Lactatingdairy cows (n=177) fed with grass and corn silage ad libitum kept in pasture, were randomly assigned to evaluate how urea nitrogen in plasma and milk can be related to their pregnancy rate. Blood and milk samples were collected on the artificial insemination (AI) day to evaluate plasma urea nitrogen (PUN) and milk urea nitrogen (MUN) as well as progesterone levels, excluding cows with ...

in order to evaluate the effect of nitrogen rate and weeding time on weed communities dynamic, a field study conducted in a research farm of chamran university, ahwaz. the experimental design was split plot based on rcb with three replications. nitrogen rates (77, 110, 143 kg/ha) were considered in the main plot and time of weeding (at 5, 8, 11, leaf stage with control and weedy plot) as sub pl...

the beet armyworm, spodoptera exigua, is one of the most important pests of sugar beet in iran. the aim of this study was to determine the effect of water and nitrogen treatments of sugar beet planton developmental time and fecundity life table parameters of the pest. an experiment was carried out under laboratory conditions (25±2oc, 70±5% r.h. and 12l: 12d) on larvae reared on sugar beet leave...

crop rotation affect on crop nitrogen uptake and nitrogen use efficiency (nue). crop rotations with high nue decrease energy use and increase level of sustainability in agro ecosystems. the objectives of this research were to determine the suitable double cropping system for enhancing nue and evaluate the effects of crop rotation, n fertilizer rate and return of crop residue on nue. this study ...

the amount of nitrogen fertilizer is an effective factor on the growth, development, and reproduction of phytophagous insects. to investigate the effect of nitrogen fertilization on intrinsic rate of increase of cabbage aphid, brevicoryne brassicae l., plants rape oilseed (rgs003cultivar) were treated with four nitrogen levels (zero (check) 50, 100, and 150% of recommended levels. the results s...

this research has been done for studying the effect of split application of nitrogen fertilizer on growth indexes and yield of three hybrids of grain corn in shahrood. a split plot experiment based on randomized complete block design with four replications was carried out in 2007. three hybrids of corn (double cross 370, single cross 447, single cross 499) were placed in main plots and split ap...