LEAF SENESCENCE IN A NONYELLOWING MUTANT OF FESTUCA-PRATENSIS - IMPLICATIONS OF THE STAY-GREEN MUTATION FOR PHOTOSYNTHESIS, GROWTH AND NITROGEN NUTRITION
B. Hauck et al., LEAF SENESCENCE IN A NONYELLOWING MUTANT OF FESTUCA-PRATENSIS - IMPLICATIONS OF THE STAY-GREEN MUTATION FOR PHOTOSYNTHESIS, GROWTH AND NITROGEN NUTRITION, Plant, cell and environment, 20(8), 1997, pp. 1007-1018
Mutation of the nuclear gene sid disables chlorophyll degradation duri
ng leaf senescence in the pasture grass Festuca pratensis. This study
investigated the effect of the mutation on photosynthesis and on leaf
and whole plant growth under a range of nitrogen regimes, When plants
were cultivated in a static hydroponic system, the chlorophyll content
of fourth leaves of the stay-green mutant Bf993 remained virtually un
changed from full expansion to complete senescence, while tissue of th
e wild-type (cv. Rossa) became completely yellow, The retention of chl
orophyll in Bf993 was not associated with maintenance of photosyntheti
c activity as shown by rates of light-saturated CO2 fixation and appar
ent quantum efficiency, Higher levels of total N in senescing leaves o
f Bf993 than in Rossa indicated reduced nitrogen remobilization in the
mutant, When using a range of [NH4NO3], dry matter production and til
lering were lower for Bf993 at all but the highest [NH4NO3], which was
supra-optimal for the wild type, In contrast to the static system, wh
ere fluctuations in N supply occurred, growth and NO(3)(-)uptake were
similar in mutant and wild type when [NO3-] was continuously maintaine
d by a flowing solution culture system. The results are discussed in r
elation to the role of N supply and the effect of the stay-green mutat
ion on N recycling.