Effect of Prohexadione-Ca and young canes removal on physiological characteristics of leaf and fruit in raspberry cultivar ‘Willamette’

The research was designed to evaluate the effect of growth regulator Prohexadione-Ca (ProCa) and young canes removal on the changes of photosynthetic pigment content and modification activities of antioxidant enzyme defense system in leaves and fruits of raspberry cultivar ‘Willamette’ (Rubus idaeus L.). The experiment was performed in the period of 2011-2012. It consisted of five treatments: control - no treatment; 2ProCa - with 2 ProCa applications; Z - one removal of young canes; Z+2ProCa - young canes removal with 2 ProCa applications; 2Z - two removals of young canes. The first series of young canes were removed for the first time in mid-April and for the second time at the begining of May. In 2ProCa and Z+2ProCa treatments foliar application of ProCa was carried out twice during the period of April-May in interval of three weeks, i.e. when the primocane growth reached 30 cm in height. The following concentrations of ProCa: 125 ppm (first application) and 200 ppm (second application) were applied. Significantly higher mean values of chlorophyll b content were registered in the 2ProCa (42.84 μg•g-1 FW) and Z+2ProCa (46.12 μg•g-1 FW) treatment. The highest SOD and POD activities were found in leaves of new young canes which developed after the young canes removal was applied. Z+2ProCa treatment significantly increased CAT activity in raspberry leaves (63.51 U mg-1 prot.). Both of implemented measures, especially applied in combination, resulted in higher activity of CAT, POD and SOD enzymes in the fruits of the examined cultivar. [Projekat Ministarstva nauke Republike Srbije, br. 46008 i br. 173040]