Nitrogen (N) and silicon (Si) are two important nutritional elements required for plant growth, and both impact host plant resistance toward insect herbivores. The interaction between the two elements may therefore play a significant role in determining host plant resistance. We investigated this interaction in rice (Oryza sativa L.) and its effect on resistance to the herbivore brown planthopp...

Beans (Phase()las valgtais L.) often respond to N fertilization; however, N fertilization is not practiced for maximum seed production in southern Idaho. This suggests that the symbiotic relationship and/or soil N sources can provide most of the N needed by this legume. Our objective was to evaluate the relative contribution of the symbiotic-nonsymbiotic N sources by studying the effects of N f...

Nutrient rich conditions often promote plant invasions, yet additions of non-nitrogen (N) nutrients may provide a novel approach for conserving native symbiotic N-fixing plants in otherwise N-limited ecosystems. Lupinus oreganus is a threatened N-fixing plant endemic to prairies in western Oregon and southwest Washington (USA). We tested the effect of non-N fertilizers on the growth, reproducti...

Agroecosystem nitrogen (N) loss produces greenhouse gases, induces eutrophication, and is costly for farmers; therefore, conservation agricultural management practices aimed at reducing N loss are increasingly adopted. However, the ecosystem consequences of these practices have not been well-studied. We quantified N loss via leaching, NH3 volatilization, N2O emissions, and N retention in plant ...

Human-caused alterations of the carbon and nutrient cycles are expected to impact tropical ecosystems in the near future. Here we evaluated how a combined change in carbon (C), nitrogen (N) and phosphorus (P) availability affects soil and litter microbial respiration and litter decomposition in an undisturbed Amazonian rainforest in French Guiana. In a fully factorial C (as cellulose), N (as ur...

Climate warming could increase rates of soil organic matter turnover and nutrient mineralization, particularly in northern high-latitude ecosystems. However, the effects of increasing nutrient availability on microbial processes in these ecosystems are poorly understood. To determine how soil microbes respond to nutrient enrichment, we measured microbial biomass, extracellular enzyme activities...

The changes in agricultural policy and the increased concern about the effects of intensive production systems on the natural environment may lead to a reduction in the levels of nitrogen Ž . N fertilization on grassland. The aim of this review is to quantify the consequences of lowering N fertilization on dairy cow nutrition. For grass species harvested at the same age of regrowth, a Ž . reduc...

We report an ion channel in the plasma membrane of unfertilized oocytes of the ascidian Ciona intestinalis that is directly gated by the second messenger ADP-ribose. The ion channel is permeable to Ca2+ and Na+ and is characterized by a reversal potential between 0 and +20 mV and a unitary conductance of 140 pS. Preinjection of the Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane- N, N, N', N'-tetra...

To evaluate plant and herbivore responses to nitrogen we conducted a fertilization study at a low and high pollution site in the mixed conifer forests surrounding Los Angeles, California. Contrary to expectations, discriminant function analysis of oak herbivore communities showed significant response to N fertilization when atmospheric deposition was high, but not when atmospheric deposition wa...