an orchard experiment was conducted at gonabad pistachio production station., khorasan, iran (1998-2003). in some pistachio trees, especially in cv. owhadi, leaf marginal chlorosis was already observed. then, gradual drying of leaves extended to the leaves' centers up to midsummer. with respect to salinity problems, some researches were done. two orchards of pistachio known as no.6 and no....

Human activities have increased N availability dramatically in terrestrial and aquatic ecosystems. Extensive research demonstrates that local plant species diversity generally declines in response to nutrient enrichment, yet the mechanisms for this decline remain unclear. Based on an analysis of >900 species responses from 34 N-fertilization experiments across nine terrestrial ecosystems in Nor...

Switchgrass (Panicum virgatum L.) is being evaluated as a bioenergy crop for the northern Great Plains. Field measurements of CO2, CH4, and N2O flux are needed to estimate the net greenhouse gas (GHG) balance of this biofeedstock. The study objective was to determine effects of recommended Nitrogen (N) fertilization (67 kg ha 1 of N applied) and unfertilized switchgrass on growing season soil-a...

Temperature and nutrients are major limiting factors in subarctic tundra. Experimental manipulation of nutrient availability along elevational gradients (and thus temperature) can improve our understanding of ecological responses to climate change. However, no study to date has explored impacts of nutrient addition along a tundra elevational gradient, or across contrasting vegetation types alon...

Mangrove ecosystems can be either nitrogen (N) or phosphorus (P) limited and are therefore vulnerable to nutrient pollution. Nutrient enrichment with either N or P may have differing effects on ecosystems because of underlying differences in plant physiological responses to these nutrients in either N- or P-limited settings. Using a common mangrove species, Avicennia germinans, in sites where g...

abstract lowland rice (oryza sativa l.) in south asia is under stress, as nitrogen removals by crops are higher than their replenishment through fertilizers. limited information is available on optimizing nitrogen dose in lowland rice to turn out higher yield. the present investigation aimed to optimize nitrogen fertilization and it’s response to the growth and yield of lowland rice. we evaluat...

this investigation was carried out in a commercial orchard in ashtian city, markazi province. the effect of n-phenyl-phthalamic acid and nutrition on fruit quantity and quality of plum cv. maragheh was studied with the aim of increasing yield. the n-phenyl-phthalamic treatments (concentrations, 0, 500 and 1000 mg/l) were performed at full bloom (80 % flowering) on 29 march. also, nutrition was ...

We examined effects of a first nitrogen (N) fertilizer application on upper-canopy needle morphology and gas exchange in ~20-m-tall loblolly pine (Pinus taeda L.) exposed to elevated carbon dioxide concentration ([CO 2 ]) for 9 years. Duke Forest free-air CO 2 enrichment (FACE) plots were split and half of each ring fertilized with 112 kg ha –1 elemental N applied in two applications in March a...

We examined effects of a first nitrogen (N) fertilizer application on upper-canopy needle morphology and gas exchange in approximately 20-m-tall loblolly pine (Pinus taeda L.) exposed to elevated carbon dioxide concentration ([CO(2)]) for 9 years. Duke Forest free-air CO(2) enrichment (FACE) plots were split and half of each ring fertilized with 112 kg ha(-1) elemental N applied in two applicat...

the host plant quality not only influences on herbivorous insects but also indirectly could impact on their natural enemies’ performance. the current study was conducted to determine the effect of different nitrogen fertilization levels of canola (brassica napus l.) on life table parameters of the predatory gall midge, aphidoletes aphidimyza rondani; diptera: cecidomyiidae, in feeding of mustar...