Studies on the Epidermic Browning of Lotus Rhizome

III. The Effects of Growth Regulators and Soil Reduction on the Browning

Abstract

We investigated the effects of strongly reductive soil conditions and applying the growth regulators, ethephon, maleic hydrazide, and 2, 4-D on the browning of lotus rhizome surface. The results obtained are summarized as follows:
1) Rhizome browning increased by applying the growth regulators, ethephon or maleic hydrazide, and decreased by applying 2, 4-D or by giving strongly reductive soil conditions.
2) Oxidation potentials of rhizome tissue showed negative value in diurnal change all day. It increased from sunset and reached minimum at midnight, then began to decrease rapidly and reached maximum in the early morning.
3) The range of the fluctuation in diurnal change of oxidation potentials descended by the treatment of ethephon or maleic hydrazide, but ascended by 2, 4-D or soil reduction.
4) Generally, all the treatments induced CN^- insensitive respiration in the rhizomes; whereas the increasing ratio of respiration under ascorbic acid substrates were inhibited by those treatments.
5) The change in the value of respiratory characteristics of CN^- sensitive respiration under ascorbic acid participation showed almost negative correlation to brightness of browning.
6) In multiple regression analysis of the data, the (partial) potentials during the night contributed to browning by 72%, and both the values of CN^- sensitive respirations under ascorbic acid substrate and Q values (respiratory quotient) contributed to browning by 67%.