Effect of moisture stress on abscisic acid levels inRicinus communisL. with particular reference to phloem exudate

摘要

Abscisic acid (ABA) increased considerably in stem apices attached toRicinusplants during a moisture stress but only slightly in stem apices which were detached and then allowed to lose water. A very marked rise in ABA also occurred in phloem-sap of moisture-stressedRicinusplants. These results suggest that in apices of moisture-stressed plants the increased ABA does not arisein situbut is translocated to the apex after synthesis in the mature leaves.