Summary:

The study was conducted in 2008-2009 at the Agricultural Experimental Station in Lipnik near Stargard, on sandy soil. The aim of this study was to determine the effect of sub-crown irrigation on the yield leaves photosynthesis and transpiration capacity, as well as CO2 concentration in the stomatal cells, and leaf greenness index of early 'Geneva Early' cv. and late 'Rubinola' cv. apple cultivars.
Irrigation was applied in the form of the sub-crown system, in which water is distributed through a mini-sprayers of Hadar type when water potential of soil fell below -0.01 MPa. The experiment was established in a randomized sub-block pattern (split-plot) in 10 replicates. The study was conducted using the four-year-old trees. The trees were planted at 4 × 2 m spacing; one hectare was planted with 1250 trees. Turf was maintained between the trees, while herbicide fallow was applied in rows. Plant material for laboratory tests was collected each year in three dates: fruit setting (date 1), harvest (date 2) and one month after the harvest (date 3). Studies have shown that leaves of the irrigated apple trees were lower content of assimilation pigments in leaves than non-irrigated ones. Leaves of late ‘Rubinola' cv. showed higher photosynthetic activity and pigments content than early ‘Geneva Early' cv. Pigment content was the highest at the second date of measurements. Better yielding late variety 'Rubinola' characterized by a greater intensity of transpiration, stomatal conductance and CO2 concentration leaves than the early variety 'Geneva Early'. The applied irrigation significantly increased the fruit yield and also increased the fruits weight of both varieties. Among the varieties of apple trees higher yield and fruit mass was found in the late variety 'Rubinola'. This treatment and the earliness of varieties had no significant effect on the content of other macro- and micronutrients.