The Dynamic of Nitrogen Uptake from Different Sources by Pea (Pisum sativum L.)

Nitrogen uptake from various sources by plants capable of biological reduction of N₂ in symbiotic systems with root nodule bacteria is influenced by many factors. The aim of the study was to examine the influence of the development stage and variety of pea (Pisum sativum L.) cultivated in years with different temperature and precipitation conditions on the dynamics of nitrogen uptake from the atmosphere (Ndfa), fertilizer (Ndff), and soil (Ndfs). Pre-sowing nitrogen fertilization with the ¹⁵N isotope and the isotope dilution method were used in the research. The highest rate of Ndfa uptake was noted between the three-internode stage and the stage of the first visible flower buds outside the leaves, while Ndff and Ndfs uptake was highest between the 4-leaf stage and the 3-internode stage. The lowest rate of Ndfa uptake was noted from sowing to the four-leaf stage, while Ndff and Ndfs uptake was lowest between the stage when 50% of pods were of typical length and full maturity. Nitrogen uptake from all sources was similar for all pea cultivars, but significantly depended on the variable temperature and precipitation conditions (years of the study).