Zl. Wang et al., SOURCE-SINK MANIPULATION EFFECTS ON POSTANTHESIS PHOTOSYNTHESIS AND GRAIN SETTING ON SPIKE IN WINTER-WHEAT, Photosynthetica, 35(3), 1998, pp. 453-459
Source-sink manipulation could regulate the net photosynthetic rate (P
-N) Of winter wheat after anthesis, however, the direction and magnitu
de of the regulation varied with time after anthesis. The P-N was sign
ificantly increased by source reduction at the initial time of grain f
illing, but sink reduction had little influence on the P-N, which sugg
ested that the sink (spike) limitation did not occur at this time. Sou
rce-sink relation markedly affected P-N during rapid grain filling. Th
e P-N was increased by source reduction and decreased by sink reductio
n significantly, which indicated that P-N Was closely associated with
the change of source or sink size. The effect of source-sink manipulat
ion on P-N had some relationship with the occurrence of plant senescen
ce at the time of late grain filling. Source reduction accelerated the
senescence and dropped the P-N, meanwhile, sink reduction delayed the
senescence and promoted the P-N A direct relation between the effect
of source-sink manipulation on P-N and stomatal limitation was not fou
nd. Removing one quarter of leaves (RQ) had little influence on spike
development after anthesis. In this case there was enough compensation
in source production through photosynthesis. Removing one half of lea
ves (RH) made grain mass per spike and mass of grains lowered, especia
lly the grain mass in the top and base positions of spike declined mar
kedly. The source supply was grain-limiting. Removing one quarter of s
pikelets (RS) was beneficial to grain-setting in the remaining spikele
ts, leading to the increase of grain mass. Thus promoting the source s
upply of photosynthates after anthesis is of major importance for grai
n to set and to develop.