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KMID : 0368419740170010015
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Journal of Plant Biology
1974 Volume.17 No. 1 p.15 ~ p.21
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Effects of Ethrel on Tobacco-Leaf Maturity-Influences by Different Levels of the Chemical, Soil Nitrogen and Time of the Chemical Application
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Abstract
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The most commonly grown economical and flue-cured tobacco cultivar Yellow Special A was used in pot-culture tests in order to study Ethrel(2-chloroethyl phosponic acid) effects on accelerating maturity of tobacco leaves in relation to the most adequate level of the chemical useful for field growing, nitrogen level in soil for the most pronounced response, and the most suitable spray period during the growth stages of pre-, post- and topping periods. The following conclusions, thus, were obtained from the present studies;
1. 500ppm Ethrel spray was reconfirmed to be adequate in the practical applications, although the extent of yellow-ripening of tobacco leaves was increased as the Ethrel level increased. The highest level treated resulted in causing chemically damaged lesions on leaves and early defoliation.
2. Ethrel-treated leaves showed deeper yellowish tinge to them than those without treatment, while different levels of the chemical had less influence on the tinge.
3. An adequate level of nitrogen supply to plants favored the Ethrel response, whereas either very low or high level of nitrogen in the soil lowered the chemical effect on accelerating the yellow-ripening. When carbohydrates versus total nitrogen ratio became relatively high, the condttion brought out some outstanding Ethrel effects.
4. Chlorophyll level of leaves increased as soil applications of nitrogen level increased, and that also increased carotenoid level of the tobacco leaves. Ethrel-treated leaves showed deeper orange tinge than those without treatment, while
the highest level of nitrogen application showed the deepest orange tinge to tobacco leaves.
5. Pre-topping treatment(12 days before topping and flowering) resulted in almost no Ethrel response, and that treatment right on the day of topping, showed response of yellow-leaf ripening at nearly bottom-half leaves of a tobacco plant. The post-topping treatment(12 days after topping) made plants showing full response of Ethrel from bottom to the top leaves of tobacco plant in accelerating the leaf maturity.
6. The extent of Ethrel responses on accelerating yellow-ripening of tobacco leaves was discussed for the modifying influenees brought about by certain environmental factors. Discussions were also made about the possible practical applications(particularly for pre-rice planting) and quality difference that may be caused by such growth environments.
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