Boron Distribution in the Developing Ovules of Clivia miniata Regel and Aesculus glabra Willd

Abstract

Summary Boron concentration changes in the developing ovules of Clivia miniata Regel and Aesculus glabra Willd were determined spectrophotometrically (absorbance measured at 600 nm wave length). It could be established that in Clivia miniata Regel, (a) boron concentration in the central vacuole sap increased from 1.63 to 3.23 µg/cm 3 during the inhibition phase of embryo growth (21-42 day-old ovules), (b) in the endosperm tissue concentration of boron increased markedly from 12.43 µg/g fr.wt. in 47-dayold ovules to 38.78 µg/gfr.wt. in 140-day-old ovules (exponential phase of embryo growth), and (c) in the embryo tissue (70-120-day-old embryos — exponential phase of growth) boron concentration decreased from 106.13 µg/gfr.wt. to 33.89 µg/gfr.wt. In older embryos (the end of exponential phase of embryo growth) an increase in boron concentration to 65.23 µg/g fr.wt. was found. In Aesculus glabra Willd, a) boron concentration in the central vacuole sap during inhibition and the beginning of exponential phases of embryo growth increased from 14.53 µg/cm 3 to 30.00 µg/cm 3 and later decreased to 17.21 µg/cm 3 , and b) boron concentration in the embryo during the exponential part of its growth was in the range 7.1935.81 µg/gfr.wt. Boron concentration (its accumulation) in the endosperm and embryo tissues was consistent with physiological activity and function of those tissues and with the previously obtained data on concentrations of K, Na, Ca, Mg, Fe, Mn, Zn and Cu in those tissues.