Positive effects of night warming on physiology of coniferous trees in late growing season: Leaf and root

Previous studies about the effects of experimental warming on tree species have focused primarily on response of morphology and physiology in leaf and biomass allocation in the growing season, and a few studies considered the importance of roots. Based on the available evidence, it is unclear whether photosynthesis rate is enhanced by night warming in late autumn an issue that deserves further investigation. Thus, we exposed two coniferous species, Picea asperata and Abies faxoniana, to night warming continued throughout the year to investigate morphological and physiological responses of roots and leaves in the autumn. The results showed that night warming caused significant increases in net influxes of NH₄⁺ and NO₃⁻ in P. asperata seedlings corresponding well with net H⁺ efflux and net influx of O₂. Meanwhile, night warming had a positive effect on foliar gas exchange such as net photosynthesis rate, apparent quantum efficiency, dark respiration rate and maximum quantum efficiency of PS II, and nitrate reductase activity of roots. Additionally, root morphology such as total roots length, surface area, specific root area and specific root length was also stimulated by night warming. In contrast, night warming decreased concentrations of non-structural carbohydrate in leaves and roots of both species in autumn. The present study demonstrates that night warming would enhance late autumn leaf photosynthetic rate, and increase N uptake capacity of roots.     

Blooming rhythms of cactus Cereus peruvianus with nocturnal peak at full moon during seasons of prolonged daytime photoperiod

Cereus peruvianus (Peruvian apple cactus) is a large erect and thorny succulent cactus characterized by column-like (cereus [L]: column), that is, candle-shaped, appendages. For three successive years (1100 days), between early April and late November, we studied the flowering patterns of eight cacti growing in public gardens and rural areas of north and central Tunisia, far from nighttime artificial illumination, in relation to natural environmental light, temperature, relative humidity and precipitation parameters. Flower blooming was assessed nightly between 23:00 h and until at least 02:00 h, and additionally around-the-clock at ~1 h intervals for 30 consecutive days during the late summer of each year of study to quantify both nyctohemeral (day–night) and lunar patterns. During the summer months of prolonged daytime photoperiod, flower blooming of C. peruvianus exhibited predictable-in-time variation as “waves” with average period of 29.5 days synchronized by the light of the full moon. The large-sized flower (~16 cm diameter) opens almost exclusively at night, between sunset and sunrise, as a 24 h rhythm during a specific 3–4-day span of the lunar cycle (full moon), with a strong correlation between moon phase and number and proportion of flowers in bloom (ranging from r = +0.59 to +0.91). Black, blue and red cotton sheets were used to filter specific spectral bands of nighttime moonlight from illuminating randomly selected plant appendages as a means to test the hypothesis of a “gating” 24 h rhythm phenomenon of photoreceptors at the bud level. Relative to control conditions (no light filtering), black sheet covering inhibited flower bud induction by 87.5%, red sheet covering by 46.6% and blue sheet covering by 34%, and the respective inhibiting effects on number of flowers in bloom were essentially 100%, ~81% and ~44%. C. peruvianus is a unique example of a terrestrial plant that exhibits a circadian flowering rhythm (peak ~00:00 h) “gated” by 24 h, lunar 29.5-day (bright light of full moon) and annual 365.25-day (prolonged summertime day length) environmental photoperiod cycles.     

Laboratory rearing of wild Arctic cod Boreogadus saida from egg to adulthood

The techniques and protocols used to successfully capture, transport and breed Arctic cod Boreogadus saida, as well as to rear their larvae through to adulthood are summarized. Breeding B. saida will increase the opportunity to study this fish species, which is a critical part of the Arctic food web.     

Host-independent artificial rearing of Eucryptorrhynchus brandti (Coleoptera: curculionidae)†

Eucryptorrhynchus brandti (Harold) is a trunk boring pest of Ailanthus altissima in China and is a potential biological control agent for invasive A. altissima in the USA. In this study, we developed a host-independent artificial rearing method for E. brandti adults and larvae, including fresh thin slices of potato for adults and a potato-based diet (referred to as diet 6) for larvae. Adults reared on thin slices of potato oviposited normally and larvae reared on diet 6 exhibited successful pupation and eclosion and short developmental duration. The rates of larval survival, pupation, and adult emergence were 63.3?±?0.26, 86.7?±?0.42, and 93.5?±?0.33%, respectively. This method could be used for the mass rearing of E. brandti.     

臭椿种子萌发最适条件研究

采用不同浓度赤霉素(GA3)处理臭椿种子,在不同温度及不同光照条件下,研究了GA3、温度及光照对臭椿种子萌发的影响。结果表明,40 mg.L-1的GA3质量浓度、30℃温度以及自然光暗交替处理为臭椿种子萌发的最适条件,臭椿属于喜高温型种子。     

Soil preferential flow in the dark coniferous forest of Gongga Mountain based on the kinetic wave model with dispersion wave (KDW preferential flow model)

Based on the law of soil water movement in unsaturated zones, the study discusses the effect of preferential flow on the movement of the researched soil through a soil column experiment using homemade experimental apparatus in four successive stages—young, middle-aged, mature and over-mature and combining dye-tracer analyses of the field process. The study proves that the preferential flow occurs in the area, and as indicated by the Reynolds numerical calculation of the preferential flow path in the 4 different successive stages, the preferential flow in the Gongga Mountain forest ecosystem is a transition flow between the laminar flow and the turbulent flow. By applying the kinetic wave model with dispersion wave (KDW preferential flow model) and comparing this model with the field experiment, the study finds that the preferential flow model has good practicability and high credibility. Verifying the KDW preferential flow model through statistic analysis indicates that the model can simulate the water movement in columns very well and the results are better in low rainfall than in high rainfall.     

A new measurement technique reveals rapid post-illumination changes in the carbon isotope composition of leaf-respired CO2

We describe an open leaf gas exchange system coupled to a tunable diode laser (TDL) spectroscopy system enabling measurement of the leaf respiratory CO(2) flux and its associated carbon isotope composition (delta(13)C(Rl)) every 3 min. The precision of delta(13)C(Rl) measurement is comparable to that of traditional mass spectrometry techniques. delta(13)C(Rl) from castor bean (Ricinus communis L.) leaves tended to be positively related to the ratio of CO(2) produced to O(2) consumed [respiratory quotient (RQ)] after 24-48 h of prolonged darkness, in support of existing models. Further, the apparent fractionation between respiratory substrates and respired CO(2) within 1-8 h after the start of the dark period was similar to previous observations. In subsequent experiments, R. communis plants were grown under variable water availability to provide a range in delta(13)C of recently fixed carbohydrate. In leaves exposed to high light levels prior to the start of the dark period, CO(2) respired by leaves was up to 11 per thousand more enriched than phloem sap sugars within the first 10-15 min after plants had been moved from the light into the dark. The (13)C enrichment in respired CO(2) then decreased rapidly to within 3-7 per thousand of phloem sap after 30-60 min in the dark. This strong enrichment was not observed if light levels were low prior to the start of the dark period. Measurements of RQ confirmed that carbohydrates were the likely respiratory substrate for plants (RQ > 0.8) within the first 60 min after illumination. The strong (13)C enrichment that followed a high light-to-dark transition coincided with high respiration rates, suggesting that so-called light-enhanced dark respiration (LEDR) is fed by (13)C-enriched metabolites.     

Multispectral imaging for quality control of laboratory‐reared Anastrepha fraterculus (Diptera: Tephritidae) pupae

The sterile insect technique (SIT) has been widely used to suppress several fruit fly species. In southern Brazil, millions of sterile flies of the South American fruit fly, Anastrepha fraterculus Wiedemann (Dipetra: Tephritidae), will be produced in a mass‐rearing facility called MOSCASUL to suppress wild populations from commercial apple orchards. In spite of standard rearing conditions, the quality of pupal batches can be inconsistent due to various factors. The quantification of poor quality material (e.g. empty pupae, dead pupae or larvae) is necessary to track down rearing issues, and pupal samples must be taken randomly and evaluated individually. To speed up the inspection of pupal samples by replacing the manual testing with the mechanized one, this study assessed a multispectral imaging (MSI) system to distinguish the variations in quality of A. fraterculus pupae and to quantify the variations based on reflectance patterns. Image acquisition and analyses were performed by the VideometerLab4 system on 7‐d‐old pupae by using 19 wavelengths ranging from 375 to 970 nm. The image representing the near infrared wavelength of 880 nm clearly distinguished among high‐quality pupae and the other four classes (i.e. low‐quality pupae, empty pupae, dead pupae and larvae). The blind validation test indicated that the MSI system can classify the fruit fly pupae with high accuracy. Therefore, MSI‐based classification of A. fraterculus pupae can be used for future pupal quality assessments of fruit flies in mass‐rearing facilities.     

A comprehensive time‐course metabolite profiling of the model cyanobacterium Synechocystis sp. PCC 6803 under diurnal light:dark cycles

Cyanobacteria are a model photoautotroph and a chassis for the sustainable production of fuels and chemicals. Knowledge of photoautotrophic metabolism in the natural environment of day/night cycles is lacking, yet has implications for improved yield from plants, algae and cyanobacteria. Here, a thorough approach to characterizing diverse metabolites—including carbohydrates, lipids, amino acids, pigments, cofactors, nucleic acids and polysaccharides—in the model cyanobacterium Synechocystis sp. PCC 6803 (S. 6803) under sinusoidal diurnal light:dark cycles was developed and applied. A custom photobioreactor and multi‐platform mass spectrometry workflow enabled metabolite profiling every 30–120 min across a 24‐h diurnal sinusoidal LD (‘sinLD’) cycle peaking at 1600 μmol photons m^?2 sec^?1. We report widespread oscillations across the sinLD cycle with 90%, 94% and 40% of the identified polar/semi‐polar, non‐polar and polymeric metabolites displaying statistically significant oscillations, respectively. Microbial growth displayed distinct lag, biomass accumulation and cell division phases of growth. During the lag phase, amino acids and nucleic acids accumulated to high levels per cell followed by decreased levels during the biomass accumulation phase, presumably due to protein and DNA synthesis. Insoluble carbohydrates displayed sharp oscillations per cell at the day‐to‐night transition. Potential bottlenecks in central carbon metabolism are highlighted. Together, this report provides a comprehensive view of photosynthetic metabolite behavior with high temporal resolution, offering insight into the impact of growth synchronization to light cycles via circadian rhythms. Incorporation into computational modeling and metabolic engineering efforts promises to improve industrially relevant strain design.