critical period for yield determination in barley (Hordeum vulgare L.) is situated in the pre-heading phases. During the latest part of the critical period one of the most important yield components (i.e. the number of grains per spike) is set in two- and six-rowed barley. In wheat, much is known about the role of the spike in assimilate acquisition for the establishment of grains per spike, but not in barley. This paper evaluates how biomass partitioning between vegetative and reproductive organs impacts floret development and primordia survival in response to radiation during different periods in the crop cycle, in barley lines. Field experiments were carried out using two- and six-rowed near isogenic barley lines differing only in spike type. Shading treatments were applied at different periods during the crop cycle (from 60 to 15 days before and after heading) reducing the intercepted radiation (ca. 70%). Dynamics of floret primordia initiation and mortality and of floret development for different spikelet positions along the spike were measured, and biomass partitioning between vegetative and reproductive structures was calculated.

Pre-heading shading reduced fertile florets per spike (P < 0.001). In the immediate pre-heading treatment, distal floret primordia could not reach a fertile floret stage due to a low rate of floral development.

The amount of assimilates partitioned to the spike at heading affected the number of fertile florets per spike in both barley types. However, when spike biomass at heading was corrected by nitrogen concentration, the fitness of the relationship did not improve in relation to the first one. In relative terms, radiation restrictions during the immediate pre-heading phase increased the amount of biomass partitioned to the growing spike.     

IPT促进稻苗种子根侧根原基的发生

０．０１～１０ｍｇ／Ｌ的ＩＰＴ能够促进稻苗种子根侧根原基的数目。与此同时,种子根的内源激素ＩＡＡ和ＡＢＡ的含量显著提高,而ｉＰＡｓ的含量下降。ＩＰＴ处理后,种苗种子根的吲哚乙酸氧化酶（ＩＡＡｏｘ）的活性下降,过氧化物酶（ＰＯＤ）的活性上升。     

外源生长素和细胞分裂素对莴苣幼苗侧根原基发生和内源激素含量的影响

以莴苣幼苗为材料,以适应浓度的生长素类物质萘乙酸（ＮＡＡ）、吲哚丁酸（ＩＢＡ）和吲哚乙酸（ＩＡＡ）处理根部２０￣３０ｈ,可使大量的侧根原基得到的启动和突起,１０．０００ｍｇ／Ｌ的ＮＡＡ,ＩＢＡ或ＩＡＡ处理的侧根原基数分别为对照的２７．９,２６．５和１３．６倍;     

低温刺激对杏鲍菇栽培效率的影响

以杏鲍菇(Pleurotus eryngii Quel.)出菇菌袋为材料,研究低温刺激对杏鲍菇出菇的影响,以建立一套出菇快速集中的高产出菇模式。结果表明,4~8℃下处理剥离塑料袋的菌袋2~3 d,可缩短菇原基形成时间,提高原基形成集中度与第一潮菇生物转化率;4~8℃下,菌丝4~6 d的后熟作用可使菇原基形成集中度提高至72.7%~76.3%,第一潮菇生物转化率提高至115.4%~121.4%;菌丝后熟作用4 d后,在低温处理前给予50~70 mg/L赤霉素(GA)处理对产量有促进作用。     

茉莉酸甲酯(JA-Me)对莴苣幼苗侧根原基形成及内源激素的影响

就茉莉酸甲酯（ＪＡ－Ｍｅ）对莴苣幼苗侧根原基的形成以及侧根原基形成过程中内源激素含量的影响进行了探讨。采用不同浓度ＪＡ－Ｍｅ以及分别配以生长素类试剂来处理莴苣幼苗,发现适当浓度的ＪＡ－Ｍｅ可促进其侧根原基形成且对萘乙酸（ＮＡＡ）、吲哚丁酸（ＩＢＡ）及吲哚乙酸（ＩＡＡ）等的促侧根形成具有明显的加合效应,进一步对其侧根原基形成过程中内源激素含量进行测定。结果表明,这与ＪＡ－Ｍｅ配合处理迅速降低根中内源［玉米素核苷（ＺＲｅ）＋异戊烯腺嘌呤（ｉＰＡｓ）］／ＩＡＡ的比值有关。     

水杨酸浸种对蚕豆种子萌发的影响

蚕豆种子于 2 5℃用 0 .0 1～ 5 .0 0mmol·L- 1 的水杨酸浸种 2 4h后 ,置于 2 0℃下萌发 ,SA对缩短发芽时间、提高发芽指数、促进胚根胚芽生长、提高根冠比、增加生物学产量、促进呼吸作用、提高植物抗逆性及侧根原基的形成有显著作用。     

Alizarin marking of whitefish, Coregonus lavaretus otoliths during egg incubation

Alizarin red S from 200 to 5000 mg L^?1 was used to mark the otoliths of whitefish embryos Coregonus lavaretus (L.) from 5 days after fertilization until shortly before hatching, to develop a method for evaluating the effect of stocking whitefish. Mark quality depended on developmental stage at the time of immersion. The best results were obtained when the otolith primordia had formed and had started aggregating to form the innermost part of the nucleus. This was verified by in vitro staining of otoliths where the primordia were more intensely stained than the remaining part of the nucleus. The volume ratio eggs to ARS solution, which was 1:10 in all but two treatments, must be observed when comparing fluorochrome concentrations, as mark quality decreased at higher ratios of 1:5 and 1:2. An average mortality rate of 35% in the most successful treatments was considered tolerable for a mass‐marking programme being used under commercial hatchery conditions. This method for marking otoliths of whitefish embryos with ARS during egg incubation is recommended for all cases where marking of larvae is not possible.     

Chromosome doubling of haploid maize seedlings using nitrous oxide gas at the flower primordial stage

In maize, inbred lines are used for the production of hybrid varieties. Corn breeders and researchers have considered using haploids to develop inbred lines; however, this procedure has not been practically applied because of the inefficiency of chromosome doubling of maize haploid seedlings. In this report, a procedure has been developed to overcome this difficulty. Maize haploid seedlings obtained from eight different genotypes were treated with nitrous oxide gas (2 days at 600 kPa). Treatment at the six‐leaf stage (flower primordia formation stage) significantly increased the occurrence of fertile sectors on both tassels and ears so that approximately half (44%) of the treated haploids produced kernels after self‐pollination. In the control, only 11% of haploids produced selfed kernels owing to spontaneous chromosome doubling. A strong genotypic effect on the occurrence of fertile sectors after the treatment was observed. This procedure can be used for inbred line development in maize breeding programmes.     

Frost hardening spruce container stock for overwintering in Ontario

Difficulties overwintering container stock in northern Ontario led to the development of the extended greenhouse culture hardening regime for spruce seedlings. Laboratories to measure shoot frost hardiness and evaluate terminal bud development were established to monitor nursery crops being hardened using this regime. Information on frost hardiness and bud development provided by these laboratories has been used by nursery managers to determine readiness of container seedlings for overwintering. Since 1982, over 200 stock lots have been monitored by these operational laboratories. This database can be used to determine the importance of nursery cultural factors and seed source on frost hardening. The database shows large differences between nurseries in approach to hardening seedlings which were reflected in levels of freezing damage, winter desiccation and overwintering success. Rates of frost hardening (i.e., the interval between terminal bud initiation and attainment of a --15°C level of shoot frost hardiness) of crops produced in north central Ontario failed to show significant seed source effects. The rate of frost hardening was faster in crops producing fewer needle primordia in terminal buds.