Application of photometry for diagnostics of nitrogen nutrition in spring barley

¹ Federal State Budgetary Institution of Sciences Tsitsin Main Botanical Garden of the Russian Academy of Sciences, Botanicheskaya st. 4, 127276 Moscow, Russian Federation
² All-Russian research Institute of Agrochemistry named after D.N Pryanishnikov, Pryanishnikova st. 31A, 127434 Moscow, Russian Federation

Abstract

The article discusses a method for diagnosing nitrogen nutrition of spring barley (Hordeum vulgare L.) in different phases of the growing season using a photometric device (N-tester) Yara. The studies were carried out in the conditions of the Moscow region (Russia) on the Mikhailovsky spring barley variety on sod-podzolic medium loamy soils with a high and medium content of phosphorus and potassium and a low content of humus (1.9). The agrometeorological conditions of the growing season of spring barley were characterized by sharp fluctuations in air temperature and the amount of precipitation over decades of the month and in comparison with average long-term observations. Abundant and prolonged precipitation during the grain ripening phase led to lodging in most of the experiments, which affected the yield. To diagnose crops, a model experiment was laid with the introduction of increasing doses of nitrogen fertilizers into pre-sowing cultivation with a step of 30, at which the dose of nitrogen ranged from 30 to 150 kg/ha. Diagnostics was carried out in three phases of vegetation: tube emergence ((Z42), earing (Z55), milk ripeness of grain (Z73) with the Yara N-tester and with the help of stem diagnostics according to the modified method of V. Zerling. The results of photometric diagnostics in the stemming phase (Z42) have a strong correlation with the yield of spring barley grain and with the results of stem diagnostics (R = 0.85). Wherein, the N-tester readings in the earing phase (Z55) and milk ripeness of grain (Z73) with yield R = 0.23 and R = 0.17, respectively, have a weak correlation. This is possibly due to lodging of crops and a change in yield, not as a result of poor plant nutrition, but with difficult mechanized harvesting.