Sap flow velocities of three mid-subtropical dominant species(Schima superba,Castanopsis carlesii and Cunninghamia lanceolata) were measured by using thermal dissipation probe method in Wanmulin Nature Reserve of Fujian Province.Meanwhile,the related environmental factors,including photosynthetically active radiation(PAR),air temperature and relative air humidity(RH) were recorded continuously by using automatic weather station.It indicated that the sap flow velocities of the selected trees varied regularly,with higher value in daytime than in nighttime and more apparent fluctuation in daytime than in nighttime.The peak values and variations of diurnal sap flow velocities of the broadleaves trees(S.superba and C.carlesii) were far more higher than that of conifer tree(C.lanceolata).The broad-leaves tree had the higher value of sap flow velocities in north than in south side,however,it was exactly opposite in the conifer tree.Sap flow velocities of the selected trees was significantly correlated with PAR,RH and vapor pressure deficit(VPD)(p<0.01),and the correlation coefficients declined following the order of VPD,RH,PAR and air temperature.

The sap flow rate(SF) of Fissistigma oldhamii and Cinnamomum chekiangense were measured with thermal dissipation probe method in Wanmulin Nature Reserve of Fujian Province.Meanwhile,related environmental factors,including photosynthetically active radiation(PAR),air temperature and relative air humidity(RH) were recorded continuously by using automatic weather station.It indicated that,for sunny days,the SF of F.oldhamii and C.chekiangense were similar during daytime,but in nighttime the value of SF in F.oldhamii was clearly higher than in C.chekiangense.The SF of both species decreased significantly in the rainy daytime.After raining,the night SF of F.oldhamii increased significantly,but the night SF of C.chekiangense was observed close to zero.Except for air temperature,the SF of F.oldhamii were significantly correlated with vapor pressure deficit(VPD),RH and PAR(P0.01),with the correlation coefficients declined following the order of VPDRHPARair temperature.Nighttime SF had no significant correlation with VPD from the result of curve estimation.Night sap flow of F.oldhamii was probably associated with water recharge in the trunk.

根据近年来转基因作物的研究,概述了转基因作物的现状、存在问题以及合理利用对策。