Study On Physiological Effects Of Partial Root-zone Drying In Nicotiana Tabacum

The yield, chemical quality, and some physiological biochemical/indexes of flue-cured tobacco plants were researched with a pot experiment under partial root-zone drying (PRD), deficit irrigation (DI) and full irrigation (FI) conditions. That was to explore the physiological mechanism for improving flue-cured tobacco yield and quality under PRD. The main results are as follows:1. Effects of different irrigation methods on biological characters of flue-cured tobacco plantsThe morphological indexes of flue-cured tobacco plants were affected by three different irrigation methods. The plant height, leaf weight, root length, root weight, leaf number and stem weight were not difference between PRD and FI, but the plant height, leaf weight, root length, root weight, leaf number and stem weight under PRD were higher than those under DI.2. Effects of different irrigation methods on root activity of flue-cured tobaccoThe effect of three different irrigation methods on root activity of flue-cured tobacco are as follows. The average root activity in four periods after treatments under PRD were higher than those under DI and FI, and there was a significant difference between under PRD and DI.3. Effects of different irrigation methods on the leaf carbohydrate content of flue-cured tobaccoThe soluble sugar, reducing sugar and starch content of flue-cured tobacco leaf under PRD were higher than those under FI. The orders are all as’partial root-zone drying> full irrigation> deficit irragation’.4. Effects of different irrigation methods on mineral element content of flue-cured tobaccoThe mineral element contents of different flue-cured tobacco parts under three different irrigation methods were determined. The orders of potassium, calcium, magnesium, phosphorus, sulfur and zinc content are all as’leaf> root> stem’, and these elements content under PRD are the highest among three different irrigation methods. 5. Effects of different irrigation methods on photosynthesis of flue-cured tobaccoStomatal conductance and transpiration rate of photosynthetic parameters were reduced with irrigation water decrease. Photosynthetic rate under PRD and FI was obviously higher than that under DI, but there was no difference between PRD and FI. Chlorophyll a, chlorophyll b and total chlorophyll content of flue-cured tobacco leaves under PRD was higher than that under DI and FI, respectively.6. Effects of different irrigation methods on nicotine content of flue-cured tobacco leavesThe order of nicotine content in flue-crued tobacco leaves under the same treatment is as’upper position leaves> middle position leaves>lower position leaves’, and that under PRD was the highest among three different irrigation methods.7. Effects of different irrigation methods on water use efficiency of flue-cured tobaccoWater use amount about four periods after treatment was tested, the result showed that the order of water use efficiency is’PRD> FI> DI, although water use amount under PRD was obviously lower than that under FI, and water use amount under PRD and DI was not significantly different.