Effect of planting scheme on photosynthetic activity and dry matter accumulation in apple leaves
Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry, Kauno 30, Babtai, LT-54333 Kaunas distr., Lithuania
This study aims to identify changes photosynthetic rate and dry matter accumulation in apple leaves with decreasing plant to plant distance of the trees. Apple tree ‘Auksis’ was grafted on dwarfing P60 rootstock and planted at different in distances: 0.5 m, 0.75 m, 1 m and 1.25 m between plant to plant distance in rows. Photosynthetic indices were measured at 1.00–1.20 m above ground inside the canopy. 20 randomly selected leaves from the whole apple tree canopy were used to determine leaf area, fresh and dry weight. Measurements were made in three different stages in May, June and September. By decreasing the distance between apple trees from 1.5 m to 0.5 m, photosynthetic rate decreases correspondingly, decreasing by 23% in spring, and decreasing by 31% in autumn. Distance between trees has no significant impact on leave mass per area (LMA), however in spring is higher by 33–51% compared to summer and 42–78% compared to autumn. Dry and fresh weight ratio (DW/FW) significantly increased in summer – by 27% and in autumn – by 37% compared to spring, also DW/FW significantly decreased by the decreasing distance from 1.5 m to 0.5 m by 4–6%. In summary, the decreasing distance reduces the photosynthetic rate, the accumulation of dry matter. Also, photosynthetic rate decreases from spring to harvest time, and on the contrary, the accumulation of dry matter increases as autumn approaches. After evaluating the obtained results, the aim is to further delve into the use and transpiration of water and the impact of the planting scheme on fruit quality.