The improved photosynthetic-fluorescence method and its application in breeding and seed production of maize

Abstract

The application of the improved non-invasive photosynthetic-fluorescence method in maize breeding and seed production was observed in order to assess the resistance and adaptability of maize inbred lines to higher and high temperatures, as well as to drought. The studies were carried out with two maize inbred lines (ZPPL 115 and A 671). The thermal characteristics of the photosynthetic apparatus of the investigated maize inbred lines were determined as follows: temperature dependency range from 25 to 60oC, critical temperatures at which phase transitions take place in the thylakoid membrane, causing significant structural and functional changes in the photosynthetic apparatus of the investigated inbred lines, activation energies (Ea, kJ/mol) were calculated along the straight lines before and after the occurrence of the critical temperature. The activation energy (Ea) is a measure of the intensity of recombining responses to chlorophyll DF, and total changes in the structure and functioning of the thylakoid membranes. The results obtained and presented parameters of total photosynthetic and thermal processes of chlorophyll DF may contribute to a more accurate characterisation of maize inbred lines in respect to their resistance and adaptability to temperatures and drought. Consecutively, this can lead to a quicker and more rational improvement maize breeding and seed production.

Poboljšani neinvazivni fotosintetično-fluorescentni metod kandiduje se za primenu u oplemenjivanju i semenarstvu radi utvrđivanja ocene samooplodnih linija kukuruza na plastičnost, tolerantnost, otpornost i adaptivnost prema višim i visokim temperaturama, kao i prema suši. Utvrđene su termalne karakteristike fotosintetičnog aparata proučavanih samooplodnih linija kukuruza, i to: određena je temperaturna zavisnost u opsegu od 25 do 60oC, otkrivene su kritične temperature na kojima dolazi do faznih transformacija u tilakoidnoj membrani, a time i do značajnih strukturnih i funkcionalnih promena u fotosintetičnom aparatu ispitivanih samooplodnih linija kukuruza, obračunate su energije aktivacije (Ea, kJ/mol) duž pravih linija pre i posle pojavljivanja kritične temperature. Energija aktivacije (Ea) je mera nastajanja rekombinacionih reakcija povezanih sa uspostavljanjem ZF hlorofila, a time i ukupnih promena u strukturi i funkciji tilakodinih membrana. Ostvareni rezultati i diskusija izloženih parametara ukupnih fotosintetično-termalnih procesa ZF hlorofila mogu doprineti egzaktnijem karakterisanju ispitivanih samooplodnih linija kukuruza u odnosu na njihovu plastičnost, tolerantnost, otpornost i adaptivnost prema temperaturi i suši, što samim tim i doprinosi bržem i racionalnijem unapređenju procesa selekcije i produktivne semenske proizvodnje.