Study On The Effect Of Temperature On Yield And Quality Of Ramie And Its Mechanism

Ramie is an important source of natural textile fibers.Under normal conditions,its yield is higher and fiber quality is much better in first season than in second and third season.Temperature is one of the most important factors among various environmental factors affecting the growth and development of plants.However,there is limited information on the effect of temperature on ramie yield and fiber quality.In recent decades,rise in global warming has greatly altered the growth conditions of ramie.Therefore,it is necessary to investigate the influence of temperature on ramie growth and development.In present experiment,three ramie cultivars viz.,Huazhu No.5,TG26 and 1504 with high,medium and low fiber fineness respectively,were used under three day/night temperature [26±2°C/18±2°C(low),30±2°C/22±2°C(medium),34±2°C/26±2°C(high)] treatments.The objective of present study was to investigate the influence of temperature from macro to micro level on ramie yield and fiber quality in terms of fiber yield and agronomic characters,dry matter,fiber physical properties,fiber supramolecular structure,fiber cell development,phloem chemical composition,phloem-related sugar content and related enzyme activities,etc.The main findings are as follows:(1)Lower temperature is suitable for the formation of ramie fiber with improved quality while,high temperature(34±2?/26±2?,the same below)adversely affects the fiber quality of Huazhu No.5,TG26 and 1504.High temperature reduced the ramie fiber fineness at 23.43%,29.13%,and 12.36% compared with low temperature(26±2?/18±2?,the same below)for Huazhu No.5,TG26 and 1504,respectively;the rubber content was increased at 42.25%,10.57% and 8.04%,respectively;improved the crystallinity of Huazhu No.5 and TG26,which was 10.53% and 8.89% higher than that of medium temperature(30±2?/22±2?,the same below),but for 1504,it was decreased by 7.42%;high temperature significantly reduced the degree of orientation above 1 percent for the three cultivars.From anatomical point of view,high temperature increased the fiber cell area,but this increase was different at different developmental stages.It was observed that high temperature has greatest impact on the immature period with an increase of 101.57%,50.78% and 11.76%,respectively,followed by the maturity and the late maturity.At the same time,the greatest impact was observed on Huazhu No.5,with the increase in three periods exceeded 70%,followed by TG26 and 1504.From the physiological and biochemical perspective,high temperature reduced the activity of sucrose synthase and sucrose phosphate synthase,but mainly decreased from the rapid growth period to the maturity.Comparing with low temperature,sucrose synthase activity was reduced by 78.15%,65.83% and 46.45%,respectively,and for sucrose phosphate synthase by 63.73%,45.30% and 57.04%,respectively.The highest effect was observed on Huazhu No.5,followed by TG26 and 1504.Furthermore,the analysis of chemical composition revealed that high temperature reduced the cellulose content,with a decrease of 3 to 7 percent,and increased water soluble substances,with an increase of 3 to 6 percent at maturity.(2)Low temperature favors high flesh biomass and fiber yield while,high temperature adversely affects flesh biomass and fiber yield of Huazhu No.5,TG26 and 1504.High temperature reduced the flesh biomass by 33.22%,53.32% and 50.96% compared with low temperature for Huazhu No.5,TG26 and 1504,respectively,and decreased fiber yield by 3.33%,14.58% and 10.53%,respectively.From the anatomical point of view,high temperature reduced the number of fiber cells per unit area,but this reduction was different at different developmental stages.It was further observed that high temperature has greatest impact on the immature period with the reduction of 40.09%,28.86% and 19.06% for Huazhu No.5,TG26 and 1504,respectively,followed by the maturity and the late maturity.Meanwhile,the greatest impact was observed on Huazhu No.5,with the reduction in three periods exceeded 37%,followed by TG26 and 1504.From the study of agronomic traits,high temperature reduced the plant height,while this reduction compared with low temperature was 29.33%,16.80% and 40.32% for Huazhu No.5,TG26 and 1504,respectively;comparing with low temperature in terms of bark thickness,there was no significant difference in Huazhu No.5 however,the decrease in TG26 and 1504 was 32.81% and 12.24%,respectively.The results of this study confirm that temperature is an important factor affecting ramie yield and fiber quality,and responses of ramie cultivars were different under different temperature which will provide support for further research and a theoretical basis for the improvement of ramie yield and fiber quality.