BVOC Emission And Photosynthetic Characteristics Of 13 Common Gymnosperms In Winter

BVOC are synthesized by plants and emitted in atmosphere and played an important role in plant defense,information transmission,atmospheric chemical cycle and carbon cycle.Gymnosperm as common landscaping species have a very important role in garden design and urban greening.In order to study the emission of BVOC and its composition of common gymnosperms in cities,In this study,13common gymnosperms(C.pisifera,J.chinensis,J.formosana,P.orientalis,S.chinensis,C.lanceolata,K.fortune,S.sempervirens,T.chinensis,C.deodara,P.elliottii,P.parviflora,P.macrophyllus)were selected for measurement,combined with the emission of BVOC of tree species under low temperature in winter,explore the relationship between the emission of monoterpene of gymnosperms and plant families,leaf types,native growth sites and photosynthetic productivity,and then the emission of BVOC plants Provide basic theoretical basis to provide data support for future scientific research.The result showed that:(1)Monoterpene are the main volatile emitted from 13 gymnosperms,and the relative proportion accounted for 85.01%of the total BVOC emission.Under the low temperature,except for the emission of C.pisifera,the emission rate of BVOC(monoterpene,aromatic compounds,GLVs and other compounds)of gymnosperms was not significantly different from the basic state.There are big differences in the species and emission rate of BVOC from gymnosperm,that is to say,the emission of monoterpene compounds in gymnosperms has obvious species specificity.(2)The J_max/V_cmax of most gymnosperms were at a high level in winter,that is to say,at this time,the V_cmax of most gymnosperms was limited.The light energy cannot be effectively used and excessive light energy under strong light,which may be a self-protection strategy for plants in winter.(3)In winter,the emission of monoterpene from Cupressaceae(Basal state:27.69±9.48nmol mg^-1 s^-1;Low temperature:19.47±5.18nmol mg^-1 s^-1),Pinaceae(Basal state:16.51±6.95nmol mg^-1 s^-1;Low temperature:18.80±8.57nmol mg^-1 s^-1)and Taxodiaceae(Basal state:10.96±3.10nmol mg^-1 s^-1;Low temperature:13.53±4.88nmol mg^-1 s^-1)in the basal state was not significantly different from that at low temperatures(P>0.05),but the emission of monoterpene from Cupressaceae plants at low temperature is lower than that of basal state,and the emission of monoterpene from Pinaceae and Taxodiaceae at low temperatures were higher than that under basal state.However,the net photosynthetic capacity of Pinaceae(7.56±1.09?mol g^-1 s^-1)and Taxodiaceae(7.45±0.77?mol g^-1 s^-1)was significantly higher than that of Cupressaceae(4.80±0.42?mol g^-1 s^-1)(P<0.05).(4)There was no significant differences in the emission of monoterpene from needle leaf(Basal state:20.22±8.41nmol mg^-1 s^-1;Low temperature:23.02±10.42nmol mg^-1 s^-1),scale leaf(Basal state:33.9±11.00nmol mg^-1 s^-1;Low temperature:19.47±5.18nmol mg^-1 s^-1),and strip leaf(Basal state:8.04±2.38nmol mg^-1 s^-1;Low temperature:10.85±3.97nmol mg^-1 s^-1)plants(P>0.05);and there was no significant difference in the emission of monoterpene from the three leaf types of plants compared with the low temperature state(P>0.05),but the emission of monoterpene from scale leaf plants at low temperature was lower than that at the base state,while the emission of monoterpene in needle leaf and strip leaf plants at low temperatures is higher than that in basic conditions.But the net photosynthetic capacity of needle leaf(8.47±0.84?mol g^-1 s^-1)plants was significantly higher than that of scale leaf(4.61±0.47?mol g^-1 s^-1)plants and strip leaf(6.35±0.80?mol g^-1 s^-1)plants(P<0.05).(5)In winter,the emission of monoterpene of native species(Basal state:6.44±1.46nmol mg^-1 s^-1;Low temperature:5.66±1.03nmol mg^-1 s^-1)was significantly lower than that of alien species(Basal state:41.08±9.48nmol mg^-1 s^-1;Low temperature:30.49±8.08nmol mg^-1 s^-1),both in the basal state and at low temperature(P<0.05),but there was no significant difference between the emission of monoterpenes in the basal state and the emission of monoterpenes in the low temperature state,regardless of the native(5.77±0.58?mol g^-1 s^-1)or alien species(7.09±0.88?mol g^-1 s^-1)(P>0.05)and no significant difference in net photosynthetic rate(P>0.05).The emission of monoterpene(R²=0.403,P=0.009),aromatic compounds(R²=0.522,P=0.002)and GLVs(R²=0.544,P=0.002)from alien species has a negative correlation with temperature;the emission of monoterpene(R²=0.278,P=0.017)from native species is positively correlated with temperature,while the emission of aromatic compounds and GLVs is not correlated with temperature.(6)In a certain range,the emission rate of monoterpene from Cupressaceae plants decreased with the increase of net photosynthetic rate(R²=0.217,P=0.013),the emission rate of monoterpene from Pinaceae plants increased first and decreased with the increase of net photosynthetic rate(R²=0.760,P=0.003),the monoterpene emission rate of Taxodiaceae plants decreased linearly with the increase of net photosynthetic rate(R²=0.376,P=0.012).And the emission rate of monoterpene of 13 gymnosperms with the net photosynthetic rate showed a similar pattern to that of Pinaceae(R²=0.299,P=9.115E-6).In summary,gymnosperms regulate the emission of monoterpene through photosynthetic electron transfer and dark respiration in the photosynthetic system,which meets their physiological needs and plays a certain role in resisting the adverse environment.The emission of gymnosperm plants has certain specificity,that is,different gymnosperms have different emission of BVOC.The BVOC emission rate of native species is at a low level,while the monoterpene emission of alien species is at a high level,which may be a reflection of the adaptation of alien species to the current environment.