Effect of water bloom-forming cyanobacterial bio-substances on the growth of submerged macrophyte Ceratophyllum oryzetorum Kom.

The different forms of cyanobacterial bio-substances on the growth and photosynthetic activity of submerged macrophyte Ceratophyllum oryzetorum Kom was investigated in present study. Results showed that all kinds of cyanobacterial bio-substances ould enhance the growth of C. oryzetorum Kom. differently. Compared with the control, the plant length of C. oryzelorum could be increased by all forms of bio-substanees, in which the dry algal material has the strongest effect, while the decomposed material has the lowest. The fresh weight of C. oryzetorum also could be promoted by all kinds of algal bio-substanees, in which the dry algal material and the fresh algal material almost have the same obvious effect, and the decomposed algal material has the lowest, while in control, the fresh weight firstly increased, and then decreased. All forms of cyanobacerial material could promote the increase of branches in C. oryzetorum, in which the fresh algal material has the strongest effect and the dry and decomposed materials lower, while in control, the branches increased also less than the algal material treated groups. The photosynthetic activity expressed by chlorophyll fluorescence suggested that the (try algal material treated C. oryzetorum had the highest activity, and the fresh algae treated one lower, and the decomposed algae and the control treated ones were the lowest. In conclusion, the different forms of cyanobacterial bio-substances could supply nutrients or growth promoters for C. oryzetorum to grow, and at the same time, other growth inhibiters might exist to inhibit the growth of C. oryzetoritm. Factors of promoting and inhibiting worked together, thus resulted in the different promoting effects by different forms of cyanobacterial bio-substances to the growth in C. oryzetorum

Comparison of the photosynthetic characteristics of two developmental stages in Nostoc sphaeroides kutzing (Cyanophyta)

The photosynthetic activities between two main developmental stages, colony and hormogonium, of the edible cyanobacterium Nostoc sphaeroides Kutzing, were compared. Hormogonia have a higher content of chlorophyll than that of colonies. It showed that the ratios of phycocyain (PC), allophycocyain (APC) and phycoerythrocyanin (PEC) in hormogonia and colonies were different. The room temperature chlorophyll fluorescence, 77 K chlorophyll fluorescence measurements of PS I and PS H activities all showed that colony has higher photosynthetic competence than hormogonia. Hormogonia had a higher respiration rate than colony, while their maximum photosynthetic oxygen evolution rates were very close. The responses of hormogonia and colonies to high light illuminations also were different. Both of their oxygen evolution rates decreased quickly with the prolonged high light illumination, but hormogonia can keep relatively higher PS II activity (F-v/F-m) than that of colonies. The results suggested that colony was photosynthetically more competent than hormogonia. while the ability of hormogonia to tolerate high light illumination was higher than that of colony