Light (about 3,000 foot-candles) neither increased nor decreased the sink strength of young, rapidly expanding leaves of Phaseolus vulgaris L. cv. Black Valentine, as measured by the comparative rates of import of (14)C-labeled photosynthates by sink leaves in the light versus dark in short term experiments. Although irradiated sink leaves accumulated more (14)C activity, the difference was ful...

Young leaves of tropical forest trees experience far higher herbivory pressure than mature leaves of the same species. Selection on young leaves has led to diverse forms of defense chemical expression. Though most allelochemicals are secondary metabolites, allelochemic function for a primary metabolite remains a possibility. We recently observed this phenomenon in the young leaves of Inga umbel...

Introduction Many widely used file organizations can be logically partitioned into two components; the index (also called directory) component and the data leaves component. The file records are maintained in data leaves where each data leaf (leaf for short) is one logical unit which is stored in contiguous disk pages. The index component is a search structure, usually a tree or a hash table, w...

Leaves are one of the most conspicuous and important organs of all seed plants. A fundamental source of morphological diversity in leaves is the degree to which the leaf is dissected by lobes and leaflets. We used publicly available segmental introgression lines to describe the quantitative trait loci (QTL) controlling the difference in leaf dissection seen between two tomato species, Lycopersi...

We examined the occurrence, mechanism and costs and benefits of leaf caching in laboratory colonies of two species of leafcutting ants, Atta cephalotes and A. colombica. If foragers returning to the nest are unable to enter because of a temporary bottleneck caused by leaves building up they may deposit their leaf pieces outside the nest entrance, forming a leaf cache. Similar leaf caches occur ...

The preference-performance hypothesis predicts that female insects should prefer to lay eggs in locations that enhance offspring performance. This study examines the choices of females regarding where to oviposit within plants, focusing on the hawkmothManduca sexta L. (Lepidoptera: Sphingidae) and its host Datura wrightii Regel (Solanaceae) in the southwestern USA. SmallerDatura leaves provide ...

The relationship between nutrients leached onto the leaf surface and the colonization of plants by bacteria was studied by measuring both the abundance of simple sugars and the growth of Pseudomonas fluorescens on individual bean leaves. Data obtained in this study indicate that the population size of epiphytic bacteria on plants under environmentally favorable conditions is limited by the abun...

The objective of this study was to determine xanthophyll cycle pool size and composition in response to N status and their relationships to non-photochemical quenching in apple leaves. Bench-grafted Fuji/M.26 trees were fertilized with different N concentrations (0-20 mM) in a modified Hoagland's solution for 6 weeks to create a wide range of leaf N status (1-4.4 g m(-2)). Chlorophyll content, ...