B. Onillon et al., DROUGHT EFFECTS ON GROWTH AND CARBON PARTITIONING IN A TALL FESCUE SWARD GROWN AT DIFFERENT RATES OF NITROGEN-FERTILIZATION, European journal of agronomy, 4(1), 1995, pp. 91-99
The effects of drought on plant water and nitrogen status, shoot growt
h and carbon partitioning between root and shoot, were studied during
two summer regrowth cycles of a tall fescue sward grown at different r
ates of application of nitrogen fertilizer. Nitrogen fertilizer was th
e main factor influencing the relative partitioning of the newly assim
ilated C-14. Drought did not prevent the expression of the effect of n
itrogen fertilization on carbon partitioning. The highest carbon parti
tioning coefficients to roots (15-30 per cent) were measured in swards
having the lowest nitrogen status. With the high nitrogen fertilizati
on rate, water shortage increased the carbon partitioning to roots fro
m 6 to 13 per cent (means for both regrowths, before rewatering). This
increase mainly occurred in the surface horizon of soil (0-20 cm). Ho
wever, an estimate in absolute terms showed that root growth was not i
ncreased by drought. Water shortage impaired the sward nitrogen status
. It is therefore proposed that at least part of the change in the car
bon allocation pattern induced by drought was mediated via an effect o
n nitrogen nutrition. The importance of the drought-induced modificati
on of carbon partitioning is discussed.