Germination control

Allelopathic test materials and controls. Some 2.5 mL of aqueous or organic extracts were required for thorough saturation. Water-soluble or partially water-soluble extracts were appUed directly to the filter paper. Distilled water controls were used. With organic solvent-soluble extracts, the solution was applied to the filter paper and allowed to dry, then distilled water was added to support germination. Controls having pure solvent applied were similarly allowed to dry before the distilled water was added, ( antification of the amount of allelopathic material applied to each sample... 

Inhibition of conidia germination % Control of leaf attack... 

Cell Division Inhibitors. The most common mode of action of soil-appHed herbicides is growth inhibition, primarily through dkect or indkect interference with cell division (163). Such growth inhibitory activity is the basis for most pre- or post-emergent herbicides intended to control germinating weed seeds. In germinating seeds, cell division occurs in the meristems of the root and the shoot. Meristematic cells go through a cycle... 

The various fumigants often exhibit considerable specificity toward insect pests, as shown in Table 8. The proper choice for any control operation is determined not only by the effectiveness of the gas but by cost safety to humans, animals, and plants flammabdity penetratabdity effect on seed germination and reactivity with furnishings. The fumigants may be used individually or in combination. Carbon tetrachloride has been incorporated with carbon disulfide, ethylene dichloride, or ethylene dibromide to decrease flammability, and carbon dioxide is used with ethylene oxide for the same purpose. 

Various assay methods have been used to detect the presence of inhibitory substances. These include some of the classical tests used by investigators of growth-promoting substances—i.e., the various Avena coleoptile assays which utilize intact, decapitated, or isolated cylinders and the split pea stem test. Effects on seed germination and seedling shoot or root growth and development have also been measured in addition to other visible expressions of inhibition. Details of many of these tests have been compiled by Mitchell et al. (99). Tests have been carried out in Petri dishes, with various solution culture techniques, and by sand and soil culture. Effects so measured may or may not be similar to those obtained under field situations— i.e., the establishment of inhibition under controlled conditions pro-... 

There was a suggestion of dose-related immunosuppressive effects in rabbits fed methyl parathion in the diet at 0.04, 0.16, 0.57, and 1.48 mg/kg/day for 4 weeks. These effects consisted of decreased numbers of plasma cells in popliteal lymph nodes (at all doses compared to controls), decreased numbers of germinal... 

The rate of germination of white clover seed was stimulated by 100 pM ferullc acid through the Initial 24 hr of the test (Table II). Germination of clover was delayed by 500 pM ferullc acid, but after 36 hr no differences were observed at 100 to 500 UM concentrations. High concentrations (1000-2000 pM) were consistently inhibitory. Radish seed germination was not affected by ferullc acid levels tested except at 24 hr when those In 500 PM were less than controls. 

Tomato root growth bloassay of leaf extracts. Three hundred mg samples of fully expanded leaves were taken from each plant studied. Each sample was ground with a Polytron1 in 30 ml of distilled water and the extract was filtered. Five ml aliquots of each extract were pipetted onto three layers of germination paper in a 10 by 10 by 1.5 cm plastic petri dish. Distilled water was used as a control treatment. Twelve tomato seeds were placed in a 3x4 array in each dish, and incubated at 20C for 168 hours, prior to root measurement. The experimental design was a completely randomized design with five replications (dishes) per treatment except the control which had 10 replications. The experiment was repeated each week for 9 weeks. 

Since the germination data obtained for the controls, regardless of solvent or pretreatment, fit normal distributions with different means and variances according to seed species, statistical analyses were made using the standard normal deviates for each species. To allow comparisons between species the germination data are shown as percent of the germination observed in the appropriate control. 

Extract (Solvent used) Concen. Seed % of Germination in Control... 

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