Diurnal Photosystem II Photochemical Efficiency and Biomass Partitioning in Acacia mellifera and Acacia laeta Seedlings Under Drying Soil

Aim of study: The study aimed to assess the impact of drying soil on diurnal photochemical efficiency of photosystem II and biomass partitioning of the seedlings of Acaia mellifera (Mf) and Acacia laeta (Lt). Study area: The study was conducted at the nursery of Department of Forestry & Range Sciences, Faculty of Environmental Sciences and Natural Resources, University of Al Fashir, North Darfur, Sudan. Materials and methods: Thirty-six seedlings of two-months old per each species were selected for study. A half of seedlings per species was kept well-watered and the other was exposed to five drought cycles before exposed to continuous drying. Main results: The results of chlorophyll fluorescence study were indicated that both species are capable to maintain sound photosynthetic machinery throughout the course of measurements. Mf manifested higher biomass production compared to Lt in control seedlings. Conversely, repeated drying cycles techniques were likely improved growth and production in Lt. Strong negative relationships were established between ΔF/Fm' and incident photosynthetically active radiation (PAR), and between Fv/Fm and leaf temperature (T). Highlights: Under the intermittent irrigation conditions during dry season in general A. mellifera would show better growth hence greater potentials for live fence and afforestation purposes in semi-arid environments compared to A. laeta