Pollen Preservation Research Articles

Pollen Preservation Approaches in Date Palm Cultivation: Assessing Effects on Viability, Fruit Quality, and Yield in ‘Mundra Selection-3’

Pollen Preservation Approaches in Date Palm Cultivation: Assessing Effects on Viability, Fruit Quality, and Yield in ‘Mundra Selection-3’

Deep learning approach for detecting tomato flowers and buds in greenhouses on 3P2R gantry robot

In recent years, significant advancements have been made in the field of smart greenhouses, particularly in the application of computer vision and robotics for pollinating flowers. Robotic pollination offers several benefits, including reduced labor requirements and preservation of costly pollen through artificial tomato pollination. However, previous studies have primarily focused on the labeling and detection of tomato flowers alone. Therefore, the objective of this study was to develop a comprehensive methodology for simultaneously labeling, training, and detecting tomato flowers specifically tailored for robotic pollination. To achieve this, transfer learning techniques were employed using well-known models, namely YOLOv5 and the recently introduced YOLOv8, for tomato flower detection. The performance of both models was evaluated using the same image dataset, and a comparison was made based on their Average Precision (AP) scores to determine the superior model. The results indicated that YOLOv8 achieved a higher mean AP (mAP) of 92.6% in tomato flower and bud detection, outperforming YOLOv5 with 91.2%. Notably, YOLOv8 also demonstrated an inference speed of 0.7 ms when considering an image size of 1920×1080\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1920 \ imes 1080$$\\end{document} pixels resized to 640×640\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$640 \ imes 640$$\\end{document} pixels during detection. The image dataset was acquired during both morning and evening periods to minimize the impact of lighting conditions on the detection model. These findings highlight the potential of YOLOv8 for real-time detection of tomato flowers and buds, enabling further estimation of flower blooming peaks and facilitating robotic pollination. In the context of robotic pollination, the study also focuses on the deployment of the proposed detection model on the 3P2R gantry robot. The study introduces a kinematic model and a modified circuit for the gantry robot. The position-based visual servoing method is employed to approach the detected flower during the pollination process. The effectiveness of the proposed visual servoing approach is validated in both un-clustered and clustered plant environments in the laboratory setting. Additionally, this study provides valuable theoretical and practical insights for specialists in the field of greenhouse systems, particularly in the design of flower detection algorithms using computer vision and its deployment in robotic systems used in greenhouses.

Analysis of Thermal Characteristics of Potato and Hop Pollen for Their Cryopreservation and Cross-Breeding.

This study investigated the thermal properties of potato and hop pollen for cryopreservation and subsequent cross-breeding. Phase transitions and frozen water content in selected pollen samples were measured using a differential scanning calorimeter (DSC). Unlike hop pollen, potato pollen showed high variability in thermal properties and water content. Three specific types of pollen samples based on their thermal characteristics and water content were distinguished by DSC in potato: (1) 'glassy', with a water content lower than 0.21 g water per g dry matter; (2) 'transient', with a water content between 0.27 and 0.34 g of water per g of dry matter; (3) 'frozen', with a water content higher than 0.34 g of water per g of dry matter. Only the 'glassy' pollen samples with a low water content showed suitable properties for its long-term storage using cryopreservation in potato and hops. Cryopreservation of pollen did not significantly reduce its viability, and cryopreserved pollen was successfully used to produce both potato and hop hybrids. The results indicate that cryopreservation is a feasible technique for the preservation and utilization of pollen of these crops in the breeding process.

Multiproxy studies on the spatially distinct surface samples to reconstruct palaeoecology and palaeoclimate from the Core Monsoon Zone of India

Palaeoclimatic reconstructions necessitate an understanding of the various biotic and abiotic responses to develop a modern analogue. The interpretation and calibration of the modern data allow us to check the lead-lag effect in different proxy parameters, which could be applied for robust palaeoclimatic reconstructions. We, in the present study, analysed pollen and diatom (biotic proxies), as well as grain size, magnetic susceptibility and geochemistry (abiotic components) of the modern soil samples, collected from the states of Madhya Pradesh and Chhattisgarh, the Core of the Monsoon Zone (CMZ) in central India. The weathered materials of the Palaeocene Cretaceous extrusive rocks and sedimentary rocks of the Late Triassic to the Upper Carboniferous are underlying the soil cover in these areas, respectively. The study revealed that the overall pollen and diatom preservation is comparatively good in the areas where the Palaeocene Cretaceous extrusive rocks are found except for the areas of human settlements, whereas the preservation of pollen and diatom was comparatively poor in areas where sedimentary rocks of the Late Triassic to Upper Carboniferous are found. The most plausible reason for this difference is the availability of nutrients which are supplied more abundantly by the easily weatherable Deccan basalt rocks compared to their sedimentary counterparts. The present study will serve as baseline information about biotic-abiotic interactions operating in the central Indian Core Monsoon Zone (CMZ). Since the intensity and duration of the rainfall in the CMZ are largely governed by the annual Indian summer monsoon rainfall (AISMR), therefore, the present study could help trace the weak or intense monsoon periods (break and active spells, respectively) of the past hundreds to thousands of years by studying the sediment profiles/cores.

Archaeobotanical data from the Sabor Valley reveal shifting moments in landscape and agriculture in NW Iberia during the Holocene

NW Iberia is dominated by Atlantic climate areas that favour pollen preservation, useful for palaeoecological studies. However, the region also includes Mediterranean sectors in which preservation of such palaeoenvironmental evidence is more difficult. To overcome these constraints, archaeological plant macroremains can be used to help characterize flora and vegetation dynamics at a local and regional level. To fill the gap in knowledge in an understudied Mediterranean region, a large archaeobotanical study was conducted at the river Sabor valley, NE Portugal. With 13 archaeological sites sampled for charcoal, fruits and seeds, it allowed the study of vegetation throughout the Holocene, starting in the Mesolithic up to Modern times, with some chronological gaps. Tree taxa dominates the older period and an expansion of shrubby taxa since Bronze age was observed. Diversification of plants used during the Iron Age and Roman period suggests an intensification of resources exploitation and deforestation. These trends seem to be related with changes in human settlements and productive strategies. During Prehistory, agricultural fields were established in flat and wide areas, and, during Iron Age, fortified granaries were used to store large amounts of grains, particularly free-threshing wheat. Drastic changes in settlement during Roman times and the establishment of small farms producing wine and/or olive oil were testified by the occurrence of Olea and Vitis in both anthracological and carpological datasets. Data from more recent periods is scarce. Results highlight that the combination of several proxies and integration of archaeological evidence helps to understand ecological dynamics in areas without pollen data and contributes to the characterization of heterogeneous areas under diverse climatic conditions and with a variety of social trends.

Vegetation diversity in response to monsoonal variability in the Eastern Himalaya, India over the past ~13 000 yrs

Monsoon precipitation plays a crucial role in shaping the diversity of vegetation in the Himalayas, both in terms of temporal and spatial distribution. While palynology has traditionally been employed to reconstruct the past climate of the Himalaya, there has been limited understanding of how monsoon-related changes affect the structure and distribution of vegetation. To address this, we analysed pollen data from a 3 m deep sedimentary profile in the higher Sikkim Himalaya to reconstruct monsoon driven changes in vegetation diversity. Our results show a highly fluctuating trend of pollen and diversity parameters at late-Pleistocene-Holocene transition for which fluctuating hydroclimatic conditions and differential pollen preservation in coarser sediments is attributed. During the Early Holocene (10,438–7934 cal yrs BP) favourable hydroclimatic conditions led to a rapid expansion of mixed broad-leaved forests, marked by higher values of richness and alpha diversity. Between 7934 and 5481 cal yrs BP, the region experienced moderate hydroclimatic conditions that facilitated expansion and diversification of woody taxa, and correlated with the global Holocene Climate Optimum (HCO). Conversely, from 5481 to3949 cal yrs BP, declining total pollen count (TPC), species richness, and alpha diversity indicates significant shifts in vegetation composition under deteriorating climatic conditions, which corresponds with the 4.2 ka event worldwide. From 3949 to 2049 cal yrs BP, an increasing yet variable trend in TPC and diversity indices, suggests warm-humid conditions prevailed in the region. During the last 1086 cal yrs, an increasing trend is recorded in the palyno assemblage and diversity parameters suggesting ameliorating climate, matches well with the Mediaeval Climate Anomaly (MCA). Our inferences suggest that the palyno assemblage and diversity parameters are quiet sensitive to warm and humid conditions.

Gamma irradiation and ozone application as preservation methods for longer-term storage of bee pollen

Bee pollen is a healthy product with a good nutritional profile and therapeutic properties. Its high moisture content, however, promotes the growth of bacteria, molds, and yeast during storage commonly result in product degradation. Therefore, the aim of this study is to assess the effectiveness of gamma irradiation (GI) and ozone (OZ) as bee pollen preservation methods for longer storage time, as well as whether they are influenced by pollen species. To do that, GI at a dosage of 2.5, 5.0, and 7.5 kGy was applied at a rate of 0.68 kGy/h and OZ application at a concentration of 0.01, 0.02, and 0.03 g/m3 was applied for one time for 6 h, to Egyptian clover and maize bee pollen, then stored at ambient temperature for 6 months. We then determined the total phenolic content (TPC) and antioxidant activity of treated and non-treated pollen samples at 0, 3, and 6 months of storage. Total bacteria, mold, and yeast count were also evaluated at 0, 2, 4, and 6 months. Statistical analyses revealed that, TPC, antioxidant, and microbial load of both clover and maize pollen samples were significantly (p < 0.05) affected by both treatment and storage time and their interaction. Both methods were extremely effective at preserving the antioxidant properties of pollen samples after 6 months of storage at room temperature. Furthermore, the highest concentrations of both GI and OZ applications completely protected pollen samples from mold and yeast while decreasing bacterial contamination. GI at the highest dose (7.5 KGy) was found to be more effective than other GI doses and OZ application in preserving biologically active compounds and lowering the microbial count of pollen samples for 6 months. As a result, we advise beekeepers to use GI at this dose for longer-term storage.

A late refugium for Classopollis in the Paleocene Lower Wilcox Group along the Texas Gulf Coast

Abstract We report a new ecological refugium for the Cheirolepidiaceae family (pollen form genus Classopollis) in the Paleocene Lower Wilcox Group in the Gulf Coast of southeastern Texas based on palynological analysis of four wells. The Cheirolepidiaceae were once thought to have gone extinct at the Cretaceous–Paleogene (K/Pg) boundary or earlier in North America; however, similar ecological refugia for this family in the Paleocene have previously been reported in China, Argentina, and potentially the Rocky Mountains of the United States. The highest relative abundances of Classopollis pollen were found in delta front, lagoon, and shoreface depositional paleoenvironments marked by high mud-fraction Sr/Ba (a geochemical proxy for salinity), and abundances generally increased down section in older Paleocene strata. The high relative abundance of Classopollis pollen in the well samples, the rarity of reworked Mesozoic palynomorphs, the generally good preservation of Classopollis pollen, and the similarity of Classopollis fluorescence spectra to other in situ Paleocene pollen all provide strong evidence for the survival of the Cheirolepidiaceae family in the coastal salt marshes of Texas through at least the late Paleocene.

Optimizing Wheat Pollen Preservation for Enhanced Viability and In Vitro Germination

Wheat pollen, which is characterized by its short lifespan, exhibits rapid germination after anthesis. The preservation of wheat pollen is contingent upon environmental factors including temperature, relative humidity, light, and wind. The aim is to explicate the process for efficiently storing wheat pollen, particularly with regard to breeding. The short longevity of wheat pollen grains renders it impractical to conduct tests for pollen viability and in vitro germination on a large scale. Herein, the impact of storage temperatures and duration was assessed on pollen viability and in vitro germination in order to optimize storage conditions for preserving pollen viability. Pollen grains from 50 diverse spring wheat genotypes, each with three replicates, were harvested and stored at temperatures of 22 °C, −20 °C, and 4 °C. Subsequently, pollen viability and in vitro germination rates were determined after storage for 1, 3, and 6 days. The results revealed that storage temperatures, durations, genotypes, and their interactions had a statistically significant impact on both pollen viability and in vitro germination. Notably, when pollen was kept at 22 °C, almost all genotypes exhibited a loss of pollen viability and in vitro germination after 1, 3, and 6 days of storage. Likewise, storage at −20 °C failed to extend pollen germination. However, at a storage temperature of 4 °C, the pollen of 36 wheat genotypes exhibited a range of 6–14% for in vitro pollen germination and even remained viable for 6 days. The ANOVA revealed a substantial variation in grain number per spike between wheat genotypes, thereby highlighting the significant influence of genetic variations on grain yield. Moreover, a slight positive association between the viability of wheat pollen and the number of grains was found in the current study, suggesting that a variety of factors affect the number of grains produced. Simple linear regression analysis further revealed a significant negative correlation between pollen viability, in vitro germination, and storage time and temperature. In conclusion, our findings underscore that 4 °C is the optimal temperature for preserving pollen viability and in vitro pollen germination in spring wheat for up to 6 days. The results of the present study suggests that the pollen viability of wheat is dependent on genotype, storage temperature, and storage duration. Thus, the 36 wheat genotypes identified during the present work could be efficiently maintained at 4 °C for short-term storage (6 days) and could be further used for genetic and breeding purposes.

Phylogeny and biogeography of the Cryptocaryeae (Lauraceae)

AbstractThe biogeographical history of many lineages within the Lauraceae remains poorly known because of the difficulty of assigning macrofossils to living genera, poor pollen preservation, and the absence of sufficiently resolved or well‐supported phylogenies. Here, we utilize plastid genome sequencing to reinvestigate the phylogenetic and biogeographic history of trees in the tribe Cryptocaryeae, an important component of broad‐leaved forests worldwide, with around 800 species that rely on vertebrate frugivores to disperse their seeds. A new time‐calibrated phylogeny with high support for 176 species was used to infer the biogeographic history and speciation rates based on inferences of BAMM analyses. A monophyletic Cryptocaryeae with Aspidostemon, Beilschmiedia, Cryptocarya, Dahlgrenodendron, and Eusideroxylon clades was confirmed. The five clades of Cryptocaryeae were estimated to share a common ancestor in tropical Africa or Asia in the Early Cretaceous around 123 Ma. The Beilschmiedia and Cryptocarya clades were estimated to have originated in South America around 66 Ma. Extant subclades of the Beilschmiedia clade could colonize Australia by 35 Ma and extant subclades of the Cryptocarya clade could colonize Australia by 42 Ma. Diversification rates of the Beilschmiedia clade accelerated 14 and 12 Ma after its origin and diversification rates of the Cryptocarya clade accelerated 18 Ma after its origin. Over 45% extant Cryptocaryeae species originated in the three periods of accelerated differentiation in the Miocene of Asia and Australia. Long‐distance dispersal has had a major influence on biogeography, with dispersal to Asia likely occurring seven times, Zealandia six times, America three times, Australia three times, Africa twice, and Oceania at least once. Over 70% extant Cryptocaryeae species which diverged before the Quaternary grow in the Southern Hemisphere, while 90% extant Cryptocaryeae species which diverged in the Quaternary grow in the Northern Hemisphere. The Cryptocaryeae originated in and diversified with the first angiosperm‐dominated broad‐leaved evergreen forests, from the Cretaceous to the Paleogene. Long‐distance seed dispersal, probably by birds, although possibly also by flotation, has allowed the tribe to track these forests in space and time, despite a failure to adapt to cold, dry, or highly seasonal environments.

Modern pollen–vegetation relationship from the Mahasamund District (Chhattisgarh), central India: implications for palaeoecological reconstruction

The study of modern pollen–vegetation relationship is crucial for the proper interpretation of fossil pollen records. In the present study, a total of 29 surface samples, collected from the edge of the forested areas of the Mahasamund District, Chhattisgarh State, central India, were palynologically analysed with the principal aims of evaluating the modern pollen assemblages and understanding the modern pollen and extant vegetation relationship. The study reveals the dominance of non-arboreal pollen (NAP) taxa over the arboreal pollen (AP) taxa, suggesting open mixed tropical deciduous forest type vegetation in and around the study area. The tree taxa, on the whole, constitute an average sum of 19.78% pollen of the total pollen sum, whereas the contribution of herbs is 43.58% pollen (average sum). The major non-arboreal taxa are Cerealia/Cereal Poaceae (average value; 5.45% pollen) and Poaceae (average value; 4.34%), whereas the cultural plant pollen taxa, such as Amaranthaceae, Caryophyllaceae, Brassicaceae, Cannabis sativa, Alternanthera, and Borreria contribute with an average sum of 11.69% pollen to the total pollen sum. Most of the common forest elements are not recorded because they are insect-pollinated or have low pollen preservation potential, and, hence, the modern pollen assemblages do not directly reflect the actual extant vegetation occupying the landscape of the study area. This bias would also be expected in late Quaternary pollen records of central India and, hence, can provide information of the actual vegetation when analysing fossil pollen samples.

Late Quaternary climatic inferences from southern Patagonia (∼53°S): A holistic palaeoecological approach to tracking the behaviour of the southern westerly winds

The glacial and vegetation patterns of Patagonia are strongly correlated to the behaviour of the Southern westerly winds (SWWs) with palaeoenvironmental evidence for the behaviour of the SWWs interpreted as past changes in southern hemisphere climate and ocean currents. To fully define shifts in the position and intensity of the SWWs palaeoenvironmental data sets must be generated from climate sensitive proxies with sites located in regions that are responsive to changes in effective moisture. Here we present a c. 15,700 yr-old record from a peat bog at Punta Arenas (53°09′S) which was analysed for pollen, pollen preservation, charcoal and organic content to reconstruct changes in the surrounding vegetation, fire history and mire surface wetness. The peat bog lies in a closed basin and so environmental changes likely reflect changes in effective moisture primarily driven by fluctuations in precipitation. During the Late glacial the landscape was virtually treeless and dominated by cold-tolerant steppe/tundra vegetation. This was followed by substantial vegetation changes as Nothofagus woodland expanded and the local site transitioned from a small lake to a fen and later a raised mire. The Early and Mid-Holocene (11,600–6000 cal a BP) was marked by a period of sustained drier conditions evidenced by reduced pollen preservation and increased fire activity. After c. 4600 cal a BP there was a shift to increased effective moisture superimposed with higher magnitude and higher frequency changes in precipitation. The palaeoenvironmental record presented here is used to better define the nature and timing of latitudinal shifts in the position of the SWWs. Careful interpretation of the Nothofagus pollen signal is required as during drier periods small increases in humidity can drive large woodland responses in the pollen record while during periods of higher humidity the woodland may appear to be unresponsive to climatic changes.

Pollen and Flora as Bioindicators in Assessing the Status of Polluted Sites: The Case Study of the Mantua Lakes (SIN “Laghi di Mantova e Polo Chimico”; N Italy)

An integrated floristic and palynological approach was carried out at the site of national interest “Laghi di Mantova e Polo Chimico” to obtain an environmental assessment useful for monitoring polluted sites. The flora of highly contaminated sectors (area A and area B) was surveyed, and the floristic composition and ecological strategies of the species were compared with a control sector (area C). A total of 195 species were observed in the three sectors. Pollen preservation of six selected species was checked as a bioindicator of environmental health in the same sectors. Area A and area B likely share similar environmental pressures, including anthropogenic stressors such as pollution, geographical proximity and a similar set of habitats, leading to similarities in flora composition. Similarly, the incidence of pollen without cytoplasm is higher in area A (9.3%) and area B (7.6%) than in area C (2.5%). The floristic differences among the sectors and the quantity of empty or abnormal pollen, together with the CSR strategies adopted by the species, suggest that the effects of anthropogenic impact on local vegetation can be detected at both macroscopic and microscopic levels. The discovery of the protected species Narcissus pseudonarcissus in area C is noteworthy, which may be important in directing efforts towards the protection of plant communities in this sector.

The distribution of fossil pollen and charcoal in stalagmites

AbstractPollen preserved in caves provides a little-appreciated opportunity to study past vegetation and climate changes in regions where conventional wetland sediments are either unavailable, contain little organic matter, and/or are difficult to date accurately. Most palynology in caves has focused on clastic infill sediments, but pollen preserved in growing speleothems provides important new opportunities to develop vegetation and climatic records that can be dated accurately with radiometric methods. However, when pollen is present in speleothems, concentrations can vary by orders of magnitude, highlighting how little we know about the processes that transport pollen into caves and onto speleothem surfaces, and that determine the pollen's preservation probability. To explore these aspects of speleothem pollen taphonomy, we investigated the distribution of pollen and microscopic charcoal within several stalagmites from southwest Australia. We examined spatial patterns in pollen and charcoal preservation in order to distinguish whether observed gradients result from preservation or are products of systematic transport processes working along stalagmite surfaces. We find that pollen grains and charcoal fragments are located preferentially on the flanks of most stalagmites. This suggests that pollen grain and charcoal deposition on speleothems is influenced by transport and accumulation of detrital debris on growing surfaces. These insights will assist in future sampling campaigns focusing on speleothem pollen and charcoal contents.

A simple and efficient method for onion pollen preservation: Germination, dehydration, storage conditions, and seed production

The preservation of viable pollen is essential to overcome the problems related to the asynchronous flowering of the parental lines in onion hybrid breeding programs. The aim of this study was to establish a simple, inexpensive, and easily reproducible protocol for medium-term onion pollen storage. First, the conditions for assessing the in vitro pollen germination were optimized. The liquid medium favored the counting of germination of pollen grains in comparison to the solid medium. The addition of 75 mg/l Ca(NO3)2. 4H2O to the medium did not improve pollen germination, while that of 150 mg/l Ca(NO3)2. 4H2O inhibited pollen germination. The highest germination percentage was achieved by incubation at 30–35 °C in the dark. Second, fresh or dehydrated pollen (maintained in a desiccator with silica gel at 25 °C for 18 h) was stored at 4, –20, and –80 °C for two years to study pollen preservation. In addition, the viability and germination capacity of stored pollen were periodically evaluated at 0, 15 and 30 days; 2 and 6 months; and 1 and 2 years. Pollen viability was best retained at low relative humidity and temperatures below zero. Dehydration was essential for pollen preservation at –20 and –80 °C. The results showed that dehydrated pollen stored at –20 °C could be used, with guarantees, for pollination throughout the flowering season. However, the highest viability and in vitro germination percentages after two years of storage (29 and 32%, respectively) were achieved with dehydrated pollen stored at –80 °C. Finally, the capacity of stored pollen to produce seeds was confirmed in crosses with male sterile lines. In this way, dehydrated pollen stored at –80 °C for two years produced an average of 47.9 seeds/100 flowers, representing 43% of the seed in the control crosses. This is the first report in onion research of seed production after pollination with preserved pollen at –80 °C for two years.

Reworked pollen reduces apparent floral change during the Paleocene-Eocene Thermal Maximum

Abstract Plant megafossils from the Paleocene-Eocene Thermal Maximum (PETM) in the Bighorn Basin, north-central Wyoming, USA, document a dramatic shift in floral composition, whereas palynofloral change from the same sections has appeared to be more subtle. We investigated this discrepancy by quantifying pollen preservation and measuring the stable carbon isotope composition of specific pollen taxa. Pollen grains belonging to two common latest Paleocene taxa are poorly preserved in PETM samples, and their δ13Cpollen is similar during the latest Paleocene and PETM. In contrast, pollen grains of a thermophilic taxon that became more abundant during the PETM are pristine, and the δ13Cpollen of PETM specimens is ∼4‰ lower than that of latest Paleocene specimens. More broadly, pollen grains belonging to lineages currently centered in temperate climates are poorly preserved when found in PETM samples, whereas in the same samples, pollen belonging to lineages now centered in the tropics are well preserved. These differences in preservation and isotopic composition indicate extensive redeposition of older pollen grains during the PETM. Increased abundance of Cretaceous palynotaxa in PETM samples confirms erosion and redeposition, likely resulting from more episodic and intense precipitation. Exclusion of reworked palynotaxa from analyses reveals that, as in the megaflora, temperate taxa were absent during the PETM at the time when dry tropical taxa briefly appeared. Major climate changes like the PETM may commonly destabilize landscapes, increase reworking, and thus smooth patterns of change in microfloras, leading to underestimates of the rate and magnitude of floral response to past global change.

Holocene upland and wetland dynamics in the Chihuahuan Desert, Cuatrociénegas Mexico

The Cuatrociénegas Basin, Coahuila MX, has the highest rate of endemism in North America and has been the source of a rich aridlands, paleoenvironmental history in the Chihuahuan Desert of North America. Understanding the recent past of the Cuatrociénegas Basin contextualizes how aridland terrestrial and wetland systems may respond to ongoing climate warming and the potential aridification in already water-limited regions. A 12.3 m long sediment core dated to ~13,500 cal yr BP was collected from Poza Cortador and examined for pollen to reconstruct the Holocene terrestrial and wetland history of the Basin. The terrestrial record indicates a transition from woodland to desert environments by ~7500 cal yr BP. This transition is characterized more by the decrease in conifer and oak pollen abundances relative to desert taxa rather than a sudden appearance of new pollen types. Wetlands appear more stable than the terrestrial record, possibly because of groundwater buffering of the wetland surface. Alternatively, there might be less obvious changes because of the overall pollen diversity of identified wetland pollen types selected in this study. Significant aridity in both the terrestrial and wetland environments is inferred between 5000 and 3000 cal yr BP based on poor pollen preservation. The record of the last 3000 cal yrs reflects the resilience of both the terrestrial and wetland systems to prolonged drought and provides hope that this unique system may have resiliency to some aspects of future climate change if the hydrologic connectivity can remain intact.

Improving Ultra-Low Temperature Preservation Technologies of Soybean Pollen for Off-Season and Off-Site Hybridization.

Preserving viable pollen is of great interest to breeders to maintain desirable germplasm for future inbreeding. Ultra-low temperature preservation of pollen is an effective and safe way for long-term storage of plant germplasm resources. In this study, we improved methods for the preservation of soybean pollen at ultra-low temperature. Soybean flowers at the initially-open stage were collected at 6–10 a.m. during the fully-bloom stage of soybean plants and were dehydrated for 10 h and then frozen and stored at −196 or −80°C. In vitro culture experiments showed that the viability of preserved pollen remained as high as about 90%. The off-season (local site Heihe) and off-site (Beijing, after long-distance express delivery from Heihe) hybridization verification was conducted, and no significant difference in true hybrid rate was founded between the preserved pollen and the fresh pollen. The ultra-low temperature preservation technology for soybean pollen could break the spatiotemporal limit of soybean hybridization and facilitate the development of engineered soybean breeding.

Rose Pollen Management Methods to Improve Productivity

Roses are one of the most highly produced and purchased ornamental plants worldwide. Procurement and preservation of pollen is essential for the production of diverse rose varieties. In this study, we analyzed pollen management conditions, such as the pollen collection stage, drying time, and storage temperature, to determine optimal conditions for rose pollen management. Pollens were stored under different conditions and the pollen vitality and germination rate were investigated through an optical microscope. The vitality of pollen was an essential factor for rose breeding and depended on the storage conditions. Collecting pollen in the seventh flowering stage resulted in a relatively higher pollen yield. Drying the flower for 5 h after the anther opened improved pollen germination. The germination rate of freshly collected pollen was similar to that of pollen stored at temperatures between −20 °C and −72 °C for up to 30 days, indicating the efficacy of pollen storage at sub-zero temperatures. Since the rate of fruiting increases when pollination is performed three times, considering the time and cost of breeding, it is appropriate to pollinate three times to increase the number of seeds. This study provides an efficient pollen management method to collect and store pollen for breeding.

Paleoenvironment reconstruction and peat-forming conditions of Neogene paralic coal sequences from Mukah, Sarawak, Malaysia

Eight coal seams containing Neogene paralic coals from the Mukah coalfield, Sarawak, Malaysia, were investigated using petrographical, palynological, and organic geochemical analyses to describe coal-forming vegetation, paleoclimatic, and paleoenvironment conditions during peat development and precursor mires, as well as their associations within a sequence-stratigraphic context. The petrographic and geochemical data of the coals imply the existence of oxygen-deficient and water-saturated conditions in the precursor mires. The reducing conditions in the mires were followed by biomass loss. The Mukah coals are suggested to be deposited in freshwater peat swamps, and the rich preservation of angiosperm pollen indicates that the organic matter in dense and lowland forest vegetation was mostly terrigenous. The overwhelming presence of Casuarina and Calamus types suggest the paleomires were closely linked to the Kerapah/Kerangas peat forest and were marginally bordered by rattan, which was supported by biomarker data. Rheotrophic–ombrotrophic mires temporarily formed due to water table fluctuations, which were strongly dependent on ever-wet climate changes and syn-depositional tectonics during the Neogene, and resulted in the balanced to high peat accumulation and preservation. A maximum thickness of 35 m of peat deposits is suggested to form between 10,000 and 175,000 years ago based on the peat:coal ratio. The coals are proposed to be influenced by transgressive to initial highstand cycles within the paralic setting.