in order to understand the effect of plant density and different fertilizers on sesame (sesamum indicum l.) production, an experiment was conducted as a factorial arrangement based on completely randomized block design with three replications. the experimental treatments were fertilizers in four levels (cow manure (30 t.ha-1), municipal compost (30 t.ha-1), chemical fertilizer (250 kg ammonium ...

The weed seed bank of a long-term tillage study in subarctic Alaska was studied at the end of 10 years of continuous spring barley (Hordeum vulgare L.). Tillage treatments were: no-till, disked once (spring), disked twice (spring and fall), and chisel plow (fall). Soil cores were obtained from each tillage treatment and seeds were manually separated from soil after washing through sieves. Tilla...

The aim of this paper is to evaluate seed bank density and composition along a semi-arid gypsum gradient in Central Spain. Seed bank density was relatively high (16,214 seed/m) with a very clumped spatial distribution. Landform and microslope were the best predictors for seed density, indicating that density can be at least partly interpreted as a result of the physical processes regulating sec...

The coexistence of numerous tree species in tropical forests is commonly explained by negative dependence of recruitment on the conspecific seed and tree density due to specialist natural enemies that attack seeds and seedlings ('Janzen-Connell' effects). Less known is whether guilds of shared seed predators can induce a negative dependence of recruitment on the density of different species of ...

Quantifying the relative importance of the multiple processes that limit recruitment may hold the key to understanding tropical tree diversity. Here we couple theoretical models with a large-scale, multi-species seed-sowing experiment to assess the degree to which seed and establishment limitation shape patterns of tropical tree seedling recruitment in a central African forest. Of five randomly...

Seed germination plays an important role in determining the composition and regeneration of plant populations (Stipa breviflora). However, the influencing factors and strategies employed for seed germination in desert grasslands under grazing remain unknown. Therefore, in this study, the reproductive allocation, seed density, seed properties, and corresponding seed germination rates of S. brevi...

to study the effects of planting date and planting density on quantitative traits of medicinal plant, schneider squash (cucurbita pepo l.), an experiment was conducted at research field of ferdowsi university of mashhad, in year 2012. a split plot arrangement based on randomized complete block design with three replications was used. treatments consisted of three planting date levels (1 may, 11...

We investigate the contribution made by small loops from a cosmic string network as seeds for large-scale structure formation. We show that cosmic string loops are highly correlated with the long-string network on large scales and therefore contribute significantly to the power spectrum of density perturbations if the average loop lifetime is comparable to or above one Hubble time. This effect ...

As pinyon–juniper (specifically, Pinus monophylla and Juniperus osteosperma) woodlands in the western United States increase in distribution and density, understory growth declines and the occurrence of crown fires increases, leaving mountainsides open to both soil erosion and invasion by exotic species. We examined if the loss in understory cover that occurred with increasing tree cover was re...