In: Phyton 54, Fasc. 1 (2014): S. 83-100 with 6 figures DOI: 10.12905/0380.phytons54(1)2014-0083

Key words: Triticum, chloroplasts, grain filling, photosynthetic activity, seawater, ultrastructure, wheat.

Summary

Aldesuquy H. S. 2014. Seawater induced decline in photosynthesis as related to chloroplast ultrastructure in flag leaf of different wheat cultivars during grain filling. – Phyton (Horn, Austria) 54 (1): 83–100, with 6 figures.

Chloroplasts ultrastructure, chloroplasts number, pigment content and photosynthetic activity were quantified during grain-filling (14 and 21 days post-anthesis) of two wheat cultivars (salt sensitive cultivar, Gemmieza-9 and salt tolerant cultivar, Sids-1) subjected to different seawater at percentage 10% and 25%. The results showed that there were slight differences between the two cultivars in response to seawater at 10 % and 14 days post-anthesis in terms of chloroplasts ultrastructure. The most obvious changes were observed with the treatment with 25 % seawater at 21 days post-anthesis. Moreover, disorganized membrane system was identified with swollen thylakoids and many plastoglobuli were recognized in the chloroplasts in comparison to control plants. Number of chloroplasts was subsequently decreased with increasing seawater concentrations in both cultivars and the reduction was higher in Gemmieza-9 than in Sids-1. Furthermore, the applied concentrations of seawater induced noticeable reduction in pigment content (i.e. Chl a, Chl b, Chl (a+b), Chl (a/b), carotenoids and anthocyanin) as well as in photosynthetic activity (i.e. soluble, insoluble, total photosynthates and ratio of soluble/ insoluble photosynthates) in both cultivars and this reduction tended to be higher in Gemmieza-9 than in Sids-1. The changes in pigment content and photosynthetic activity of flag leaf appeared to depend mainly on chloroplast ultrastructure and its numbers, showing a positive correlation between chloroplasts number and pigment content.