this experiment was conducted to quantify leaf production and senescence in wheat. the experiment was carried out at research farm of the gorgan university of agricultural sciences and natural resources, gorgan, iran in 2005 using a randomized complete design considering sowing dates as environment. treatments were sowing date (14 december, 20 jan and 21 feb, 2005) and cultivars (aria, atrak, k...

Ecosystems worldwide are facing increasingly severe and prolonged droughts during which hydraulic failure from drought-induced embolism can lead to organ or whole plant death. Understanding the determinants of xylem failure across species is especially critical in leaves, the engines of plant growth. If the vulnerability segmentation hypothesis holds within leaves, higher order veins that are m...

(in a chimney plume of an near-source oil palm processing plant) (MacKenzie et al., 2011). The aerosol loadings in the experiments performed here start well below these levels, and then increase through each run to reach levels considerably higher than the loadings in northern Borneo. Thus, it is likely that we observe more higher volatility species in the aerosol phase than we would at atmosph...

The pervasive difficulties encountered with studying Galactia in the eastern USA necessitate additional typifications to stabilize the taxonomy. Galactia purshii is lectotypified here as the earliest available but overlooked name for a fairly common species of the Atlantic Coast and peninsular Florida. Galactia volubilis is epitypified here since the characterization of the species has been lim...

Rhythmic rotational movements with the midvein as the axis have been observed in the unifoliate leaves of Phaseolus angularis Wight grown under controlled environmental conditions with continuous light. The mean period of this movement for all leaves was 53.2 +/- 4.3 minutes and remained constant as the leaf matured, except after removal of the apical meristem and emerging trifoliate leaf when ...

• Co-occurring species often differ in their leaf lifespan (LL) and it remains unclear how such variation is maintained in a competitive context. Here we test the hypothesis that leaves of long-LL species yield a greater return in carbon (C) fixed per unit C or nutrient invested by the plant than those of short-LL species. • For 10 sympatric woodland species, we assessed three-dimensional shoot...