Long-Term Waterlogging: Nutrient,Gas Exchange,Photochemical and Pigment Characteristics of Eucalyptus nitens Saplings

Imposition of waterlogging for eight months induced morphological adaptation in Eucalyptus nitens in the form of adventitious and aerenchymatous roots and hypertrophy of stems. Foliar calcium (1.3-fold), potassium (2-fold) and phosphorus (2.4-fold) were lower and iron (5.6-fold) was higher in waterlogged than control saplings. Stem Ca (1.7-fold) was lower, whereas Mn (1.8-fold) and Fe (117-fold) were higher in waterlogged than control saplings. Distinct purple pigmentation was observed in xylem tissues of waterlogged saplings. A significant reduction in the maximum photosynthetic rate and photochemical efficiency was observed in waterlogged compared to control saplings. Although chlorophyll levels were similar, the xanthophyll cycle pool size was significantly greater in waterlogged saplings and may have contributed to the relatively greater capacity for light energy dissipation observed. Predawn xanthophyll cycle engagement was significantly greater in waterlogged than control saplings, despite relatively mild temperatures. Foliar anthocyanin concentration was higher in waterlogged than control saplings.     

Detection and validation of single feature polymorphisms using RNA expression data from a rice genome array

Background  

A large number of genetic variations have been identified in rice. Such variations must in many cases control phenotypic differences in abiotic stress tolerance and other traits. A single feature polymorphism (SFP) is an oligonucleotide array-based polymorphism which can be used for identification of SNPs or insertion/deletions (INDELs) for high throughput genotyping and high density mapping. Here we applied SFP markers to a lingering question about the source of salt tolerance in a particular rice recombinant inbred line (RIL) derived from a salt tolerant and salt sensitive parent.     

Does biochar influence soil physical properties and soil water availability?

Aims

This study aims to (i) determine the effects of incorporating 47 Mg ha^?1 acacia green waste biochar on soil physical properties and water relations, and (ii) to explore the different mechanisms by which biochar influences soil porosity.

Methods

The pore size distribution of the biochar was determined by scanning electron microscope and mercury porosimetry. Soil physical properties and water relations were determined by in situ tension infiltrometers, desorption and evaporative flux on intact cores, pressure chamber analysis at ?1,500 kPa, and wet aggregate sieving.

Results

Thirty months after incorporation, biochar application had no significant effect on soil moisture content, drainable porosity between –1.0 and ?10 kPa, field capacity, plant available water capacity, the van Genuchten soil water retention parameters, aggregate stability, nor the permanent wilting point. However, the biochar-amended soil had significantly higher near-saturated hydraulic conductivity, soil water content at ?0.1 kPa, and significantly lower bulk density than the unamended control. Differences were attributed to the formation of large macropores (>1,200 μm) resulting from greater earthworm burrowing in the biochar-amended soil.

Conclusion

We found no evidence to suggest application of biochar influenced soil porosity by either direct pore contribution, creation of accommodation pores, or improved aggregate stability.