Determination of barley nitrogen status with chlorophyll meter for high β-amylase in grains

Abstract

The production of β-amylase is of great importance in two-rowed spring barley cv. Kymppi (Hordeum vulgare L.) in the Finland, where long-day conditions favour high enzyme activities. Nitrogen (N) fertilization of a crop is the main means of manipulating barley β-amylase activity for industrial purposes. In this study, leaf chlorophyll content determined with a portable chlorophyll meter (Minolta SPAD-502) in the field, was used to predict N availability of cv. Kymppi for β-amylase production. Critical chlorophyll meter readings (SPAD values) were calculated from data deriving from experiments with various N fertilizer levels using the Cate-Nelson procedure. According to the results of this study it can be stated that the critical SPAD values at pollination (i.e. pollen grains on well-developed stigmatic hairs, GS 52-58) are 37 SPAD units for grain yield and 41 SPAD units for β-amylase activity. The optimum grain yield occurred at 41 SPAD units and optimum P-amylase activity was reached at 45 SPAD units. Determination of leaf chlorophyll content using the chlorophyll meter led to more appropriate fertilizer application recommendations and subsequently increased β-amylase activity in grains. Grain protein concentration could be an effective diagnostic tool for post-harvest evaluation of grain β-amylase activity in cv. Kymppi.