SHUTLER, D., and MULLIE, A. 1991. Size-related foraging behaviour of the leaf-cutting ant Atta colombica. Can. J . Zool. 69: 15301533 In a Costa Rican forest adjacent to cattle pasture, larger individuals of the leaf-cutting ant Atta colombica carried heavier loads and foraged farther from the colony, as predicted by foraging theory. Counter to foraging theory, individual ants did not increase ...

Important goals in understanding leaf development are to identify genes involved in pattern specification, and also genes that translate this information into cell types and tissue structure. Loss-of-function mutations at the JAGGED (JAG) locus result in Arabidopsis plants with abnormally shaped lateral organs including serrated leaves, narrow floral organs, and petals that contain fewer but mo...

In vitro studies with chloroplasts isolated from maize populations differing in juvenile productivity by the sixth leaf stage of growth demonstrated differences in rates of ferricyanide reduction and of non-cyclic photophosphorylation. Similar results were obtained for two independent sets of replicate selections for high and for low productivity. Chloroplasts from low productive selections had...

Plantlets grown in conventional tissue culture systems usually encounter physiological and anatomical abnormalities including inability to photosynthesize, low chlorophyll content, open stomata, lack of a cuticle layer in the leaf, abnormal xylem parenchyma etc. Photoautotrophic and photomixotrophic systems could diminish these problems. The purpose of this study was to increase the chlorophyll...

We present a novel measurement setup for monitoring changes in leaf water status using nondestructive terahertz time-domain spectroscopy (THz-TDS). Previous studies on a variety of plants showed the principal applicability of THz-TDS. In such setups, decreasing leaf water content directly correlates with increasing THz transmission. Our new system allows for continuous, nondestructive monitorin...

The leaf carbon isotope ratio (δ(13) C) of C3 plants is inversely related to the drawdown of CO2 concentration during photosynthesis, which increases towards drier environments. We aimed to discriminate between the hypothesis of universal scaling, which predicts between-species responses of δ(13) C to aridity similar to within-species responses, and biotic homoeostasis, which predicts offsets i...

Juvenile growth and bud set phenology were analyzed to study the biological basis of heterosis (hybrid vigor) in interspecific hybrids of Populus tremuloides Michx. (T) and P. tremula L. (Ta). Growth, measured as seedling volume index, was significantly higher for each of the two reciprocal interspecific crosses, T x Ta and Ta x T, than for the T x T intraspecific cross. Broad-sense heritabilit...

Fifty-one genotypes of sugarcane (Saccharum spp.) or closely related germplasm were evaluated in a pot experiment to examine genetic variation in transpiration efficiency. Significant variation in whole plant transpiration efficiency was observed, with the difference between lowest and highest genotypes being about 40% of the mean. Leaf gas exchange measurements were made across a wide range of...