Tobacco growth regulation

Flumetralin is a plant growth regulator, used to control sucker growth in tobacco... 

This compound, l,2-dihydro-3,6-pvridazinedione, is also used as a growth regulator, herbicide, and plant modifier. It is used in the treatment of tobacco plants as a post-harvest sprouliug inhibitor and as a sugar content stabilizer in sugar beets. 

Efforts may now have been successful Whereas normal tobacco cells require auxin for division, sequence tagged (TDNA) lines encoding an adenylyl cyclase were obtained which were auxin-independent but cAMP-dependent. From one line (axi 141), a complementary DNA encoding adenylyl cyclase has been isolated with characteristic leucine repeats and similarity to yeast adenylyl cyclase (Ichikawa et al., 1997). The result seems not to be the expression of an alternative division pathway from the normal auxin-driven division since it is blocked by auxin inhibitors and is activated by cAMP and the cyclase activator forskolin. Perhaps a link to G-protein at the membrane will now bring plant growth regulation even closer to that of animals. 

Disease development often appears to be influenced by growth regulators. Most of these studies concern wilt diseases in various crops, especially caused by Fusarlum spp. and Verticilllum spp. (12). However, kinetin has been shown to be active against other types of diseases, such as the powdery mildews of cucumber (10) and tobacco (8). The mode of action of growth regulators in the disease control... 

Several diterpenes present in tobacco plants were evaluated by Cutler (240) for growth-regulating activity in wheat coleop-tile bioassays. Except for isodihydroabienol and B-levantenolide, all of the endogenous tobacco diterpenes showed growth inhibition of the wheat coleoptiles at concentrations of 10 3m or less (Table 14). 

For more than two decades, maleic hydrazide has been used extensively on tobacco to prevent the formation of suckers (auxiliary buds), which decrease leaf quality. Before this material was developed, large amounts of hand labor were required to remove the buds. This use for maleic hydrazide is one of the great success stories in the plant growth regulator field. 

With such cooperation, mutual support and obviously some "luck" (23), plant growth regulators, including abscission agents, may still be expected to be developed (24, 25) not only to enhance quality and yields of major crops e.g., cotton, corn, tobacco, but also important fruit crops e.g., apples, oranges (citrus), grapes, cherries, etc. 

Limonene is used as a starting material for growth regulators of tobacco plants. Hydroaminomethylation is able to reduce the number of reactions steps for their production to one. The reaction takes place with yields up to 93% after 20 h with a rhodium dimer as a catalyst (Scheme 20). 

Cutler, H. G., Cole, R. J., and Wells, J. M. 1976. New naturally occurring plant growth regulators potential use in tobacco culture. Proc. 6th. International Tobacco Scientific Congress, Tokyo, 124-125... 

The effect of these resistances has been to drive chemical control from one insecticide to the next. In most parts of the Nile delta the cotton leafworms can still be controlled by some OP compound, such as chlorpyrifos, supplemented where necessary with the insect growth regulator Dimilin. But in southern Texas, Mexico, Nicaragua and Peru the multiple resistances of the tobacco budworm, and to a less extreme degree of H. zea and Spodoptera sunia, have made even 20 insecticide applications a season quite worthless, and indeed there is less damage to the cotton if no chemicals are applied at all. The only materials that can be relied upon to kill these multiresistant H. viresoens are the dichlorovinyl pyrethroid NRDC-143 and the Heliothis nuclear polyhedrosis virus. 

The multiresistant strains now extant also show a certain cross-tolerance, but not resistance, to the third-generation insecticides such as the juvenile-hormone mimics and other so-called insect growth regulators, as was found in strains of the housefly, flour beetle and tobacco budworm. Resistance to the JH mimic methoprene and Monsanto-585 has been induced by laboratory selection of Culex taxsalis (28) and Culex pipiens (29), and to Monsanto-585 in Culex quinquefasstatus (30). Whatever insect or IGR is chosen, the result of exposure to selective doses in successive generations is usually the development of resistance, repeating our previous experience with chemosterilants, and the... 

Uses plant growth regulator, fruit, vegetables, cereals, tobacco, cotton,... 

The relationship between the development of the tobacco harvester and chemical growth regulators is one of direct interaction. One of the major problems that needed resolution was the inability of the mechanical harvester to distinguish a leaf from axillary regrowths. If these axillary regrowths, which are more commonly known as suckers, are allowed to grow, they can so thoroughly confuse the mechanical harvester that it is virtually impossible to operate. 

The story is far from complete in tobacco because new growth regulants are now being evaluated which will cause all the leaves on the plant to mature at one time. Conceivably the day will soon be reached when a program based upon chemical growth regulants and mechanization will reduce the harvesting of flue-cured tobacco from five trips to one. 

The most important nonmilitary application is synthesis of maleic hydraz-ide, which is used as a plant-growth regulator for tobacco suckering and tree pruning. Another important nonmilitary chemical is semicarbazide which is obtained by reacting hydrazine with urea ... 

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