The physiological and physical components of the feedback loop involving intercellular CO(2) concentration (c(i)) and stomata are identified. The loop gain (G) is a measure of the degree of homeostasis in a negative feedback loop [the expression 1/(1-G) represents the fraction to which feedback reduces a perturbance]. Estimates are given for the effects of G on responses of stomata and c(i) to ...

Homoalanosine having a herbicidal activity was isolated from the culture filtrate of a soil isolate SC-1688 which was classified as Streptomyces galilaeus. The chemical structure of homoalanosine was determined to be L-2-amino-4-nitrosohydroxyaminobutyric acid by analyses of spectral and biological data. The antibiotic has high herbicidal activity at low concentrations against especially common...

The plants of the cerra(lo and caatinga ecological provinces of Brazil, the suggested original home of pineapple (3), have many and varied mechanisms whereby they have adapted to the frequent development of moisture stress. The pineapple planit presenits a peculiarly interestinig combination of those traits that have been l)ropose(l for xerophytic and sc!erophyllous plants (10, 15). Preferentia...

BACKGROUND AND AIMS Leaf longevity is controlled by the light gradient in the canopy and also by the nitrogen (N) sink strength in the plant. Stand density may influence leaf dynamics through its effects on light gradient and on plant growth and reproduction. This study tests the hypothesis that the control by the light gradient is manifested more in the vegetative period, whereas the opposite ...

Different formae speciales of Fusarium oxysporum are the main causal agent of Fusarium wilts. In 2008 and 2009 we collected F. oxysporum samples from symptomless Abutilon theophrasti, xanthium strumarium, Chenopodium album, Matricaria perforata, Ambrosia artemisiifolia, Polygonum lapathifolium, Sonchus arvensis, Amaranthus blitoides, Amaranthus retroflexus, Datura stramonium, Sorghum halepense ...

A 65-year-old man presented with recurrent generalized itching since 1 year. Examination revealed lichenified skin over the face and extensors of both extremities. He gave a history of rubbing the pulp of Aloe vera leaves on to his lesions whenever his itching worsened. Clinically, we suspected allergic contact dermatitis, possibly aggravated with Aloe vera. He was patch tested with the plant s...