Studies On Characteristic And Heredity For Potassium Content Of Tobacco

Field and water culture experiments were conducted to study the characteristic of potassium content of tobacco leaf, difference among genotypes, heredity, heterosis, and physiology characteristic, morphology characteristic, mechanism of rich potassium in leaf, characteristic of the accumulation of dry matter and potassium of leaves of tobacco breeding with high potassium content. Tentative results obtained are as follows: (1) potassium content of tobacco leaf is a quantitative character, which can be studied by analysis methods for quantitative heredity; (2) There exists essential difference for potassium content of tobacco leaf among genotypes, and variation coefficient is also big. Measures of genetic improvement could raise potassium content of tobacco leaf; (3) In later stage of growth, variation of potassium content of tobacco leaf tends to become stable among different genotypes; There is a significant correlation between potassium content of leaf of later stage and potassium content of toasted leaf; (4) In water culture experiment, heterosis of hybrid(Fl) is most obvious, and difference of potassium content of shoot could be embodied among different tobacco genotypes; The bigger assimilative surface of root is a feature for tobacco varieties with high potassium content. However, potassium content of tobacco leaf is less influenced .by active assimilative surface of root. The higherdistributive proportion of potassium from root to shoot is another feature for tobacco breeding with high potassium content. For higher potassium content of shoot, transfer and accumulation of potassium from root to shoot should be promoted; (5) In-field experiment, tobacco breeding with high potassium content has the characteristic of higher diastase activity, higher stalk height, more leaf number and wider stalk circumference; Among three factors (stalk height, leaf number, stalk circumference),stalk circumference has a greater contribution to the improvement of potassium content of tobacco leaf compared with stalk height and leaf number, and the formula, y=19.6844+2.7968x2+0.2204x3-0.2907x2x3 could reflect the relationship of the regression of stalk circumference and leaf number to potassium content of tobacco leaf; (6) In the growth of tobacco, tobacco breeding with high potassium content has two features as follows: 一, potassium content of tobacco leaf is relatively higher in early growth;二, drop extent of potassium content of tobacco leaf is slower, or not sharply slow in a period of later stage of growth ;The peak of absolute potassium value of tobacco leaf should be put off, which is advantageous to promote potassium content of tobacco leaf; Dilution effect is one of causes of sharp drop of potassium content of tobacco leaf, but it can not fully explain the phenomenon; (7) There are dominance effect and additive effect of gene for potassium content of tobacco leaf, and dominance effect is bigger than additive effect. Potassium content of tobacco leaf is stable among generations and it is greatly influenced by environment; (8) Heterosis of potassium content of tobacco leaf over the mid-parent parent exists widely in tobacco hybrids; heterosis over the better parent exists only in some hybrids. Therefore, heterosis of hybrid (F,) can promote ?potassiumcontent of tobacco leaf. Parents of hybrid are asked for as follows: 一, Genetic variation should be large; 二, potassium content of tobacco leaf for parent with low potassium content should also be large enough.