EVALUATION OF CHINESE AND KYRGYZSTAN GRASS GERMPLASM COLLECTIONS FOR MAINTENANCE OF GREEN COVER UNDER LIMITED IRRIGATION IN WESTERN NORTH AMERICA

摘要

An important strategy to save irrigation water on turf is to develop cultivars with improved drought tolerance,especially in the arid and semi-arid North American West.In this region,maintenance of green cover during summer with reduced levels of irrigation is of paramount importance.Germplasm of various turfgrass genera were collected in Inner Mongolia of the People’s Republic of China and in Kyrgyzstan and then evaluated under the climatic conditions of the Intermountain West of North America.These were evaluated for the amount of green cover retained during the summer drought season.Digital photographs were used for measuring percent green cover (PGC) and green color (Dark Green Color Index,DGCI) of the plots besides visual turf quality ratings.Among Poa species,P.pratensis was the species group that maintained the overall highest turf quality throughout the study with a number of individual collections exhibiting higher turf quality and PGC than check varieties.Other Poa species that exhibited high ratings included P.tibetica,P.secunda,P.sphondylodes,and P.versicolor.Poa pratensis exhibited the greatest variation in turf quality and PGC.Among other species,Festuca rubra and Phleum phleoides maintained favorable turfgrass quality and PGC during the summer drought period.These species were followed by Agrostis gigantea,Avenula pubescens,Helictotrichon tianschanicum,Hordeum bogdanii,Koeleria macrantha,Hordeum brevisubulatum,Schedonorus pratensis and Trisetum sibiricum.Based on these results,the greatest potential for drought tolerance and adaption to the North American West appears to be in Poa pratensis,at least among the collections and germplasm originating from Inner Mongolia and Kyrgyzstan.