-To maximize net gain of a tree, leaves must be replaced when net gain of a leaf per unit time over the leaf's life span is maximum. A model in which leaf longevity is determined to maximize the net gain of a leaf per unit time is constructed. The model predicts that leaf longevity is short when initial net photosynthetic rate of the leaf is large, long when the construction cost of the leaf is...

The influence of leaf-wetness duration and temperature on infection of Amelanchier alnifolia (saskatoon) by Entomosporium mespili was quantified in controlled-environment studies. Plants were inoculated with a conidial suspension and then subjected to a period of leaf wetness (0, 6, 12, and 24 h), after which they were moved to a growth room set at a fixed temperature (10, 15, 20, 25, and 30°C)...

Understanding variation in SW (seed weigh) is of major importance in understanding SY (seed yield) variation. The objective of this study was to determine factors such as SN (seed number) per unit area, SFD (seed filling duration) and SFR (seed filling rate) and temperature, LAI (leaf area index), LAD (leaf area duration), above-ground dry matter, CGR (crop growth rate), leaf dry matter re...

In temperate portions of North America, some bats that remain active during winter undergo short periods of hibernation below leaf litter on the forest floor during episodes of below-freezing weather. These winter roosts may provide above-freezing conditions, but the thermal conditions under leaf litter are unclear. Further, little is known of the relationship between temperatures under litter ...

ABSTRACT-The critical period of weed control is a part of crop life cycle during which weeds must be kept weed-free to avoid yield losses due to competition. In order to evaluate the effect of deficit irrigation on critical period of redroot pigweed (Amaranthus retroflexus L.) in sunflower (Helianthus annuus L.), an experiment was carried out  as split plot ba...

Experiments were undertaken with field-grown potato (Solanum tuberosum L.) plants to test the hypothesis that altering leaf:tuber water potential gradients within a plant subjected to low soil moisture will allow greater Ca accumulation in tubers and reverse Ca deficiency-related tuber necrosis. Antitranspirant formulations containing a wax emulsion and a spreader/sticker surfactant increased l...

BACKGROUND AND AIMS Leaves expand during a given period of time until they reach their final size and form, which is called determinate growth. Duration of leaf expansion is stable when expressed in thermal-time and in the absence of stress, and consequently it is often proposed that it is controlled by a robust programme at the plant scale. The usual hypothesis is that growth cessation occurs ...

Two basic experiments defined a long-day inhibitory effect on Xanthium flowering: the basal half of a single leaf on long day inhibits response of the tip half to a short day; and a long-day leaf inhibits response of a short-day leaf, providing it is between the short-day leaf and a receptive bud (whether above or below the short-day leaf). Five hypotheses were explored with the conclusions tha...

abstract genetic diversity of german chamomile (matricaria chamomilla l.) populations in iran was evaluated using morphological, agronomical and phonological characteristics and compared with three cultivars from germany, hungary and iran. in this experiment, statistical design of rcbd with three replications was used, sixteen quantitative traits were measured such as yield, flower number per p...