Chemically induced cuticle mutation affecting epidermal conductance to water vapor and disease susceptibility in Sorghum bieoJor L. For instance, isomeric diols, ex and f3 isomers of 4,8,13-duvatriene-1,3-diol found in the chloroform-soluble leaf surface extracts from tobacco Nicotiana tabacum L. Investigations in sorghum noted that bloomless and sparse bloom mutants were more resistant in the field to the greenbug aphid Schizaphis graminum Rondani than wildtype. The chemical composition of epicuticular waxes is diverse, and it is difficult to determine what role particular wax constituents play in plant-pathogen interactions, and whether changing wax chemistry would be an effective way to enhance plant resistance. Thidiazuron and paclobutrazol appear to mimic cytokinin and auxin influences on organ regeneration and protein profiles in cultured melon cotyledons.
Further studies are needed to assay fungal secretions for their ability to degrade epicuticular wax constituents. Comparative responses of a perennial ryegrass seed crop to four plant growth regulators. For example, many plants have distinct epicuticular wax composition on various tissues Table 1. Jetter and Riederer 1995 recently demonstrated that minor amounts of alkanediols mixed with nonacosan-10-ol acted to stabilize tubular wax structures. Consistent with this hypothesis are reports indicating that plants with well-developed layers of epicuticular wax have lower leaf and canopy temperatures, reduced rates of transpiration, and improved water status relative to comparable controls Johnson et a1. Epicuticular waxes could be made thicker or more hydrophobic using genetic approaches such that herbicides could be applied at greater rates in field cropping systems without damaging the crop. Due to its low persistence, such a compound can be used flexibly for site-specific growth control.
A greater understanding of plant-microbial interactions, characterization of soil microflora species, and an understanding of their response to cultural practices could lead to the increased trend of using microbial inoculants for crop growth enhancement Arshad and Frankenberger 1998. Values represent the percentage of each chemical class identified in the respective study. Gonzalez, R Rodriguez, and W. The microclimate in which a plant grows can have a dramatic effect on epicuticular wax content. Epicuticular wax precursors are secreted through 10 nm pores at the base of secretory holes in a modified cuticle Foldi 1981. Partial purification ofthe acyl-CoA elongase of Allium porrum leaves.
Fruit calcium and proline concentration were also increased but nitrogen and nitrogen:calcium ratio decreased Zhang 1990. Leaf wax fine structure and ontogeny in Eucalyptus demonstrated by means of a specialized fixation technique. Specific studi~s to elucidate how cuticular waxes might block chemical sorption and penetration may lead to novel spray formulations, new spray application procedures, or genetically altered crops with reduced sorption and thus increased rates of agrichemical penetration through the plant cuticle. Water loss through plant cuticles may be more complicated than simple diffusion through a waxy layer. If professional advice or other expert assistance is required, the services of a competent professional person should be sought. Comparative activity of the enantiomers of triadi- 3. Paclobutrazol protects wheat seedlings from heat and paraquat injury: Is detoxification of active oxygen involved? Do separate cytoplasmic secretory pathways exist for separate epidermal secretory products, such that separate vesicles carry cell wall and surface lipid components? Experimental observations showed that beetles clung less effectively onto the glaucous juvenile leaves compared to the nonglaucous adult leaves.
Influence of cuticular waxes on penetration of pear leaf cuticle by l-naphthaleneacetic acid. Effect of paclobutrazol on canopy size control and flowering of mango, cv. In addition, changes in wax chemical composition in response to simulated acid rain have been reported to occur in several species Percy and Baker 1987, 1990. However, when these surface compounds were reapplied to these same leaves, rates of P. Trichoderma improved the growth of radish Paulitz et al. Additional evidence for the role of epicuticular waxes in inhibiting insect feeding behaviors came from studies on cabbage and rape.
Effects oftemperature, surfactants, and other adjuvants on rates of uptake of organic compounds. This transacylase may have 36 M. In vitro reconstitution of epicuticular wax crystals: formation of tubular aggregates by long-chain secondary alkanediols. Natural enemy activity was minimal in these plots, perhaps due to the history of intensive pesticide applications in the area Rosset 1989. This in no way matches the reported increase in yield by 12-62% with hydrogen cyanamide Henzell et al.
Although high light generally boosts wax load, Brussels sprouts grown at 25°C did not have increased wax levels under the high light levels as did comparable plants grown at 15°C Reed and Tukey 1982. In 1977, Shang Fa and a Ph. While diligently developing a series of experiments to test one hypothesis, he has always been able to step back and consider alternative interpretations of the data. Cutin, which exists as a polyester composed of primarily C16 and C18 fatty acids having hydroxyl groups in ro- and midchain positions, is a major constituent of the cuticle that underlies the epicuticular wax layer. Such results are not surprising since fatty acids and terpenoids are much less hydrophobic than those other wax constituents. These chemicals may increase partitioning of assimilates to economically important plant parts such as roots or tubers, and by restricting shoot elongation may indirectly improve yield per unit land area by permitting increased crop density. Likewise, it is not clear whether drought conditions in the soil directly or indirectly affect epicuticular wax production processes.
Mapson observed that methionine was converted to ethylene in a model system, and in 1966 their research group confirmed the biological production of ethylene from methionine. Les modalites de la penetration du Botrytis cinerea Pers. Plum high-density planting-l0 year trials. Participatory approach to development: To assure development of appropriate technologies, farmers need to be involved in all stages of the technology development process, including problem diagnosis, research, and the technology transfer process. The morphological changes induced by these chemicals are more akin to those observed with xerophytic species.
The levels of potential nutrient losses from commercial production systems was shown by Lowrance and Smittle 1988 in Georgia. Mutagen specificity in barley for 1580 eceriferum mutants localized to 79 loci. Drought-stressed plants generally have greater amounts of epicuticular wax per unit leaf area than non-stressed plants. Mutants in Arabidopsis thaJiana altered in epicuticular waxes and leaf morphology. While it has been assumed that the amount of epicuticular and subcuticular waxes plays a major role in limiting the conductance of agricultural chemicals through plant cuticular layers, instances where no correlation between the amount of cuticular waxes and cuticular permeability suggest that wax thickness alone does not fully explain the physicochemical basis for permeability. In a study carried out in Cuba on 'Valencia' orange c. The use of white or black plastic mulch, the planting of two successive cucumber crops to minimize trellising costs in areas with low pest pressure, plus establishment of a tomato-cucumber double-cropping program to minimize staking costs were also part of their production package Hanna and Adams 1989, 1993.
Wax and the Boundary Layer Above Plant Surfaces D. Small arrows indicate the location from which epicuticular wax filaments emerge. Elongation of the C28 constituents appeared to be inhibited in the cer19 mutant in arabidopsis M. Desirable traits for green manure species include ease of establishment, high and fast biomass production rates, effective nodulation with indigenous rhizobia, ease of eradication, and inability to host important pests or diseases Sanginga et al. Ashworth Department of Horticulture and Landscape Architecture, Purdue University West Lafayette, Indiana 47907-1165 1. Burr, Richardo Hernández, Chieri Kubota, Christopher J.