Peak Flowering Research Articles

A comparison of herbarium and citizen science phenology datasets for detecting response of flowering time to climate change in Denmark

Phenology has emerged as a key metric to measure how species respond to changes in climate. Innovative means have been developed to extend the temporal and spatial range of phenological data by obtaining data from herbarium specimens, citizen science programs, and biodiversity data repositories. These different data types have seldom been compared for their effectiveness in detecting environmental impacts on phenology. To address this, we compare three separate phenology datasets from Denmark: (i) herbarium specimen data spanning 145 years, (ii) data collected from a citizen science phenology program over a single year observing first flowering, and (iii) data derived from incidental biodiversity observations in iNaturalist over a single year. Each dataset includes flowering day of year observed for three common spring-flowering plant species: Allium ursinum (ramsons), Aesculus hippocastanum (horse chestnut), and Sambucus nigra (black elderberry). The incidental iNaturalist dataset provided the most extensive geographic coverage across Denmark and the largest sample size and recorded peak flowering in a way comparable to herbarium specimens. The directed citizen science dataset recorded much earlier flowering dates because the program objective was to report the first flowering, and so was less compared to the other two datasets. Herbarium data demonstrated the strongest effect of spring temperature on flowering in Denmark, possibly because it was the only dataset measuring temporal variation in phenology, while the other datasets measured spatial variation. Herbarium data predicted the mean flowering day of year recorded in our iNaturalist dataset for all three species. Combining herbarium data with iNaturalist data provides an even more effective method for detecting climatic effects on phenology. Phenology observations from directed and incidental citizen science initiatives will increase in value for climate change research in the coming years with the addition of data capturing the inter-annual variation in phenology.

Changing the main course: strong bat visitation to the ornithophilous mistletoe Psittacanthus robustus (Loranthaceae) in a Neotropical savanna

AbstractThe Neotropical genus Psittacanthus comprises mostly specialized ornithophilous mistletoes, with rare exceptions. Psittacanthus robustus is a common ornithophilous species from the South American savannas whose bright yellow flowers secrete copious diluted nectar. Due to a three‐day‐long anthesis and a short, non‐restrictive floral tube, we suggest that the species also serves as a resource for flower‐visiting bats. In a Cerrado area in central Brazil, we investigated the usage of the species by bats through systematic bat captures for pollen sampling, its nocturnal nectar secretion dynamics, mating system, and the relative dependence on diurnal and nocturnal pollinators for reproduction. Nine phyllostomid bat species visited P. robustus. Up to 50% of pollen samples from bats contained the species during peak flowering, equating or surpassing the prevalence of chiropterophilous species and representing roughly a third of the floral resources consumed by specialized nectarivores Glossophaga soricina and Anoura caudifer. Flowers actively produced nectar at night with volume and concentration values in the ideal ranges for bat consumption. Nectar is continuously secreted after sunset and accumulates in the absence of visitors. Psittacanthus robustus is self‐compatible but seeds are set mostly by diurnal visitors. Nocturnal animals had a low and secondary contribution to plant fitness. This is the second report of bat pollination for the genus Psittacanthus, and the largest assemblage of bat visitors for the family Loranthaceae. Although ornithophilous, P. robustus is an important resource for bats in the Brazilian savanna, potentially representing a mixed or early transitional state toward bat pollination.Abstract in Portuguese is available with online material.

Range expansion decreases the reproductive fitness of Gentiana officinalis (Gentianaceae)

Plants living at the edge of their range boundary tend to suffer an overall decline in their fitness, including growth and reproduction. However, the reproductive performance of plants in artificially expanded habitats is rarely investigated, although this type of study would provide a better understanding of range limitations and improved conservation of ex situ plants. In the current study, we transplanted a narrowly dispersed species of Gentiana officinalis H. Smith (Gentianaceae) from its natural area of distribution to two different elevations and natural elevation to comprehensively study its pollination biology, including flowering phenology and duration, floral display, reproductive allocation, pollinator activity, and seed production. The findings indicated that the starting point and endpoint of the flowering phenology of G. officinalis were earlier at the low elevation, but the peak flowering periods did not differ significantly between any of the experimental plots. When transplanted, the flowering duration, especially the female phase, was reduced; the floral display, including spray numbers, flower numbers, and flower size (length and width), decreased, especially at high elevations. Moreover, the pollen numbers and pollen-ovule ratio were decreased at both high and low elevations, although the ovule numbers showed no change, and aboveground reproductive allocation was decreased. Furthermore, pollinator richness and activity were significantly decreased, and the seed-set ratio decreased under both natural conditions and with supplemental pollination. Finally, more severe pollen limitation was found in transplanted individuals. These results indicated an overall decrease in reproductive fitness in plants living outside their original area of distribution when the geographical range of G. officinalis was expanded.

A field experiment characterizing variable detection rates during plant surveys.

Surveys aimed at finding threatened and invasive species can be challenging due to individual rarity and low and variable individual detection rates. Detection rate in plant surveys typically varies due to differences among observers, among the individual plants being surveyed (targets), and across background environments. Interactions among these 3 components may occur but are rarely estimated due to limited replication and control during data collection. We conducted an experiment to investigate sources of variation in detection of 2 Pilosella species that are invasive and sparsely distributed in the Alpine National Park, Australia. These species are superficially similar in appearance to other yellow‐flowered plants occurring in this landscape. We controlled the presence and color of flowers on target Pilosella plants and controlled their placement in plots, which were selected for their variation in cover of non‐target yellow flowers and dominant vegetation type. Observers mimicked Pilosella surveys in the plots and reported 1 categorical and 4 quantitative indicators of their survey experience level. We applied survival analysis to detection data to model the influence of both controlled and uncontrolled variables on detection rate. Orange‐ and yellow‐flowering Pilosella in grass‐ and heath‐dominated vegetation were detected at a higher rate than nonflowering Pilosella. However, this detection gain diminished as the cover of other co‐occurring yellow‐flowering species increased. Recent experience with Pilosella surveys improved detection rate. Detection experiments are a direct and accessible means of understanding detection processes and interpreting survey data for threatened and invasive species. Our detection findings have been used for survey planning and can inform progress toward eradication. Interaction of target and background characteristics determined detection rate, which enhanced predictions in the Pilosella eradication program and demonstrated the difficulty of transferring detection findings into untested environments.

Spatiotemporal Variation of Osmanthus fragrans Phenology in China in Response to Climate Change From 1973 to 1996.

Climate change greatly affects spring and autumn plant phenology around the world consequently, and significantly impacts ecosystem function and the social economy. However, autumn plant phenology, especially autumn flowering phenology, has not been studied so far. In this study, we examined the spatiotemporal pattern of Osmanthus fragrans phenology, including both leaf phenology (the date of bud-bust, BBD; first leaf unfolding, FLD; and 50% of leaf unfolding, 50 LD) and flowering phenology (the date of first flowering, FFD; peak of flowering, PFD; and end of flowering, EFD). Stepwise multiple linear regressions were employed to analyze the relationships between phenophases and climatic factors in the long term phenological data collected by the Chinese Phenological Observation Network from 1973 to 1996. The results showed that spring leaf phenophases and autumn flowering phenophases were strongly affected by latitude. BBD, FLD, and 50LD of O. fragrans were delayed by 3.98, 3.93, and 4.40 days as per degree of latitude increased, while FFD, PFD and EFD in O. fragrans advanced 3.11, 3.26, and 2.99 days, respectively. During the entire study period, BBD was significantly delayed across the region, whereas no significant trends were observed either in FLD or 50LD. Notably, all flowering phenophases of O. fragrans were delayed. Both leaf and flowering phenophases negatively correlated with growing degree-days (GDD) and cold degree-days (CDD), respectively. BBD and FLD were negatively correlated with total annual precipitation. In addition to the effects of climate on autumn flowering phenology, we found that earlier spring leaf phenophases led to delayed autumn flowering phenophases. Our results suggest that future climate change and global warming might delay the phenological sequence of O. fragrans. Our findings also advanced the flowering mechanism study of autumn flowering plants, and facilitated the accurate prediction of future phenology and climate change.

Fire influences reproductive outcomes by modifying flowering phenology and mate-availability.

A recent study posited that fire in grasslands promotes persistence of plant species by improving mating opportunities and reproductive outcomes. We devised an investigation to test these predicted mechanisms in two widespread, long-lived perennials. We expect fire to synchronize flowering, increase mating and boost seed set. We quantified individual flowering phenology and seed set of Liatris aspera and Solidago speciosa for 3yr on a preserve in Minnesota, USA. The preserve comprises two management units burned on alternating years, allowing for comparisons between plants in burned and unburned areas within the same year, and plants in the same area across years with and without burns. Fire increased flowering synchrony and increased time between start date and peak flowering. Individuals of both species that initiated flowering later in the season had higher seed set. Fire was associated with substantially higher flowering rates and seed set in L. aspera but not S. speciosa. In L. aspera, greater synchrony was associated with increased mean seed set. Although fire affected flowering phenology in both species, reproductive success improved only in the species in which fire also synchronized among-year flowering. Our results support the hypothesis that reproduction in some grassland species benefits from fire.

Tree to tree variation in reproductive phenology in Indian sandalwood (Santalum album Linn)

In the present study, reproductive phenology of 15 individuals of Indian sandalwood (Santalum album) was carried out at the campus of Forest Training Institute, Gungaragatti, Dharwad, Karnataka. Results showed that there was tree to tree variation for time of flowering and fruiting in Indian sandalwood. Marked individuals showed two peak flowerings in a year viz first peak during Jun-Aug and second during Dec-Jan. Among 15 individuals, one tree showed peak flowering in Sept and Nov. Fruiting phenology showed that all individuals fruited during Aug to May except during Jun to Jul. Peak fruiting period for seed collection was between Apr to May and Oct to Nov.

Phenological Characteristics of Hawthorn, Crataegus songarica K Koch. in Kashmir Himalayas

Phenological analysis of trees provides a potential tool to address critical questions related to modelling and monitoring of climate change. Therefore present study was conducted to study the phenology of crataegus species in Kashmir Himalayas. The aim of study was to generate a baseline data and were described in different phases of growth throughout the seasons. The data was collected with respect to bud set, bud burst/break, leaf initiation/flush, flowering, fruit formation, fruit/seed fall, leaf tint, leaf fall and fruit fall. For collection of data five trees were selected randomly. In each tree, 4 branches were selected and a total of 20 observations were taken at weekly interval from February onwards. It was observed that the bud set starts from 3rd week of February and bud bursting from 4th week of March. Leaves fully open from 1st week of April. It was observed that flowering starts from 4th week of April and continues till 4th week of May. However, peak flowering was observed in the 2nd week of May. Investigations conducted revealed that fruiting starts from 4th week of July, fruit fall from 2nd week of September and continues till 3rd week of October. It was also observed that leaf tint occurs during the 3rd week of September. Leaf fall starts from 4th week of September and continues till 1st week of November. Investigations conducted revealed that pheno-phases of Crataegus songarica were completed in 9 months 3 weeks.

Studies On The Effect Of Micronutrients In Acid Lime (Citrus aurantifolia Swingle) var. PKM-1

Acid lime (Citurs aurantifolia Swingle) belongs to the family Rutaceae and widely grown in tropical and subtropical regions of India. India is the largest producer of acid lime in the world. In India, Maharashtra, Andhra Pradesh, Tamil Nadu, Gujarat, Rajasthan and Bihar are grown in larger area. In Tamil Nadu, commercially cultivated in Tirunelveli, Tenkasi, Turicorin, Dindigul, Madurai, Theni, Virudhunagar and Perambalur districts. Fruits are being used for preparation of pickles and beverages. They are rich in vitamin C, minerals and salts. Micronutrients such as Zinc, Iron and boron play a vital role in acid lime for growth and development. With this background, the present experiment on studies on the effect of micronutrients in acid lime var. PKM-1 was conducted at Citrus Research Station (TNAU), Sankarankovil during 2020-21 to study the effect of micronutrients on growth, yield and quality of acid lime. Foliar application was given twice in a season viz., the first spray was given during peak flowering stage and next spray during fruit set stage on selected five trees for each treatment at farmer’s field. The trial was laid out in a randomized block design (RBD) with thirteen treatments and replicated thrice.

Developmental Pattern and Reproductive Biology of Nymphaea micrantha Guill. & Perr. and Nymphaea nouchali Burm. f. in Kerala

Water lily (Genus Nymphaea L.) has got immense ornamental, medicinal and cultural significance. The study was carried out to understand developmental pattern and reproductive biology of two species in Genus Nymphaea, which is fundamental for any crop improvement programme. Flowers were found to be solitary, pedicellate, and complete with various floral whorls in a spiral fashion on the floral axis. Significant variability was observed for various floral characters among the two species evaluated. The flowers were found opened in the morning and closed in the evening hours and the process was repeated on the subsequent days. Blossom life lasted for three days in Nymphaea micrantha and four days in Nymphaea nouchali. The peak flower production was observed during September to November period. The dehiscence of pollen occurred by the longitudinal splitting of the anthers in both the species and proceeded from the outer whorl to the inner whorl. The pollen grains retained viability only for 30 to 40 minutes. The stigma became receptive 17 hours before flower opening and receptivity was retained up to 32 hours after flower opening. Very low fertility of pollen was observed in both the species used for the study. No fruit or seed development was observed in both the species under study.

DO HABITAT SHIFTS ALTER FLOWERING PHENOLOGY OVERLAP IN CLOSE RELATIVES? IMPLICATIONS FOR LOCAL COEXISTENCE

Flowering time in plants is a highly variable trait that influences species' resource use and exchange of pollen with con- and heterospecifics. Levin (2009) suggested that habitat shifts within species might cause plastic shifts in flowering phenology, reducing pollen exchange across habitats. Coupled with divergent selection across habitats, diverged flowering time might thus pave the way towards ecological speciation. Some of these ideas may apply across species as well. If close heterospecific relatives share phylogenetically conserved flowering times and negatively affect each other's fitness, habitat shifts to microallopatry might provide a means for local coexistence by close relatives by reducing resource competition, shared enemies, or negative interactions via pollination. Habitat shifts might also select for diverged flowering time, or cause flowering time divergence, if phylogenetically conserved cues arrive at different times across habitats. Here, we ask if flowering phenology is phylogenetically conserved for 208 species at our coastal field site in northern California, whether flowering phenology differs systematically across habitat types, and whether habitat shifts are associated with phenological separation, especially in congeners. Because annuality and perenniality have been shown to be associated with habitat traits and flowering time, we included life history in our analyses as well. We also explore the frequency of habitat shifts between congener and noncongener pairs. We use both field observations and data from Jepson eFlora/Jepson Manual 2 (Baldwin et al. 2012) to explore patterns in flowering phenology. The two data sources were well-correlated across 59 species. Phylogeny, habitat, and life history all influenced flowering time, and habitat and life history were also phylogenetically conserved across 208 spp. Congeners differed in habitat more often than noncongener pairs, and also overlapped more in flowering time. Habitat shifts were not associated with shifts in flowering time in congeners, despite mean peak flowering time differences across habitats, and phylogenetic conservatism in habitat use. Congeners that differed in both habitat use and life history, however, did have the greatest difference in peak flowering dates. Habitat shifts likely play a role in local coexistence of close relatives, but our data do not support habitat-mediated changes in phenology as a possible mechanism. Experimental approaches may elucidate the role of phenology, resource competition, pollinators, and other associates in mediating coexistence of congeners at our coastal California field site.

Analysis of varietal diversity, decorativeness and peculiarities of growth and development of cultivars Dahlia cultorum Thorsrud & Reisaeter in the collection of the biostationary of Bila Tserkva NAU

Aim. In order to identify promising cultivars of Dahlia cultorum for use in landscaping in Kyiv region, the analysis of the system of qualitative and quantitative indicators of cultivars of dahlias, the peculiarities of their growth and development in the absence of irrigation is conducted. Methods. To analyze the diversity of Dahlia cultorum cultivars at the biostationary of Bila Tserkva NAU, the classification developed by the American Society of Dahlia (ADS classification) was used. The cultivar assortment of dahlias was studied according to the descriptions of the catalog of the company “SontseSad”, which transferred 108 cultivars of Dahlia cultorum to Bila Tserkva NAU biostationary in 2014. Phenological rhythms of growth and development of dahlias were studied according to the methods of B. K. Shybniev, H. D. Yurkevych, and D. S. Holod. The increment of dahlias was measured during the period of active growth, the size of the flower — during the period of its full opening with the help of a measuring ruler on 5 specimens of each cultivar every decade. Results. Based on the analysis of the varietal composition of Dahlia cultorum collection of dahlia cultivars of Bila Tserkva NAU biostationary, it was found that the largest number of 36% belongs to the cultivar group of decorative dahlias, 12% — to cactus, 7% — to spherical and 1% to pompoms and anemones. The mixed cultivar of dahlias is 43.4%, among them the most numerous group of dahlias with dissected leaves “Deer antlers” — 48%, “Karma” — 19%, pot — 12%, French collection — 21%. According to the color spectrum, the collection is dominated by dahlias of red color — 29%, pink — 19%, yellow and orange — 16% each, violet — 12%, white color — 6%. Two-color cultivars amount to only 2%. Observations show that in May–June, due to the long and dry period and the lack of artificial irrigation, all cultivars of dahlias at Bila Tserkva NAU biostationary were marked by very slow growth. As of July 15, the height of dahlia bushes averaged 30–50 cm, which was significantly less than the size presented in the catalog of the magazine “SontseSad”. Conclusions. The collection of dahlias at Bila Tserkva NAU biostationary includes 108 cultivars belonging to seven main cultivar groups, including 11 cultivars from the new French collection. Early in the first decade of July, the cultivars ‘Islande’, ‘Maki’, ‘Sir Alf Ramsay’, ‘Mingus Alex’, ‘Glorie van Heemstede’ begin to bloom. Latest of all, in August, cultivars ‘Babylon Rose’, ‘Amanda’, ‘Aitara Bronwyn’, ’Karma Gold’, ‘Gallery Rembrandt’, ‘Lilac Time’, and ‘Star Spectacle’ began flowering. It is established that the period from the appearance of the bud to the opening of the flower in dahlia cultivars lasts 25-30 days. The first buds appeared in early July, but their peduncles were very short and such flowers were not suitable for cutting. In fact, the blooming central flower itself was 5-10 cm lower than the second-order buds around it, and therefore had a limited view from the inflorescence, which led to a loss of decorativeness in the cultivars ‘Romance’, ‘Candlelight’, and “Karma Bon Bini”. The duration of flowering of one dahlia flower in different cultivars ranged from 5 to 17 days. The longest period of blooming of one flower is 14-17 days in ‘Autumn Fairy’, ‘Nagano’, ‘Idylle’, ‘Babylon Brons’, ‘Duet’ cultivars. The shortest blooming period of one flower is 5-7 days for ‘Ellen Huston’, ‘Champs Elysees’, ‘ThykiYori No Shisha’, ‘Aspen’ cultivars. Due to the high air temperature and the long rainless period, the peak of flowering of dahlias in the conditions of Bila Tserkva NAU biostationary was at the beginning of September.

Perennial ryegrass (Lolium perenne) culm and inflorescence density in lawns: Effects of nitrogen fertilization and scalping timing and height

AbstractDuring late spring and early summer, perennial ryegrass (Lolium perenne L.) produces reproductive structures (i.e., culm and inflorescence), that decrease turf quality due to stemminess (i.e., culm remaining) after mowing. Research is required to understand the impact of management practices on visible culm and inflorescence presence. Field experiments were conducted to evaluate perennial ryegrass culm, inflorescence, and turf canopy responses due to various nitrogen (N) fertilization levels, scalping timings and heights. In Experiment 1, N fertilization rates ≥24 kg N ha−1 applied in early May with a slow‐release fertilizer prior to peak flowering (i.e., late May to early June) visibly decreased culms and inflorescences compared with 0 and 12 kg N ha−1. Higher N fertilizer levels, especially 98 kg N ha−1, also resulted in fewer necrotic culms remaining later in the summer along with greater overall turf quality and reduced weed cover. In Experiment 2, scalping perennial ryegrass at 3.8 or 5.1 cm on 25 May, the closest proximity prior to peak flowering, provided the lowest area under the curve (AUC) of green flowering culms. Scalping during or after peak flowering resulted in similar AUC values compared with nonscalped (7.6 cm) turf but did decrease the presence of necrotic culms later in summer to help improve turf quality. Overall, N fertility with a slow‐release fertilizer or a well‐timed scalping influences spring culm and inflorescence density and necrotic culm stemminess in perennial ryegrass turf systems. Additional research on physiological responses, such as carbohydrate partitioning, to these management practices is required.

Seed Production of Red Clover (Trifolium pratense L.) under Danish Field Conditions

High and stable seed yield is critical for red clover (Trifolium pratense L.) seed production and the commercial exploitation of the crop. A three-year experiment was conducted from 2013 to 2015 under Danish field conditions to explore the influence of precipitation during peak flowering on the seed yield of three red clover cultivars. We investigated the flowering duration and intensity based on a visual scale assessment, seed yield, and thousand seed weight in all three experimental years. In 2014 and 2015 we measured the seed yield components of floret number per flower head, seed number per flower head, and seed set. During the experimental period, high seed yields of more than 1000 kg ha−1 were obtained for the diploid cultivars ‘Rajah’ and ‘Suez’. Although a relatively high seed yield of 500 kg ha−1 was obtained in the tetraploid cultivar ‘Amos’, this was only around half of the seed yield and seed set of the diploid cultivars. Precipitation during peak flowering positively influenced the seed yield and thousand seed weight for the three cultivars. We conclude that observations of flowering phenology are required to determine the impact of environmental conditions on seed yield in red clover cultivars. Further, adequate water supply during peak flowering is important to obtain the high seed yield of red clover.

THE FEATURES OF REPRODUCTIVE ADAPTION OF CARNIVOROUS PLANT Utricularia aurea

Carnivorous plant (Utricularia aurea) is a suspended aquatic. Inflorescence erect, glabrous, scales absent, bracts basifixed, broadly ovate to orbicular. Calyx lobes ovate, subequal, apex rounded to subacute; lower lobe often slightly broader than upper lobe. Corolla pale yellow, pubescent or glabrous; lower lip transversely elliptic, base with a prominent 2-lobed swelling, apex rounded to emarginate. Filaments 1- 1.5 mm, curved; another thecae confluent. Ovary ovoid; style evident; stigma lower lip semicircular, upper lip obsolete. Fruit: capsule, ovoid, many seeds. The pollen of Utricularia aurea has one morphological form: heterocolpate (polar view). The diameter of fertile pollen is 32,97 ± 0,20 µm, the diameter of infertile pollen is 28,17 ± 0,20 µm. The percentage of fertile pollen is low (< 50%): 26,92% (in peak flowering) and 23,94% (in rare flowering). The percentage of fertile pollen has a positive and close correlation with the diameter of pollen (R = 0,95). Although this species has two reproductive forms (vegetative and sexual), the efficiency of sexual reproduction isn’t high. Vegetative reproduction is always dominant.

Shading decreases and delays NDVI and flowering of prostrate Arctic shrubs

Increases in shrub growth and canopy cover are well documented community responses to climate warming in the Arctic. An important consequence of larger deciduous shrubs is shading of prostrate plant species, many of which are important sources of nectar and berries. Here, we present the impact of a shading experiment on two prostrate shrubs, Vaccinium vitis-idaea L. and Arctous alpina L., in northern Alaska over two growing seasons. We implemented three levels of shading (no shade, 40% shade, and 80% shade) in dry heath and moist acidic tundra. Plots were monitored for soil moisture content, surface temperature, normalized difference vegetation index (NDVI), and flowering. Shading was shown to, on average, lower surface temperature (0.7 °C to 5.3 °C) and increase soil moisture content (0.5% to 5.6%) in both communities. Both species- and plot-level NDVI values were delayed in timing of peak values (7 to 13 days) and decreased at the highest shading. Flower abundance of both species was lower in shaded plots and peak flowering was delayed (3 to 8 days) compared with controls. Changes in timing may result in phenological mismatches and can impact other trophic levels in the Arctic as both the flowers and resulting berries are important food sources for animals.

Flowering Biological Characteristics of Camellia weiningensis Y.K. Li.

This study aimed to investigate the flowering biological characteristics, floral organ characteristics, and pollen morphology of Camellia weiningensis Y.K. Li. These features of adult C. weiningensis plants were observed via light microscopy and scanning electron microscopy (SEM). Pollen viability and stigma receptivity were detected using 2,3,5-triphenyltetrazole chloride (TTC) staining and the benzidine–hydrogen peroxide reaction method. C. weiningensis is monoecious, with alternate leaves and glabrous branchlets. Its flowering period lasts 2 to 4 months, and the flowering time of individual plants lasts ≈50 days, with the peak flowering period from the end of February to the middle of March. It is a “centralized flowering” plant that attracts a large number of pollinators. Individual flowers are open for 12 to 13 days, mostly between 1230 and 1630 hr, and include four to six sepals, six to eight petals, ≈106 stamens, an outer ring of ≈24.6-mm-long stamens, an inner ring of ≈13.4-mm-long stamens, one pistil, and nine to 12 ovules. The flowers are light pink. The style is two- to three-lobed and 16.6 mm long, showing a curly “Y” shape. The contact surface of the style is covered with papillary cells and displays abundant secretory fluid and a full shape, facilitating pollen adhesion. The pollen is rhombohedral cone-shaped, and there are germ pores (tremoids). The groove of the germ pore is slender and extends to the two poles (nearly reaching the two poles). The pollen is spherical in equatorial view and trilobate in polar view. The pollen vitality was highest at the full flowering stage, and the stigma receptivity was greatest on days 2 to 3 of flowering. The best concentration of sucrose medium for pollen germination was 100 g/L. The number of pollen grains per anther was ≈2173, and the pollen-to-ovule ratio was 23,034:1. C. weiningensis is cross-pollinated. Seventy-two hours after cross-pollination, the pollen tube reached the base, and a small part entered the ovary. The time when the pollen tube reached the base after pollination was later than that in commonly grown Camellia oleifera. The results of this study might lay an important foundation for the flowering management, pollination time selection, and cross-breeding of C. weiningensis.

Phenological Study of Elaeis guineensis (Jacq.) Growing in Ihiala, Anambra State, South-East Nigeria

The aim of the study was to provide a phenological data and baseline information on the phenology of Elaeis guineensis Jacq. The study was conducted with exotic species at Ihiala, South-East, Nigeria, a tropical climate. The initiation and completion of different phenophases of the tree, such as budding, leafing, flowering, fruiting and ripening were recorded at two weeks interval. The combination of the principal growth stages and the secondary growth stages produced 2-digit codes, were used to delineate the time-dependent phenophases. The results revealed that E. guineensis showed a cyclical and seasonal appearance of the phenophases observed in the course of the year. Bud formation and leaf development phenophases were very gradual and steady across the months observed. Peak flowering time of August through November and peak ripening time of April was recorded in this study. Also, the study revealed that difference existed in the extent of phenophases of the observed species. The study also showed that E. guineensis belong to the family (Arecaceae) had different time frames for the phenophases. It is concluded that the phenological records obtained from the study can be very useful in planning and management of orchards, and can provide reference records in tracing changes in the phenology of E. guineensis in the future.

Modelling the effects of cold temperature during the reproductive stage on the yield of chickpea (Cicer arietinum L.)

During the reproductive stage, chilling temperatures and frost reduce the yield of chickpea and limit its adaptation. The adverse effects of chilling temperature and frost in terms of the threshold temperatures, impact of cold duration, and genotype-by-environment-by-management interactions are not well quantified. Crop growth models that predict flowering time and yield under diverse climates can identify combinations of cultivars and sowing time to reduce frost risk in target environments. The Agricultural Production Systems Simulator (APSIM-chickpea) model uses daily temperatures to model basic crop growth but does not include penalties for either frost damage or cold temperatures during flowering and podding stages. Regression analysis overcame this limitation of the model for chickpea crops grown at 95 locations in Australia using 70 years of historic data incorporating three cultivars and three sowing times (early, mid, and late). We modified model parameters to include the effect of soil water on thermal time calculations, which significantly improved the prediction of flowering time. Simulated data, and data from field experiments grown in Australia (2013 to 2019), showed robust predictions for flowering time (n = 29; R2 = 0.97), and grain yield (n = 22; R2 = 0.63–0.70). In addition, we identified threshold cold temperatures that significantly affected predicted yield, and combinations of locations, variety, and sowing time where the overlap between peak cold temperatures and peak flowering was minimal. Our results showed that frost and/or cold temperature–induced yield losses are a major limitation in some unexpected Australian locations, e.g., inland, subtropical latitudes in Queensland. Intermediate sowing maximise yield, as it avoids cold temperature, late heat, and drought stresses potentially limiting yield in early and late sowing respectively.

Supporting wild pollinators in agricultural landscapes through targeted legume mixtures

Insect-pollinated legumes are rich in plant-based proteins making them a vital constituent of sustainable healthy diets for people and livestock. Furthermore, they deliver or support a range of ecosystem services that underpin agricultural production and their prevalence in agricultural landscapes is likely to increase. Under typical implementation and management, the value of legumes to pollinators has, however, been questioned. Through exploring a range of legume crops, grown as monocultures and mixtures, this study aims to identify multifunctional legume cropping systems that optimise forage availability for a diversity of wild pollinators whilst delivering a wide range of agronomic and environmental benefits. This study innovatively explores legume mixtures concurrently with monocultures of the component species using replicated small-plot field trials established in two geographical locations. Observational plots assessed the richness and abundance of floral resources, and wild pollinators (i.e. bumblebees and hoverflies) throughout the peak flowering period. Densely flowering, highly profitable legumes (e.g. Trifolium incarnatum and Trifolium mixes) supported abundant and rich pollinator assemblages. The functional makeup of floral visitors was strongly influenced by flower structure and hoverflies, with their shorter proboscises, were largely constrained to legumes with shallower corolla and open weed species. Floral richness was not a key driver of pollinator assemblages; however, clear intra-specific differences were observed in flowering phenology. Combining functionally distinct legumes with respect to flower structure and phenology, will support a wider suite of pollinating insects and help stabilise the temporal availability of forage. For highly competitive legumes (e.g. Vicia faba and Vicia sativa), planting in discrete patches is recommended to reduce the risk of less competitive species failing in mixtures. Legumes can provide valuable forage for pollinators; however, they fail to meet all resource requirements. They should therefore be used in combination with agri-environmental measures targeted to promote early-season forage (e.g. hedgerows and farm woodlands), open flowers for hoverflies, saprophytic hoverfly larval resources (e.g. ditches and ponds) and nesting habitats (e.g. undisturbed field margins).