Selection for early flowering in progenies of interspecific crosses of ten species in the genus Dianthus

Summary Twenty-seven progenies of interspecific crosses, involving ten Dianthus spieces (D. caryophyllus, D. chinensis, D. superbus, D. barbatus, D. japonicus, D. brachyzonus, D. versicolor, D. trifasciculatus, D. serotinus and D. knappii) and some complex interspecific hybrids (Diantini genotypes and D. Allwoodii selections) were grown from seed under 8 hr days at two light intensities: 12 W/m² and 22 W/m². Observations on individual plants were made on vegetative development and date of flowering. After six months, 178 plants were selected from 23 seedling progenies and the resulting clones were compared under 22 W/m² and two photoperiods: 8 hrs and 24 hrs per day for a period of nearly six months. In the seedling stage, large differences were observed between progenies, e.g. in percentage generative plants (0–100%), plant length (3–78 cm) and plant fresh weight (0.5–68 g). Effects of light intensity were most pronounced in plant fresh weight (0.2–18 g in 12 W/m² and 0.5–68 g in 22 W/m²). Progenies of D. chinensis were the earliest to flower. Most progenies of crosses between D. superbus and D. barbatus segregated into flowering and non-flowering (rosetting) plants. In the clonal stage, most clones originating from non-flowering seedlings remained vegetative (rosetting), while all clones from flowering seedlings were either in flower or in bud within six months. Average dates of flowering of seedling progenies and of their clones were highly correlated, suggesting that selection on flowering date at the seedling stage is effective. High correlations were also found between the average flowering date of seedling progenies and the number and total weight of flowers harvested per plant in their clones within six months from planting. Overall effects of LD in the clonal stage were much less spectacular than the effects of light intensity in the seedling stage.     

Variation in the photoperiodic response on several characters in soybean,Glycine max (L.) Merrill

Summary The photoperiodic response on 12 characters in 40 soybean, Glycine max (L.) Merrill, cultivars were investigated using 10-hour (short day) and 16-hour (long day) photoperiods. Seventeen cultivars showed no significant difference between photoperiods for all 12 characters. Seven cultivars showed significant difference for only one trait. Phenotypic changes in 17 cultivars may be due to factors other than photoperiod. Number of pods per plant, days to maturity, and number of nodes per plant were highly correlated with yield per plant in both photoperiods. Invariably, the cultivars which had significant differences in the numbers of flowers produced per plant between the two photoperiods also had significant differences in the numbers of pods per plant and yield. First node to flower, plant height at flowering, days to flowering, nodes at flowering, and the 100-seed weight were least influenced by the photoperiods in most of the cultivars, while the height at maturity, number of nodes at maturity, number of days to maturity, and yield were most influenced.AVRDC Journal paper 46 (78–88).     

Reproductive capacity of F1 hybrids from Rosa rugosa and Chinensis cultivars

Summary Reciprocal crosses were carried out for 6 combinations of 4 R. rugosa with 3 R. chinensis cultivars. The parental combinations were evaluated for successful pollinations, seed germination and flowering and seed setting seedlings in populations of 3 year old plants. Seeds and viable seedlings were obtained from each of the 12 seedling populations. Only 3 populations produced female fertile offssprings. The average of seed setting seedlings was 1.5%. The percentage of flowering seedlings was significantly reduced in the offspring from certain parents. The success of cross pollination, seed germination and the ability to initiate flowers were influenced by cytoplasmic factors.The differences in fertility between the present hybrids and the only other rugosa x chinensis hybrid described, R. calocarpa (Andrê) Willmott, are discussed.Contribution No. 73/2.     

The genetic variability of the yield components in the Kenyan pyrethrum population

Summary Pyrethrum is grown for the insecticidal pyrethrins, extracted from the dried and ground flowers. It is a cross-fertilizing, self-incompatible perennial plant, which can be propagated vegetatively.The genetic variation of several, commercially important, characteristics was studied. The range of observed variation is very wide for fresh flower yield, flower size, number of flowers per stem, pyrethrins content, lodging resistance and the Pyrethrins I/Pyrethrins II ratio, and quite narrow for the dry matter content of the flowers. Populations to select from are obtained by crossing two (single crosses) or more clones (polycrosses). The genotypic variation of two single and one polycross (42 clones) was studied. The single crosses showed, for the three characteristics measured, pyrethrins content, flower size and Py. I/Py. II ratio, a considerable transgression. The progeny means were very similar to the mid-parent values. This indicates a polygenic inheritance for these traits. The variation of the polycross for these three traits was not greater than those of the two single crosses, suggesting a very high level of heterozygosity in the parental clones. It is in fact possible to reconstitute a large part of the genotypic variation observed in Kenya from only a very few single crosses. In view of the selection relationships between traits were investigated. Flower size appeared negatively related to dry matter content of the flowers and to flower yield. A suspected negative relation between flower yield and pyrethrins content could not be confirmed. The results indicate, that large genetic improvements are possible in a fairly short time.     

Seed set and seedling variation in greater yam (Dioscorea alata L.)

Summary A high degree of fruit and seed set was obtained in Dioscorea alata L. by hand pollination. The sexual progeny was studied in comparison with the clonal plants. In general, the seedlings were poor in growth vigour, flowering and tuber production but the variations observed in the different characters were unprecedented, indicating scope for efficacious genetic improvement in this vegetatively propagated crop.     

不同浓度赤霉素对地被菊‘紫重楼’开花特性的影响

笔者探讨不同浓度赤霉素(GA3)对地被菊‘紫重楼’ 株高、冠幅、开花特性（花期、开花量、花朵重瓣性、花径）和花粉生活力的影响,旨在为地被菊杂交育种、花期调控提供参考依据。试验结果表明,喷施100~500 mg/L GA3后,‘紫重楼’露色期、始花期及盛花期分别提前6~10天、7~12天和2~7天;GA3有利于节间伸长和株高增加,但植株开花量和花瓣重瓣性降低,冠幅、花径减小。其中,500 mg/L GA3处理下的地被菊节间长度与株高显著高于其他水平;100~300 mg/L GA3处理可促进花粉生活力,500 mg/L对花粉生活力有抑制作用。     

Effects of irradiance and juvenility on the selection of chrysanthemums

Summary Chrysanthemum morifolium seedlings and cuttings from those seedlings were grown to flowering at 17°C, short days (8 h) and two levels of irradiance (10 and 30 W m^–2). The cuttings flowered more readily than the seedlings at both irradiances, Especially at 10 W m^-2 many seedlings remained vegetative. The delay in flowering of the seedlings was accompanied by a higher number of leaves produced before flowering.The number of leaves produced by the seedling in excess of the number of leaves produced by the cutting from that seedling varied considerably between genotypes. The correlations between seedlings and the corresponding cuttings for days to flowering and number of leaves were low but generally significant.It is concluded that cuttings are preferred over seedlings in breeding programmes that aim at developing chrysanthemums for low light winter production.     

陆地棉亚红株突变的质量遗传规律研究

分析了陆地棉亚红株突变体的淡红叶性状与当日红花性状的质量遗传规律,结果显示,淡红叶性状是受一对不完全显性基因控制的质量性状。连锁分析表明:淡红叶性状与当日红花性状完全连锁,是受同一对显性基因控制的质量性状;淡红叶与棕絮性状符合两对性状完全独立分离规律,不存在连锁遗传关系。等位性测定显示,淡红叶性状与经典红叶性状杂交后代,符合两对显性基因控制的独立分离理论比例,表明控制亚红株突变的基因与控制经典红叶的R1基因不在同一基因位点。根据以上试验结果,推定陆地棉亚红株突变是一个新的质量突变性状,暂将它的基因符号定为RS。     

Photoperiod response in mungbeans (Vigna radiata (L.) Wilczek)

Summary Five strains of mungbeans were grown at 8-, 12-, 13-, 14-, 15-, and 16-hour photoperiods in plant environmental chambers. The strains did not differ in days to flower at the 8- and 12-hour photoperiods, but flowering was delayed and plant height increased differentially when the photoperiod was increased beyond 12 hours. Two strains exhibited only slight sensitivity over the range of photoperiods studied. Two strains failed to flower within a 180-day period at the 16-hour photoperiod. The results corroborate observations in the First International Mungbean Nursery in which 28 strains grown at low latitudes (short photoperiods) had a narrow range in days to flowering, with the range becoming wider at the higher latitudes (longer photoperiods). The results provide evidence that response to photoperiod is important in the adaptation of mungbean strains in different latitudes.Contribution No. 6890 from the Missouri Agricultural Experiment Station.     

CIMMYT牧草DNA导入普通玉米后植物学形态变异研究

本研究以CIMMYT牧草和4个普通玉米自交系为遗传交配材料,比较研究了CIMMYT牧草和4个杂交（回交）后代的植物学形态特征及其与普通玉米的差异。结果表明,CIMMYT牧草能将其生长繁茂、分蘖力强、生物产量高的特性遗传给杂交后代,并有较强的世代传递能力;该牧草幼苗、植株及其生长习性、花器官、种子特征等与普通玉米差异明显,其与普通玉米的杂交后代基本保持了它的生长发育特性,但花器官和种子特征更偏向于普通玉米;回交后代除保持了一定的分蘖特性、明显的多穗和返祖现象外,其余特征特性与普通玉米基本没有区别。     

不同类型栽培基质对海南钻喙兰生长发育的影响

海南钻喙兰是具有较高发展潜力的新型热带花卉,花色美丽、芳香扑鼻,但缺乏切实可行的栽培管理技术,产业发展难以为继。本文分别以海南钻喙兰组培幼苗、成苗为研究对象,探讨不同基质对其生长、开花的影响,以期解决海南钻喙兰生产过程中各苗期栽培基质的选择问题。结果表明：(1)水苔是适宜的幼苗栽培基质,大棚、荫棚环境成活率为97.5 %,能较好的促进植株生长；松鳞处理成活率分别为100.0%与90.0%,对根长有较好的促进作用,为次优处理。(2)松树皮、木炭、火山岩混合基质利于成苗叶片、根系增长,是营养生长期适宜栽培基质,但不利于开花；1.0-2.0cm火山岩、松鳞处理开花率分别为90.0%、75.0%,对叶宽、茎高、根粗增长有一定的促进作用,适用于成苗促花栽培,其中松鳞较为经济环保,是优选促花基质。     

CIMMYT牧草与普通玉米杂交后植物学形态变异研究

[研究目的]为发掘利用CIMMYT牧草生长繁茂和抗逆能力强等优良遗传特性,改良普通玉米材料的抗逆性和创制新型饲草材料.[方法]以CIMMYT牧草和4个普通玉米自交系为遗传交配材料,比较研究了CIMMYT牧草和4个杂交(回交)后代材料的植物学形态特征及其与普通玉米的差异.[结果]CIMMYT牧草能将其生长繁茂、分蘖力强、生物产量高的特性遗传给杂交后代材料,并有较强的世代传递能力;该牧草幼苗、植株及其生长习性、花器官、种子特征等与普通玉米差异明显,其与普通玉米的杂交后代基本保持了它的生长发育特性,但花器官和种子特征更偏向于普通玉米;回交后代除保持了一定的分蘖特性、明显的多穗和返祖现象外,其余特征特性与普通玉米基本没有区别.[结论] CIMMYT牧草生长繁茂和生物产量高的特性能遗传给杂交后代,世代传递能力较强,通过遗传改良途径,能将CIM-MYT牧草的优良特性转育到普通玉米中,培育出饲草玉米育种新材料.     

Variation among heritability estimates for strawberries obtained by offspring-parent regression with relatives raised in separate environments

Summary Data on fruit yield, fruit size and a commercial appearance score were collected for strawberry seedlings from biparental progenies planted at two test locations. Similar data for 8 advanced selections from the California Strawberry Improvement Program were collected, with selections each subjected to three preplanting cold storage treatments and planted at a single location. Each progeny tested had at least one of the 8 selections as a parent. Offspring-parent regression heritabilities were computed using data from each combination of offspring location and parental treatment. Heritability estimates for yield and appearance differed significantly when different combinations of data were used; corresponding estimates for fruit size were unaffected. Gains predicted using heritabilities estimated by the convenient procedure of regressing unselected seedling values on those for vegetatively propagated parents will be reliable only for traits that are robust to rank shifts induced by planting/propagation treatments.     

机插稻超秧龄秧苗的生长特点研究

水稻机插移栽中秧苗不能及时机插而生长过度, 形成超秧龄秧苗。本试验以扬粳9538为供试品种, 在不同床土培肥条件下, 观测了超秧龄秧苗的生长特征。在超秧龄初期阶段(至播种后28 d), 秧苗地上部仍维持一定的生长, 秧苗干重和单位苗高干重尚有一定增加, 尚能维持糖氮代谢。但秧苗叶色(SPAD值)迅速下降, 地下部生长停滞, 根长、根数停止增加, 根系活力迅速下降, 根冠比明显降低。在严重超秧龄阶段(至播种后36 d), 苗高依然快速增加, 单位苗高干重大幅下降, 秧苗叶色维持在较低水平。根系活力低, 根系生长处于最低水平。超秧龄生长过程中秧苗糖代谢反应敏感, 氮代谢相对稳定, 糖氮比在严重超秧龄时大幅下降。床土肥力显著影响超秧龄秧苗生长, 高培肥水平下的秧苗茎基粗没有显著变化, 但苗高迅速增加, 单位苗高干重大幅降低, 地下部生长较低培肥处理更弱, 根数和根长较低, 根系活力下降迅速, 根冠比与低培肥处理相比大幅减小。床土培肥水平对秧苗的碳氮代谢影响显著, 高培肥处理的超龄秧苗营养状态更为劣化。以上结果表明, 超秧龄阶段特别是在严重超秧龄阶段的秧苗生长, 很大程度上取决于育秧阶段(适栽期)的育秧条件和生长状况, 低培肥处理的秧苗在超秧龄生长中糖氮比能维持相对较高的水平, 从而维持秧苗相对较好的营养状态。     

The possibilities of early selection of late-flowering almonds as a function of seed germination or leafing time of seedlings

Obtaining new, late‐flowering almonds by crossing is a very long process, mainly due to the long juvenile period of the seedlings obtained. It would be very useful to have an early selection method to identify the late‐flowering genotypes, which would increase the efficiency of the breeding programmes. In this work, a study was made of the possibility of using the chilling requirements of seeds for germination and the leafing time of seedlings as criteria for early selection of flowering time, in 502 seedlings belonging to 13 families, over a four‐year period. Crossings were carried out in 1997. Seeds were stratified at 7°C. and the number of weeks necessary for germination was determined. Seedlings were planted in 1998. Between 1999 and 2002 the leafing time was recorded, and in 2001 and 2002 the time of flowering was also recorded. The results showed that, although some correlation was observed between the germination or leafing time and the flowering time, these correlations were not strong enough to be used as efficient criteria for early selection of late‐flowering seedlings within each family. for which variability was limited. To obtain late‐flowering cultivars. the best method is to cross progenitors which flower as late as possible, and later select the seedlings according to their flowering time. Leafing time could be used for early selection with certain success when progenitors have very different flowering times (VCTJ early and very late), since the expected variability within families will be very large.     

Genotype by environment interactions and combining ability for strawberry families grown in diverse environments

Ten seedlings from 36 crosses representing eastern and western North American short day and remontant genotypes were evaluated in 2011 and 2012 in California, Michigan, New Hampshire and Oregon, for phenology, flower related traits, plant characteristics, fruit characteristics and fruit chemistry traits. There was significant variability among genotypes, locations and evaluation year for most of the characteristics; however, few genotype × location and genotype × year interactions were detected. General combining ability variance components were significant for all traits and greater than SCA variance components for peduncle length, total flowering weeks, flowering cycles, truss size, growing degree days for harvest data, remontancy, achene position, ease of capping, fruit weight, percent soluble solids, titratable acidity and soluble solids/titratable acidity. ‘Sarian’ was identified as the best contributing parent for remontancy. Narrow-sense heritability estimates were moderate to high (0.33–0.78) for total flowering weeks, flowering cycle, truss size, remontancy, number of runners, fruit weight, pH, and titratable acidity. Having a better understanding of these attributes will provide breeders guidance on the most effective breeding strategies for incorporating superior traits from this germplasm into their programs.     

Effect of vernalization and photoperiod on flax flowering time

Vernalization and photoperiodism are two important physiological processes related to yield of many cool-season annual crops. The flowering response of 20 flax (Linum usitatissimum L.) genotypes to two vernalization regimes (vernalized and unvernalized) and two photoperiod treatments (10 and 14 h) was evaluated in a growth chamber study in 2010 and 2011. The results suggest that photoperiod, vernalization, and genotype all had an effect on earliness as measured by days to anthesis. Unlike flax grown in the Upper US Midwest and Canada, Texas flax is grown in the fall due to high spring and summer temperatures. Genotype interaction was observed with both vernalization and photoperiod. Specifically, flax genotypes from Texas (winter type) were sensitive to both vernalization and photoperiods for flowering. Texas genotypes delayed anthesis for 7 days or more in unvernalized seedlings, whereas flowering time of most other spring grown flax genotypes was unaffected by the vernalization treatments. Texas genotypes also delayed anthesis for 12 days or more under vernalized and short day conditions, whereas most other genotypes were not influenced by photoperiodism in vernalized seedlings. The selection for vernalization and photoperiodic sensitivity in Texas genotypes and introgression of these traits into recently adapted spring grown genotypes is needed for development of high yielding flax genotypes for southern Great Plains production areas.     

Path analysis of the relationships between seed yield and some morphological and phenological traits in safflower (Carthamus tinctorius L.)

Path analysis was performed on plant characters of six safflower genotypes grown in a two year field experiment to determine for seed yield, the direct and indirect effects of the following traits: total biomass, stem yield, number of primary branches/plant, number of secondary branches/plant, number of seeds/m², number of seeds/capitulum, number of capitula/plant, capitulum diameter, 1000-seed weight, seed weight/capitulum, distance between ground level and the first fertile branch, plant height, number of days to the beginning of branching, number of days to the beginning of flowering, number of days to 50% flowering, number of days to full flowering and flowering duration. Seed yield was significantly correlated with the following traits: total biomass, stem yield, capitulum diameter, 1000-seed weight, seed weight/capitulum, distance between ground level and the first fertile branch, number of days to the beginning of branching and flowering duration. Total biomass, seed weight/capitulum, distance between ground level and the first fertile branch, 1000-seed weight and flowering duration had substantial direct effects, in that order, on enhancement of seed yield. The significant positive correlation coefficient of capitulum diameter with seed yield resulted from positive indirect effects of total biomass, seed weight/capitulum and 1000-seed weight. Conversely, the significant negative correlations between number of days to the beginning of branching and distance between ground level and the first fertile branch and seed yield resulted from negative indirect effects of the same three traits. Stepwise multiple regression analysis showed that 94% of the total variation in seed yield could be explained by variation in total biomass and by number of days to the beginning of branching (84 and 10%, respectively). Results suggest that total biomass and number of days to the beginning of branching are primary selection criteria for improving seed yield in safflower.     

番茄试管苗与实生苗的幼苗生长及前期产量构成

为了摸清番茄试管苗与实生苗幼苗素质与产量的差异,明确番茄试管苗应用于实际生产的可行性,开展了番茄试管苗与实生苗的幼苗生长及其前期产量构成的比较试验,结果表明：番茄试管苗幼苗与实生苗幼苗的幼苗生长及前期产量构成差异显著,试管苗幼苗生长发育较快,株高适中,根系更发达,外观健壮,干物质积累更快,根冠比、G值、壮苗指数、根系活力等幼苗素质指标均更好;试管苗幼苗的干物质积累量呈现明显的叶>茎>根,而实生苗幼苗呈现叶、茎>根;番茄试管苗幼苗根的干物质积累量占干物质总积累量的比例要明显高于实生苗;试管苗番茄的始花节位降低,开花提前,坐果数与坐果率提高,前期产量和理论产量均提高。由此可见,番茄试管苗在番茄实际生产中具有较大前景。由于番茄试管苗移栽成活率较低,其炼苗、移栽育苗技术仍需进一步研究。     

Breeding for improvement of flowering attributes of winterhardy Rosa rugosa hybrids

Summary The purpose of this study was to determine at what stage of seedling development the flowering attributes in winterhardy R. rugosa hybrids could be assessed and if these attributes could be improved through breeding. The analysis of flowering was based on the duration of the flowering period and on amount of flowers produced.Most seedlings from rugosa hybrids could be assessed at an age of 3 years. The duration of the flowering period and flower productivity were not correlated. Several seedlings were improved in both attributes over the longer flowering and more floriferous parent.