The Effect Of Drought Stress To Agronomic Traits And Physiological Property Of Yunyan87and K326

The emergence of drought stress could be in the stages of whole growth period of theflue-cured tobacco which affect the flue-cured tobacco growth and physiology. Anexperiment was conducted with potted flue-cured tobacco Yuyan87and K326tocomparative analysis the effects of drought stress to Yuyan87and K326on yield and theagronomic characters, photosynthesis, chemical composition in different stages. Thedrought time were set as7d,10d,13d,16d, long term-drought and CK(the control) inrosette stage, vigorous growing stage, budding period respectively. The results are showedthat:1. The plant height, stem, average leaf area of Yunyan87and K326in rosette stage,vigorous growing stage, budding period were decreased by drought stress, the impact couldbe worsen by extending the drought time and there were minimum values when droughttime is16d. The plant height, stem and average leaf area in different stages of Yunyan87and K326to respond to drought are different, there was a significant inhibitory action ofeffect of drought stress to the plant height in vigorous growing stage, the influence ofdrought to the plant height of K326in budding period is bigger than to Yunyan87. Thedecline of stem of Yunyan87was less than K326in rosette stage, in vigorous growingstage the declines of stem of these two varieties were almost the same and which ofYunyan87was bigger than K326.The change of the leaf area in the whole stages showedthat drought resistance of Yunyan87was bigger than K326in earlier stages and which didnot show obvious advantage in middle and later stages. The variation trends of theroot-shoot ratio of Yunyan87and K326in rosette stage and vigorous growing stage werefirst declining then rising after regaining water which were falling in budding period. Thesoil water content corresponding to Yunyan87and K326stopping growing in differentstages was biggest in vigorous growing stage which showed that the maximum of waterconsumption of flue-cured tobacco in the whole stages is in the vigorous growing stage.2. The stomatal conductance, transpiration rate and photosynthetic rate of Yunyan87and K326in rosette stage, vigorous growing stage, budding period respectively showed adecreased tendency with drought time prolonging. The intercellular CO2concentrationdisplayed a trend that going significantly down first then rising gradually and there was aminimum value when drought time is10d. The water use efficiency of Yunyan87wasdropping slightly first then increasing and falling substantially at last by the effects of drought stress, especially in the rosette stage and budding period, and the change of wateruse efficiency of K326in vigorous growing stage was different from which of Yunyan87, itshowed a falling slowly first then sharply declining trend. The chlorophyll content ofYunyan87in different stages all displayed the decreased tendency especially in vigorousgrowing stage and there was a a minimum value when drought time is16d. the chlorophyllcontent of K326would have a rise phenomenon when the drought time is10d or13d butthe value was under the control level3. In rosette stage, vigorous growing stage, budding period would the drought stressbrought down the content of reducing sugar and potassium of Yunyan87and K326. Thelonger the drought time was,the greater the effect, especially in the budding period. Withthe drought time prolonging, the content of total nitrogen and nicotine increasedsignificantly which was more remarkable in the budding period. The increase amplitudecaused by drought stress of total nitrogen content of K326was less than which ofYunyan87in rosette stage and vigorous growing stage and they were just on the contrary.There was no significant difference of nicotine content between Yunyan87and K326. Theratio of nitrogen to nicotine value of the two varieties were both less than one, and theyshowed a decreased trend in rosette stage and vigorous growing stage which showed afalling trend first then rising in budding period.4. The drought stress in rosette stage, vigorous growing stage and budding periodcould bring the yield of Yunyan87and K326down significantly, the longer the droughttime was, the greater the yield per plant drop. The long-term drought (DL) in rosette stagecould cause the two varieties almost no yield, and except long-term drought, the harmbiggest degree to the yield by drought stress was in vigorous growing stage, and throughthe contrast analysis, the influence of drought to the yield of Yunyan87was less than thatof K326.