Dynamics of generating transients of delayed fluorescence induction signal and photosynthetic antennas: A possible relationship: Mathematical modeling approach

A mathematical model was developed for resolved temporal transients of experimentally recorded delayed fluorescence (DF) induction signal. During an intermittent light regime, antennas of the photosynthetic apparatus were treated as targets, repeatedly hit by potentially absorbable photons within a series of consecutive light flashes. Formulas were derived for the number of antennas, cumulatively hit by a specific number of photons, as function of the flash serial number (time). Model parameters included: number of absorbable photons in one flash, antenna sizes and numbers. A series of induction curves were analyzed, obtained from a ZeamaysL. leaf segment and differing in the previous dark period (td). Each curve, consisting of the two most prominent DF transients (C and D), was fitted with several model types, differing in the number of absorbed photons. For both transients, the best fitting result was achieved when DF induction was linked to the second absorbed photon. As expected, model parameters related to antenna sizes showed weaker dependence on td than those referring to antenna numbers. With restrictions applied in this model, the two DF induction transients may be related to two classes of photosynthetic antennas. Their different sizes may have a predominant influence on the efficiency of photon absorption, and possibly time-dependent appearance of DF transients

Sixty years of ZP maize hybrid breeding

The modern ZP maize hybrids breeding at the Maize Research Institute, Zemun Polje, begun during the fifties of the 20(th) century. Collecting of the initial material was the first step in conducting maize breeding programs. The maize inbred line-developing programs from three local populations has initiated in 1953. That was beginning of breeding first cycles ZP maize hybrids. From that period up to present time, we have had five generations of ZP maize hybrids. Each generation has characterized by introduction of the new potentially higher yielding hybrids and with better other agronomics characteristics. According to results from different studies, the genetic yield potential of ZP maize hybrids over the last 40 years amounted to 100 kg.ha(-1) per year. ZP 755 was the first registered maize hybrid in the country in 1964. Total 499 ZP maize hybrids have released by the State Government Commission's since 1964 and 99 ZP maize hybrids have registered in 15 countries. Since the seventies biotechnology methods have been applied in the breeding programs. The main part of biotechnology work is based on the molecular marker application for determining genetic diversity, QTL mapping for drought tolerance and identification of chromosome regions harbouring QTLs for economically important traits (yield, kernel oil content)