@Article{phyton.2025.065961,
AUTHOR = {Antonela Markulj Kulundžić, Daniela Horvat, Marija Kovačević Babić, Anto Mijić, Aleksandra Sudarić, Maja Matoša Kočar, Tomislav Duvnjak, Ivica Liović, Ivana Varga, Marija Viljevac Vuletić},
TITLE = {Leaf Position on the Sunflower Stem Determines Physiological Condition during Flowering},
JOURNAL = {Phyton-International Journal of Experimental Botany},
VOLUME = {94},
YEAR = {2025},
NUMBER = {7},
PAGES = {2075--2095},
URL = {http://www.techscience.com/phyton/v94n7/63215},
ISSN = {1851-5657},
ABSTRACT = {Sunflower leaf photosynthesis strongly depends on the leaf position in the plant stem conditioning, which directly affects other physiological processes. Therefore, a study of the leaf’s physiological status regarding the leaf position in the stem was performed on sunflowers in the flowering stage. Eight differently positioned leaves were investigated, starting with the youngest leaf on the top of the stem to the leaves of the stem bottom, assigned as the oldest senescent leaves. According to chlorophyll fluorescence (ChlF) parameters connected to photosystem II (PSII) processes, significant changes in PSII functioning occurred only in the senescent leaves, while photosystem I (PSI) describing parameters showed a linear decrease with leaf age, i.e., position on the stem. The antioxidative status of the leaves was dynamic, as stress indicators (lipid peroxidation and hydrogen peroxide content) fluctuated regarding leaf position on the stem, but no link was found between the activities of antioxidative enzymes and oxidative stress indicators. Linear decrease trend of secondary metabolites (mainly phenolic compounds) correlated with antioxidant activity, except for some phenolic acids (caffeic and ferulic acid), which increased in senescent leaves. The most changes in the physiological status of the leaves were confirmed in senescent leaves, which stand out the importance of younger leaves in maintaining the plant’s vitality after flowering, which is the most important for sunflower yield.},
DOI = {10.32604/phyton.2025.065961}
}