Background:Summer vegetative dormancy is a desirable trait in cool-season grasses when they are interplanted with annual crops.Sandberg bluegrass(Poa secunda J.Presl.)shows summer dormancy,but the environmental cues t...Background:Summer vegetative dormancy is a desirable trait in cool-season grasses when they are interplanted with annual crops.Sandberg bluegrass(Poa secunda J.Presl.)shows summer dormancy,but the environmental cues that control dormancy remain unknown.Methods:A controlled environment study using temperature and day length combinations of 32.2℃/15 h,26.6℃/14 h,21.1℃/13 h,and 15.5℃/12 h was conducted with P.secunda accessions PI232347,PI639272,and PI232348,and‘Audubon’red fescue as a nondormant control to determine the optimum treatment for dormancy induction.A second study using treatments of 26.6℃/14 h,21.1℃/13 h,and 15.5℃/12 h was conducted to determine the thresholds for dormancy release.A third study used a factorial experiment with two temperatures(32.2℃ and 15.5℃)and two day lengths(15 and 12 h)to differentiate between temperature and day length effects on dormancy induction.Results:Of the four temperature and day length combinations,all except for 15.5℃/12 h resulted in dormancy by the end of 6 weeks,with 32.2℃/15 h inducing dormancy in only 17 days.Of the three treatments for dormancy release,15.5℃/12 h broke dormancy the fastest in all accessions and released the most number of plants from dormancy.Considerable variation existed between accessions for the speed of dormancy release in the 21.1℃/13 h and 26.6℃/14 h treatments.The third study showed that temperature is the primary inducer for summer dormancy,while longer day length may promote dormancy under inductive temperatures.Conclusions:This study identified the optimum photothermal for induction and release of summer dormancy in P.secunda,which will help future studies in elucidating the mechanism of summer dormancy.展开更多
基金supported by a grant from USDA-NIFA(Award Number 2017-67019-26370 to K.J.M.,A.W.L.,&S.F.)a grant from the Iowa Nutrient Research Center(Grant no.2019-04 to S.F.,A.W.L.,K.J.M.,&A.A.C.).
文摘Background:Summer vegetative dormancy is a desirable trait in cool-season grasses when they are interplanted with annual crops.Sandberg bluegrass(Poa secunda J.Presl.)shows summer dormancy,but the environmental cues that control dormancy remain unknown.Methods:A controlled environment study using temperature and day length combinations of 32.2℃/15 h,26.6℃/14 h,21.1℃/13 h,and 15.5℃/12 h was conducted with P.secunda accessions PI232347,PI639272,and PI232348,and‘Audubon’red fescue as a nondormant control to determine the optimum treatment for dormancy induction.A second study using treatments of 26.6℃/14 h,21.1℃/13 h,and 15.5℃/12 h was conducted to determine the thresholds for dormancy release.A third study used a factorial experiment with two temperatures(32.2℃ and 15.5℃)and two day lengths(15 and 12 h)to differentiate between temperature and day length effects on dormancy induction.Results:Of the four temperature and day length combinations,all except for 15.5℃/12 h resulted in dormancy by the end of 6 weeks,with 32.2℃/15 h inducing dormancy in only 17 days.Of the three treatments for dormancy release,15.5℃/12 h broke dormancy the fastest in all accessions and released the most number of plants from dormancy.Considerable variation existed between accessions for the speed of dormancy release in the 21.1℃/13 h and 26.6℃/14 h treatments.The third study showed that temperature is the primary inducer for summer dormancy,while longer day length may promote dormancy under inductive temperatures.Conclusions:This study identified the optimum photothermal for induction and release of summer dormancy in P.secunda,which will help future studies in elucidating the mechanism of summer dormancy.
