The critical period for weed control (CPWC) is the period in the crop growth cycle during which weeds must be controlled to prevent unacceptable yield losses. Field studies were conducted in 2005 and 2006 in the University of Birjand at the south east of Iran to determine CPWC of corn using a randomized complete block design with 14 treatments and three replications. The treatments consisted of...

abstract field bindweed is an important perinial weed of agricultural crops word-wide. there are plant pathogen fungus which could cause necrotic spots on the leaves and stems of convolvulus arvensis under natural coditions. in order to evaluate the effects of weed growth stage and length of dew period on disease development causes by aletrnaria alternata and fusarium sp. two expriments were pe...

A trial for estimating leaf chlorophyll content based on leaf reflectance was conducted for three major plant species in Daegu, South Korea. To estimate the chlorophyll content in a leaf, we measured the leaf elongation and related the leaf reflectance to its absorbance. Leaves of the target species were found to start elongating around the middle of April and continued elongation until the mid...

this research which aims to survey the relation between tobacco leaf yield and its components is done by using 118 varieties of tobacco in a research farm of guilan tobacco research institute. regarding to five random selections of plants, twenty three traits of each variety were evaluated. correlation between dry matter of leaf yield with plant height, stem diameter, leaf length, leaf width, l...

velvetleaf (abutilon theophrasti) is one of the most important weeds of soybean fields in golestan province. a field experiment was conducted in gorgan agricultural research station in 2007 to determine the critical period for velvetleaf control in williams soybean (glycine max (l.) merr.) cultivar using a randomized complete block design with 4 replications. treatments were included two sets o...