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ARS Home » Pacific West Area » Corvallis, Oregon » Forage Seed and Cereal Research Unit » Research » Publications at this Location » Publication #119713
Title: CYTOKININ EFFECTS ON CREEPING BENTGRASS RESPONSES IN HEAT STRESS I. SHOOT AND ROOT GROWTH

Author
item LIU, XIAOZHONG - KANSAS STATE UNIVERSITY
item HUANG, BINGRU - RUTGERS UNIVERSITY
item Banowetz, Gary

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/2/2001
Publication Date: 1/31/2002
Citation: Liu, X., Huang, B., Banowetz, G.M. 2002. Cytokinin effects on creeping bentgrass responses in heat stress i. shoot and root growth. Crop Science.42:457-465.

Interpretive Summary: Cool-season grasses exposed to elevated temperatures often show reduced turf quality and seed yield. This heat-related injury can result from the inhibition of the synthesis of a group of plant hormones, cytokinins, in roots. The objective of this study was to determine whether external application of a cytokinin, zeatin riboside (ZR) to the root zone enhanced the tolerance of creeping bentgrass (Agrostis palustris L.) to high soil temperature or in combination with high air temperature. When bentgrass plants were exposed to elevated temperatures of 35C, turf visual quality, canopy photosynthetic rate, leaf photochemical efficiency, and leaf growth rate decreased while root mortality and root electrolyte leakage increased. Application of 1 and 10 umol of ZR to the roots reduced the amount of heat-related injury. The higher concentration was more effective. The externally applied cytokinin was taken up by the roots because the measured amount of root cytokinin increased. These results suggest that genetic or management strategies that maintain cytokinin levels will improve bentgrass turf quality during heat stress.

Technical Abstract: Heat stress injury may involve inhibition of cytokinin biosynthesis in roots. The objective of this study was to examine whether exogenous application of zeatin riboside (ZR) to the root zone enhanced tolerance of creeping bentgrass (Agrostis palustris L.) to high soil temperature or in combination with high air temperature. Turf visual quality, canopy net photosynthetic rate, leaf photochemical efficiency, and leaf growth rate decreased when plants were exposed to chronic temperatures of 35C. Root mortality and root electrolyte leakage increased. Application of 1 and 10 umol of ZR mitigated heat stress injury. The higher concentration was more effective. Endogenous shoot and root cytokinin content increased after exogenous ZR was applied at these two concentrations. These results suggest that maintaining shoot and root cytokinin levels is beneficial when bentgrass is exposed to chronic elevated temperatures.