| Experiment in pot was carried out to studied effects of ABT rootone, malic acid and humic acid on tobacco growth, physiological characters and chemical elements.The results were as follows:1 Effects of regulators on soil nutrient and pHThe content of soil available nitrate, available phosphorus and available potassium declined slowly before stem with round leave stage and sharply from which to vigorous growth stage. After vigorous growth stage, their declining speed became slow again. All of the treatments aggrandized absorption of soil nutrients from stem with round leaves stage. ABT used soil nutrients so quickly at early stage as to its nitrogen, phosphorus, potassium of soil declined rapidly. But on average, malic acid's effects was prominent, then were ABT and humic aicd. Treatments all absorbed more soil nutrient than CK.The pH of Soil with malic acid and humic acid were lower than that of Ck at early period at after transplantation, but the pH of ABT was higher than that of CK and descended approximately to it from button stage. After topping treatments' roots grew vigorous, then soil nitrification made soil around roots more acetic and the pH of soil lower than CK. As little molecule organic acid Malic acid is, the pH of soil was lowest at early period but roughly equal to the one with malic acid at late period. While ABT also made soil acid declined for thrive growth of tobacco and increased of roots secretion.2 Effects of regulators on endogenous hormones and the activity of enzymes concerned in tobacco rootIt was known that hormone is important to control tobacco roots from the the growth of roots and the vitality tendency of its endogenous hormones .Endogenous auxin could promote tobacco roots occurring. But within certain scope, it promoted tobacco roots' primordius' coming into being When the concentration was lower, restrained which and promoted elongation of them when concentration was higher. Cytokinin was beneficial to roots' occurring to some extent and gibberellin could refrain. At vigorous growth stage malic acid's hormones was greater than ABT, then was humic acid. All treatments were better than CK.The vitality regulation of auxin oxidase, peroxidase and polyphenol oxidase illustrated auxin's reducement to tobacco root further more. The contrary tendency between activity of auxin oxidase, peroxidase's and the quantity of auxin made it clear that they could oxidize auxin and consequently lessen it and restrain tobacco roots. It showed that humic acid's was higher than ABT's, then was malic acid's, all treatments were lower than CK. Vitality of polyphenol oxidase tendency was highest, then were ABT's and humic acid's. All treatments were higher than CK.3 Effects of regulators on the amino acid and the activity of enzymes concerned in tobacco rootsThe research of the amino acid quantity in tobacco roots can indirectly reflect it's nitrogen metabolism. Amino acid quantity in tobacco roots which was a little higher during stem with round leaves stage increased during vigorous growth stage, then came to descend until button stage. The treatments showed that malic acid was superior to ABT, then was humic acid.Nitrate reductase dynamic in tobacco roots rose with the growth of tobacco at incipience. While declined inversely from button stage. Glutamine synthetase which was the same as NR declined from vigorous growth stage. So the transformation law of the two key enzymes in roots was unanimous with the growth of tobacco roots. In tobacco roots dynamic of NR and GS were closely related to the quantity of amino acid. NR and GS's activity of malic acid was highest, then were ABT's and humic acid's, the last was CK.30 days after transplanting amino acid of roots and NR were significant negative correlation. 60 days after transplanting it was extremely significantly positive correlation with GS.4 Effects of regulators on cured tobacco biological charactersBiological characters of treatments' tobacco roots were all better than CK. Before stem with round leave stage malic acid's advantages was obvious, then was ABT's. From vigorous growth stage , ABT's promotion effects was most prominent, dry/fresh weight and volume of roots, first class lateral roots and adventive roots' increasing breadth were greatest.Besides from humic acid others didn't show any advantage at early stage. Before vigorous growth stage ABT was superior to malic acid and humic acid at stem length, stem circumference and number of leaves, but after the stage malic acid was superior to ABT. At button stage, all treatments showed obvious advantages. |
