REVIEW Frequently asked questions about chlorophyll fluorescence, the sequel Hazem M. Kalaji 1 • Gert Schansker 2 • Marian Brestic 3 • Filippo Bussotti 4 • Angeles Calatayud 5 • Lorenzo Ferroni 6 • Vasilij Goltsev 7 • Lucia Guidi 8 • Anjana Jajoo 9 • Pengmin Li 10 • Pasquale Losciale 11 • Vinod K. Mishra 12 • Amarendra N. Misra 13 • Sergio G. Nebauer 14 • Simonetta Pancaldi 6 • Consuelo Penella 5 • Martina Pollastrini 4 • Kancherla Suresh 15 • Eduardo Tambussi 16 • Marcos Yanniccari 16 • Marek Zivcak 3 • Magdalena D. Cetner 1 • Izabela A. Samborska 1 • Alexandrina Stirbet 17 • Katarina Olsovska 18 • Kristyna Kunderlikova 18 • Henry Shelonzek 19 • Szymon Rusinowski 20 • Wojciech Ba ˛ba 21 Received: 26 June 2016 / Accepted: 17 October 2016 / Published online: 4 November 2016 Ó The Author(s) 2016. This article is published with open access at Springerlink.com Abstract Using chlorophyll (Chl) a fluorescence many aspects of the photosynthetic apparatus can be studied, both in vitro and, noninvasively, in vivo. Complementary tech- niques can help to interpret changes in the Chl a fluorescence kinetics. Kalaji et al. (Photosynth Res 122:121–158, 2014a) addressed several questions about instruments, methods and applications based on Chl a fluorescence. Here, additional Chl a fluorescence-related topics are discussed again in a question and answer format. Examples are the effect of connectivity on photochemical quenching, the correction of F V /F M values for PSI fluorescence, the energy partitioning concept, the inter- pretation of the complementary area, probing the donor side of PSII, the assignment of bands of 77 K fluorescence emis- sion spectra to fluorescence emitters, the relationship between prompt and delayed fluorescence, potential problems when sampling tree canopies, the use of fluorescence parameters in QTL studies, the use of Chl a fluorescence in biosensor Hazem M. Kalaji and Gert Schansker have contributed equally to this paper. & Hazem M. Kalaji hazem@kalaji.pl & Gert Schansker gert.schansker@gmail.com Marian Brestic marian.brestic@uniag.sk Filippo Bussotti filippo.bussotti@unifi.it Angeles Calatayud calatayud_ang@gva.es Lorenzo Ferroni lorenzo.ferroni@unife.it Vasilij Goltsev goltsev@gmail.com; goltsev@biofac.uni-sofia.bg Lucia Guidi lucia.guidi@unipi.it Anjana Jajoo anjanajajoo@hotmail.com Pengmin Li Lipm@nwsuaf.edu.cn Pasquale Losciale pasquale.losciale@crea.gov.it Vinod K. Mishra mishravkbhu@gmail.com Amarendra N. Misra misraan@yahoo.co.uk; misra.amarendra@gmail.com Sergio G. Nebauer sergonne@bvg.upv.es Simonetta Pancaldi simonetta.pancaldi@unife.it Consuelo Penella penella_con@gva.es Martina Pollastrini martina.pollastrini@unifi.it Kancherla Suresh sureshkancherla@rediffmail.com Eduardo Tambussi tambussi35@yahoo.es Marcos Yanniccari marcosyanniccari@conicet.gov.ar Marek Zivcak marek.zivcak@uniag.sk Alexandrina Stirbet stirbet@verizon.net 123 Photosynth Res (2017) 132:13–66 DOI 10.1007/s11120-016-0318-y