Seasonal Changes in Magnesium Concentration of Bearing Plum Shoots

Tijekom dvije vegetacije istra.ivana je dinamika koncentracije Mg u pojedinim dijelovima rodnih izbojka šljive Bistrice (drvo, kora, pupovi, listovi i plodovi). U pokusu su bile dvije varijante: kontrola, u kojoj nije obavljana obrada tla, gnojidba i rezidba, i poboljšani sustav održavanja uz primjenu agrotehničkih i pomotehničkih zahvata. U vegetativnim i generativnim pupovima u periodu od početka vegetacije do završetka cvatnje koncentracija Mg neznatno je varirala. Koncentracija Mg u drvu i kori rodnih izbojka neznatno se smanjila do cvatnje, a zatim je uslijedio jači pad do prestanka rasta mladica. Nakon toga koncentracija Mg u kori se postupno povećavala do perioda mirovanja. Koncentracija Mg u drvu u istom razdoblju nije se bitno mijenjala. U kori mladica najmanja koncentracija Mg bila je u vrijeme prestanka njihovog rasta, a zatim se postupno povećavala do kraja vegetacije. U drvu mladica koncentracija Mg nije se bitno mijenjala tijekom vegetacije. Koncentracija Mg u plojkama lišća povećavala se do sredine vegetacije, a zatim se do otpadanja lišća nije mijenjala. U peteljkama lišća koncentracija Mg bila je najmanja u periodu prestanka rasta mladica u du.inu a zatim je do kraja vegetacije postupno rasla. U plodovima je koncentracija Mg bila najveća u periodu prestanka rasta mladica, a zatim je proporcionalno opadala sve do sazrijevanja plodova. Istraživanja su pokazala da primijenjeni zahvati nisu utjecali na dinamiku, a neznatno na razinu koncentracije magnezija.The Seasonal changes in Mg concentration in the tissues of plum shoots taken from mature trees of the cultivar Bistrica were determined over two growing seasons. Samples were taken from trees that were growing in grass sward and from trees under improved management (with pruning, manure and fertilizer application, soil cultivation under the trees and mowing of the grass sward between the alleys). In the vegetative and generative buds from the beginning of vegetation until the end of blooming magnesium concentration was relatively stable. Magnesium concentration in the wood and bark of the previous year shoots slightly declined in the period from the beginning of vegetation to blooming and then significantly declined to the time of shoot growth cessation. After that, magnesium concentration in the bark gradually rose to the end of vegetation. In the same period magnesium concentration in wood tissue wasn’t changed substantially. In the bark of the new growth magnesium concentration was the lowest at the period when terminal shoots stopped growing and then gradually rose to the end of vegetation. In the wood tissue of the new growth magnesium concentration remained stable during the vegetation. The concentration of magnesium in the leaf blade increased to the middle of vegetation and after that wasn’t changed. In the petiole magnesium concentration was increased during the vegetation. Magnesium concentration in whole fruits was the highest in the period when terminal shoots stopped growing. After that, magnesium concentration decreased proportionally to the time of fruit ripening. The investigation showed that management had no effect on the seasonal tendency and had a little effect on Mg concentration level