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Nitrogen deficiency increases the residence time of respiratory carbon in the respiratory substrate supply system of perennial ryegrass
Author(s) -
LEHMEIER CHRISTOPH ANDREAS,
LATTANZI FERNANDO ALFREDO,
SCHÄUFELE RUDI,
SCHNYDER HANS
Publication year - 2010
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2009.02058.x
Subject(s) - perennial plant , respiratory system , residence time (fluid dynamics) , environmental science , substrate (aquarium) , nitrogen , residence , agronomy , chemistry , biology , medicine , ecology , economics , engineering , organic chemistry , geotechnical engineering , demographic economics
Plant respiration draws on substrate pools of different functional/biochemical identity. Little is known about the effect of nitrogen deficiency on those pools' sizes, half‐lives and relative contribution to respiration, and consequently, of carbon residence time in respiratory metabolism. Here we studied how nitrogen fertilization affects the respiratory carbon supply system of shoots and roots of Lolium perenne , a perennial grass. Plants grown at two nitrogen supply levels in continuous light were labelled with 13 CO 2 / 12 CO 2 for intervals ranging from 1 h to 1 month. The rate and isotopic composition of shoot, root and plant respiration were measured, and the time‐courses of tracer incorporation into respired CO 2 were analysed by compartmental modelling. Nitrogen deficiency reduced specific respiration rate by 30%, but increased the size of the respiratory supply system by 30%. In consequence, mean residence time of respiratory carbon increased with nitrogen deficiency (4.6 d at high nitrogen and 9.2 d at low nitrogen supply). To a large extent, this was due to a greater involvement of stores with a long half‐life in respiratory carbon metabolism of nitrogen‐deficient plants. At both nitrogen supply levels, stores supplying root respiration were primarily located in the shoot, probably in the form of fructans.