When a plant invests in construction of a leaf, the revenue-stream that accrues is shaped by three variables: first, the light-capture area per milligram dry mass invested, analogous to a potential rate of return on investment; second, the longevity of the leaf, analogous to the expected duration of the revenue stream; and third, a time-discount rate, quantifying the fact that light-capture are...

This study was undertaken to identify morphological changes in young seedlings of 5 Iranian almond species (Prunus dulcis, P. eburnea, P. eleagnifolia, P. haussknechti, and P. scoparia) under polyethylene glycol-induced drought stress. Drought stress caused a significant reduction in plant growth parameters such as fresh and dry weights of plant organs, leaf number, total leaf area, and leaf re...

We introduce the simultaneous optimisation of water-use effi ciency and nitrogen-use effi ciency of canopy photosynthesis. As a vehicle for this idea we consider the optimal leaf area for a plant in which there is no self-shading among leaves. An emergent result is that canopy assimilation over a day is a scaled sum of daily water use and of photosynthetic nitrogen display. The respective scali...

Lotus leaves have become an icon for superhydrophobicity and self-cleaning surfaces, and have led to the concept of the 'Lotus effect'. Although many other plants have superhydrophobic surfaces with almost similar contact angles, the lotus shows better stability and perfection of its water repellency. Here, we compare the relevant properties such as the micro- and nano-structure, the chemical c...

Leaf area index is one of the most important parameters in ecological and environmental studies. This paper presents a method for single leaf area measurement based on the counting of the leaf pixels in digital leaf image. Initially, the target leaf is put on a piece of white paper on which four endpoints of an equal-length and orthogonal cross are printed. A background color threshold is then ...

Shoot growth, chlorophyll concentrations, gas exchange and starch concentrations were studied in lychee (Litchi chinensis Sonn.) seedlings of cultivar "Wai Chee" grown in a heated greenhouse at Nambour in subtropical Australia (27 degrees S). We also examined the effects of shoot defoliation and root pruning on leaf expansion. Shoot growth showed a rhythmic cycle under constant greenhouse condi...

this paper aims at investigating the influence of partial replacement of portland cement with ultrafine fillers compared to limestone powder on the durability and mechanical characteristics of concrete. for this purpose, ultrafine calcium carbonate materials with different specific surface areas of 9.7 and 15.1 m2/g and limestone powder (0.72 m2/g) were used. the results indicate that the ultra...

Background.  Durability of antiretroviral (ARV) therapy is associated with improved human immunodeficiency virus (HIV) outcomes. Data on ARV regimen durability in recent years and clinical settings are lacking. Methods.  This retrospective follow-up study included treatment-naive HIV-infected patients initiating ARV therapy between January 2007 and December 2012 in a university-affiliated HIV c...

Spring wheat cv. Minaret was grown under three carbon dioxide (C02) and two ozone (O3) concentrations from seedling emergence to maturity in open-top chambers. Under elevated CO2 concentrations, the green leaf area index of the main shoot was increased, largely due to an increase in green leaf area duration. Biomass increased linearly in response to increasing CO2 (ambient, 550 and 680 ppm). At...