Research Of Temperature Regulating On Dry Matter Accumulation During Developing Of Cotton Boll

Field experiments were carried out in Nanjing in 2006 and two cotton cultivars, nan-nong 7 and su-mian 12,were used to study the temperature response on the cotton dry matter accumulation,the physiological metabolize of cotton boll and the quality of fibre. The temperature difference was created by different sowing date.The main results were as follows:The effect of different temperature on cotton dry matter accumulation showed that the accumulation rate of total dry matter,seedcotton and fibre dry matter accord with the "S" curve,respectively,could be simulated with Logistic equation,the simulated effect is all right and the correlation coefficient reached more than 0.97.Cotton boll dry weight has remarkable plus correlation with the daily average temperature,the=15℃available accumulated temperature and =30℃temperature days after flower formation,but has obvious negative correlation with the =19℃temperature days after flower formation. During the floriferous period 7/14-8/16,at the daily average temperature range of 23.6-28.8℃in boll phase,the fast accretion of cotton boll dry matter,fibre and seed dry matter present to 12-50 d,14-53d,16-52d和13-53d,respectively,after flower formation;the maximal accumulation rate appear at 27-32d,28-36d,25-37d和27-35d after flower formation and the duration of the maximal accumulation rate were 32-37d,27-35d,18-27d和28-37d,the =25℃available accumulated temperature is crucial to the dry matter accumulation rate.The dry matter accumulation at different fruit branch parts and different flowering date were used to draw the conclusion that the dry matter transportation rate of the first Sympodial node of the eighth fruit branch boll were much higher than the first Sympodial node of the forth and twelfth branch.The matter accumulation and transportation of shell revealed that as to the flowers formed during 7/14-8/4,the daily average temperature were above 28℃and 25℃respectively during 0-20d and 21-40d after flower formation,shell dry matter accumulation fastigium was about 20d after flower formation.The accumulation rate of shell and transportation rate from shell to fibre and cotton seed were high,the accumulation capacity were decreased in some sort and finally the dry weigh of fibre and cotton seed were relatively high.In contrast,for the flowers formed during 8/9-8/16,the daily average temperature during 0-20d after flower formation were above 28℃(but lower than the flowers formed during 7/14-8/4) and below 25℃after 31d,41d respectively which result in that the transportation rate of dissolvable matter from shell to seed cotton was inhibited,matter accumulation fastigium was delayed to 30d,40d after flower formation.Moreover,the transportation rate of nutriment from shell to fibre and seed was low and ultimately the dry weigh of fibre and seed cotton were relatively low.The effect of different temperature on the cotton boll physiological characteristic indicated that as to cotton boll in different floriferous phase,the soluble sugar content in cotton fruit leaf reduce accord with the depressed temperature and its peak value advanced after flower formation.The peak value of soluble sugar accumulated content in the first Sympodial node of the eighth fruit branch boll was supreme and reduced sharply after the apex.The soluble sugar and protein content in shell declined along with the aging of cotton boll.The peak value of soluble matter in cotton boll which flower formed during 7/14-8/4 was high and reduced sharply after the apex,the temperature during the boll phase was above 28℃which was relative high,therefore it is obvious that high temperature was propitious to the transportations of soluble matter from shell to the fibre and seed.The peak value of soluble matter at 25℃was low and soluble sugar and protein content increased after the apex which show that the transfer rate of organic matter was restrained by relatively low temperature and due to the drop of seed cotton accumulation and fibrous quality.Protected enzyme active and MDA content in the first Sympodial node of the eighth fruit branch boll were determined and the conclusion was that the SOD and POD active of shell were sensitive to temperature,the enzyme active have remarkable difference in different temperature and the MDA content was contrary,the change of MDA content in prophase of cotton boll growth also have no obvious difference.The fiber soluble sugar was significant negative correlation to cellulose content.The soluble sugar content increased during the early development stage of fiber but decreased afterward in company with the increased temperature.Relative high temperature lead to the relative preponderant cellulose accumulation quantity.Accordingly,high temperature make for the soluble sugar accumulation at early age and transfer from soluble sugar to cellulose subsequently.