Soybean (Glycine max (L.) Merr.) Yield Reduction due to Late Sowing as a Function of Radiation Interception and Use in a Cool Region of Northern Japan

Yields decrease when soybean is sown later than recommended in the cool climate of the Tohoku region of Japan. However, the factors responsible for this decrease are not fully understood. We investigated the effects of late sowing on growth, phenological development, yield, yield components, and radiation interception of three soybean cultivars in two consecutive years and analyzed the relationships of those variables with temperature and soil volumetric moisture content (SMC). Averaged across years and cultivars, yields decreased significantly when plants were sown approximately three weeks late. Yield reductions were partially due to reductions in node number per plant, dry matter production, and capture of cumulative irradiance, resulting from slowed canopy development during vegetative and early reproductive stages. The number of seeds per pod was one of the major determinants of the variation in yield. Owing to the delay in sowing date, the reduction in seeds per pod was likely due to low temperatures during the 20 days after seed filling began. Occasional lower SMC during reproductive stages did not affect yield, yield components, and growth parameters. However, these results were obtained from the two years’ experiments. Therefore, further investigations of the relationship of yield with temperature and SMC under different years and sites are needed.

Characterization of novel regulators for heat stress tolerance in tomato from Indian sub-continent

The footprint of tomato cultivation, a cool region crop that exhibits heat stress (HS) sensitivity, is increasing in the tropics/sub-tropics. Knowledge of novel regulatory hot-spots from varieties growing in the Indian sub-continent climatic zones could be vital for developing HS-resilient crops. Comparative transcriptome-wide signatures of a tolerant (CLN1621L) and sensitive (CA4) cultivar-pair short-listed from a pool of varieties exhibiting variable thermo-sensitivity using physiological, survival and yield-related traits revealed redundant to cultivar-specific HS-regulation with more up-regulated genes for CLN1621L than CA4. The anatgonisiticly-expressing genes include enzymes; have roles in plant defense and response to different abiotic stresses. Functional characterization of three antagonistic genes by overexpression and TRV-VIGS silencing established Solyc09g014280 (Acylsugar acyltransferase) and Solyc07g056570 (Notabilis), that are up-regulated in tolerant cultivar, as positive regulators of HS-tolerance and Solyc03g020030 (Pin-II proteinase inhibitor), that is down-regulated in CLN1621L, as negative regulator of thermotolerance. Transcriptional assessment of promoters of these genes by SNPs in stress-responsive cis-elements and promoter swapping experiments in opposite cultivar background showed inherent cultivar-specific orchestration of transcription factors in regulating transcription. Moreover, overexpression of three ethylene response transcription factors (ERF.C1/F4/F5) also improved HS-tolerance in tomato. This study identifies several novel HS-tolerance genes and provides proof of their utility in tomato-thermotolerance.HighlightNovel heat stress regulatory pathways uncovered by comparative transcriptome profiling between contrasting tomato cultivars from Indian sub-continent for improving thermotolerance. (20/30)

The Implications of an Idealized Large-Scale Circulation for Mechanical Work Done by Tropical Convection

A thermodynamic analysis is presented of an overturning circulation simulated by two cloud-resolving models, coupled by a weak temperature gradient parameterization. Taken together, they represent two separated regions over different sea surface temperatures, and the coupling represents an idealized large-scale circulation such as the Walker circulation. It is demonstrated that a thermodynamic budget linking net heat input to the generation of mechanical energy can be partitioned into contributions from the large-scale interaction between the two regions, as represented by the weak temperature gradient approximation, and from convective motions in the active warm region and the suppressed cool region. Model results imply that such thermodynamic diagnostics for the aggregate system are barely affected by the strength of the coupling, even its introduction, or by the SST contrast between the regions. This indicates that the weak temperature gradient parameterization does not introduce anomalous thermodynamic behavior. We find that the vertical kinetic energy associated with the large-scale circulation is more than three orders of magnitude smaller than the typical vertical kinetic energy in each region. However, even with very weak coupling circulations, the contrast between the thermodynamic budget terms for the suppressed and active regions is strong and is relatively insensitive to the degree of the coupling. Additionally, scaling arguments are developed for the relative values of the terms in the mechanical energy budget.

Spatial and temporal variation of kelp forests and associated macroalgal assemblages along the Portuguese coast

Kelp communities are in decline in many regions. Detecting and addressing population declines require knowledge of patterns of spatial and temporal variation in the distribution and abundance of kelps and their associated organisms. We quantified kelp and associated macroalgal assemblages three times over a period of 2 years, at three regions along a natural gradient in temperature and nutrient availability across the Portuguese coast. Kelps were mostly found at the northern cool region (Viana do Castelo), which was also clearly separated from the two more southerly regions (Peniche, Sines) in terms of algal assemblage structure. This pattern was consistent, although varying in intensity, through time, providing support for this general spatial configuration. The overall richness of taxa increased towards lower latitudes. These findings indicated that kelp beds in southern Europe are currently restricted to northern Portugal, though supporting less diverse macroalgal assemblages compared with those located in central and southern Portugal.

Habitat associations of species show consistent but weak responses to climate

Different vegetation types can generate variation in microclimates at local scales, potentially buffering species from adverse climates. To determine if species could respond to such microclimates under climatic warming, we evaluated whether ectothermic species (butterflies) can exploit favourable microclimates and alter their use of different habitats in response to year-to-year variation in climate. In both relatively cold (Britain) and warm (Catalonia) regions of their geographical ranges, most species shifted into cooler, closed habitats (e.g. woodland) in hot years, and into warmer, open habitats (e.g. grassland) in cooler years. Additionally, three-quarters of species occurred in closed habitats more frequently in the warm region than in the cool region. Thus, species shift their local distributions and alter their habitat associations to exploit favourable microclimates, although the magnitude of the shift (approx. 1.3% of individuals from open to shade, per degree Celsius) is unlikely to buffer species from impacts of regional climate warming.

A Fibril Structure Model for Stellar Prominences

Extensive observational background exists about the presence of cool material clouds embedded in the stellar coronae of rapidly rotating, late-type stars. Observations of such clouds in HKAqr (Gliese 890) and HD 197890 suggest that the clouds are at heights smaller than the star’s corotation radius and could be looked at as a phenomenon similar to that of solar prominences. Recent observations of solar prominences have reinforced the evidence about their fibril structure made of many long, thin magnetic flux tubes making angles about 25 degrees with the direction of the filament channel, with only the central 10–20% of the magnetic flux tubes filled with cool matter, which can produce a depression at the summits of the flux tubes. Then, assuming a similar structure for the stellar cool clouds, we have looked for the physical characteristics of such stellar prominences, i.e. the size of the flux tube depression, the density, temperature, half-width and supported mass of the cool region, taking into account gravity variation with height and centrifugal acceleration, since such clouds have been detected at great heights within stellar coronae belonging to rapid rotators.