Quantitative trait locus analysis of multiple agronomic traits in the model legume Lotus japonicus.

The first quantitative trait locus (QTL) analysis of multiple agronomic traits in the model legume Lotus japonicus was performed with a population of recombinant inbred lines derived from Miyakojima MG-20 x Gifu B-129. Thirteen agronomic traits were evaluated in 2004 and 2005: traits of vegetative parts (plant height, stem thickness, leaf length, leaf width, plant regrowth, plant shape, and stem color), flowering traits (flowering time and degree), and pod and seed traits (pod length, pod width, seeds per pod, and seed mass). A total of 40 QTLs were detected that explained 5%-69% of total variation. The QTL that explained the most variation was that for stem color, which was detected in the same region of chromosome 2 in both years. Some QTLs were colocated, especially those for pod and seed traits. Seed mass QTLs were located at 5 locations that mapped to the corresponding genomic positions of equivalent QTLs in soybean, pea, chickpea, and mung bean. This study provides fundamental information for breeding of agronomically important legume crops.     

Improvement of Biomass Partitioning, Flowering and Yield by Triadimefon in UV-B Stressed Vigna radiata (L.) Wilczek

Elevated UV-B radiation (12.2 kJ m^–2 d^–1) as against the ambient level of 10 kJ m^–2 d^–1 affected flowering, productivity and biomass partitioning of green gram [Vigna radiata (L.) Wilczek cv. KM-2]. UV-B stress delayed flowering initiation and achievement of 50 % flowering, reduced flower retention by 25 %, potential yield by 18 % and all yield attributes such as pod number (25 %), pod mass (41 %), seed number (32 %) and seed mass (45 %). Harvest index and shelling percentage were also reduced by 31 and 7 %, respectively. Application of triadimefon (20 mg dm^–3) to unstressed plants accelerated flowering and enhanced flower retention (21 %), potential yield (15 %) and yield attributes (7 to 44 %). The partitioning of biomass between plant parts also showed improvement over the control plants. In UV-B-stressed plants, triadimefon treatment compensated the inhibitions to varying extents.     

Carbon Transfer and Partitioning between Vegetative and Reproductive Organs in Pisum sativum L

Assimilate partitioning was studied in the common pea (Pisum sativum L.) by feeding ¹⁴CO₂ to whole plants and measuring radioactivity in different organs 48 hours after labeling. Two experimental protocols were used. For the first, one reproductive node was darkened with an aluminum foil, to prevent photosynthesis during labeling. The aim was to study assimilate translocation among nodes. The second was carried out to assess any priority among sinks. Whole plants were shaded, during labeling, to reduce carbon assimilation. Various developmental stages between the onset of flowering and the final stage in seed abortion of the last pod were chosen for labeling. When all photosynthetic structures at the first reproductive node were darkened at any stage of development after the formation of the first flower, the first pod was supplied with assimilates from other nodes. In contrast, later developed pods, when photosynthetic structures at their node were darkened, received assimilates from other nodes only when they were beyond their final stage in seed abortion. Reducing illumination to 30% did not change distribution of assimilated carbon between vegetative and reproductive structures, nor among pods. It appears that the relative proportion of ¹⁴C allocated to any one pod, compared to other pods, depends on the dry weight of that pod as a proportion of the total reproductive dry weight. When the plant was growing actively, following the start of the reproductive phase until a few days before the end of flowering, the top of the plant (i.e., all the organs above the last opened flower) had a higher sink strength and a higher relative specific activity than pods, suggesting that it was a more competitive sink for assimilates. The pattern of assimilate distribution described here provides an explanation for pod and seed abortion.     

Factors affecting pollinator movement and plant fitness in a specialized pollination system

The rate of pollen exchange within and among flowers may depend on pollinator attraction traits such as floral display size and flowering plant density. Variations in these traits may influence pollinator movements, pollen receipt, and seed number. To assess how floral display size and flowering plant density affect parameters of pollinator visitation rate, pollen receipt per flower, seed number per fruit and the between-plant pollinator movements, we studied the self-incompatible plant, Nierembergia linariifolia. Per-flower pollinator visitation rate and bout length increased linearly with increasing floral display size. Pollen receipt per flower increased linearly with increasing flowering plant density. For seed number per fruit, a polynomial model describing an increased seed number per fruit at low density and a decreased seed number per fruit at high density provided a significant fit. Per-flower pollinator visitation rate was not associated with pollen receipt per flower and seed number per fruit. Bees visited plants located near to the center of the population more frequently than plants located at the periphery. Increases in both floral display size and flowering plant density led to an increased chance of a plant being chosen as the center of the pollinator foraging area. These results suggest that even though large floral displays and high flowering plant density are traits that attract more pollinators, they may also reduce potential mate diversity by restricting pollen movement to conspecific mates that are closely located.     

Some effects of environmental stress on seed yield of cowpea (Vigna unguiculata (L.) walp.) cv. Prima

Summary Separate experiments examined nodulation and seed yield of cowpea cv. Prima after (a) changes in the level of combined nitrogen from 25 to 0 or 60 ppm N, (b) cycles of wilting and rehydration, and (c) shading to ca 50% full daylight. Plants were grown in the simulated tropical environment of a plastics bubble house and experienced these changes over the growth stages: emergence to first flower, first flower to mid pod-fill or mid pod-fill to maturity.Seed yields of nodulated plants were unaffected by combined nitrogen supply and almost double those of non-nodulated plants (100 g cf 56 g per plant)-due mainly to increases in pod number per plant and mean seed weight. Reducing the nitrogen level from 25 to 0 ppm N, especially between mid pod-fill and maturity, reduced seed yields of non-nodulated plants to 36 g per plant. At the first flowering stage, plants grown without combined nitrogen had nitrogenase activities less than 10% of those supplied with 25 ppm N; 60 ppm N at any stage of development more than halved nitrogenase activity when compared with plants supplied with 25 ppm.Repeated wilting prior to flowering markedly reduced seed yields compared with the unstressed controls (41 g cf 76 g per plant)-mainly by decreasing subsequent pod production. Nodule weight and nitrogenase activity per plant were also much reduced. Wilting after flowering did not reduce yield, and nitrogenase activity was less affected.Shading throughout, or from first flower onwards, reduced seed yield by about 25% because fewer pods were produced. All shading treatments significantly increased mean seed weight compared with unshaded controls (116–121 mg cf 105 mg).One of a series of papers describing work undertaken in a collaborative project with the International Institute of Tropical Agriculture, Nigeria, sponsored by the U.K. Ministry of Overseas Development.Soil Microbiology Department, Rothamsted Experimental Station, Harpenden, Herts.Soil Microbiology Department, Rothamsted Experimental Station, Harpenden, Herts.     

Comparisons of Earlier- and Later-formed Pods of Chickpeas (Cicer arietinum L.)

In chickpeas (Cicer arietinum L.) flowering and pod developmentproceed acropetally. In plants grown under normal field conditionsat Hyderabad, in peninsular India, and at Hissar in north India,at successively apical nodes of the branches there was a declinein pod number per node, weight per pod, seed number per podand/or weight per seed. The percentage of nitrogen in the seedswas the same in earlier and later-formed pods at Hyderabad;at Hissar the later-formed seeds contained a higher percentage.Earlier- and later-formed flowers contained similar numbersof ovules. The decline in seed number and/or weight per seedin the later-formed pods of 28 out of 29 cultivars indicatedthat pod-filling was limited by the supply of assimilates orother nutrients. By contrast, in one exceptionally small-seededcultivar there was no decline in the number or weight of seedsin later-formed pods, indicating that yield was limited by ‘sink’size. Cicer arietinum L., chickpea, flowering, pod development, seed number, seed weight, nitrogen content     

In vitro culture provides additional variation for pigeonpea

Summary The present study is an attempt to exploit somaclonal variation for the varietal improvement of pigeonpea [Cajanus cajan (L) Millsp.]. The pigeonpea plants were regenerated from cotyledon explants, and their progeny was screened for variability. The regenerated R1 plants exhibited a spectrum of alterations in floral morphology and architecture that were absent in the control population. The field-sown R2 plants segregated for traits such as flower color, leaf shape, seed size, color and strophiolation, flowering habit, and fertility. Tissue culture produced different mutational events resulting in both dominant and recessive alleles. Significant variation was observed for plant height, seed mass, and damage due to the insect pest Helicoverpa armigera. The R3 plants, obtained from seed of R2 generation selected for traits such as white seed coat, strophiolation, reduced plant height, seed mass and low damage due to Helicoverpa, maintained the traits when compared with the seed-derived control populations. The results indicate a definite gene for white seed coat and the possibility of additional genes for pest tolerance and high seed mass in an adapted background. Submitted as Journal Article No. 1906 by International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).     

Improvement of Early Maturing and Climate Resilient Chickpea (<i>Cicer arietinum</i> L.) Cultivars Suitable for Multiple Environments in Bangladesh

Ensuring food security for the rapidly increasing population and changing climatic scenarios are requisites for exploiting the genetic divergence of food crops. A study was undertaken to sort out an early maturing chickpea variety for fitting easily between rice-rice cropping systems in the Eastern Indo-Gangetic Plain of Bangladesh. The trial was comprised of eight elite lines of chickpea and executed at various localities in Bangladesh from 2014– 15 to 2017–18. The result explored the chickpea genotype, BARI Chola-11 remained superior to the rest of the elite genotypes for having a short maturity period (100–106 days), and lesser days to 50% flowering (47– 55 days). The same genotype was recorded to have robust vegetative and reproductive yield attributes including plant height (49–57 cm), podsplant⁻¹ (37–50), and optimum 100 seed weight (19.5–20.6 g). Owing to better yield attributes, BARI Chola-11 resulted in the maximum seed yield (1200–1500 kg ha⁻¹ ) of chickpea and might be recommended for general adoption in the region for boosting nutritional security status through improved productivity under changing climate.     

Factors affecting fruit and seed production of Paeonia ostii “Feng Dan”, an economically important oil tree

Many factors may affect reproduction of animal-pollinated species. In this study, the effects of pollen limitation, attractive traits (flower number, plant height and flower width) and flowering phenological traits (flowering onset, duration and synchrony) on female reproduction, as well as the patterns of variation in fruit and seed production within plants, were investigated in Paeonia ostii “Feng Dan” over two flowering seasons (2018 and 2019). Fruit set was very high (90%), and pollen supplementation did not increase fruit and seed production in either year, indicating no pollen limitation. Fruit set, ovule number per fruit and mean individual seed weight per fruit were not affected by any of the six attractive and phenological traits in either year, whereas seed number per fruit was related to the three attractive traits in one or both years. Seed number per plant was positively affected by the three attractive traits and best explained by flower number in both years, but the effect of each of the three phenological traits on seed number per plant differed between years. Within plants, the fruit set, ovule number, seed set and seed number per fruit declined from early- to late-opening flowers, presumably because of resource preemption, but the mean individual seed weight did not vary across the flowering sequence. Our study shows that attractive traits of Paeonia ostii “Feng Dan” are more important than flowering phenological traits in the prediction of total seed production per plant.     

Consequences of variation in flowering phenology for seed head herbivory and reproductive success in Erigeron glaucus (Compositae)

Summary We examined the relationship between flowering phenology, reproductive success (seed production only), and seed head herbivory for 20 similarly sized clones of Erigeron glaucus growing at Bodega Bay Reserve, northern California, USA. Although clones tended to reach peak flowering on the same date, they differed in the proportion of their total flowers produced around that date (flowering synchrony). Clones also differed in the number and density of flower heads presented at any one time to pollinators and herbivores (floral display). Both of these characteristics had consequences for herbivory and plant reproductive success. The proportion of flower heads damaged by insect herbivores was greater for clones that concentrated flowering activity during the main flowering period for the population as a whole (high synchrony) compared to clones that spread flowering out temporally. The primary reason for this result was that clones with low flowering synchrony produced a significant proportion of their flower heads during the fall and therefore, escaped attack by the tephritid fly, Tephritis ovatipennis. Clones with intermediate synchrony had lower seed success (total number of viable seeds produced over the year) than clones with either low or high synchrony. The proportion of flower heads damaged by insect herbivores and number of tephritid flies reared from flower heads were both negatively correlated to floral display while seed head mass and germination rates were positively related to display. Thus, clones which produced dense floral displays were favored both in terms of reduced herbivory and increased successful seed production.     

Flowering phenology of Campanula on Mt Olynipos, Greece

We studied the fowering phenology of the genus Campanula (represented by nine species) along the elevation gradient of Mt Olympos (Greece) in order to assess whether there are elevation patterns at the genus level and whether these relate to patterns previously observed along such gradients at the community level. The traits examined were time and duration of the flowering period, flower life span, and duration of male and female flower phases. Floral attributes, such as number of flowers per plant, flower biomass, flower size, were also studied in order to examine whether they change with elevation or influence flower phenology. Flowering of Campanula species started in mid-May and ended in late September. The average duration of flowering of the genus was ca 27 d and the average floral longevity 4 d. In all but one species, the female phase lasted longer than the male. Campanula versicolor differed remarkably from all others in flower phenology and other floral trails. Nearly all Campanula populations studied had right or positively skewed flowering distributions indicating that flowering begins more abruptly than it ends. At the genus level, the time of flowering increased with elevation by 2 3d for every 100 m. Floral longevity also increased with elevation, by 0,2 d for every 100 m. Neither duration of flowering nor duration of the flower phases showed any consistent change with elevation. The same is true of the non–phenological floral traits examined. No trade–off between duration of flowering and flower life span or between structure and maintenance of flowers was apparent. The pattern of increasing floral longevity along the elevation gradient suggests a mechanism of compensation for reduecd pollinator availability.     

Genotypic variability in physiological,biomass and yield response to drought stress?in pigeonpea

Three pigeonpea (Cajanus cajan L. Millsp.) genotypes- GT-1, AKP-1 and PRG-158 with varying crop duration, growth habit and flowering pattern were evaluated for variability in their response for drought stress. Drought stress was imposed at initiation of flowering and the observations on biomass and seed yield parameters were recorded at harvest. The magnitude of response of individual component to drought stress was found to be genotype specific. Drought stress significantly decreased photosynthetic rate (P_N), transpiration rate (Tr) and relative water content (RWC) in all the genotypes, however the magnitude of reduction differed with genotype. With drought stress, the reduction of P_N was highest in GT-1 while reduction in Tr was highest in PRG-158. The genotype AKP-1, accumulated significantly higher concentrations of osmotic solutes especially proline under water deficit stress, this facilitated it to maintain higher relative water content (RWC) and lower malondialdehyde (MDA) content as compared to other genotypes. Drought stress also impacted biomass production and their partitioning to vegetative and reproductive components at harvest. There was significant variability between the genotypes for seed yield under drought stress while it was non-significant under well-watered condition. Drought stress enhanced flower drop and decreased flower to pod conversion resulting in reduced pod number and seed number in PRG-158 and GT-1. The genotype AKP-1 recorded superior performance for seed yield under stress environment due to its ability in maintaining pod and seed number as well as improved test weight (100 seed weight). Under drought stress, significant positive association of seed yield with proline, seed number, pod number and test weight clearly indicating their role in drought tolerance.     

Influence of photosynthetic restriction due to defoliation at flowering on seed abortion in lucerne (Medicago sativa L.)

The seed yield of lucerne is poor, in contrast to its good vegetativegrowth. This is partly due to a lack of pollination under naturalconditions, pod abortion and the production of only a few seedsper pod. In this study, lucerne plants were grown in controlledconditions and about 30% of the inflorescences were pollinatedmanually. There were about 10 ovules per flower, which remainedconstant throughout the flowering period. There were 4.5 seedsper pod, indicating over 50% seed abortion. One group of plantswas defoliated and the lack of recent assimilates at floweringcaused a small but significant decrease in the number of seedsper pod (4.1). The effect of defoliation varied with seed age;the youngest fertile inflorescences were the most affected andthere was no effect at around 400C d^–1 . This stage markedthe end of the lag phase, which was determined separately incontrol plants. Thus, it is assumed that this date is the abortionlimiting stage (ALS) for this species. The long lag phase forlucerne could be a key influence on seed yield. The longer theALS, the greater the risk of vegetative competition, thus reducingreproductive development. Key words: Lucerne, flowering, pollination, abortion limiting stage (ALS), seed production     

Variation in the Agronomic and Morphological Traits of Iranian Chickpea Accessions

Landraces of chickpea (Cicer arietinum L.) in Iran have not been adequately characterized for their agronomic and morphological traits. Such characterization would be helpful in the development of improved cultivars, so in this study 362 chickpea accessions, collected from the major chickpea growing areas of Iran, were evaluated to determine their phenotypic diversity. High coefficients of variation (CVs)were recorded in pods/branch, seeds/pod, yield/plant, seeds/plant, pods/plant and branches/plant. Using principal component (PC) analysis, the first four PCs with eigenvalues more than 1 contributed 84.10% of the variability among accessions, whereas PC5 to PC10 were less than unity. PC1 was positively related to days to first maturity, days to 50% flowering and days to 50% maturity. The characters with the greatest weight on PC2 were seeds/plant and yield/plant, whereas PC3 was mainly related to pods/plant, seeds/pod and 100-seed weight, and PC4 was positively related to pods/branch and negatively to branches/plant. The germplasm was grouped into four clusters using cluster analysis. Each cluster had some specific characteristics of its own and the cluster I was clearly separated from clusters Ⅱ, Ⅲ and Ⅳ. These accessions are an important resource for the establishment of a core collection of chickpeas in the world.     

两种互逆资源梯度影响下刺叶锦鸡儿的种子选择性败育格局

种子的选择性败育在被子植物中普遍存在,开展结籽格局及其影响因素的研究有助于深入了解种子的形成机制及多样化的生殖对策。以刺叶锦鸡儿Caragana acanthophylla为材料,通过传粉过程、胚珠发育动态和资源分配状况的研究,以探讨种子的选择性败育格局及相关影响因素。结果显示：(1)刺叶锦鸡儿具高度自交不亲和性,为泛化的传粉系统,蜂类是主要的传粉者。自然状态的结实率为(86.00±4.96)%,不存在传粉限制,但受精具明显的时间效应。(2)刺叶锦鸡儿单花期4—5d,每朵花有(14.00±0.14)粒胚珠。胚珠的发育从荚果顶部开始,其中,开花后第3天荚果顶部胚珠开始膨大;第11天绝大多数胚珠出现了膨大,此时,在荚果基部的胚珠开始败育,随后荚果顶端受精后的胚珠也出现败育,最终仅荚果中部形成2—3粒种子。其结籽格局为成熟荚果中部胚珠,而败育荚果顶部和基部胚珠的选择性败育类型。(3)受微地形影响,居群内开花植株具斑块分布,对较少开花植株通过添加水肥进行资源调控后,结籽率显著提高,说明在种子形成过程中存在资源限制。综上所述,受精顺序和资源限制两个互逆的资源梯度决定了刺叶锦鸡儿的结籽格局。其中,...     

北黄花菜的开花物候及传粉特性研究

北黄花菜是百合科萱草属的优秀观赏植物材料,也是进行品种创新的极有价值的野生种质资源。该研究对野生环境中北黄花菜的开花物候与传粉特性进行了连续三年的追踪观测,探讨其开花进程和传粉机制。结果表明:(1)北黄花菜种群的开花物候只有1个高峰期;种群始花时间为5月末,盛花期为6月中旬,开花时间在30 d以上,单株花期为6～12 d;开花同步性指数(Si)分别为0.36、0.27和0.21,种群内个体开花时间重叠程度较低。(2)北黄花菜的开花数量与坐果数呈显著正相关(P<0.05),坐果数与单株花期长度呈极显著正相关(P<0.01),单株花期长度与始花时间呈显著负相关(P<0.05),表明北黄花菜开花数量越多,其坐果数越高。(3)北黄花菜的访花昆虫分属于4目10科共10种;各访花昆虫的访花时间和行为区别较大;主要的传粉昆虫有4种,其活动范围大,活动特点与北黄花菜午后开放的规律相匹配,能保证传粉效果;部分访花昆虫虽然活动范围小,但可以帮助植物进行自花授粉;两类访花昆虫的共同作用,使得北黄花菜的自然结实得到较大保障。上述结果可为北黄花菜的引种栽培和资源创新发挥实际作用。     

Effects of patch size and density on flower visitation and seed set of wild plants: a pan-European approach

1.  Habitat fragmentation can affect pollinator and plant population structure in terms of species composition, abundance, area covered and density of flowering plants. This, in turn, may affect pollinator visitation frequency, pollen deposition, seed set and plant fitness.
2.  A reduction in the quantity of flower visits can be coupled with a reduction in the quality of pollination service and hence the plants' overall reproductive success and long-term survival. Understanding the relationship between plant population size and/or isolation and pollination limitation is of fundamental importance for plant conservation.
3.  We examined flower visitation and seed set of 10 different plant species from five European countries to investigate the general effects of plant populations size and density, both within (patch level) and between populations (population level), on seed set and pollination limitation.
4.  We found evidence that the effects of area and density of flowering plant assemblages were generally more pronounced at the patch level than at the population level. We also found that patch and population level together influenced flower visitation and seed set, and the latter increased with increasing patch area and density, but this effect was only apparent in small populations.
5.   Synthesis. By using an extensive pan-European data set on flower visitation and seed set we have identified a general pattern in the interplay between the attractiveness of flowering plant patches for pollinators and density dependence of flower visitation, and also a strong plant species-specific response to habitat fragmentation effects. This can guide efforts to conserve plant–pollinator interactions, ecosystem functioning and plant fitness in fragmented habitats.     

Changes in polyamine pattern are involved in floral initiation and development in Polianthes tuberosa

In the day-neutral plant Polianthes tuberosa (cv. Double) putrescine and spermine in corms at the early floral initiation stage decreased by 26 and 36%, respectively, compared with that in the vegetative stage. In contrast, a sharp increase in spermidine and cadaverine titers in corms was recorded at the early floral initiation stage. However, cadaverine in corms disappeared at the flower development stage. Polyamines in the roots were generally lower than those in the leaves and corms. In no case was the change in endogenous polyamine titers in the roots and leaves associated with floral initiation and flower development in P. tuberosa. Exogenous application of spermidine at 5, 25 or 150 microg per plant at the vegetative stage did not affect flower primordium counts. However, addition of a spermidine synthase inhibitor, cyclohexylamine, at 150 or 250 microg per plant (each dose was applied two times in total at an interval of 4 days) significantly reduced flower primordium counts, indicating that spermidine is involved in floral initiation and floral development in P. tuberosa. In P. tuberosa corms at the vegetative stage arginine decarboxylase activity rises and decreases at the early floral initiation stage. In contrast, ornithine decarboxylase activity reaches the highest level at the early floral initiation stage and declines significantly at the vegetative stage. Results indicate that an increase in spermidine and a transient increase in cadaverine titers in the corms seem characteristic of early floral initiation in P. tuberosa. It is also suggested that a significant reduction in putrescine and spermine in the corms is involved in the early floral initiation in P. tuberosa.     

Divergence in drought‐response traits between sympatric species of Mimulus

Differential adaptation to local environmental conditions is thought to be an important driver of speciation. Plants, whose sedentary lifestyle necessitates fine‐tuned adaptation to edaphic conditions such as water availability, are often distributed based on these conditions. Populations occupying water‐limited habitats may employ a variety of strategies, involving numerous phenotypes, to prevent and withstand desiccation. In sympatry, two closely related Mimulus species—M. guttatus and M. nasutus—occupy distinct microhabitats that differ in seasonal water availability. In a common garden experiment, we characterized natural variation within and between sympatric M. guttatus and M. nasutus in the ability to successfully set seed under well‐watered and drought conditions. We also measured key phenotypes for drought adaptation, including developmental timing, plant size, flower size, and stomatal density. Consistent with their microhabitat associations in nature, M. nasutus set seed much more successfully than M. guttatus under water‐limited conditions. This divergence in reproductive output under drought was due to differences in mortality after the onset of flowering, with M. nasutus surviving at a much higher rate than M. guttatus. Higher seed set in M. nasutus was mediated, at least in part, by a plastic increase in the rate of late‐stage development (i.e., fruit maturation), consistent with the ability of this species to inhabit more ephemeral habitats in the field. Our results suggest adaptation to water availability may be an important factor in species maintenance of these Mimulus taxa in sympatry.