Wang Zhenlin

Source-sink manipulation effects on postanthesis photosynthesis and grain setting on spike in winter wheat

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.

Effects of phosphorus fertilizer on accumulation of high molecular weight glutenin subunits and glutenin macropolymer size distribution in wheat grain.

For gaining insights into the relationship between the accumulation of high-molecular-weight glutenin subunit(HMW-GS) and the distribution of glutenin macropolymer(GMP) in wheat(Triticum aestivum L.),Shannong 12,a cultivar with high glutenin,was used in a field experiment with four phosphorus(P) application levels(0,40,100,and 160 kg ha-) under low nitrogen(112.5 kg ha-1) and normal nitrogen(225 kg ha-1) conditions,respectively.The result showed that HMW-GS in grains formed before 14 d after anthesis,and its content at maturity was higher in P application treatments than in the treatment with no P fertilizer applied.Phosphorus was in favor of the accumulation of HMW-GS under the low nitrogen(N) condition,but caused a negative effect in high P levels under the normal N condition.The content of GMP particle in 10 μm in diameter was significantly reduced with increasing P application.The effect increased with increasing P level under the low N condition,but showed the largest reduction at P level of 100 kg ha-1 and the smallest reduction at P level of 40 kg ha-1.For GMP particle in 10–100 μm and 100 μm groups,their contents tended to increase with more P applied under both N conditions.Under the normal N condition,there was no significant effect of P level on the number distribution of GMP particle.At maturity,the content of HMW-GS was negatively correlated with the volume of GMP particle in 10 μm group,but positively correlated with that in 10–100 μm group.The result suggested that larger GMP particles have higher HMW-GS content than the smaller GMP particles.