Study On Physiological Responses Of Phyllostachys Edulis To Water Storage In Their Stumps

Phyllostachys edulis(moso bamboo)is widely cultivated in South China.Water supply is one of the key factors that affect the growth of moso bamboo forest.But in recent years,the seasonal distribution of precipitation in southern China is becoming uneven because of the global climate change,and the production of moso bamboo declined and the quality of moso bamboo decreased,and even the moso bamboo forest ecosystem is seriously damaged.In 2013,Zhejiang Province has experienced more than 40 days of extreme high temperature and dry weather,a large area of moso bamboo forest appeared dead phenomenon,and even some of moso bamboo grew in the conditions of water supply better had been leaf curl phenomenon,affecting the photosynthetic productivity of moso bamboo forest.High temperature and drought greatly reduced the soil water content,affecting the regeneration of moso bamboo forest and the differentiation of moso bamboo shoots,which had a serious decline in winter production in Zhejiang Province in 2013.Moso bamboo as a clonal plant,it can be through the underground whip in ramets between water transport and sharing,so as to realize the water physiological integration of moso bamboo.In order to reveal the physiological response of moso bamboo to water storage in stumps,and provide theoretical reference for the establishment of water saving irrigation measures and production of large diameter timber.The effects of water storage in stumps on the physiological and photosynthetic transpiration characteristics of moso bamboo in simulated soil drought environment and the effect of water storage in moso bamboo stumps on the monthly variation and seasonal variation of photosynthetic and transpiration characteristics of moso bamboo in the natural environment,water absorbing capacity of bamboo stump wall and its relationship with environmental factors,and relationship between root physiological characteristics and irrigation years were studied in the moso bamboo forest which located at Miaoshanwu nature reservation of institute of subtropical forestry,chinese academy of forestry in Fuyang district of Hangzhou city during2015 to 2016.The following main conclusions are presented in this thesis:1 Physiological responses of moso bamboo to water storage in their stumps under simulated soil drought environentThe experiment with three different irrigation treatments,i.e.CK(0 stumps with water storage),T1(40 stumps with water storage per mu)and T2(60 stumps with water storage per mu)was established and laying plastic film in the bamboo forest to simulate the soil drought environment.The results showed that the photosynthetic transpiration rate and antioxidant ability of moso bamboo were significantly increased by adding water storage in bamboo stumps in moso bamboo forest.In simulated soil drought environment at 30 d,60 d and 90 d,the net photosynthetic(Pn)and transpiration rate(Tr)and photosynthetic pigment content of moso bamboo were positively correlated with the number of water storage in stumps,and the contents of malondialdehyde(MDA),relative conductivity,superoxide dismutase(SOD),catalase(CAT)and peroxidase(POD)were negatively correlated with the number of water storage in their stumps.The longer soil drought stress lasted and the lower relative water content of soil had,the effect of water storage in bamboo stumps on moso bamboo forest was more significant.2 Effects of water storage in moso bamboo stumps on physiological characteristics of moso bamboo with different ages under a simulated soil drought environmentAfter simulated soil drought environment two months,increasing water storage in their stumps in moso bamboo forest can produce great influence on photosynthetic ability of transpiration,leaf photosynthetic pigment content,MDA content and antioxidant enzyme system(SOD,CAT and POD)activity for three different ages of moso bamboo.With the degree of simulated drought increased(ie,the reduction in the number of water storage in their stumps),the Pn,Tr and Chl a,Chl b and Car contents were decreased in different degrees,and the content of MDA,the SOD,CAT and POD activities increased in different degrees.The Pn,Tr and photosynthetic pigment content of three eges old of moso bamboo were positively correlated with the number of water storage in their stumps and the MDA content and SOD,CAT and POD were negatively correlated with the number of water storage in their stumps.3 Effect of water storage in their stumps on photosynthesis and transpirationcharacteristics of moso bamboo under the simulated soil droughtAfter simulated soil drought environment two months,The trend of net photosynthetic and transpiration rate of moso bamboo in the day was consistent.Both of them were presented as unimodal curves and the "photosynthetic noon break" phenomenon had not been found.Pn and Tr of moso bamboo increased with the number of water storage in stumps rised and the order was T2?T1?CK.With water storage stumps increasing,it could significantly improve the ability of photosynthesis and transpiration of moso bamboo,also it could enhance the accumulation of photosynthetic products of moso bamboo,the Pn,Tr of moso bamboo was positively correlated with the number of water storage in stumps.For the three treatments,the water use efficiency(WUE)of moso bamboo was shown as a bimodal curve,with the number of water storage stumps increased,the water use efficiency of moso bamboo decreased and the tendency was CK?T1?T2.The WUE of moso bamboo and the number of water storage in stumps was negatively correlated,drought stress can improve the WUE of moso bamboo.4 Monthly variation of photosynthetic and transpiration characteristics of moso bamboo with water storage in their stumpsUnder natural conditions,the experiment with three different irrigation treatments,i.e.CK(0 stumps with water storage),T1(40 stumps with water storage per mu)and T2(60 stumps with water storage per mu)was established in moso bamboo forest.The Pn,Tr,WUE,stomatal conductance(Gs)and stomatal limitation(Ls)of moso bamboo were T2> T1> CK and the CO2 concentration in the intercostal cells(Ci)was CK> T1> T2 in different treatments.The Pn and Tr of moso bamboo with T1,T2 treatment compared to CK treatment,the largest increasement was in May;the WUE of moso bamboo with T1,T2 treatment compared to CK treatment,the largest increasement was in July and November respectively;the Gs of moso bamboo with T1,T2 treatment compared to CK treatment,the largest increasement was in May and October respectively;the Ci of moso bamboo with T1,T2 treatment compared to CK treatment,the largest drop was in October.the Ls of moso bamboo with T1,T2 treatment compared to CK treatment,the largest increasement was in January and October respectively.Increasing water storage in stumps in the moso bamboo forest can change the correlation between Pn,Tr of mosobamboo and environmental factors.5 Seasonal variation of photosynthetic and transpiration characteristics of moso bamboo with water storage in their stumpsIn the natural state,the Pn and Tr of different treatments were T2> T1> CK in four seasons.The diurnal variation of Pn and Tr were the same in spring and winter,they were single peak curves.In summer and autumn,the diurnal variation of Pn and Tr of CK were the double peak curve and had a "light lunch break" phenomenon,while the diurnal variation of Pn,Tr of T1 and T2 treatments showed a single peak curve.In different seasons,the the diurnal variation of Ls,WUE and Gs of moso bamboo in different treatments were T2> T1> CK,while the the diurnal variation of Ci in different treatments was CK> T1> T2.Increasing water storage in stumps in the moso bamboo forest can change the relationship between Pn,Tr of moso bamboo and the main environmental factors of the four seasons.6 The water absorption capacity of moso bamboo stump wall and its relationship with environmental factorsUnder natural conditions,the absorption of 10-15 cm diameter of moso bamboo stump was negatively correlated with the rainfall(P < 0.05),and highly negative correlation with the soil humidity significantly(P < 0.01).The water absorption of the inner wall of moso bamboo stumps were bimodal in the whole year,the two peaks of the water absorption of the inner wall of bamboo stumps were from January to March and August to October respectively.The minimum monthly absorption of the inner wall of moso bamboo stumps was in April,and the month of maximum water absorption appeared in August.Through the analysis of the data of water for one year,we can see that it is better to add water in the rainy season about 50 days,and the dry season is about 20 days.7 The relationship between root physiological characteristics and years of irrigationThe research on the irrigation of moso bamboo stumps for different years shows that,the activity of SOD,POD and CAT in roots of moso bamboo stumps increased with the irrigation duration increased,and the oxidase activities of root were positively correlated with irrigation duration.The root activity and antioxidant capacity decreased with the increase of irrigationyears,the relative electrical conductivity and MDA content of moso bamboo root were positively correlated with the irrigation years,and the root activity and the content of soluble protein were negatively correlated with the irrigation duration.With the increase of moso bamboo stump irrigation period,cell membrane lipid peroxidation of moso bamboo stump root increased and osmotic adjustment ability of moso bamboo stump root reduced.The comprehensive analysis shows that the water absorption capacity of the moso bamboo stumps were relatively good for one year.8 The comparison of main physiological responses of moso bamboo to water storage in their stumps under two environmental conditionsComparing the physiological indexes of moso bamboo after increasing water storage in stumps under two kinds of environmental conditions,the results showed that in the case of increasing the same amount of water storage in stumps,the total water absorption of the moso bamboo stumps in the simulated soil droughty plots was higher than that in the natural plots.Throughout the experiment,the Pn and Tr of moso bamboo grew in plots with 18 water storage in stumps under a soil drought environment was slightly higher than or more than the moso bamboo grew in natural state with none of water storage in stumps.Therefore,in order to avoid the influence of the dry season on the normal growth of moso bamboo,the effect of increasing60 water storage instumps per mu in the bamboo stand is better.