Surface Of Cabbage Research Articles

A kinetics model for the absorption of 2,4-D acid and butoxyethanol ester into cabbage ( Brassica oleracea L.) cotyledons

Cabbage ( Brassica oleracea L.) var. Late Flat Dutch cotyledons were treated with [2,4- 14C]-dichlorophenoxyacetic acid (2,4-D) and butoxyethanol ester. After treatment, methanol was used to remove the herbicides from the cabbage surface and hydrophilic regions of the cuticle, and chloroform was used to remove the herbicides from the lipophilic regions of the cuticle. The plant tissue was then combusted to determine the amount of radioactivity in the tissue. A kinetics experiment was conducted and the amount of radioactivity in the methanol, chloroform, and internal compartments was determined for time intervals up to 32 hr. The radioactivity in the methanol compartment was subjected to an analysis similar to that used in pharmacokinetics. The observed data for both herbicides fit their respective biexponential equations; however, the individual kinetic rate constants were not accurate. This was evidenced by the lack of fit of the rate equations for the chloroform and internal compartments to the observed data. Utilizing data from the methanol, chloroform, and internal compartments an algorithm was devised and used to solve the rate equations for each individual rate constant. For both herbicides, the kinetic model indicated that an equilibrium was established between the methanol and chloroform compartments. The chloroform compartment appeared to serve only as a reservoir for the two herbicides. The kinetic model suggested that movement of both herbicides occurred from the hydrophilic portions of the cuticle (methanol compartment) to the internal compartment.

Inhibition of Epicuticular Wax Deposition on Cabbage by Ethofumesate

The weight of epicuticular wax on the surface of cabbage (Brassica oleracea var. Capitata ;Market Prize') leaves was reduced by soil treatments of ethofumesate (2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulfonate) and EPTC (S-ethyl dipropylthiocarbamate). Separation of epicuticular wax into major components by gas-liquid chromatography indicated that ethofumesate decreased the deposition of n-nonocosane and n-nonocosan-15-one on cabbage leaves but increased the deposition of a minor component, the long chain waxy esters. EPTC was less inhibitory to n-nonocosan-15-one deposition than was ethofumesate. EPTC did not increase long chain waxy ester deposition. Scanning electron micrographs revealed that ethofumesate almost totally eliminated the epicuticular wax on cabbage leaves while EPTC only diminished it. Cuticular transpiration was increased by ethofumesate but not by EPTC. Ethofumesate appears to be a more potent inhibitor of epicuticular wax deposition than EPTC.

Factors affecting postharvest infection of stored cabbage tissue by Botrytis cinerea

Single-spore isolates of Botrytis cinerea from commercially stored cabbage exhibited a broad range of virulence. Spore germination and hyphal growth required an exogenous source of nutrients. The ability of either spores or mycelium to cause infection of stored cabbage tissue was also dependent upon exogenous nutrients. Nutrients required for infection could be supplied in the form of glucose, cabbage leaf extract, potato dextrose agar (PDA), or by a wound at the site of inoculation. The concentration of nutrients and (or) spores influenced the ability of B. cinerea to cause tissue decay whereas spore age and bacterial populations did not. Spores on the surface of cabbage leaves germinated within 4 to 8 h in nutrient solution; an additional 8 to 16 h in nutrient solution were required for successful infection. The optimum temperature for fungal growth and for infection was 20 to 25C. The optimum relative humidity for decay was above 97%; decay did not occur at relative humidities below 93%.

The effects of sunlight on a purified granulosis virus of Pieris brassicae applied to cabbage leaves

When a highly purified preparation of the known granulosis virus of Pieris brassicae is exposed to direct sunlight, on the upper surface of cabbage leaves, carefully oriented so that no part is in shade, the virus is rapidly inactivated. For example, after an exposure of 3 hr, the suspension applied to the leaves gave very significantly less kill of larvae than a nonirradiated control suspension one-tenth its concentration. Total inactivation of the virus, under these circumstances, took between 12 and 19 hr. These results are discouraging from the point of view of using purified, unprotected, granulosis virus for biological control and emphasize the importance of finding some means of screening or protecting the virus from ultraviolet radiation.