The Study On Effects Of Transplanting Stage On Growth,Chemical Compositions And Yield Of Flue-cured Tobacco In Mudanjiang Region

The effects of transplanting time on morphological and physiological characters of flue-cured tobacco cultivars of Longjiang911and Longjiang851were investigated in this experiments, which including growth rhythm, vigour, photosynthetic capacity, chemical components, and leaf quality, meanwhile we also have explored the changes of dry matter and accumulation pattern on nitrogen (N), phosphorus (P) and potassium (K). The results were shown as follows:1.The flue-cured tobacco seedlings were transplanted during April30-May20; all the growth parameters (plant height, stem girth, foliation number, leaf length, and leaf width) were in accordance with Logistic growth model. However, with the delay of tansplanting time, the stem girth and leaf numbers of the flue-cured tobacco were decreased, in contrast, the plant height, leaf length and width were increased.2.Growing looks:in rosette stage the plant height was20-30cm, stem girth was5-6cm, foliation numbers were22-24, maximum leaf length and width was about40cm and20cm, respectively; in budding stage the plant height was110-160cm, stem girth was8-9cm, foliation numbers were30-32, maximum leaf length and width was about40-50cm and25-30cm, respectively; in dome stage plant height was120-160cm, stem girth was8-9cm, reserved leaf numbers were14-16, maximum leaf length and width was about60-70cm and30-35cm. respectively. The plant type showed a drum model:crown width was about75cm, base width100-110cm, leaf layer width and height was120-130cm and110-130cm, the position of leaf layer width occurs at65-70cm of leaf layer height.3.Leaf photosynthetic characteristics:The values of net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs) and water use efficiency (WUE) have showed higher of seedlings transplanted on May10and May20while value of intercellular CO2concentration Ci was lower. These implied that the delay of transplanting time enchanced leaf gas exchange and water use capacities by improving stomatal opening and transpiration rate. In contrast, the seedlings transplanted on April30the indexes of Pn, Tr, Gs and WUE were lower and Ci was higher, which indicated that early-transplanting leaves had a relatively weak gas exchange and water use capacity.The characteristics of major chemical components:the seedlings transplanted on May10and May20showed a better balance of chemical components than that transplanted on April30, this may be due to the improvement of chemical component balance in the lower leaves. The seedlings transplanted on April30had a similar contents of nicotine, total nitrogen, potassium (K), chlorinity (Cl) and the ratio of K/Cl in the lower leaves with that transplanted on May10and May20, but had a higher reducing sugar and total sugar content, and the ratio of sugar to nicotine, ratio of nitrogen to nicotine and Shmuck value were beyond the reference ranges. These would influence the coordination of chemical components and further decrease industrial usability of the lower leaves.4.Quantity and quality of the flue-cured tobacco:all the indexes including single leaf weight, the proportion of high class leaf and middle-high class leaf of the flue-cured tobacco, average price, acre yield, acre output value and class index were the highest for the seedlings transplanted on May10, while lowest for the seedlings transplanted on April30. The seedlings transplanted on May10had an increment of0.66g for single leaf weight,9.57%for high class leaf proportion of the flue-cured tobacco,1.10yuan/kg for average price,0.05for classs index,18.9kg for acre yield, and41.5yuan for acre value as compared to the seedlings transplanted on April30. The seedlings transplanted on May20had an increment of13.9kg for acre yield and150yuan for acre value as compared to the seedlings transplanted on April30.5.Changes of dry matter and N, P, K accumulation:dry matter of flue-cured tobacco began to accumulate from rosette stage with the growth and development, the accumulation of dry matter in the organs of roots, stems and leaves showed a "slow-fast-slow" pattern that is a S-type curve. Dry matter flow was from below-ground parts to above-groud parts and further to developing leaves. Therefore, in the whole growth period, distribution proportion and the accumulation of dry matter were both leaf> stem> root. For the mineral element accumulation, N, P, K accumulation was listed in the decreasing order:leaf> stem> root. N, P, K accumulation of leaf was increased significantly from rosette stage to budding stage and from vigorous growth period to budding stage. In the whole growth period, there were insignificantly fluctuation on N, P, K accumulation in roots and accumulation strength.