Source-sink manipulation could regulate the net photosynthetic rate (PN) of winter wheat after anthesis, however, the direction and magnitude of the regulation varied with time after anthesis. The PN was significantly increased by source reduction at the initial time of grain filling, but sink reduction had little influence on the PN, which suggested that the sink (spike) limitation did not occur at this time. Source-sink relation markedly affected PN during rapid grain filling. The PN was increased by source reduction and decreased by sink reduction significantly, which indicated that PN was closely associated with the change of source or sink size. The effect of source-sink manipulation on PN had some relationship with the occurrence of plant senescence at the time of late grain filling. Source reduction accelerated the senescence and dropped the PN, meanwhile, sink reduction delayed the senescence and promoted the PN. A direct relation between the effect of source-sink manipulation on PN and stomatal limitation was not found. 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 leaves (RH) made grain mass per spike and mass of grains lowered, especially the grain mass in the top and base positions of spike declined markedly. The source supply was grain-limiting. Removing one quarter of spikelets (RS) was beneficial to grain-setting in the remaining spikelets, leading to the increase of grain mass. Thus promoting the source supply of photosynthates after anthesis is of major importance for grain to set and to develop. and Zhenlin Wang ... [et al.].
DPC played an important role in regulating the production, translocation and partítioning of i‘*C-assimilates in cotton {Gossypium hirsutum L.) plants. Seed soaking with DPC increased the partítioning of cotton assimilates into roots aitd main stem, and decreased the partítioning into seedling tip which was beneficial for the seedling. After the appearance of a square, spraying with DPC decreased the partítioning of assimilates into the main stem, branches and their growing points, and increased the partítioning into reproductíve organs and roots. This helped to avoid or reduce spindling, ensured a steady growth, coordination of the relatíon between vegetatíve and reproductíve organs, and improved the development of floral buds. From bloom to boll-setting,. sprayings with DPC greatly increased the partítioning of assimilates into reproductíve organs and decreased the partítioning into vegetatíve organs, which was usefiil for the growth and development of squares and bolls.