caa a22 4500 397520875 CHVBK 20180308164632.0 cr unu---uuuuu 161202e199504 xx s 000 0 eng 10.1093/jxb/46.4.407 doi (NATIONALLICENCE)oxford-10.1093/jxb/46.4.407 Limitations to net photosynthesis as affected by nitrogen status in jack pine (Pinus banksiana Lamb.) seedlings [Elektronische Daten] [Weixing Tan, Gary D. Hogan] Relative limitations of nitrogen (N) status on the processes contributing to photosynthetic rate (A) were investigated. Jack pine {Pinus banksiana Lamb.) seedlings from seeds grown in sand culture were supplied with four different N treatments for 6 weeks, which resulted in a needle N content ranging from 50-85 mmol m−2 (14-32 mg g−1 dry weight). Leaf gas exchange at varying CO2 levels was measured and limitations on A350 (A at ambient CO2 level) caused by finite, limiting carboxylation efficiency (c.e.), maximum A (Amax)and stomatal conductance were estimated from an analysis of the response of A to internal CO2 concentration. Although c.e. and Amax decreased linearly with the decline in needle N, the magnitudes of their changes relative to A350 differed. Amax varied with A350 and always exceeded A350 by 37-38% c.e., however, declined faster than A350, as needle N level decreased. Consequently, relative limitation on A350 caused by inefficient Amax remained constant, but limitations caused by c.e. increased by 10-15% at low N levels. In contrast, the limitation by stomatal conductance declined initially, but remained stable when N content dropped below 75 mmol m−2. The results suggest: (1) a decrease in biochemical capacity, but not stomatal conductance, contributed to the reduction of A350 induced by N-deficiency in jack pine seedlings; and (2) the capacity of carboxylation appeared to be impaired more than that of electron transport and/or photophosphorylation and its reduction may be the major reason for the reduction in A350. © Oxford University Press Articles nationallicence A-Ci analysis nationallicence carboxylation efficiency nationallicence electron transport nationallicence nitrogen deficiency nationallicence stomatal conductance nationallicence Tan Weixing Natural Resources Canada, Canadian Forest Service, Ontario Region, PO Box 490, 1219 Queen St. E., Sault Ste. Marie, Ontario, Canada P6A 5M7 aut Hogan Gary D. Natural Resources Canada, Canadian Forest Service, Ontario Region, PO Box 490, 1219 Queen St. E., Sault Ste. Marie, Ontario, Canada P6A 5M7 aut Journal of Experimental Botany Oxford University Press 46/4(1995-04), 407-413 0022-0957 46:4<407 1995 46 exbotj https://doi.org/10.1093/jxb/46.4.407 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1093/jxb/46.4.407 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Tan Weixing Natural Resources Canada, Canadian Forest Service, Ontario Region, PO Box 490, 1219 Queen St. E., Sault Ste. Marie, Ontario, Canada P6A 5M7 aut NATIONALLICENCE 700 1- Hogan Gary D. Natural Resources Canada, Canadian Forest Service, Ontario Region, PO Box 490, 1219 Queen St. E., Sault Ste. Marie, Ontario, Canada P6A 5M7 aut NATIONALLICENCE 773 0- Journal of Experimental Botany Oxford University Press 46/4(1995-04), 407-413 0022-0957 46:4<407 1995 46 exbotj Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford