Longer Flowering Duration Research Articles

Effects of short- and long-term experimental warming on plant–pollinator interactions and floral rewards in the Low Arctic

Plant phenological and growth responses to experimental warming are widely documented, but less is known about warming effects on plant–pollinator interactions. We investigated the effects of short- and long-term passive warming on flowering phenology, insect visitation, fruit production, and floral rewards in the Low Arctic in northern Alaska. To better understand the role of insect visitors in plant reproductive success, we quantified pollen loads on floral visitors and tested for pollen limitation in four species. Long-term warming advanced flowering onset in evergreen shrubs and forbs. Warming, in general, increased the duration of flowering for forbs, evergreen shrubs, and deciduous shrubs. Considering all growth forms together, long-term warming increased floral density. This pattern was primarily driven by deciduous and evergreen shrubs. Dipterans accounted for more visits than Hymenopterans, although Hymenopterans had higher pollen loads. Insect exclusion and warming decreased fruit set in the forb, Bistorta officinalis Delarbre. Nectar volume in the deciduous shrub, Vaccinium uliginosum, was higher in the warmed plots than the control, but nectar quality did not differ. Advanced flowering onset, longer flowering duration, and increased flower density and nectar volume may have important implications for the pollinator community, warranting further research on long-term warming effects on tundra ecosystems.

Evaluation of genetic variability in fragrant rose (Rosa × hybrida L.) cultivars under open field cultivations

Twenty six rose (Rosa × hybrida L.) cultivars grown for open field conditions were characterized using 16 vegetative and floral traits to obtain information on the nature and magnitude of existing genetic variability. The cultivars, Night Time, Christian Dior and Pusa Abhishek were early in flowering and Local Collection 3, Local Collection 4, Kashmir Velvet and Edouard had longer flowering duration; Christian Dior and Bonne Nuit had bigger flowers; Pusa Bahadur had long flower stalk; Local Collection 3, Local Collection 4, Edouard and Kashmir Velvet were having more number of flowers per plant and Pusa Bahadur, Night Time and Christian Dior were found with higher flower weight and shall help in further selection and hybridisation. The higher genotypic and phenotypic coefficients of variation were recorded for plant height, plant spread (E-W), plant spread (N-S), stem girth, number of shoots/ plant, number of petals/ flower, flower stalk length, number of flowers/ plant and 100-flower weight, indicating that genotypic variation contributed markedly towards total variability for the above traits. There is a greater scope for selection in improving flower yield. The high heritability with high expected genetic advance over mean (GAM) was observed for plant height, plant spread (E-W), plant spread (N-S), stem girth, number of shoots/ plant, flower bud length, flower diameter and flower stalk length. This also revealed the lesser influence of environment on these traits. Therefore, simple selection based on phenotypic values for these traits could be useful in their improvement for achieving higher flower yield. The trait specification identified genotypes could ideally be used as donor parents in rose breeding programme to develop desired genotypes for open field cultivation.

Graft success, growth, and early flowering onset, as affected by grafting time in topworked tea plants

ABSTRACTTopworking method of grafting has immense practical applications in reducing the excessive time consumption in conventional breeding programs in tea (Camellia sinensis (L.) O. Kuntze). Hence, the present study was designed to know the influence of grafting time on growth and flowering in topworked scions. Scions from the clone TRF-4 were used for topworking on the field-grown plants of the clone UPASI-9. Topworking was performed during winter (January), pre-monsoon (May), and post-monsoon (September) seasons. The graft success rate was assessed 1 month after grafting. Twelve months after grafting, vigor of the topworked scions was evaluated by measuring length, number, and diameter of branches. Further assessments were carried out on the onset of flowering, length of the flowering period, and the number of flowers per scion during the flowering season. The results showed that the graft success rate, growth, and early onset of flowering were higher when topworking was done in May and September rather than in January. However, the flowering duration and number of flowers were significantly lower in the scions grafted in September. Therefore, topworking of suitable scions in May seems to be appropriate for attaining improved graft survival rate, early flowering onset, a higher number of flowers, and longer flowering duration in tea.

Impact of flowering duration in linseed (Linum usitatissimum L.) resistance to the bud flies (Dasyneura lini Barnes) in Central Uttar Pradesh

A field experiment conducted for screened 288 elite gen pool of linseed against bud fly infestation at Kanpur, India during rabi 2011-12 and 2012-13. The flowering duration showed significant positive relationship (r=0.9278 and 0.9368) with bud infestation. The maximum flowering duration 32.80 and 31.44 days was recorded on variety A-44 with highest bud infestation of 62.29 and 69.99 percent during respective years against variety C-C-1-2 which had a shortest flowering duration of 8.80 and 12.94 days with the minimum 16.38 and 14.30 percent bud fly infestation. Categorization on the basis of flowering duration and damage caused by the bud fly, were found, flowering duration range (11.80- 18.30) and (12.94-21.44), number of entries 11 and 8 were resistant, (0-10 %), flowering duration range (11.80-20.80) and (11.44-25.94), number of entries, 164 and 146 moderately resistant, (10 to 25%), flowering duration range (12.80-30.80) and (11.44- 28.94), number of entries 98 and 116 moderately susceptible, (25 to 50%), flowering duration range (24.80-33.30) and (21.94-32.44), number of entries 15 and 18 susceptible, (50 to 75%), none of the varieties found highly susceptible (more than 75%) to be bud fly attack during 2011-12 and 2012-13, respectively. The variety having longer flowering duration was severely infested by bud fly as compared to those with shorter flowering duration.

Short-term changes in plant functional traits and understory functional diversity after logging of different intensities: a temperate fir-beech forest experiment

The concept of plant functional traits has been demonstrated to be very effective in unravelling the ecological mechanisms governing plant community response to disturbance, especially when research is focused on short-term post-disturbance vegetation dynamics. In this study, we established an experiment to quantify how logging intensity affects the trait composition and functional diversity of understory communities in fir-beech forests in the Dinaric Mountains in Slovenia. Three different silvicultural treatments were implemented: control (no logging), 50% of the growing stock removed and 100% of the growing stock removed. Vegetation surveys of vascular plants were made before (in 2012) and two years after (in 2014) logging. Changes in species traits, C-S-R plant strategies (sensu Grime) and community-level functional diversity were analysed. The importance of traits such as small and light diaspores, short life span and anemochory increased with logging intensity. Moreover, species with the ability of both sexual and vegetative reproduction, longer flowering duration and overwintering green leaves increased in abundance after logging. C-S-R strategies mainly shifted from stress-tolerators in pre-logging conditions towards a more ruderal component in post-logging stands. Logging in the short term increased functional diversity, mainly due to newly colonized species being functionally dissimilar from persistent residents. Results suggest that logging intensity strongly influences the magnitude of change in both functional composition and diversity, which also has important implications for biodiversity conservation. At the landscape scale, increasing spatial heterogeneity by creating a mosaic of forest stands subjected to different logging intensities will likely contribute to the enhancement of plant functional diversity.

Trait identification of faba bean ideotypes for Northern European environments

Abstract European pulse production faces a continued loss of cultivated area along with decreasing or stagnant yields. Vicia faba is a traditional legume with high genetic diversity cultivated in a wide range of European climates. Therefore V. faba is promising to identify stable and high yielding genotypes for specific target environments. The Nordic-Baltic region is challenging for legume growing due to short vegetation period and heat/drought stress in continental climates. Within the pan-European Eurolegume project a set of 18 V. faba accessions containing var. minor and major local landraces and modern cultivars of different geographical origin was evaluated in multi-environmental trials. The aim of this study was to identify ideotypes for Northern Europe and reveal key phenotypic traits conferring high yield potential and stability. Four target environmental clusters represented the range of Nordic growing conditions with yield levels from 128 g m−2 to 380 g m−2. Multivariate classification differentiated distinctive groups of var. minor and var. major accessions with few overlapping genotypes, the former having higher average yield, taller structure, more pods per node and longer flowering duration. Late sowing under long-day conditions above 55°N latitudes resulted in early flowering due to short vegetative development (650 °Cd). Extended flowering duration and tall stature were the most important traits conferring high yields. A negative trade-off between yield potential and yield stability was detected, with yield advantages of stress resistant genotypes only in a limited range of low yielding target environments ( It was concluded that Baltic landraces are promising ideotypes, with adapted flowering phenology and morphological structure, for increased V. faba yields in Nordic target environments.

Hydrological gradients and functional diversity of plants drive ecosystem processes inPoyang Lakewetland

AbstractFunctional trait approaches have greatly improved the mechanistic understanding of the impacts of biodiversity in ecosystem. We evaluated how hydrological gradients (i.e., soil water content and elevation) affected the taxonomic diversity, functional identity, and functional diversity and assessed how changes in these measures of diversity ultimately drove variations in above‐ground biomass (AGB). Results showed that a combination of hydrological gradients and functional trait composition (i.e., the community weighted means, the single‐trait functional diversity and the multiple‐trait functional diversity) better explained variations (40.8%) of AGB. No significant relationships between taxonomic diversity and AGB were observed. The dominant species became taller with thicker stem, and co‐occurring species showed greater divergent distribution of stem diameter towards higher soil water content. As elevation increased, the dominant plant had thinner leaves with later onset of flowering and longer flowering duration, and co‐occurring species showed less divergent distribution of lamina thickness and leaf dry‐mass content. Our results highlighted that the positive biodiversity–ecosystem functioning relations were largely attributed to the co‐operations of selection and complementary effects, as evidences showed that the dominant trait values (i.e., community weighted mean of shoot height) and trait diversity (i.e., functional evenness) improved biomass production of wetland plants.

Standardisation of growing media and its depth for rooftop gardening of chrysanthemum (Dendranthema grandiflora Tzvelev) cv. Prof. Harris

An experiment was conducted to study the standardisation of growing media and its depth for rooftop gardening of chrysanthemum (Dendranthema grandiflora Tzvelev) cv. Prof. Harris during 2016. The experiment was laid out in two-factor completely randomized block design comprising five growing media having different components by volume at three different depths viz., D1: 10 cm, D2: 20 cm and D3: 30 cm depths. The media compositions were G1: Soil+sand+coco peat+vermicompost (1: 1: 2: 2), G2: Sand+coco peat+vermicompost (1: 2: 2), G3: Sand+coco peat+vermicompost +vermiculite (1: 2: 2: 0.5), G4: Sand+coco peat+vermicompost+perlite (1: 2: 2: 0.5) and G5: Sand+coco peat+vermicompost+vermiculite+perlite (1: 2: 2: 0.25: 0.25). Among the depths of growing media, D3 i. e. 30 cm was found best for increasing the plant and flower characters. It induced early flowering (bud visibility at 46.53 days, bud opening at 61.89 days and full bloom at 75.84 days), greater flower number 47.13/plant and longer flowering duration 62.37 days. Among the media, G5 responded best in terms of flower earliness (bud visibility at 49.00 days, bud opening at 64.35 days and full bloom at 78.85 days), more number of sprays per plant i. e. 7.01 sprays per plant and longer duration of 54.52 days compared to other growing media. The treatment combination of media depth D3 i. e. 30 cm and growing media G5 was best for rooftop gardening of chrysanthemum.

Plant size and leaf area influence phenological and reproductive responses to warming in semiarid Mediterranean species

Changes in vegetative and reproductive phenology rank among the most obvious plant responses to climate change. These responses vary broadly among species, but it is largely unknown whether they are mediated by functional attributes, such as size or foliar traits. Using a manipulative experiment conducted over two growing seasons, we evaluated the responses in reproductive phenology and output of 14 Mediterranean semiarid species belonging to three functional groups (grasses, nitrogen-fixing legumes and forbs) to a ∼3°C increase in temperature, and assessed how leaf and size traits influenced them. Overall, warming advanced flowering and fruiting phenology, extended the duration of flowering and reduced the production of flowers and fruits. The observed reduction in flower and fruit production with warming was likely related to the decrease in soil moisture promoted by this treatment. Phenological responses to warming did not vary among functional groups, albeit forbs had an earlier reproductive phenology than legumes and grasses. Larger species with high leaf area, as well as those with small specific leaf area, had an earlier flowering and a longer flowering duration. The effects of warming on plant size and leaf traits were related to those on reproductive phenology and reproductive output. Species that decreased their leaf area under warming advanced more the onset of flowering, while those that increased their vegetative height produced more flowers. Our results advance our understanding of the phenological responses to warming of Mediterranean semiarid species, and highlight the key role of traits such as plant size and leaf area as determinants of such responses.

Effect of type and time of pruning on flowering behaviour of Crape Myrtle (Lagerstroemia indica L.) in sub-tropical landscape

An experiment was carried out to study the effect of type and time of pruning on flowering behaviour of Crape Myrtle (Lagerstroemia indica L.) in sub-tropical landscape during 2013–15. The experiment was laid out in two-factor randomized block design comprising four different levels of pruning viz., P0 (unpruned), P1 (45 cm height from ground level), P2 (60 cm height from ground level), P3 (75 cm height from ground level) and five different times of pruning viz., T1(15th October 2013), T2(15th November 2013), T3(15th December 2013), T4 (15th January 2014) and T5 (15th February 2014). Among the levels of pruning, pruning at height of 75 cm from ground level was found to be best for increasing flowering period, quantity and quality. It induced early flowering (bud visibility at 151.53 days, bud opening at 165.33 days, full bloom at 177.87 days), greater flower number 699.33/plant and longer flowering duration 109.73 days. Among the months, February (2014) month responded best in terms of flower earliness (bud visibility at 102.25 days, bud opening at 117.58 days, full bloom at 132.50 days), more number of flowers per plant i. e. 676.33/plant and longer flowering duration 105.92 days compared to other pruning levels and time. The treatment combination pruning at 75 cm from ground levels in February month was the best for good quality flower production.

Genotypic variation in grain yield and flowering pattern in terminal and intermittent drought screening methods in rainfed lowland rice

Rainfed lowland rice in the Mekong region is mostly grown in drought-prone areas, and drought resistant varieties could be selected using either terminal drought (severe water stress after flowering) or intermittent drought (frequent mild stress) screening. Delay in flowering is considered as a putative trait for selection of drought resistant genotypes, and its effectiveness as an indirect selection trait and its association with genotype's flowering duration, i.e. the time taken from the first to last flower in a plot, was evaluated under the two drought screening methods. These screening methods together with flood control were used at two locations, Chum Phae and Ubon in north-east Thailand using a total of 70 genotypes with different growing duration. Delay in flowering was estimated for the two drought screening methods and flowering of individual panicles within a plot was recorded to determine flowering duration of each genotype in the flood and terminal drought conditions.Mean reduction in grain yield was 52–55% under the terminal drought screening while it was 10–19% for the whole population and 23–33% for early flowering genotypes in the intermittent drought. Delay in flowering under intermittent drought condition at both locations was associated with yield reduction; genotypes that exhibited shorter delay in flowering had smaller yield reduction percentage and larger number of panicles. At Chum Phae, where grain yield reduction was associated with flowering time, genotypes with longer flowering duration under terminal drought had smaller yield reduction, and this was found even among genotypes that flowered about the same time under flood condition. However, there was no association between delay in flowering and flowering duration. It is concluded that delay in flowering appears promising as a selection criterion under intermittent drought conditions, provided a higher yield reduction can be achieved for example by using an increased irrigation interval.

Complex trait divergence contributes to environmental niche differentiation in ecological speciation of Boechera stricta.

Ecological factors may contribute to reproductive isolation if differential local adaptation causes immigrant or hybrid fitness reduction. Because local adaptation results from the interaction between natural selection and adaptive traits, it is crucial to investigate both to understand ecological speciation. Previously, we used niche modelling to identify local water availability as an environmental correlate of incipient ecological speciation between two subspecies in Boechera stricta, a close relative of Arabidopsis. Here, we performed several large-scale glasshouse experiments to investigate the divergence of various physiological, phenological and morphological traits. Although we found no significant difference in physiological traits, the Western subspecies has significantly faster growth rate, larger leaf area, less succulent leaves, delayed reproductive time and longer flowering duration. These trait differences are concordant with previous results that habitats of the Western genotypes have more consistent water availability, while Eastern genotypes inhabit locations with more ephemeral water supplies. In addition, by comparing univariate and multivariate divergence of complex traits (Q(ST)) to the genomewide distribution of SNP FST , we conclude that the aspects of phenology and morphology (but not physiology) are under divergent selection. In addition, we also identified several highly diverged traits without obvious water-related functions.

Plant traits across different habitats of the Italian Alps: a comparative analysis between native and alien species

While it is well known that the success of alien plants in new environments greatly depends on their functional traits, to date only a few other studies have tested whether coexisting alien and native species show converging or diverging functional attributes. To our knowledge, no comparative analysis between native and alien species has been carried out in the same mountain habitats. We characterized the main habitats of the Italian Alps on the basis of plant species traits and we then tested for evidence of functional axes of variation among the habitats for native and alien plants. Finally, we tested the ‘try-harder’ and the ‘join-the-locals’ hypotheses to understand whether coexisting native and alien plant species showed converging or diverging functional attributes. Ordination analysis showed a distribution of the habitats according to the Grime’s CSR strategies, and associated to plant growth form and resource acquisition. Co-inertia analysis showed a significant association between native and alien plant traits at habitat level (RV = 0.73; Monte-Carlo test, p = 0.035). Across all species and habitats, the comparative analysis of individual traits showed that alien species have 25% higher plant height, 250% higher leaf mass, 19% lower leaf dry matter content, 10% higher SLA, and 17% longer flowering duration than native species. Overall, our findings demonstrated that aliens differ in many traits from native species in the Italian Alps, but that many of these differences disappear when one compares aliens and natives that co-occur in the same types of habitats.

Brassica juncea Canola in the Northern Great Plains: Responses to Diverse Environments and Nitrogen Fertilization

Brassica juncea var. juncea canola is a new oilseed species that is developed from B juncea (L.) Czern. mustard with its oil and meal quality equivalent to conventional canola species. Understanding of the phenological characteristics and yield responses to diverse environments will allow the crop to be better adapted to target production areas. This study determined the responses of the juncea canola to various soil‐climatic conditions and was compared with B napus L. canola, B rapa L. canola, juncea mustard, and Sinapis alba L. mustard. The five oilseed species/cultivars were grown under various N fertilizer rates (0, 25, 50, 100, 150, 200, and 250 kg N ha−1), at four Saskatchewan locations from 2003 to 2005. On average, flowering began 40 d after seeding (DAS) for alba mustard and rapa canola (earliest), 49 DAS for napus canola (latest), and 44 DAS for juncea canola (intermediate). Flowering duration was longest for juncea canola (30 d) and shortest for napus canola (22 d). The napus canola and juncea mustard produced higher (1684 kg ha−1) seed yields than the three other oilseeds (1303 kg ha−1 on average). For all oilseed species, the seed yield was highly responsive to N fertilizer rates from zero to about 100 kg N ha−1, and thereafter, the rate of yield responses declined. The amount of N fertilizer required to achieve the maximum seed yield was 106 kg N ha−1 for rapa canola, 135 kg N ha−1 for alba mustard and napus canola, and 162 kg N ha−1 for the two juncea spp. Overall, juncea canola had lower seed yield than more popular hybrid napus canola, and the yield stability of juncea canola was lowest among the five oilseed species when examined across diverse environments. Earlier flowering, longer flowering duration, and greater tolerance to drought stress exhibited by juncea canola make the crop best adapted to the drier areas of the northern Great Plains. The improvement of seed yield and yield stability is the key to potentially adapt this new oilseed species to a wider range of environmental conditions.