BIOCHEMICAL-CHANGES IN SUGAR-BEET LINES IN DEPENDENCE ON SOIL-MOISTURE

Nine sugar beet lines were grown in a glasshouse on chernozem soil wat ered to 35, 50 and 65% of maximal soil water capacity. After 12 d, pla nt water potential, net photosynthetic rate, contents of soluble prote ins, DNA and RNA, proportion of ribulose-1,5-bisphosphate carboxylase/ oxygenase (RUBISCO) protein, and carbonic anhydrase activity were meas ured. As soil moisture decreased, the leaf water potential and net pho tosynthetic rate decreased. DNA and RNA content and carbonic anhydrase activity decreased under moderate drought, and increased with severe drought. RUBISCO protein proportion did not change significantly under decreased soil moisture, while the total soluble protein content decr eased.