Statistical method for testing the neutral mutation hypothesis by DNA polymorphism.

A positive temperature coefficient is the term which has been used to indicate that an increase in solubility occurs as the temperature is raised, whereas a negative coefficient indicates a decrease in solubility with rise in temperature.

Effect of Temperature

http://utsc.utoronto.ca/%7Ebritto/publications/amtox.pdf

NH4+ toxicity in higher plants: a critical review

The predominant emphasis on harmful effects of environmental stresses on growth of woody plants has obscured some very beneficial effects of such stresses. Slowly increasing stresses may induce physiological adjustment that protects plants from the growth inhibition and/or injury that follow when environmental stresses are abruptly imposed. In addition, short exposures of woody plants to extreme environmental conditions at critical times in their development often improve growth. Furthermore, maintaining harvested seedlings and plant products at very low temperatures extends their longevity. Drought tolerance: Seedlings previously exposed to water stress often undergo less inhibition of growth and other processes following transplanting than do seedlings not previously exposed to such stress. Controlled wetting and drying cycles often promote early budset, dormancy, and drought tolerance. In many species increased drought tolerance following such cycles is associated with osmotic adjustment that ...

Acclimation and adaptive responses of woody plants to environmental stresses

The function of anthocyanins in green, vegetative tissues has always been a contentious issue. Here we evaluate their proposed photoprotective function since recent findings have shown that anthocyanins reduce photoinhibition and photobleaching of chlorophyll under light stress conditions. Anthocyanins generally accumulate in peripheral tissues exposed to high irradiance, although there are some exceptions (e.g. accumulation in abaxial leaf tissues and in obligatory shade plants) and accumulation is usually transient. Anthocyanin accumulation requires light and generally coincides with periods of high excitation pressure and increased potential for photo-oxidative damage due to an imbalance between light capture, CO2 assimilation and carbohydrate utilization (e.g. greening of developing tissues, senescence and adverse environmental conditions). Light attenuation by anthocyanin may help to re-establish this balance and so reduce the risk of photo-oxidative damage. Although it has been suggested that anthocyanins may act as antioxidants, the association between anthocyanins and oxidative stress appears to relate to the ability of anthocyanins to reduce excitation pressure and, hence, the potential for oxidative damage. The various aspects of anthocyanin induction and pigmentation presented here are compatible with, and support, the proposed general role of anthocyanins as photoprotective light screens in vegetative tissues.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1469-8137.2002.00482.x

Anthocyanins in vegetative tissues: a proposed unified function in photoprotection

Production of biomass for bioenergy will depend on the sustainability of the production resource-base: the soil, water, air and the diversity of the ecosystem as a whole. For soil, potential sustainability indicators, including soil nitrogen and phosphorus, total organic matter, components associated with soil erosion and bulk density are discussed. Indicators related to the water resource water quality, water availability index, nitrate levels in water and biological oxygen demand are also discussed. Greenhouse gases and their sequestration potentials are discussed for maintaining atmospheric air qual- ity. For biodiversity, a biodiversity index and soil biota index were selected as potential indicators. In addition to the pro- duction resource-base, the paper also discusses the importance of economic and social sustainability indices. To summa- rize, we are suggesting that a common method of visualizing the above indicated indices is to generate amoeba diagrams. This paper also provides a review on the term 'sustainability' and specific indicators, with metrics where possible, are de- scribed as candidates for inclusion as potential indicators appropriate for agroforestry based bioenergy systems in Canada. Three agroforestry based bioenergy systems are described and specific indicators are discussed within the bounds of these systems.

/pdf/sustainability-indicators-of-biomass-production-in-15g8s0yh5q.pdf

Sustainability Indicators of Biomass Production in Agroforestry Systems

Summary Water content and mobility, which are factors known to be associated with dormancy induction in woody plants on a tissue level, were measured using nondestructive magnetic resonance microimaging (MRMI). Two cultured poplar clones (‘Okanese’ – temperatureinsensitive dormancy and ‘Walker’ – temperature-sensitive dormancy) were subjected to dormancy differentiating temperature regimes, 18.5/3.5 � C and 18.5/13.5 � C (day/ night), under a short photoperiod. Apparent diffusion coefficient, an indicator of water mobility, correlated with dormancy development in the axillary bud and vascular bud trace regions. In contrast, T1 relaxation time, an indicator of static biophysical water properties, did not correlate significantly with dormancy in the regions that were examined. Although MRMI studies using T1 relaxation measurements have dominated the phytological field, our work indicates that water mobility is an important factor in studies examining water changes during dormancy induction in the critical tissues of woody plants.

Magnetic resonance microimaging indicates water diffusion correlates with dormancy induction in cultured hybrid poplar (Populus spp.) buds.

The influence of temperature on dormancy induction and plant survival in woody plants.

Physiological experiments have established that plant roots possess multiple transport systems for nitrogen absorption. These include at least three active transporter systems for nitrate absorption, and two transporters, one active and one passive, for ammonium absorption. In addition, there exist amino acid transporters, although their importance for nitrogen acquisition in agricultural soils is uncertain. The integration of these transport systems, in the context of satisfying whole plant demand for nitrogen, requires mechanisms for root to shoot signaling as well as signal transduction within the root. Evidence from physiological studies has been interpreted in terms of a nitrogen cycling model, in which reduced nitrogen, in the form of amino acids, returns to the root via the phloem to signal plant demand for nitrogen uptake. Thus far, details of the mechanisms of these putative regulatory processes have not been established.

Inorganic Nitrogen Absorption by Plant Roots

Nucleotide polymorphisms in two North American balsam poplars (Populus trichocarpa Torr. & Gray and P. balsamifera L.; section Tacamahaca), and one Eurasian aspen (P. tremula L.; section Populus) were compared using nine loci involved in defense, stress response, photoperiodism, freezing tolerance, and house- keeping. Nucleotide diversity varied among species and was highest for P. tremula (hw = 0.005, pT = 0.007) as compared to P. balsamifera (hw = 0.004, pT = 0.005) or P. trichocarpa (hw = 0.002, pT = 0.003). Across species, the defense and the stress response loci accounted for the majority of the observed level of nucleotide diversity. In general, the studied loci did not deviate from neutral expectation either at the individual locus (non-significant normalized Fay and Wu's H) or at the multi-locus level (non- significant HKA test). Using molecular clock analysis, sec- tion Tacamahaca probably shared a common ancestor with section Populus approximately 4.5 million year ago. Divergence between the two closely related balsam poplars was about 0.8 million years ago, a pattern consistent with an isolation-with-migration (IM) model. As expected, P. tremula showed a five-fold higher substitution rate (2 9 10 -8 substitution/site/year) compared to the North American species (0.4 9 10 -8 substitution/site/year), probably reflecting its complex demographic history. Link- age disequilibrium (LD) varied among species with a more rapid decay in the North American species (\400 bp) in comparison to P. tremula (� 400 bp). The similarities in nucleotide diversity pattern and LD decay of the two balsam poplar species likely reflects the recent time of their divergence.

http://link.springer.com/content/pdf/10.1007/s00239-012-9504-5.pdf

Salim N. Silim

Papers

Sustainability Indicators of Biomass Production in Agroforestry Systems

Magnetic resonance microimaging indicates water diffusion correlates with dormancy induction in cultured hybrid poplar (Populus spp.) buds.

The influence of temperature on dormancy induction and plant survival in woody plants.

Inorganic Nitrogen Absorption by Plant Roots

Comparative Nucleotide Diversity Across North American