| In order to study the effects of ABA on chilling resistance and its regulated mechanism in whipgrass(Hemarthria compressa),provide the theory for promotion of six new whipgrass lines,experiments were conducted udder controlled conditions,and the regional adaptability experiment were carried out during 2006 to 2008 among six clonal accessions of whipgrass in Sichuan Province's Yaan,Sichuan Province's Hongya, Sichuan Province's Nanchong,Chongqing Province's Rongchang."Gguangyi" and "Chonggao" are the check varieties,the results were follows:1.By measuring the electrolyte leakage of "Guangyi " and "Chonggao" under chilling after spraying different concentrations(0 mg/L,2 mg/L,5 mg/L,10 mg/L,15 mg/L,20 mg/L,25 mg/L,30 mg/L) of ABA,it showed that the electrolyte leakage of leaves treated by 10 mg/L ABA was the lowest,this concentration was the best choice for experiment.2.Chilling increased electrolyte leakage of both water- and ABA-treated of "Gguangyi" and "Chonggao",while RWC decreased under chilling conditions. ABA-treated plants had lower electrolyte leakage,MDA content and higher RWC than those of water-treated plants.ABA-treated whipgrass retained higher levels of SOD,CAT than water-treated ones under chilling conditions,but there were no significant differences of POD activity between the ABA-treated plants and the water-treated ones.it suggested that ABA can activated or induced the gene expression of SOD and CAT. Souble sugars,souble protein and proline contents increased under chilling stress.Under chilling condition,no significant differences of soluble sugar was found between the ABA-treated and the water-treated of two materials,while the souble protein in ABA-treated was higher than in water-treated plants,proline content in ABA-treated plants was lower than water-treated plants during the chilling treatment and after the plants were rewarmed for 2 days.The results suggestd that enchancement in chilling resistance by ABA treatment was not correlated to soluble sugar and proline,but closely related to souble protein.The accumulation of proline in chilling condition was not induced through ABA,but it might be correlated to water stress induced damage on plants.ABA is applicable for increasing chilling resistance of whipgrass after analyzing by subordinate function.3.According to comparing on the phonological stages of the six whipgrass lines,we found that H019 couldn't carry out reproductive growth,but no significant differences in other areas;the time of start reproductive growth were early about a week in Nanchong and Rongchang.According to comparing on the average height and regrowth speed of three years among six new lines,the results showed that H2003-5 had the highest height and growth speed,its average regrowth speed was increase by 4.23%,3.21%,2.96%than "Guangyi" and 35.38%,52.99%,50.35%than "Chonggao" respectively,it showed that H2003-5 had obvious advantage of regrowth..In nutritive value,H2003-5 had the minimum ratio of stem and leaf(2.007),lower than "Chonggao" and "Guangyi",it showed that H2003-5 had rich leaf and best palatability.4.According to comparing on the yield of six new lines,the results showed that H2003-5 was the best.In Yaan,its average fresh yield and hay yield of three years was 147997 kg/hm~2 and 35318 kg/hm~2 respectively,in Hongya was 111592 kg/hm~2 and 26580 kg/hm~2 respectively,in Nanchong was 96661 kg/hm~2 and 22048 kg/hm~2 respectively,in Rongchang was 161335 kg/hm~2 and 34446 kg/hm~2 respectively.Except in Yaan,its yield were higher than two check varieties,and there were very remarkable difference with "Chonggao" in four areas(P＜0.01).The average fresh yield of three years in four areas was 129391 kg/hm~2,increased by 4.39%and 26.51%than "Guangyi" and "Chonggao" respectively,the average hay yield was 29598 kg/hm~2,increased by 87.57%and 39.44% than "Guangyi" and "Chonggao" respectively.There were significant difference of fresh yield among four areas of six new lines,the yield of Rongchang and Yaan were higher than other areas. 5.The regional adaptability experiment were carried out among six clonal accessions and two check varieties of whipgrass through comparison the growth speed, plant height,yield,and stem/leaf ratio.The results showed that H2003-5 was the best and adaptable to ecological environment in above four areas,this new line had many good traits such as high regrowth speed,tall plant height,high herbage yield,rich leaf,adapt to the ecological environment of subtropical sub-humid areas,and should be expanded in above areas.
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