Seed production, seed dispersal and recruitment are critical processes in population dynamics, because they are almost never completely successful. We recorded the recruitment dynamics for the population of Dipteryx oleifera in a tropical rainforest in eastern Nicaragua (12 degrees 05' N., 83 degrees 55' W.) from March 2002 to August 2006. Seeds and seedlings had highly clumped distributions, w...

abstract the pythium spp. are known as the principle agents of seedling blight, damping-off and root rot of cucurbits. this study was performed for determination of pythium species involved in this diseases as well study their pathogenecity on different cucurbits. the numerous samples were taken at cultivation seasons 2006- 2007 from the fields of cucumber, tomato, egg plant, muskmelon, cucurbi...

In a test of early genetic evaluation of the growth potential of 14 families of open-pollinated Douglas-fir (Pseudotsuga rnenziesii [Mirb.] Franco), measures of growth and phenology of seedlings grown in a coldframe were correlated with height of saplings in evaluation plantations at 9, 12, and 15 years. Fifteen-year height was most strongly correlated with measures of seedling budset (r = -0.5...

Reduced seedling growth is a consequence of seed deterioration. The heterotrophic seedling growth can be considered as the product of three components: (1) initial seed weight, (2) the fraction of seed reserves which are mobilized, and (3) the conversion efficiency of mobilized seed reserves to seedling tissues. It is not clear which of these component (s) is affected by seed deterioration. To ...

Forest community structure may be influenced by seedling density dependence, however, the effect is loosely coupled with population dynamics and diversity in the short term. In the long term the strength of conspecific density dependence may fluctuate over time because of seedling abundance, yet few long-term studies exist. Based on 11 years of seedling census data and tree census data from a 2...

Low seedling quality is a pervasive problem for smallholder forestry in the Philippines. Intervention measures to improve seedling quality are being examined in a research project funded by the Australian Centre for International Agricultural Research. Field trials have been established as part of this ‘seedling enhancement project’ to compare performance on outplanting of Gmelina arborea when ...

Forward genetics is a powerful approach used to link genotypes and phenotypes, and mutant screening/analysis has provided deep insights into many aspects of plant physiology. Gravitropism is a tropistic response in plants, in which hypocotyls and stems sense the direction of gravity and grow upward. Previous studies of gravitropic mutants have suggested that shoot endodermal cells in Arabidopsi...

The effect of auxin application on auxin metabolism was investigated in excised hypocotyl cultures of carrot (Daucus carota). Concentrations of both free and conjugated indole-3-acetic acid (IAA), [2H4]IAA, 2,4-dichlorophenoxyacetic acid, and naphthaleneacetic acid (NAA) were measured by mass spectroscopy using stable-isotope-labeled internal standards. [13C1]NAA was synthesized for this purpos...

Cellulase activity was measured in soybean (Glycine max) leaf abscission zones, flower abscission zones, pod abscission zones, apical buds, and adventitious rooting hypocotyls. Immunoprecipitation data showed that a cellulase immunologically similar to the bean abscission cellulase (isoelectric point 9.5) is present in soybean leaf, flower, and pod abscission zones, but is not present in soybea...