氮钙协同对杨树生长、光合特性及叶绿素荧光的影响

Effects of Nitrogen-calcium Synergy on Growth,Photosynthetic Characteristics and Chlorophy Ⅰ Fluorescence of Populus L.

杨树(Populus L.)是我国重要的经济林和生态防护林树种,由于钙的空间异质性和氮沉降的影响,导致各区域的杨树人工林生长出现显著差异。为明确氮钙协同对杨树生长、光合特性及叶绿素荧光的影响,促进杨树的生长,为杨树人工林的培育提供理论依据,以杨树“中辽一号”为试验材料,设置2个不同氮梯度(5,20mmol·L^(-1))和5个不同钙梯度(0,2.5,5,10,20mmol·L^(-1)),使用营养液培养,通过对杨树生物量、光合特性和叶绿素荧光的测定,探究氮钙协同对杨树生长发育的作用与意义。结果表明:在不同氮处理水平下,随着钙浓度的增加,杨树幼苗的生物量、净光合光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、潜在光化学效率(Fv/F0)和最大光化学效率(Fv/Fm)均呈现先升高后降低的趋势。其中在低氮水平(5mmol·L^(-1))下,以5mmol·L^(-1)钙水平下杨树生长发育达到最优;而高氮水平(20mmol·L^(-1))下,以10mmol·L^(-1)钙水平下杨树生长发育达到最优,与其他钙水平处理存在显著差异(p<0.05)。当氮与钙的任一处理过低或过高时就会对杨树的生长产生胁迫,降低光合作用,抑制生长发育。综上,氮钙协同显著促进杨树生长,且在5mmol·L^(-1)的氮处理和5mmol·L^(-1)的钙处理时,杨树幼苗生长、光合特性和叶绿素荧光达到最优值。

Populus L.is an important economic forest and ecological shelterbelt species in China.Due to the spatial heterogeneity of calcium and the nitrogen deposition,the growth of Populus plantation was significantly different in different regions.To determine the effects of N-Ca synergy on growth,photosynthetic characteristics and chlorophyll fluorescence of Populus,to promote the growth of Populus,it provides theoretical basis for the cultivation of poplar plantation.In this paper,Populus“Zhongliao No.1”was used as the experimental material,set 2 different nitrogen gradients(5mmol·L^(-1) and 20mmol·L^(-1))and 5 different calcium gradients(0,2.5,5,10 and 20mmol·L^(-1)),and the biomass,photosynthetic characteristics and chlorophyll fluorescence of the Populus were measured by means of nutrient solution culture to study the synergistic effect of nitrogen and calcium on Populus growth and development.The results indicate that:The biomass,net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr),potential photochemical efficiency(Fv/F0)and maximum photochemical efficiency(Fv/Fm)of Populus seedlings all increased first and then decreased with the increase of calcium concentration at different nitrogen treatment levels.Populus growth and development reached the optimal level at a low nitrogen level(5mmol·L^(-1))and a calcium level of 5mmol·L^(-1),and that reached the optimal level with 10mmol·L^(-1) calcium at a high nitrogen level(20mmol·L^(-1)),which was significantly different from other calcium levels(p<0.05).Therefore,the cooperation of nitrogen and calcium significantly promotes the growth of Populus(p<0.05).When the nitrogen and calcium side is too low or too high,Populus growth will be stressed,photosynthesis will be reduced,and growth and development will be inhibited.Totally,there was indeed a synergistic mechanism of nitrogen and calcium on regulating Populus growth,the optimal value of these indicators occurred in the combination treatments of 5mmol·L^(-1)(nitrogen concentration)and 5mmol·L^(-1)(calcium concentration).