Comparative Analysis of Primary Photosynthetic Reactions Assessed by OJIP Kinetics in Three _Brassica_ Crops after Drought and Recovery  
[PERSON]  
1 Department of Biology, [PERSON] University of Osjek,In the last few decades, drought has been recognized as one of the most severe stresses adversely affecting plant development and yield. Significant economic losses have been recorded in recent years, and the situation is expected to worsen in the near future. Hence, climate change will undoubtedly affect the human food chain [10; 11; 12]. Plants have evolved a variety of complex metabolic pathways to ensure survival in harsh environments [13; 14; 15; 16; 17]. Still, to cope with the new challenges, plant changes and adaptations are required over and over. Scientists aspire to explore and improve the structural and functional properties of the photosynthetic apparatus to enable the more efficient and effective use of water and mineral resources [10; 13; 18; 19]. Photosynthesis is one of the essential physiological processes directly related to plant growth and biomass accumulation. Plants must adjust their photosynthetic apparatus according to environmental stresses [20; 21]. The inhibition of photosynthesis induced by the lack of water correlates well with the decrease in the leaf water content [22] and stomatal conductance [23; 24]. Stomatal closure is the earliest response that prevents additional water loss from transpiration pathways at mild and moderate drought stress [15; 25]. An insufficient supply of CO\({}_{2}\) drives the oxygenase function of Rubisco [26], consequently leading to the loss of ATP [27]. Inhibited light energy utilization causes the disturbance of the electron transport chain [28], promotes reactive oxygen species production [29], changes the ratio of the photosynthetic pigments, and also affects the disorganization of thylakoid membranes [30; 31]. Permanent metabolic and structural changes were recorded after extreme or prolonged drought stress [32; 33]. Further, the effect of drought on the photosynthetic apparatus depends on the species, genotypes, stress intensity, and duration. Many papers have described an adverse impact on the plant's photosynthetic apparatus [34; 35; 36; 37; 33]. To summarize the main findings, drought causes changes in the redox state of PSI, impairs an electron transfer at the donor and acceptor side of PSII, affects the oxygen-evolving complex (OEC), decreases the efficiency of both PSII and PSI and the energetic connectivity between them, and inhibits the overall electron transfer capacity [38]. The damage resulting from the lack of CO\({}_{2}\), called photoinhibition, occurs primarily on PSII [39; 40; 41]. However, compared to PSI, PSII is less sensitive to water deficit, and permanent adverse effects occur only in extreme drought conditions [42; 43]. Chlorophyll \(a\) fluorescence measurement (Chl) is a commonly used technique that provides a large amount of information on the physiological state of plants and also enables the early detection of invisible changes in the photosynthetic apparatus function and structure affected by certain environmental conditions [44; 45; 46; 47]. Previous research indicates the potential possibility of using this method for screening sensitive and tolerant genotypes of different plant species [48; 49; 50; 51]. While many papers describe the influences of water deficit on photosynthesis in food crops growing worldwide [52; 53; 54; 55], limited studies have been conducted on _Brassica oleraea_ varieties and other cabbages growing in the arid and semi-arid Mediterranean environment. The influence of drought length on _Brassica oleraea_ var. _capitata_ seedlings was investigated in the forest-savannah transition zone in Ghana on a morphological and physiological level, without insight into photosynthesis [56]. The impact of water deficit on photosynthetic performance and growth was explored in aeroponically grown Tuscan kale (_Brassica oleraea_) in a tropical greenhouse [57] and also in juvenile Chinese kale (_Brassica oleraea_ var.