Accurate Evaluation of Photoperiodic Sensitivity and Genetic Diversity in Common Buckwheat under a Controlled Environment

Abstract

Photoperiodic sensitivity is one of the most important factors determining whether a crop can adapt to and be cultivated under a broad range of conditions. In common buckwheat (Fagopyrum esculentum Moench), flowering time (flowering of the first flower) is a complex trait influenced by photoperiod, light quality, and temperature, which change daily under natural conditions, and their interaction. Common buckwheat shows a large genetic variation because of the outcrossing reproductive strategy of this species. Thus, flowering time variation within a population reflects both environmental and genotypic variations, and accurate evaluation of photoperiodic sensitivity in common buckwheat requires cultivation under controlled environmental conditions. Here, we investigated photoperiodic sensitivity and its genetic diversity in two buckwheat cultivars, the autumn ecotype Miyazakizairai and the summer ecotype Botansoba, by controlling photoperiod during cultivation under the same temperature regime. Our results showed that (1) the summer ecotype consisted of early-flowering genotypes, including genotypes not found in the autumn ecotype; (2) the autumn ecotype consisted of various genotypes, including early-flowering genotypes and a large number of late-flowering genotypes not found in the summer ecotype; (3) the autumn ecotype showed larger genetic diversity than the summer ecotype in long-day treatments; and (4) genetic diversity first became evident in the 14.5-hr photoperiod in the autumn ecotype, and in the 15.0-hr photoperiod in the summer ecotype. These results support the hypothesis based on previous studies that common buckwheat summer ecotypes were derived from autumn ecotypes by adaptation to climate in northern Japan.     

施氮对高产大豆结实性垂直分布的影响

以亚有限结荚习性大豆吉育60为材料,在田间研究了4种不同施氮量(0、60、120、180 kg·hm-2)对单株荚数、粒数、腔数和结实率垂直分布的影响.结果表明:主茎各节的荚数、总荚腔数、粒数增幅因施氮量而异,适宜施氮量处理(120 kg·hm-2)15～19节的荚数、总荚腔数和粒数较不施氮对照增幅明显大于10～14节...     

Effects of Day Length and Air Temperature on Stem Growth and Flowering in Sesame

Abstract

The effects of day length and air temperature on the growth and flowering of sesame (Sesamum indicum L.) were examined to analyze the effect of seeding date on the seed yield. Short day (10-h light/14-h darkness) treatment decreased the final stem-length relative to natural day length (14.1～13.4-h), although it hardly affected the length of the stem-elongation period. The short-day treatment shortened the duration to the first flower and lowered the first flowering-node. It prolonged the flowering period, but decreased the flowering-node number on the main stem resulting from the slower rate of increase in nodes with flowers. Under a low day/night temperature condition (23/18ºC), the stem growth was very slow and flowering did not occur. As compared with a high temperature (30/23ºC), a low temperature (22/15ºC) during 15 days after emergence suppressed the seedling growth temporarily, but the seedlings resumed growth after the temperature treatment. The growth and flowering behavior after the treatment were unaffected by a low temperature during the seedling stage. On the other hand, a low temperature during the flowering period decreased the flowering-node number resulting from the slower rate of increase in nodes with flowers, although it prolonged the flowering period. In this study, the decrease in the flowering-node number by short days and low temperature was smaller than that by delay of seeding date as observed in our previous study. Thus, the effects of day length and air temperature were not the sole factors responsible for the effect of seeding date on the flowering-node number.     

Stem elongation in Pennisetum purpureum results from a fixed pattern of vegetative development potentially enhanced by the initiation of flowering

The characterization of stem elongation is of fundamental importance in C4 tropical grasses as it affects forage quality and determines optimal management practices. The objectives of this study were to analyse the determinants of stem elongation and leaf area production in shoots of Pennisetum purpureum cv. Napier (elephant grass) using unstressed isolated plants. Three experiments were conducted in Brazil during the spring, summer and autumn seasons. Regular measurements of leaf and pseudostem length were performed on the main and primary axes. Ten destructive measurements were also performed during each experiment to monitor apical meristem height, internode length and the number of initiated leaves. The onset of stem elongation occurred at the same vegetative stage (i.e., appearance of leaf 13) irrespective of the seasons and experiments. The first internode to elongate belonged to phytomer 8, and a constant lag of five phyllochrons was systematically observed between internode production and its rapid elongation period. Higher stem and internode elongation rates were observed during the reproductive phase (autumn) versus the vegetative phase (summer and spring group). Maximal internode length reached 8–10 cm in summer and spring and 20 cm in autumn, at approximately phytomers 12–13. A similar pattern was reported for all primary axes irrespective of the experiments, the position of the first internode to elongate descending regularly down the main axis. These results provide key elements to predict the onset of stem elongation in the field from simple measurements. They could contribute to improving crop models for perennial tropical C4 grasses.     

Flowering and fruit set dynamics at phloem-isolated nodes in soybean

The dynamics of flowering and pod set of soybean (Glycine max (L.) Merrill) was evaluated in two greenhouse experiments with a girdled node system. Plants (cv. Elgin 87) were grown in 3.0 l pots filled with a soil–vermiculite mixture (2:1, v/v) and the main stem below node seven (node one was node with unifolioliate leaves) (one-node treatment) or node five (three-node treatment) was girdled when the first flower opened at node seven. The main stem above node seven was removed as were the leaves at nodes five and six on the three-node treatment. Flower production, from daily counts of open flowers, followed a bi-modal distribution with the first cohort representing flowers on the main raceme while the second cohort contained flowers from sub-branches. Pods ≥10 mm long were marked with acrylic paint and the color was changed every 2 or 3 days to define at maturity when the surviving pods were initiated. The initiation of surviving pods followed the same pattern as flowers, and pods in the first cohort had nearly 100% survival while second cohort generally had survival rates <60%. Initial development of pods in the second cohort coincided with lower concentrations of stem sugars and a rapid increase in pods with ≥3 mm seeds. The three-node treatment had more flowers and pods in the first cohort and more pods at maturity. Utilization of large amounts of assimilate by rapidly growing early pods may contribute to the high levels of abortion of late developing flowers and pods. Thus, synchronous flowering may increase pod set by decreasing this competition between early and late developing pods.     

Differences in Flowering Habit between Determinate and Indeterminate Types of Soybean

Summary

The differences of flowering habit, yield and yield components between determinate (cultivar Tatisuzunari) and indeterminate (cultivar Touzan 69) soybean were examined in relation to raceme order. Although flowering habit, i.e., successive flowering from basal to apical nodes was the same in both types, the succession of flowering on low order racemes on the main stem increased more rapidly (1.4 nodes per day) in Tatisuzunari than in Touzan 69 (0.8 nodes per day). In Tatisuzunari flowering on a higher order raceme began after flowering of the first order raceme had finished, but in Touzan 69 flowering on the first order raceme continued upto higher nodes accompanied with flowering on higher order racemes thus producing a higher number of flowers. In Tatisuzunari, the flower shedding rate was higher, the higher was the raceme order, but in Touzan 69 the shedding rate was highest in the first and second order racemes. The pod setting ratio on all racemes was higher in Tatisuzunari than in Touzan 69. In Tatisuzunari, the 100 seed weight was similar on every raceme, although that on the second order racemes with compound leaves was slightly higher. In Touzan 69, it decreased with the increase of raceme order. The second order raceme with compound leaves played a pivotal role for the determination of total number of nodes, number of flowers, pod setting ratio, number of pods per plant and 100 seed weight in Tatisuzunari. However, in Touzan 69, racemes contributing to yield were limited to the first and second racemes. In Touzan 69, leaf length decreased drastically from basal to apical nodes, favoring the even distribution of light in the canopy, whereas, in Tatisuzunari, the leaf length increased from lower to higher nodes.     

Sowing date, harvest date and the yield of forage brassica crops

The effect of sowing date, within the period from late May to mid-August, on the DM yield of five leafy forage brassica crops sown to a stand was examined over the period 1976–78. Kale was the crop most sensitive to variation in sowing date and yields declined progressively with later sowings. There was no yield benefit from sowing rapes or stubble turnips earlier than mid- to late-June. Raphanobrassica produced yields as good as rape when sown in June. In 1978, DM yields of rape, kale and Raphanobrassica increased from September to early November, largely as a result of stem growth; kale was slower to accumulate DM than rape in late summer but continued growing longer into the autumn. The DM concentrations of all crops increased from September to December. Rape had a higher DM concentration than stubble turnip. Raphanobrassica was 10–25 g kg^-1 lower in DM concentration than rape or kale. Raphanobrassica produced 23–59% flowering plants from late-May to early-June sowing. Harvest date affected DM yield and concentration, leaf: stem ratio and flowering percentage. The effects of sowing dale on DM concentration were small.     

温度和结角部位对春油菜结籽率的影响

在春油菜开花期间,开花后第一天的日平均温度是影响结籽率的主要因素,其它日期的日平均温度以及日最高温度、日最低温度对结籽率的影响较小。春油菜主序的结籽率、每角饱粒数、总胚珠数极显著高于分枝。     

Performance of oat (Avena sativa L.) sown in late summer for autumn forage production in Central Europe

Spring‐sown oat (Avena sativa L.) is well adapted for forage production in Central Europe; however, environmental conditions make this crop susceptible to crown rust disease (Puccinia coronata) when grown in summer. The objective of this study was to assess oat cultivars sown in late summer, when conditions for crown rust are less favourable, and harvest in autumn for forage with potential use for feeding lactating dairy cows. Three oat cultivars: Berdysz, Zuch and ForagePlus, the first two from Poland and the latter from United States, were sown 1 and 15 August, and 1 September, over three consecutive years, and harvested for forage in late October. The two Polish cultivars had 61% leaf area affected by rust with 1 August sowing, but ForagePlus was not affected by rust with any sowing date. Sowing 15 August significantly reduced crown rust incidence and increased DM yield of the Polish cultivars 21% relative to the 1 August sowing date, but decreased ForagePlus DM yield by 35%. Sowing 1 September resulted in best forage nutritive value, but the lowest DM yields for all cultivars. Calculated milk production per ton of forage for all cultivars was lowest with the 1 August sowing date. Calculated milk production per hectare was greatest for Berdysz sown in mid‐August. Oat can be sown 15 August and harvested in autumn for forage production, avoiding crown rust disease during summer in Poland. Nutritive value of autumn oat forage is adequate to meet forage requirements of lactating dairy cows.     

Variability and regulation of the number of ovules, seeds and pods according to assimilate availability in winter oilseed rape (Brassica napus L.)

The number of pods per plant and the number of seeds per pod are the most variable yield components in winter oilseed rape (WOSR). Both the number of ovules per pod and the potential for the ovule to develop into a mature seed may depend on pod position in the plant architecture and time of appearance. The complex developmental pattern of WOSR makes it difficult to analyse. The objectives of this study were to investigate the variability of the following yield components (a) ovules/pod, (b) seeds/pod, and (c) pods/axis in relation to two explanatory variables. These two variables include (1) flower and inflorescence position and (2) time of pod appearance, linked to the effect of assimilate availability.Field experiments were conducted with the variety Mendel. Different trophic states were created by clipping the main stem or ramifications. The number and position of flowers that bloomed within the inflorescence were recorded based on observations every two to three days throughout the flowering season.On the control plants, for the main stem we observed that the number of ovules per pod decreased for a few ranks and then tended to increase and again to decrease at the end. On ramification R1 and R4, the number of ovules increased at first, and then remained constant with the pod rank. Furthermore, the number of ovules per pod remained constant along the inflorescence on the other ramifications and increased with ramifications from top to bottom. The number of seeds per pod did not vary with the pod rank at the basal positions on inflorescences and decreased afterwards along the inflorescence. The clipping of the main stem or ramifications increased the number of ovules per pod, seeds per pod and pods per axis. The number of ovules and seeds per pod did not vary with the time of pod appearance for the pods located at normalised rank 0.01-0.1. However, the number of ovules and seeds per pod can be impacted by the time of pod appearance on the plant scale. Thus, our results indicate that the amount of available assimilates was the primary determinant of pod and seed production during the flowering period. The distribution of resources was significantly affected by both the positions of pods within an inflorescence and the position of inflorescences within a plant.     

山东大豆品种主要农艺性状的演进

对50多年来山东省不同时期42个主要推广大豆品种的主要农艺性状的遗传演进进行了研究,结果发现,品种的结荚习性由无限结荚习性为主到以有限、亚有限结荚习性为主;生育日数均缩短5.6d;株高降低23.2%,其中上世纪50年代至60年代降低27.1%,60年代至80年代降低0.4%,80年代至90年代以后增加5.8%;主茎节数减少3.1个;节间长度缩短0.4cm～0.9cm;分枝数减少1.5个;单株荚数减少33.7%;单株粒数减少31.7%;百粒重增加37.9%;单株生产力平均增加13.9%;产量提高48.7%.在本试验条件下,研究认为,今后大豆育种要从提高单株生产力着手,适当增加株高,缩短节间长度,增加主茎节数,进而增加主茎荚数,以达到提高产量的目的.     

Changes during growth in the nutritive value of components of berseem clover (Trifolium alexandrinum L.) under different cutting treatments in a Mediterranean region

The nutritive value of berseem clover (Trifolium alexandrinum L.) may be influenced by changes in the nutrient concentrations of morphological fractions as a consequence of cutting treatment. The aim of this study was to evaluate the effects of different cutting treatments on the nutritive value of herbage and leaf and stem components in two Mediterranean berseem genotypes during growth in order to develop management approaches for harvesting forage with a high nutritive value. Spring growth of genotypes of Egyptian (cv. Giza 10) and Italian (cv. Sacromonte) origins was harvested in each of 2 years beginning 196 days after sowing and thereafter every 6 days (twelve harvests in total) to measure dry matter (DM) yield and nutritive value. Cutting treatments were initiated at sixth internode elongation (A) and early flowering (B) and there was an uncut control treatment (C). In vitro digestibility of organic matter (IVOMD) and crude protein (CP) concentration were determined for leaf, stem and total forage of each cultivar at each harvest. For both cultivars, in the uncut treatment (C), DM yield increased linearly to a maximum of 14 800 kg ha^?1, on average, by 250 days after planting, the same time at which stem DM accumulation peaked, whereas the nutritive value, in terms of IVOMD and CP concentration, declined with age, coinciding with a reduction in leaf:stem ratio (LSR) from 1·00 to 0·30. Plant parts differed (P < 0·01) in nutritive value with stems being of lower nutritive value than leaves, in the two cutting treatments. There were strong positive correlations between LSR and herbage IVOMD and CP concentration, in both cutting treatments, indicating that, during growth, part of the changes in IVOMD and CP concentration of berseem clover plants was due primarily to the changes in the LSR. Defoliation induced a considerable reduction in DM yield, but an increase in the LSR and a small increase in nutritive value. Plants cut at the sixth internode elongation (A) showed a small proportional decrease (0·19) in total DM yield, but higher LSR values and similar or higher IVOMD and CP concentration than initiating cutting at early flower (B). Delaying defoliation to the early flowering stage (B) increased the proportion of stems and, therefore, decreased nutritive value. Therefore, harvest management in which cuts are applied at the stage of sixth internode elongation appears to be the most favourable for obtaining relatively high yields of forage with high nutritive value in berseem clover grown in Mediterranean regions.     

植物生长调节剂和温度对蝴蝶兰双梗率、花期及花朵性状的影响

以蝴蝶兰品种‘富乐夕阳’（‘Fullers Sunset’）和‘双霞’（‘Shuang Xia’）为试验材料,研究不同植物生长调节剂和温度处理对其双梗率、花期和花朵性状的影响。结果表明：（1）6-BA对提高蝴蝶兰双梗率的效果要好于GA₃以及GA₃+6-BA,其中6-BA使用浓度为200 mg/L时,2个品种的双梗率都达到最佳,而且植株的花朵数最多;（2）GA₃可使2个品种均提前开花,在一定浓度范围内浓度越高开花时间越早,但使用GA₃同时会导致花期缩短和花朵畸形;（3）2个品种均在日/夜（18 ℃/18 ℃）处理时双梗率最高,且在一定温度范围内,温度越低萌发双梗的时间越早;（4）2个品种均在日/夜（18 ℃/18 ℃）处理时花期最长,在日/夜（25 ℃/18 ℃）处理时花朵数量最多及花朵直径最大。     

Genotypic and Environmental Variation of Lag Period of Pod Growth in Soybean

Abstract

Pod growth in soybean (Glycine max(L.) Merr.) begins several days after flower opening, compared with more immediate growth in other beans. We investigated the relationship between genotype, raceme order of pod set, assimilate supply or photoperiod and the length of lag period of pod growth (LP, days from flower opening to the time when pod length reaches 10 mm). Soybean (five cultivars) plants were grown in a greenhouse and in the field in 2001. The lengths of pods developed from 20 flowers which opened on the same day and set on the same raceme order, were measured every other day. The length of LP varied with the cultivar from 5 to 16 days and it was longer in late cultivars. The LP in the primary raceme (early flowers) was 15 days but that in the secondary raceme (late flowers) was 8 days. Both late sowing and short photoperiod (lOh) after the start of flowering shortened the LP by up to 7 days in Enrei and 5 days in Fukuyutaka. However, neither sink (except the target racemes) removal nor BA application to the target racemes at the start of flowering affected the length of LP, even though these treatments were expected to stimulate pod growth.     

Flowering and true seed production in potato (Solanum tuberosum L.). 2. Effects of stem density and pruning of lateral stems

Summary Field experiments were carried out to evaluate the effect of stem density and pruning of lateral stems on flowering and true seed production in potato (Solanum tuberosum L.). Increasing stem density reduced flowering, berry and seed production from every inflorescence in all cultivars. Increasing density increased the proportion of primary flowers in the total number of flowers per plant and reduced the proportion of flowers on lateral stems, but its effect on the quality of the seed production was small. Differences in total seed production were principally determined by differences in flowering. There was an interaction between stem density and cultivars for the number of flowers produced and on the yield of true seed per m². Pruning lateral stems enhanced flowering of the main stem and decreased the total number of flowers per plant, but it did not affect berry and seed production from main-stem inflorescences.     

大豆“短青春期”品种的光（温）反应研究：Ⅱ．对短日照的反应

在分析“短青春期”品种对播季反应的基础上，通过比较不同品种出苗至开花数与开花至成熟天数对短日处理的反应，以进一步明确夏大豆型“短青春期”品种的光（温）敏感性特征。研究结果表明：春播条件下，开花前短光照处理，“短青春期”品种中豆24和巨丰出苗至开花天数仅缩短2－14d，敏感度较小，与春大豆型品种相似，而与典型夏大豆品种，秋大豆品种和“长青春期”品种明显不同，中豆24和巨丰的出苗至开花天数对短光照不敏感。同为“短青春期”品种的中豆24和巨丰，其开花至成熟天数对短日处理的反应有明显差异，并者与春大豆相似，而后者的开花至成熟天数的短日照敏感不仅大于复大豆，而且也大于秋大豆。生育前期对短日照不敏感的品种，其短日处理效应在生育后期表现更加明显。本文还讨论了不同品种短日处理后效应的传递特征。     

Breaking Strength of Pedicel as an Index of Grain-Shattering Habit in Autotetraploid and Diploid Buckwheat (Fagopyrum esculentum Moench.) Cultivars

Abstract

The grain-shattering habit was compared among diploid and autotetraploid cultivars of common buckwheat (Fagopyrum esculentum Moench.). In the first experiment, one diploid and one autotetraploid cultivar were grown in the field, and the number of grains shed naturally by wind or rain, and the number of grains detached by threshing the plants (by dropping from 1 m height onto a concrete floor, five times) were measured to evaluate grain shattering. The number of the naturally shed grains in the field was higher in the diploid than in the autotetraploid cultivar, although the number of grains detached by threshing was not different between the two cultivars. In another set of experiments, breaking bending strength and breaking tensile strength of pedicels were measured as indices of grain-shattering habit to examine the difference in shattering among two autotetraploid and four diploid cultivars (two summer types and two autumn types). They were grown in summer and autumn seasons to examine the environmental effect on grain shattering. Both breaking strengths were about two times higher in the autotetraploid cultivars than in the diploid cultivars. The breaking strength was well correlated with the diameter of pedicels. The values of grain-shattering resistance traits obtained in the autumn cropping season were higher than those obtained in the summer cropping season.     

不同品系橡胶树的花序性状差异研究

以具有亲缘关系的橡胶树(Hevea brasiliensis Muell. Arg.)热研88-13、热试47、热试62为研究对象，对不同品系橡胶树开花侧枝上的花序和花序上的一级花序、雌花、一级雌花、二级雌花的数量和位置分布进行了调查和统计分析。结果表明：不同品系橡胶树间开花侧枝上花序、一级花序、雌花、一级雌花、二级雌花的数量和位置分布差异显著，不同品系橡胶树间花序上雌花、一级雌花和二级雌花的数量和位置分布差异显著；橡胶树开花侧枝上的花序数、雌花数、一级雌花数、二级雌花数之间相关性显著，花序上的雌花数，一级雌花数和二级雌花数之间相关性显著。可以将开花侧枝上的花序数和/或花序上的雌花数作为品种识别的指标之一，将花序上的一级花序数、一级雌花数和二级雌花数作为品种识别的辅助指标。     

Does the “high sugar” trait of perennial ryegrass cultivars express under temperate climate conditions?

The objective was to evaluate water‐soluble carbohydrate (WSC) and crude protein (CP) concentration of perennial ryegrass (PRG) cultivars with different genetic potential for producing WSC under two contrasting agronomic managements in temperate climate (southern Chile). A 4 × 2 factorial design was randomly allocated to 24 plots (31 m² each, three blocks): four PRG cultivars (diploid standard cultivar, “2nSt”; tetraploid standard cultivar, “4nSt”; diploid high sugar cultivar developed in New Zealand, “2nHSNZ”; and tetraploid high sugar cultivar developed in Europe, “4nHSEU”) and two agronomic managements (“favourable,” defoliations at three leaves per tiller and nitrogen (N) fertilization rate of 83.3 kg N ha^?1 year^?1; “unfavourable,” defoliations at two leaves per tiller and N fertilization rate of 250 kg N ha^?1 year^?1). Herbage samples were collected in early spring, spring, summer and autumn. Concentration of WSC did not differ among cultivars in spring and summer, averaging 194 and 251 g/kg DM, respectively. The cultivar 4nHSEU had the greatest WSC concentration in early spring and autumn (187 and 266 g/kg DM, respectively) and the greatest CP concentration across samplings (average 230 g/kg DM). Favourable management improved WSC concentrations in early spring and summer and decreased CP in spring, summer and autumn. Annual DM yield did not vary with cultivar or management, averaging 8.43 t/ha. Within a 12‐month study at one site in a temperate environment in southern Chile, PRG cultivars have not shown a consistent expression of the “high sugar” trait, where a genetic × environment interaction might be operating.     

Effect of plant density on the inflorescence production of stems and the distribution of flower production in potato

Summary A knowledge of the pattern of flowering and seed production is required for the development of large-scale field production of True Potato Seed (TPS). At the highland experimental station of the International Potato Center in Peru, data on flowering and seed production were collected from three cultivars planted at three densities. Main stems in which flowering was delayed ceased shoot growth at an earlier stage and produced fewer inflorescences. Inflorescences produced later had fewer flowers, a lower berry set and yielded less seed. Inflorescences flowering at the same time performed similarly, irrespective of their position on the plant. Increasing plant density resulted in cessation of shoot growth at an earlier stage and concentrated inflorescence and flower production at primary positions of early-flowering shoots. With cvs Renacimiento and Yungay a higher plant density increased the percentage of flowers produced in the first three weeks of the flowering period, but with cv. Atzimba the effect of plant density on the distribution of flower production was off-set by a slower stem development.