1.1 Biological nitrogen fixation and nitrogen nutrition in soybean plants Biological nitrogen fixation is one of the most important processes for ecosystem to access available N for all living organisms. Although N2 consists 78% of atmosphere, but the triple bond between two N atoms is very stable, and only a few group of prokaryotes can fix N2 to ammonia by the enzyme nitrogenase. Annual rate ...

this experiment was conducted to evaluate the effects of different sowing densities and nitrogen fertilizer rates on quantitative and qualitative corn forage yield in an agroforestry system with orange trees. the treatments consisted of 4 nitrogen fertilizer levels of 0, 100, 200, and 300kg n/ha (allocated to main plots) and 4 sowing densities of 80000, 110000, 140000 and 170000 of corn seeds (...

: In order to study the effect of different nitrogen levels on yield components and seed yield of three barley cultivars, an experiment was conducted in 2011-2012 in a research farm of farming building of Islamic Azad University Khorasgan (Isfahan) Branch located in Khatunabad village (latitude 32o /40' N and Longitude 51o /48' E). A split plot layout within randomized com...

nitrogen is one of the most limiting nutrients for cereal production in many parts of iran. the effects of crop residue incorporation [0 (control), 25 and 50% of wheat (triticum aestivum l.)] and nitrogen (n) levels (0, 150, and 300 kg ha-1) on corn (zea mays l.) grain yield and nitrogen use efficiency were investigated at agricultural research station, shiraz university, shiraz, iran for two y...

extinction coefficient (k) is an important index that shows the rate of light decrease in canopy. net biomass accumulation is linearly related to cummulative light interception. the slope of this relationship is termed radiation use efficiency. a split plot experiment within randomized complete block design with three replications was conducted in april 2001 in sugar beet research station in ka...

the study was carried out to examine the effects of urban sewage and nitrogen fertilizer levels on yield quantity and quality forage of sweet corn was evaluated in yasouj at 2009. the main experimental factor consisted of 5 irrigation levels including: common irrigation water without sewage effluent until the end of plant growth (i1), the first half of plant growth period with sewage effluent a...

ebrahim panahpour1*, parviz ahmadi2,  mahmoud shomeili3 1,2- department of soil science, college of agriculture, ahvaz branch, islamic azad university, ahvaz, iran 3- manager agronomi department sugarcane research and training institute khuzestan, iran *corresponding author email: [email protected] received: 22 july 2015                                                                       ...

this experiment was conducted to evaluate rate and duration of grain filling among old, modern and promising rice cultivars under different nitrogen levels in fields of  sari agricultural sciences and natural resources university, during 2008. two factors consisted of different urea fertilizer (0, 100 and 200 kg ha-1) as main plot and four promising lines (jelodar, partou, danesh and jahesh), 2...

to study the effects of plant density and nitrogen rates on the ability of canola (regent  cobra; an inbred variety) to compete with weeds, an experiment was conducted as a factorial complete block design with four replications. the treatments included four levels of plant density at 150, 190, 230, and 270 plants m-2, and four levels of nitrogen (n) fertil-izer at 0, 46, 92, and 138 kg ha–1. r...