Effect of planting scheme on photosynthetic activity and dry matter accumulation in apple leaves

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 dwaring P60 rootstock and planted at different in distances: 0.5 m, 0.75 m, I 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 irom 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/W 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

Problems of a longtime strawberry growing in one plot

Long term investigations revealed that cultivation of strawberries (Fragaria magna Thuill.) for 10 years continuously in one plot reduces their vitality: the number of the produced runners decreases by 41%, of leaves – by 30%, form only 28% of inflorescence, the yield reduces by 50% in comparison with strawberries grown for two years in a new plot. Evident decline in the vitality and productivity of strawberries was detected during 4th–6th years of cultivation. Unequal reaction of the tested cultivars upon the durability of cultivation was noticed; strawberries of the cultivar ‘Senga Sengana’ reacted slightly, while the ones of the cultivar ‘Nida’ – strongly. It is related with different sensibility of these cultivars towards the disease agents of root rots. It was determined that long-term cultivation of the Fragaria genus plants results in the accumulation of the parasitic fungi propagules in soil: Ascochyta fragaricola, Cercospora fragariae, Fusarium oxysporum, F. solani, Perenospora fragariae, Phytophthora cactorum, Pythium intermedium, P. ultimum, Plasmodiophora brassicae, Sclerotium rolfsii, Verticillium alboatrum. Therefore, cultivation of strawberries in the same plot for longer time increases the phytopathogenic potential of soil, and short interval (1–2 years) between planting has little significance upon it. The second reason for low productivity of strawberries cultivated for a long in one plot is soil tiredness caused by fungi, synthesising and excreting into surrounding toxic secondary metabolites, widespread in the rhizosphere, especially those belonging to the Penicillium genus: P. janthinellum, P. verruculosum var. verrucosum, P. canescens, P. spinulosum.Wieloletnie badania wykazały, że uprawa truskawki (Fragaria magna Thuill.) na jednym polu przez 10 lat spowodowała zahamowanie ich wzrostu i rozwoju. Uprawiane w ten sposób truskawki tworzą o 41% mniej rozłogów, o 30% mniej liści, o 28% mniej kwiatostanów oraz tworzą o 50% mniej owoców w porównaniu z truskawką uprawianą przez dwa lata na danym polu. Najczęściej do obniżenia wzrostu i plonowania truskawki dochodzi w 4–6 roku uprawy. Nie wszystkie uprawiane odmiany reagują jednakowo obniżeniem wzrostu i plonowania. Najmniej podatną na choroby korzeni jest odmiana ‘Senga Sengana’, natomiast bardziej podatna okazała się odmiana ‘Nida’. Stwierdzono, że długotrwała uprawa truskawki powoduje wzrost potencjału infekcyjnego gleby, co związane jest ze wzrostem jednostek propagacyjnych takich grzybów chorobotwórczych, jak Ascochyta fragaricola, Cercospora fragariae, Fusarium oxysporum, F. solani, Peronospora fragariae, Phytophthora cactorum, Pythium intermedium, P. ultimum, Plasmodiophora brassicae, Sclerotium rolfsii, Verticillium albo-atrum. W wyniku prowadzonych badań wykazano, że 1-2 letnia przerwa w uprawie truskawki nie ma większego wpływu na wzrost i plonowanie oraz porażenie roślin truskawki przez fitopatogeny. Ponadto przy długotrwałej uprawie truskawki na tym samym polu zwiększa się liczebność grzybów z rodzaju Penicillium: P. janthinellum, P. verruculosum, P. canescens, P. spinulosum. Przypuszcza się, że grzyby te w strefie korzeniowej roślin tworzą związki fitotoksyczne będące produktami ich metabolizmu