Excess irradiance causes early symptoms of senescence during leaf expansion in photoautotrophically in vitro grown tobacco plants |
| |
Authors: | B. Radochová I. Tichá |
| |
Affiliation: | (1) Department of Biomathematics, Institute of Physiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ-142 20 Praha 4-Krč, Czech Republic;(2) Faculty of Science, Department of Plant Physiology, Charles University Prague, Viničná 5, CZ-128 44 Praha 2, Czech Republic |
| |
Abstract: | Photosynthetic parameters, growth, and pigment contents were determined during expansion of the fourth leaf of in vitro photoautotrophically cultured Nicotiana tabacum L. plants at three irradiances [photosynthetically active radiation (400–700 nm): low, LI 60 μmol m−2 s−1; middle, MI 180 μmol m−2 s−1; and high, HI 270 μmol m−2 s−1]. During leaf expansion, several symptoms usually accompanying leaf senescence appeared very early in HI and then in MI plants. Symptoms of senescence in developing leaves were: decreasing chlorophyll (Chl) a+b content and Chl a/b ratio, decreasing both maximum (FV/FM) and actual (ΦPS2) photochemical efficiency of photosystem 2, and increasing non-photochemical quenching. Nevertheless, net photosynthetic oxygen evolution rate (P N) did not decrease consistently with decrease in Chl content, but exhibited a typical ontogenetic course with gradual increase. P N reached its maximum before full leaf expansion and then tended to decline. Thus excess irradiance during in vitro cultivation did not cause early start of leaf senescence, but impaired photosynthetic performance and Chl content in leaves and changed their typical ontogenetic course. |
| |
Keywords: | KeywordHeading" >Additional chlorophyll a fluorescence leaf area leaf dry mass leaf ontogeny net oxygen evolution rate Nicotiana photosynthesis |
本文献已被 SpringerLink 等数据库收录! |
|