“…However, nothing has been investigated on the transport of endogenous plant growth regulators in rice phloem sap, although phloem sap of other various plants has been examined for plant hormones such as gibberellins [10,21], indole-3-acetic acid (IAA) [6,12], abscisic acid (ABA) [7,8,9,21] and cytokinins [21], as well as polyamines [5] . In contrast, rice tissue was analyzed for a variety of endogenous growth regulators such as gibberellins [13], cytokinins [18], auxins [12], ABA [17] and polyamines [1,15] in relation to the growth of rice.…”