Loss of leaf area usually results in yield loss grain crops, but the amount varies with extent and timing defoliation. Grass such as corn sorghum, are particularly sensitive to near time seed set because there is little opportunity for plant compensate. An experiment quantify reductions associated various levels defoliation imposed at different stages sorghum development was conducted Manhattan...

Removal of cyclobutane pyrimidine dimers (CBPDs) in vivo from the DNA of UV-irradiated eight-leaf seedlings of Arabidopsis thaliana was rapid in the presence of visible light (half-life about 1 hour); removal of CBPDs in the dark, presumably via excision repair, was an order of magnitude slower. Extracts of plants contained significant photolyase in vitro, as assayed by restoration of transform...

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...

There are complex inter- and intra-relations between regressors (independent variables) andyield quantity (W) and quality (Q) in tobacco. For instance, nitrogen (N) increases W butdecreases Q; starch harms Q but soluble sugars promote it. The balance between (optimizationof) regressors is needed for simultaneous increase in W and Q components [higher potassium(K), medium nicotine and lower chlo...

Leaf senescence and associated changes in redox components were monitored in commercial pea (Pisum sativum L. cv. Phoenix) plants grown under different nitrogen regimes for 12 weeks until both nodules and leaves had fully senesced. One group of plants was inoculated with Rhizobium leguminosarum and grown with nutrient solution without nitrogen. A second group was not inoculated and these were g...

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 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...

The impact of different levels of whole plant partial defoliation (WPPD) on the photosynthesis andprimarymetabolismofwheat,TriticumaestivumL.,was evaluatedat thevegetative and reproductive (grain-Þlling) developmental stages. Photosynthetic parameters such as photosynthesis, stomatal conductance, and transpiration, chlorophyll a ßuorescence, and plant morphological parameters, such asmain stemh...

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...

Studies were conducted to examine the spatial distribution of immature Bemisia argentifolii Bellows & Perring and immature Eretmocerus eremicus Rose & Zolnerowich on cantaloupe vines and to develop efÞcient sampling plans. More B. argentifolii eggs were found on the 3rd leaf from the terminal of a cantaloupe vine than on any other leaf. The density of whiteßy nymphs peaked at leaf position 8, w...