The leaf nitrogen content is generally accepted as an indicator of food quality and as a factor affecting host selection by phytophagous insects. The alate pea aphids (Acyrthosiphon pisum Harris, Aphididae) were given a choice among non-nodulated pea plants (Pisum sativum L.) supplied with one of four nitrate-N levels (0, 3, 15 and 30 mM). When whole plants were exposed to aphids for 7 days, th...

abstract growth retardants are new chemical organic compounds that increase period of flowering, leave chlorophyll, lateral shoot number, flower number and decrease vegetative growth. they also increase dry, cold and heat tolerance. paclobutrazol and cycocel are examples of these compounds. this study was conducted to evaluate the effect of paclobutrazol and cycocel on some quantitative and qua...

background and objectives: early watergrass (echinochloa oryzoides) is considered as a new-introduced species and then as a potential invader. investigation of competitive traits of this species, in comparison with barnyardgrass (e. crus-galli), one of the most important weeds in rice fields of guilan province, would be useful to determine its spreading possibility as an aggressive weed. theref...

bemisia tabaci (homoptera: aleyrodidae) is one of the most important pests of cotton in khorasan which causes crop damage and yield reductions as a result of direct feeding of plant and passing pathogenic viruses. using resistant varieties is an economic and environmental friendly method for controlling this pest. the resistance of seven cotton varieties (green leaf okra, red leaf okra, mehr, v...

there is some report about the hypoglycemic effect of juglans rejia l. leaf in alloxan induced diabetic rats and hypoglycemic effect of its fruit peel administered intra peritoneally. thirty male wistar rats divided into five groups, to evaluate the hypoglycemic and pancreas β-cells regenerative effects of oral methanolic extracts of leaf and fruit peel of walnut. rats were made diabetic by int...