Endogenous Cytokinin Levels and Growth Responses to Extended Photoperiods for Creeping Bentgrass under Heat Stress

摘要: Summer bentgrass decline is associated with inhibition of plant growth and cytokinin production. This study was designed to investigate whether shoot root production for creeping (Agrostis stolonifera L.) exposed heat stress would be improved by extending photoperiod. 'Penncross' plants were initially grown in chambers at 20/15°C (day/night) a 14-h photoperiod 60 d, then 33/28°C (heat stress) three different photoperiods: 14 (control), 18, 22 h (extended photoperiod) daily 32 d. Root number, fresh weight, viability, turf quality, extension rate declined during the The delayed suppressed from 18 or h. growth, increased Cytokinin content roots leaves also decreased Plants 22- 18-h photoperiods maintained higher 16 d stress. differences total among treatments mainly due variations transzeatin [6-(4-hydroxy-3-methylbut-2-enylamino) purine], zeatin riboside (6-[(E)-4-hydroxy-3-methylbut-2-enylamino]-9-β-D-ribofuranosyl-purine} isopentenyl adenosine [iPA, 6-(3,3-dimethylallylamino)-9-β-D-ribofuranosylpurine]. 14- stress, but 22-h it did not decrease until These results demonstrated that extended endogenous levels under suggesting could alleviate injury bentgrass.