Ten varieties and eight generations (2F1, 2F2, 2B1 and 2B2) of durum wheat derived from two crosses were evaluated for resistance to natural infection by Stagonospora nodorum blotch (SNB) at the 2-3 and 6-7 leaf stages at two sites over two years. There were significant differences in the incidence of SNB between leaf stages in most of the wheat varieties, with resistance being most evident at ...

Quantitative levels of indole-3-acetic acid (IAA) were determined in leaf blades of two sugarbeet cultivars by a double standard isotope dilution assay using column chromatography followed by reverse phase C(18) high performance liquid chromatography and gas-liquid chromatography with nitrogen thermionic detection. The double standard method was validated as a quantitative tool by gas chromatog...

Apterous populations of Chaitophorous populicola Thomas (Homoptera: Aphididae) appear to track Eastern cottonwood (Populus deltoides Bartr.) leaf development. Few aphids occur onmature leaves.Marked individual aphids on leaves of different developmental stageswereobserved through a period of new leaf initiation. Nymph and adult C. populicola frequently track leaf development bymoving up to youn...

determination of chlorophyll content and chlorophyll fluorescence has the potential needed to analyze the efficiency of photosynthesis in plants against environmental stresses, especially salinity, and its simplicity facilitates stress evaluation. in order to study the response of different photosynthetic characters to salinity stress at different sugar beet growth stages, two separate experime...

abstract in order to determine the time of maximum demand of winter wheat (triticum aestivum l.) to phosphorous fertilizers and p and zinc (zn) distribution in different parts of wheat at various growth stages and study their relation to the contents of these elements in soil p and zn under field conditions, samples were collected from different parts of the plants at seven growth stages (i.e.,...

Corn flea beetles, Chaetocnema pulicaria, vector Erwinia stewartii (synamorph Pantoea stewartii), which causes Stewart’s bacterial wilt of corn (Zea mays) (10,11). Flea beetles introduce E. stewartii into plant tissues that are wounded during feeding. Movement of E. stewartii in the vascular system of resistant plants is restricted to within a few centimeters of flea beetle feeding wounds. The ...

Midday leaf CO2 exchange rate (CER), concentration of chlorophyll (Chl) and soluble protein and activity of the primary enzymes involved in leaf photosynthesis and sucrose metabolism were determined during leaf ontogeny for sugarcane plants grown at ambient (360 mmol mol ) and double-ambient (elevated, 720 mmol mol ) CO2. Although leaf CER of both CO2 treatments increased and was highest at 14 ...

The population dynamics of the rubber plantation litter beetle, Luprops tristis Fabricius 1801 (Coleoptera: Tenebrionidae) was assessed in relation to the phenology of leaf shedding and defoliation pattern of para rubber trees, Hevea brasiliensis Müll. Arg (Malpighiales: Euphorbiaceae), during a two year study period. The abundance of adults, larvae and pupae per 1m(2) of litter sample was reco...

Canopy structural parameters and light radiation are important for evaluating the light use efficiency and grain yield of crops. Their spatial variation within canopies and temporal variation over growth stages could be simulated using dynamic models with strong application and predictability. Based on an optimized canopy structure vertical distribution model and the Beer-Lambert law combined w...