Relationship between Root Morphological Characteristics and Nitrogen Use Efficiency in Six Potato Cultivars

Nitrogen use efficiency and root morphology of different potato (Solanum tuberosum L.) cultivars were compared in two field and greenhouse trials and root morphology response to nitrogen concentration was investigated. In field experiment, treatments consisted of four nitrogen application rates (0, 90, 180 and 270 kg ha-1) and six potato cultivars (Fontane, Kuras, Agria, Miriam, Cosmos and Picasso). Greenhouse experiment was conducted at sand culture method and effects of different nitrogen concentrations (100, 200 and 300 mg l-1) on root morphological characteristics were studied. Different nitrogen application rates affected total tuber yield and nitrogen efficiency of potato cultivars. Maximum tuber yield was obtained in 270 kg ha-1 N treatment. There was no significant difference between tuber yields in 180 and 270 kg ha-1 N treatments. Nitrogen use efficiency and agronomic efficiency of potato cultivars decreased with increasing nitrogen application. Cosmos, Kuras and Picasso had the highest yield, nitrogen use efficiency and agronomic efficiency among potato cultivars. In greenhouse trial, different nitrogen concentrations had significant effects on all root morphological characteristics, except root average diameter. In all potato cultivars, root volume, root fresh weight, root dry weight, total root area, total root length and shoot dry weight increased and root/shoot ratio and specific root weight decreased with increasing nitrogen concentration. Potato cultivars differed in root morphological traits and cultivars with higher nitrogen efficiency had larger and stronger root system in all nitrogen concentrations.