Abstract:

The photosynthesis of flag leaf and non-leaf green organs (sheath, peduncle and ear parts) makes a major contribution to final grain yield in wheat; however, there have been the few attentions paid to photosynthetic characteristics of the non-leaf green organs other than flag leaf. In order to increase wheat productivity through improving photosynthetic capacity of the whole plant, it is important and necessary to understand photosynthetic characteristics of the non-leaf green organs. In the present experiment, net photosynthetic rate and carbon assimilation enzyme activities in different green organs (flag leaf blade, sheath, peduncle and ear parts) after anthesis were studied with five genotypes of wheat. The results showed that the net photosynthetic rate and RuBPC and PEPC activities were different among green organs or genotypes. Compared with flag leaf blade, non-leaf organs (sheath, peduncle and ear parts) had lower net photosynthetic rates in the early stage of grain growth, but more slowly decreased ones in the later stage of grain growth. RuBPC activity was highest in flag leaf blade, then in awn, sheath, lemma, peduncle and glume in turn; PEPC activity was higher in every non-leaf organs than in flag leaf blade. The ratio of PEPC/RuBPC activities in various organs of all genotypes gradually increased from 0 to 23d after anthesis, and that of every non-leaf organs was higher than that of flag leaf blade. All of these showed that the non-leaf organs are very important in the photosynthesis of whole plant in the later growth stages, and PEPC may play an important role in maintaining carbon assimilation activity of the non-leaf organs. It is suggested paying more attentions to photosynthetic traits of the non-leaf organs in wheat breeding.

Key words: Wheat, Non-leaf organs, PEPC, RuBPC, Net photosynthetic rate