Studies on physico-chemical properties of expressed plant juice in wintering naked barley and wheat, and some effects of stamping on these properties of wheat

The author studied the physico-chemical properties of the expressed cell sap in both naked barley (Shirochinko) and wheat plants (Shikoku, no. 65) during the cold winter, in relation to winter hardiness of these plants. The main results obtained in this investigation were as follows:

(1) Naked barley plant showed the symptoms of cold injuries at the marked drop of air temperature in early winter, but wheat plant did not at all.
(2) Tillering of less hardy naked barley plant was more vigorous as compared with wheat plant.
(3) The changes of water contents based on dry materials of these two kinds of plants were generally similar, but naked barley plant showed larger amounts of water than wheat plant. Water contents were more changeable with change of air temperature in the case of naked barley plant.
(4) The concentration of the expressed cell sap in both plants increased remarkably, and the concentration in wheat plant was markedly larger as compared with that in naked barley plant. The total amount of soluble substances in cell sap presumed by the corrected indices of the concentration was large in wheat plant and kept nearly constant values, but in naked barley plant an increase of those substances did not happen.
(5) The osmotic pressure of these two plants increased remarkably with the marked drop of air temperature in early winter, but scarcely increased at low temperature which occurred afterwards. Wheat plant showed usually higher osmotic pressure as compared with naked barley plant. The total amount of osmotically active substances suggested from the corrected indices of the osmotic pressure declined with the progress of season in these plants, but in wheat plant it increased somewhat in early winter. Naked barley plant showed usually the larger amounts of osmotically active substances as compared with wheat plant.
(6) Participating degree of electrolytes m osmotic pressure m contrast to organic substances was small in these plants during the winter season. However, the degree In naked barley plant was usually larger as compared with that in wheat plant.
(7) The relative viscosity increased linearly, in general, with the progress of season m both plants, but in wheat plants it was markedly larger as compared with that in naked barley plant. On the other hand, the total amounts of hydrophilic colloids and viscous substances presumed by the corrected indices of the viscosity were markedly large in naked barley plant, but they declined remarkably in early winter as compared with that in wheat plant.
(8) The relative electric conductivity in naked barley was larger as compared with that in wheat plant and the former plant kept almost constant values. But in wheat plant it decreased with the drop of air temperature. The total amounts of ions decreased remarkably in these plants with the drop of air temperature in early winter. In naked barley plant, the ion amounts increased linearly after the drop of temperature in early winter, but wheat plant kept the low amounts of ions till the dead of winter.
(9) Having summed up the results mentioned above, the author presumed that wheat plant was more tolerant against cold injuries than naked barley plant, by means of its smaller contents of water, higher values of the concentration (caued by both its smaller contents of water and the increase of total amount of soluble substances in cell sap), higher osmotic pressure (caused by both its smaller contents of water and the increase of total amount of osmotically active substances in cell sap), higher relative viscosity (chiefly caused by its small contents of water) and lower relative electric conductivity (chiefly caused by its small ion amounts) of the expressed cell sap.
(10) Wheat plant stamped by foot was characterised by its smaller contents of water, higher values of the concentration, osmotic pressure and relative viscosity and lower relative electric conductivity of the expressed cell sap as compared with non-treated one. But such an increase of its concentration, osmotic pressure and relative viscosity was not caused by the increase of respective substances participating in these properties, but chiefly by the decrease of water contents in the plant tissues caused by the treatments of stamping.