Measurement of the cell sap concentration of plant's leaves for irrigation's scheduling

Abstract

The results of the investigations of the relationship between the Cell Sap Concentration (CSC) of leaves of tilled crops and their moisture availability are presented. The relationships between the CSC of leaves and the time of day, as well as patterns of changes in the CSC’s index in different parts of the leaf: in the handle, middle and tip, were investigated. Field experiments during 2010-2012 were carried out on the sugar beet, tomato and potato crops, which were grown under drip irrigation. The CSCs of leaves were determined by the digital refractometer Atago PAL-Alpha in 10 replications. It is established that between leaf’s CSC and soil moisture, there are reliable inverse correlation dependencies in all phases of plants growth, in particular, CSC of leaf tends to increase with decreasing of soil moisture. The correlation coefficients (r) and the error of the correlation coefficient (mr) are calculated. The dynamics of CSC’s changes during the day depended on the temperature and humidity of the surface air layers and did not depend on the type of culture and the phase of its development. The highest correlation between CSC and soil moisture was recorded in the morning hours: from 07:00 to 09:00, and then, during the day, it tended to decrease. The definition of CSC in different parts of the leaf showed that the minimum indices are typical for the petiole, and the highest was in samples taken from the leaf apex. This dependence was typical for all cultures regardless of the phase of their development. The change in the size of the CSC of the leaf, depending on the canopy level, had no regularities. For a more reliable determination of the CSC, samples must be taken from the middle of a leaf of one layer in the morning at one time; the replication of the determination is at least 5 samples.