Terms Of Phenology Research Articles

The Co-occurrence Matrix and the Correlation Network of Phytophagous Insects Are Driven by Abiotic and Biotic Variables: the Case of Canola.

Co-occurrence a correlation profiles are driven by different factors (exogenous and endogenous) and drawing a profile of association between species based on co-occurrence, without assessing how these species vary in terms of ecological niche can lead to wrong conclusions. The objective was to determine the co-occurrence and correlation patterns of phytophagous insects in canola crop and to evaluate how these patterns varied according to the crop stage (phenology-biotic) and sowing times (agricultural practice-abiotic). We found that the patterns of co-occurrence and correlation between species were reflections of population variations due to the phenology and sowing times of canola. Variations in the multi-species abundance matrix were influenced by mean air temperature and accumulated rainfall. The main species associated with canola in southern Brazil, in terms of abundance, were P. xylostella, D. speciosa, and N. viridula. These species were mostly negatively associated. When evaluating their population variations, we found that they explore different temporal niches, whether in terms of phenology or sowing times. Finally, we demonstrate empirically that despite being important, association patterns based on co-occurrence and correlation should be interpreted in light of the understanding of patterns of niche exploitation and temporal variation of species.

Phenology, production, and fruit quality of blackberry cultivars under greenhouse in southern Brazil

Knowing the phenology, production, and fruit quality of blackberry cultivars grown in greenhouses enables growers to develop and/or improve assertive orchard management. The aim of this study was to investigate whether phenology, production, and fruit quality differ among blackberry cultivars grown under greenhouse. The treatments were four blackberry cultivars (‘BRS Cainguá’, ‘BRS Tupy’, ‘BRS Xavante’, and ‘BRS Xingu’), arranged in a randomized block design, with four replications and three plants per plot. Phenology, production, and fruit quality were assessed. ‘BRS Xingu’ had an earlier start than all the phenological stages assessed, proving to be the earliest to achieve fruit harvest stage. ‘BRS Cainguá’ was the latest to harvest. ‘BRS Xingu’ showed the highest total production values, followed by ‘BRS Cainguá’, with the largest longitudinal diameter, and ‘BRS Tupy’, with the largest transverse diameter. Fruit quality was not influenced by the cultivars. In conclusion, the four blackberry cultivars differ in terms of phenology and fruit production potential under greenhouse. This allows production to be staggered around 15 days in terms of the start and end of the harvest.

Genetics and epigenetics of Pinus nigra populations with differential exposure to air pollution.

Forest species in the course of their evolution have experienced several environmental challenges, which since historic times include anthropogenic pollution. The effects of pollution on the genetic and epigenetic diversity in black pine (Pinus nigra) forests were investigated in the Amyntaio - Ptolemais - Kozani Basin, which has been for decades the largest lignite mining and burning center of Greece, with a total installed generating capacity of about 4.5 GW, operating for more than 70 years and resulting in large amounts of primary air pollutant emissions, mainly SO2, NOx and PM10. P. nigra, a biomarker for air pollution and a keystone species of affected natural ecosystems, was examined in terms of phenology (cone and seed parameters), genetics (283 AFLP loci) and epigenetics (606 MSAP epiloci), using two populations (exposed to pollution and control) of the current (mature trees) and future (embryos) stand. It was found that cone, seed, as well as genetic diversity parameters, did not show statistically significant differences between the exposed population and the control. Nevertheless, statistically significant differences were detected at the population epigenetic level. Moreover, there was a further differentiation regarding the intergenerational comparison: while the epigenetic diversity does not substantially change in the two generations assessed in the control population, epigenetic diversity is significantly higher in the embryo population compared to the parental stand in the exposed population. This study sheds a light to genome dynamics in a forest tree population exposed to long term atmospheric pollution burden and stresses the importance of assessing both genetics and epigenetics in biomonitoring applications.

The effects of heading time on yield performance and HvGAMYB expression in spring barley subjected to drought

In the lifetime of a plant, flowering is not only an essential part of the reproductive process but also a critical developmental stage that can be vulnerable to environmental stresses. To ensure survival during drought, plants accelerate the flowering process, and this response is known as “drought escape.” HvGAMYB—transcription factor associated, among others, with flowering process and anther development in barley—has also an important role in developmental modification and yield performance in plants subjected to stressed conditions. Due to the fact that information about the mechanisms associated both with the flowering acceleration and the anther or pollen disruption is limited, the exploration of the potential HvGAMYB role in flower development may shed light on pollen and spike morphology formations in plants grown under unfavorable water conditions. The aim of this study was to characterize differences in responses to drought among early- and late-heading barley genotypes. These two subgroups of plants—differentiated in terms of phenology—were analyzed, and traits linked to plant phenotype, physiology, and yield were investigated. In our study, the drought stress reactions of two barley subgroups showed a wide range of diversity in terms of yield performance, anther morphology, chlorophyll fluorescence kinetics, and pollen viability. The studied plants exhibited different yield performances under control and drought conditions. Moreover, the random distribution of genotypes on the biplot showing variability of OJIP parameters in the second developmental point of our investigation revealed that prolonged drought stress caused that among early- and late-heading plants, the studied genotypes exhibited different responses to applied stress conditions. The results of this study also showed that the HvGAMYB expression level was correlated positively with traits associated with lateral spike morphology in the second developmental point of this investigation, which showed that this association occurred only under prolonged drought and highlighted the drought stress duration effect on the HvGAMYB expression level.

Evaluation of ‘Alata Yıldızı’בBebeco’ apricot hybrids in terms of phenology, plant, and fruit quality characteristics

Amaç: Bu çalışma Alata Bahçe Kültürleri Araştırma Enstitüsü Müdürlüğü (Erdemli/Mersin) arazisinde bulunan kayısı ıslah parselindeki ‘Alata Yıldızı’בBebeco’ (AY×B) melezlerinin fenolojik, bitkisel ve meyve kalite özelliklerini incelemek amacıyla yürütülmüştür. Materyal ve Yöntem: Çalışmada, ‘Alata Yıldızı’ ve ‘Bebeco’ çeşitleri ile melezlerine ait 2017 yılında 18 birey ve 2018 yılında da 12 birey incelenmiştir. Ebeveynlerin ve melez bireylerin bitkisel özelliklerinin incelenmesinde UPOV tarafından hazırlanmış olan kayısı deskriptörü kullanılmıştır. Çalışmada ebeveyn ve melez bireylere ait fenolojik gözlemlerden ilk çiçeklenme, tam çiçeklenme, çiçeklenme sonu ve hasat tarihi, meyve kalite özellikleri ve meyve kabuk renk özellikleri L, a*, b*, C ve h° değerleri olarak ölçülmüştür. Araştırma Bulguları ve Tartışma: Çalışma sonucunda, AY×B5 ve AY×B11 melezleri meyvelerini 10 Mayıstan önce olgunlaştırarak erkencilik bakımından ümitvar bulunmuştur. Genel olarak, melezlerin ebeveynlerine ait fenolojik, bitkisel ve meyve kabuk renk özelliklerin sınıf aralıklarında yer almıştır. Ancak, hibritlerdeki meyve ağırlığının ebeveynlerdekine göre daha düşük olduğu belirlenmiştir. Sonuç: AYxB kombinasyonundan elde edilen erkenci genotiplerden daha iyi meyve rengi oluşturmak amacıyla bu genotiplerin kırmızı renkli çeşitlerle melezlenmeleri ve geriye melezleme çalışmalarının yapılabileceği düşünülmektedir.

Early or late? The role of genotype phenology in determining wheat response to drought under future high atmospheric CO2 levels.

The combination of a future rise in atmospheric carbon dioxide concentration ([CO2 ]) and drought will significantly impact wheat production and quality. Genotype phenology is likely to play an essential role in such an effect. Yet, its response to elevated [CO2 ] and drought has not been studied before. Here we conducted a temperature-controlled glasshouse [CO2 ] enrichment experiment in which two wheat cultivars with differing maturity timings and life cycle lengths were grown under ambient (aCO2 approximately 400 μmol mol-1 ) and elevated (eCO2 approximately 550 μmol mol-1 ) [CO2 ]. The two cultivars, bred under dry and warm Mediterranean conditions, were well-watered or exposed to drought at 40% pot holding capacity. We aimed to explore water × [CO2 ] × genotype interaction in terms of phenology, physiology, and agronomic trait response. Our results show that eCO2 had a significant effect on plants grown under drought. eCO2 boosted the booting stage of the late-maturing genotype (cv. Ruta), thereby prolonging its booting-to-anthesis period byapproximately 3 days (p < 0.05) while unaffecting the phenological timing of the early-maturing genotype (cv. Zahir). The prolonged period resulted in a much higher carbon assimilation rate, particularly during pre-anthesis (+87% for Ruta vs. +22% for Zahir under eCO2 ). Surprisingly, there was no eCO2 effect on transpiration rate and grain protein content in both cultivars and under both water conditions. The higher photosynthesis (and transpiration efficiency) of Ruta was not translated into higher aboveground biomass or grain yield, whereas both cultivars showed a similar increase of approximately 20% in these two traits at eCO2 under drought. Overall, Zahir, the cultivar that responded the least to eCO2, had a more efficient source-to-sink balance with a lower sink limitation than Ruta. The complex water × [CO2 ] × genotype interaction found in this study implies that future projections should account for multifactor interactive effects in modeling wheat response to future climate.

Climate change creates nutritional phenological mismatches

Climate change is creating phenological mismatches between consumers and their resources. However, while the importance of nutritional quality in ecological interactions is widely appreciated, most studies of phenological mismatch focus on energy content alone. We argue that mismatches in terms of phenology and nutrition will increase with climate change.

Toxic Impact of Soil Microplastics (PVC) on Two Weeds: Changes in Growth, Phenology and Photosynthesis Efficiency

Experimental evidence on the bio-ecological effects of microplastics on terrestrial plants is still lacking. In this study, we hypothesized that soil polluted with polyvinyl chloride (PVC) microparticles can negatively influence plant traits, photosynthetic efficiency and phenology of two weeds but with different strength in relation to the species’ life traits. Therefore, we conducted an experiment in a common garden growing the wild species Senecio inaequidens and Centaurea cyanus for about 60 days. The possible toxic effects of soil microplastics (1% of PVC in 100 g of soil medium) were investigated, coupling an analyses on plant traits with an evaluation of the microplastic-induced changes in terms of phenology and photosynthetic efficiency. Overall, results showed that plants in control pots were higher and larger than those in treated ones (C. cyanus plant width: p &lt; 0.05; S. inaequidens—plant height: p &lt; 0.05; plant width: p &lt; 0.05). Moreover, for C. cyanus, photosynthetic efficiency (index Fv/Fm) was significantly lower in the treatment than that in control (p &lt; 0.05). About phenology, the second leaf of S. inaequidens emerged earlier in control than that in treatments (day 12.2 ± 0.25 and 14.3 ± 0.3, respectively; p &lt; 0.001). The obtained results highlight that PVC microparticles may have had negative effects on soil–plant system reducing the performance of plants. Since, up to now, research on the interaction between soil microplastics and terrestrial plants has mainly focused on agricultural plants, this work fills a gap of knowledge regarding wild species (weeds), highlighting the possible future impact of microplastics on biodiversity.

Amplified Drought and Seasonal Cycle Modulate Quercus pubescens Leaf Metabolome.

The intensification of summer drought expected with climate change can induce metabolism modifications in plants to face such constraints. In this experiment, we used both a targeted approach focused on flavonoids, as well as an untargeted approach, to study a broader fraction of the leaf metabolome of Quercus pubescens exposed to amplified drought. A forest site equipped with a rainfall exclusion device allowed reduction of natural rainfall by ~30% over the tree canopy. Leaves of natural drought (ND) and amplified drought (AD) plots were collected over three seasonal cycles (spring, summer, and autumn) in 2013 (the second year of rain exclusion), 2014, and 2015. As expected, Q. pubescens metabolome followed a seasonal course. In the summer of 2015, the leaf metabolome presented a shifted and early autumnal pattern because of harsher conditions during this year. Despite low metabolic modification at the global scale, our results demonstrated that 75% of Quercus metabolites were upregulated in springs when trees were exposed to AD, whereas 60 to 73% of metabolites (93% in summer 2015), such as kaempferols and quercetins, were downregulated in summers/autumns. Juglanin, a kaempferol pentoside, as well as rhododendrin derivatives, were upregulated throughout the year, suggesting an antioxidant ability of these metabolites. Those changes in terms of phenology and leaf chemistry could, in the end, affect the ecosystem functioning.

Rootstock and potassium fertilization, in terms of phenology, thermal demand and chemical evolution, of berries on Niagara Rosada grapevine under subtropical conditions

This study aimed to assess the effect of rootstocks (IAC 572 and IAC 766) and potassium fertilization at different concentrations (0, 75, 150 and 300 kg·ha-1 K2O) on the phenology and thermal demand of the Niagara Rosada grapevine, and to evaluate the development of chemical traits during maturation stage. The length of the main phenological stages was recorded within two production seasons. Total thermal demand was calculated using the degree-day concept. The berries’ titratable acidity and soluble solids contents were determined during maturation. Results indicated that IAC 572 and IAC 766 rootstocks along with potassium fertilization had no influence on the phenological cycle or thermal demand of the Niagara Rosada grapevine. The production cycle lasted 144 to 148 days with thermal demands ranging from 1,465.2 to 1,615.1 degree-days. For better grape quality, i.e., with a balance between soluble solids and acidity levels, it is estimated that the grape harvest is carried out around 21 to 24 days after the veraison.

A process-based model reveals the restoration gap of degraded grasslands in Inner Mongolian steppe

Due to the influence of climate change and extensive grazing, a large proportion of steppe grassland has been degraded worldwide. The Chinese government initiated a series of grassland restoration programs to reverse the degradation. However, the limiting factors and the restoration potential remain unknown. Here we present a process-based model to assess the restoration gap (RG) defined as maximum biomass differences between non-degraded and degraded grasslands with different degrees of soil and vegetation degradation. The process-based model Agricultural Production Systems Simulator (APSIM) was evaluated utilizing observation data from both typical and meadow steppes under natural conditions in terms of phenology, dynamics of above-ground biomass and soil water content. Scenario analysis and sensitivity analysis were subsequently performed to address the RG and controlling factors during 1969–2018. The results showed that the calibrated model performed well with r > 0.75 and model efficiency factor EF > 0.5 for all the simulation components. According to our model results, the RG was larger in typical steppe compared to that of meadow steppe and it increased with increasing soil and/or vegetation degradation, to ~60% under extremely degraded scenarios. Both soil and vegetation degradation led to reduced water use efficiency, with an elevated proportion of soil evaporation to evapotranspiration (Es/ET), however, the limiting factor for RG varied. The degradation of soil water holding capacity contributed more to RG regardless of climate conditions for typical steppe in all years and for meadow steppe in dry years. In wet years the importance of vegetation coverage reduction increased for RG in meadow steppe, where the relative importance of vegetation coverage (valued at 62.8%) was 25.6% higher than that of soil degradation. Our results demonstrated the importance of considering climate variations when developing protection and restoration programs for grassland ecosystems.

Interactive effect of elevated tropospheric ozone and carbon dioxide on radiation utilisation, growth and yield of chickpea (Cicer arietinum L.).

An experiment was conducted in the Free Air Ozone and Carbon dioxide Enrichment (FAOCE) facility to study the impact of elevated O3, CO2 and their interaction on chickpea crop (cv. Pusa-5023) in terms of phenology, biophysical parameters, yield components, radiation interception and use efficiency. The crop was exposed to elevated O3 (EO:60ppb), CO2 (EC:550 ppm) and their combined interactive treatment (ECO: EC+EO) during the entire growing season. Results revealed that the crop's total growth period was shortened by 10, 14 and 17 days under elevated CO2, elevated O3 and the combined treatment, respectively. Compared to ambient condition, the leaf area index (LAI) under elevated CO2 was higher by 4 to 28%, whilst it is reduced by 7.3 to 23.8% under elevated O3. Theyield basedradiation use efficiency (RUEy) was highest under elevated CO2 (0.48 g MJ-1), followed by combined (0.41 g MJ-1), ambient (0.38 g MJ-1) and elevated O3 (0.32 g MJ-1) treatments. Elevated O3 decreased RUEy by 15.78% over ambient, and the interaction results in a 7.8% higher RUEy. The yield was 31.7% more under elevated CO2 and 21.9% lower in elevated O3 treatment as compared to the ambient. The combined interactive treatment recorded a higher yield as compared to ambient by 9.7%. Harvest index (HI) was lowest under elevated O3 (36.10%), followed by ambient (39.18%), combined (40.81%), and highest was under elevated CO2 (44.18%). Chickpea showed a positive response to elevated CO2 resulting a 5% increase in HI as compared to ambient condition. Our findings quantified the positive and negative impacts of elevated O3, CO2 and their interaction on chickpea and revealed that the negative impacts of elevated O3 can be compensated by elevated CO2 in chickpea. This work promotes the understanding of crop behaviour under elevated O3, CO2 and their interaction, which can be used as valuable inputs for radiation-based crop simulation models to simulate climate change impact on chickpea crop.

Evaluation of Habanero Pepper (Capsicum chinense Jacq.) Varieties under Shade House Conditions in Yucatan, Mexico

Habanero pepper (HP) is the main emblematic horticultural species of the Yucatan Peninsula in Mexico and it is highly valuable for commercial purposes. Since the Yucatan Peninsula has been qualified by official instances with the Denomination of Origin, a very promising horizon is opened for new varieties to be demanded by the local and abroad commercial markets. Nowadays all varieties are being produced under open field conditions but its agronomic and qualified behaviour has never been evaluated under shade house production systems. Keeping in mind the foregoing, the Jaguar (Ja), Mayapan (Ma) and Calakmul (Ca) varieties were evaluated and compared with a control, the Rey Pakal (RP) hybrid during the Fall-Winter season. A 1200 m2 shade house was used, covered with a white mesh with a density of 52 × 25 threads/square inch. RP and Ma reached the highest height (68.29 and 63.14 cm) and stem diameter (4.48 and 4.46 cm), compared to the rest of the evaluated varieties (Ca and Ja). A greater precocity is projected in Ca and RP to set flower buds, flowers and fruits than in Ja and Ma. In general, flower buds setting was recorded between 23.4 and 25.6 days after transplanting (DAT), flowering was from 30.3 to 40.5 DAT and the fruit set from 42.2 to 45.3 DAT. The four genetic materials had a similar behavior in terms of phenology. RP (hybrid) and Ma (Variety) showed the higher yields.

Sentinel-2 Satellite Imagery for Agronomic and Quality Variability Assessment of Pistachio (Pistacia vera L.)

The objective of this work is to evaluate the agronomic, phenological, nutritional quality and organoleptic characteristics of pistachios (Pistacia vera L.) based on the NDVI (Normalized Difference Vegetation Index) calculated in the phenological stage of nut filling from Sentinel satellite imagery. Based on this index, three pistachio tree orchards were studied and classified into two levels of vigour: high and low. The results obtained have discriminated the production per tree, which is strongly related to yield. Regarding the nutritional quality parameters, significant differences were not observed between vigour levels, although the most vigorous trees have shown nuts with a higher percentage of fibre and protein. In terms of phenology, there have not been differences between trees of different vigour, only a slight advance of some phenological stages has been observed in several high-vigour trees. Triangular tests have been made successfully to discriminate the origin of the dry nut and the vigour of the trees. In conclusion, for a given nut quality within a given orchard, the NDVI is a good index to classify different areas according to productive capacity and can be useful to apply variable management, irrigation and fertilization according to vigour.

Best environmental predictors of breeding phenology differ with elevation in a common woodland bird species.

Temperatures in mountain areas are increasing at a higher rate than the Northern Hemisphere land average, but how fauna may respond, in particular in terms of phenology, remains poorly understood. The aim of this study was to assess how elevation could modify the relationships between climate variability (air temperature and snow melt‐out date), the timing of plant phenology and egg‐laying date of the coal tit (Periparus ater). We collected 9 years (2011–2019) of data on egg‐laying date, spring air temperature, snow melt‐out date, and larch budburst date at two elevations (~1,300 m and ~1,900 m asl) on a slope located in the Mont‐Blanc Massif in the French Alps. We found that at low elevation, larch budburst date had a direct influence on egg‐laying date, while at high‐altitude snow melt‐out date was the limiting factor. At both elevations, air temperature had a similar effect on egg‐laying date, but was a poorer predictor than larch budburst or snowmelt date. Our results shed light on proximate drivers of breeding phenology responses to interannual climate variability in mountain areas and suggest that factors directly influencing species phenology vary at different elevations. Predicting the future responses of species in a climate change context will require testing the transferability of models and accounting for nonstationary relationships between environmental predictors and the timing of phenological events.

Drought tolerance is determined by species identity and functional group diversity rather than by species diversity within multi-species swards

Abstract Low-input grasslands depend on the presence of grasses and legumes for the provision of nitrogen and a sufficient amount and quality of herbage for livestock. Increasing variability in the amount and distribution of rainfall, associated with climate change, is a major factor affecting production from permanent grassland and particularly grass-clover swards. Previous work has shown that introduction of deep-rooting dicotyledonous forbs into grass-legume mixtures increases functional trait diversity (FTD), which facilitates the resistance and resilience of grassland to drought. It also increases species diversity and functional group diversity (FGD). However, the role of species diversity at a given level of FGD and associated FTD for the resistance and resilience of low-input grassland towards drought remains unclear. This knowledge is required to design forage mixtures adapted to drier climatic conditions. We conducted a drought-stress experiment with 16 different sown sward types, grown in cylindrical mesocosms, combining three levels of species diversity (one, three, five) and three levels of FGD (one, two, three) all being associated with FTD in terms of phenology, rooting depth and nitrogen fixation to determine whether maximum levels of species diversity or FGD promote adaptation to drought. The study was conducted over three drought-stress cycles in an open-sided greenhouse where the climate followed ambient natural conditions. Over the duration of 685 days, we found no clear species diversity effect but a distinct species identity effect on biomass production and agronomic water use efficiency. A positive species identity effect depended largely on white clover presence and on the FGD within mixtures. The best performing mixtures for resistance and resilience combined FGD and FTD in a complementary way, irrespective of whether the swards contained three or five species, as FGD and FTD were already maximized within the best-performing three-species swards. Increasing complementarity of traits by species grown in carefully designed mixtures is one measure to achieve diversity effects and facilitate future sustainable grassland production. We propose to exploit the benefits of species identity and functional group diversity in designing future mixtures to cope with drought.

Adaptation of common bean lines to high temperature conditions: genotypic differences in phenological and agronomic performance

The common bean is the most important legume for human consumption and is grown in areas under conditions of varied rainfall and temperature that limit its yield. The objective of the present study was to identify genotypic differences in adaptation of 91 bean genotypes to high temperature under environmental conditions of a tropical dry forest ecosystem. We quantified differences among genotypes in terms of phenology, dry matter partitioning indices and grain yield. Common bean lines were derived from interspecific and intraspecific crosses among Phaseolus species of P. vulgaris, P. acutifolius, P. coccineus and P. dumosus. We identified three germplasm accessions of P. acutifolius (G 40001, G 40027, G 40141); two lines from the cross of P. vulgaris × P. acutifolius (INB 837, SIN 524); two lines from the cross of P. vulgaris × P. acutifolius × P. coccineus (SEF 14, SEF 42) and eight lines of P. vulgaris (BFS 10, SEN 46, SEN 48, SEN 70, SMN 99, SMC 140, SMR 139-1G, AMADEUS-EAP-9510-77) that are better adapted to higher temperature stress conditions, evidencing the significant contribution of P. acutifolius to heat tolerance derived from interspecific crosses in common beans. We also found a few Andean lines of growth habit I (SAP 1, SAP 1-15, SAP 1-16, G 122, SAB 618, DAB 525) with superior level of adaptation to heat stress. The superior performance of all these above identified genotypes under higher temperature conditions was attributed to early maturity, high pollen viability and greater ability to partition dry matter to reproductive growth together with greater grain filling.

Advances in phenology and harvest characterization of the Chilean Vitis sp. germplasm collection and its use in table grape breeding

Germplasm collection and characterization is essential for plant breeding. Chile holds a collection of 347 Vitis accessions at Instituto de Investigaciones Agropecuarias, La Platina, that have been successfully used to develop new table grape cultivars such as Maylen®. Located in the central valley of Chile, a section of the Vitis collection was characterized for two consecutive seasons for phenology as well as fruit quality parameters at harvest. In terms of phenology, the collections can be grouped in four main clusters, with a higher representation of individuals at the middle and late timing. Fruit phenotyping showed significant differences among wine and table grapes for cluster and berry weight, seed number and fresh seed weight, polar and equatorial diameters, as well as the ratio among these parameters. Interestingly, rachis weight, a novel parameter associated with fruit storage capacity, did not show differences among groups. Other novel traits, such as the combination of commercial seedleesness and berry equatorial diameters above 2cm were less represented, suggesting the need to create and introduce genetic variability for table grape breeding purposes.

The power of numbers: dynamics of hatching and dormant egg production in two populations of the water flea Daphnia magna

Many organisms that live in inland standing waters produce dormant life stages that can accumulate in propagule banks to survive temporarily unfavourable periods. These egg banks have important effects on the ecology of populations and communities in terms of phenology, population densities, the probability of extinction, species diversity and habitat connectivity in time and space. They also have important consequences for the evolutionary versatility of populations. Although diapause and dormant egg banks in freshwater zooplankton have been studied for several decades, little is known about the quantitative contribution of egg production and hatching to yearly egg bank budgets and their seasonality in natural ponds and lakes. Here we quantified inter- and intra-annual variation in hatching and dormant egg production in the water flea Daphnia magna in two natural shallow ponds in Flanders (Belgium) using high-intensity sampling and in situ measurements. Hatching started in spring and occurred in several bouts (April–July), accumulating to a yearly average total of 3.5 × 103 hatchlings m−2. Dormant egg production occurred in one-to-three bouts mainly during late spring and summer (May–August), resulting in a total yearly production ranging from 1.2 × 104 up to 17.3 × 104 ephippia m−2. In both years, there was an average surplus of 3.14 × 104 and 15.24 × 104 ephippia produced m−2 for ponds OM2 and OM3, respectively, contributing to the accumulation of the persistent egg bank. We discuss the ecological and evolutionary consequences of both the high number of ephippia that are produced and the high number of hatchlings at the start of each growing season.

Causal relationships of Raphidiopsis (formerly Cylindrospermopsis) dynamics with water temperature and N:P-ratios: A meta-analysis across lakes with different climates based on inferential modelling

Raphidiopsis raciborskii is a tropical toxic cyanobacterium that is rapidly expanding to diverse lake habitats in different climate zones by sophisticated adaptation mechanisms.This meta-analysis investigated correlations of R. raciborskii with water temperature and N:P (nitrogen to phosphorus)-ratios across four lakes with different climates and trophic states by means of long-term time series and the hybrid evolutionary algorithm HEA. The results have shown that in the lakes with temperate and Mediterranean climate, R. raciborskii is strongly correlated with water temperature since germination and growth rely on rising water temperatures in spring. In contrast, there was a weaker correlation with water temperature in subtropical and tropical lakes where pelagic populations of R. raciborskii are overwintering, and are present all year round. However, the highest abundances of R. raciborskii coincided with highest water temperature for the Mediterranean, subtropical and tropical lakes, whilst in the temperate Langer See the highest abundances of R. raciborskii occurred at 24.1 °C, even though temperatures of up to 27 °C were recorded in 2013 and 2014. The correlation of R. raciborskii with N:P-ratios proved to be strongest for the meso- to eutrophic Lake Kinneret (r2 = 0.8) and lowest for the eutrophic Lake Paranoa (r2 = 0.16). However, the assumption has been confirmed that R. raciborskii is growing fastest when waters are N-limited regardless of trophic states. In terms of phenology, the temperate and Mediterranean lakes displayed “fastest growth” in spring and early summer. In contrast, the growing season in subtropical and tropical lakes lasted from spring to autumn most likely because of overwintering populations, and growing importance of direct and indirect biotic regulating factors such as competition, grazing, remineralisation of nutrients along warming climate. In order to carry out a meta-analysis of time series across four different lakes, HEA served as powerful tool resulting in inferential models with predictive capacity for population dynamics of R. raciborskii just driven by water temperature or N:P-ratios, whilst coefficients of determination r2 served as criteria for hypotheses testing.