| Centipedegrass (Eremochloa ophiuroides (Munro.) Hack), with strong stolons, beautiful leaves and dwarf swards, is the only one species of Eremochloa ssp. used as turfgrass (Bouton,1983; Hanna,1995). Due to low level of maintenance requirement and good adaptation to poor soil, centipedegrass has been widely used in the lawn of home yard, recreational turf and soil conservation turf from subtropical to tropical zones (Beard,1973; Hanson et al.,1969). However, the cold-resistance of centipedegrass is weaker than that of bermudagrass and zoysiagrass, which limits its wide application in the North of subtropical zone and temperate zone (Cardona et al.,1997; Fry et al.,1993; Fry et al.,1991; Philley et al.,1995). Therefore, the improvement and regulation of cold-resistance of centipedegrass is of great importance to its wide application.Based comprehensive turf quality evaluation of165native accessions of centipedegrass, the high quality accession E126was selected to establish the regeneration system with axillary buds and seeds as the explant for its cold resistance improvement. The callus of E-126were screened at low temperature, and the survival callus were regererated and the cold resistance and difference of molecular marker of the variant and check were tested; at the same time, E126were treated with fertilizers and regulators to improve the cold resistance and extend the green period. The main result is stated as followings:The turf quality, inflorescence density and the mosiac virus resistance of165accessions of Eremochloa ophiuroides are observed, and the turf quality, inflorescence densitythe, mosiac virus resistance and comprehensive turf quality of18good performance accessions are compared with’Common’and’TifBlair’as the checks to provide the experimental basis for the Chinese germplasm utilization of Eremochloa ophiuroides. The result shows:(i) Average inflorescence density of Eremochloa ophiuroides is6.2with CV as29.5%, which are ranked as the greatest variation characteristics; average mosiac virus resistance is6.83with CV as16.7%, in which CV in spring is greater than CV in summer; the average turf quality is4.85, the CV of turf quality during cool season is twice of the CV of turf quality during warm season; the average comprehensive turf quality is22.7with the CV as10.0%when the accessions are used as vegetative propagation, whereas the average comprehensive turf quality is20.3with the CV as12.1%when the accessions are used as seed propagation.(ii) the comprehensive turf quality of12accessions including E126is significantly higher than that of checks when used as vegetative propagation, whereas only the comprehensive turf quality of one accession E022is obvious higherExperiments of centipedegrass seeds treated with NaOH, H2SO4, KNO3, chafe or low temperature were progressed in laboratory. Results indicated that the seeds germinated best when they were treated with5%NaOH for15min,germination rate, germination potentialand Germination index of seed respectively were97.5%,72.5%and45.36, which respectively increased by77.5%,72.5%and43.10compared with checks. The plant regeneration system was established with the axillary bud and seed of Chinese selection E-126centipedegrass as explant. The optimum medium of growing axillary bud, callus induction, callus differentiation, shoot growth, plantlets rooting respectively were MS medium with6-BA2.0mg/L+NAA0.8mg/L,2,4-D1.0mg/L+6-BA0.1mg/L, KT2.0mg/L,6-BA2.0mg/L+NAA0.8mg/L and NAA0.6mg/L; the optimum medium of seed callus induction, callus differentiation, plantlets rooting respectively were MS medium with2,4-D1.0mg/L+mannitol30g/L+coconut milk50ml/L, KT2.0mg/L+coconut milk50ml/L and NAA0.6mg/L+coconut milk50ml/L. In conclusion, the plant regeneration system was successfully developed in this study, hopefully providing basic reference for screening of somatic variants and genetic transformation of centipedegrass. Poor cold-resistance of centipedegrass is one of the major factors limiting its wide application. The objective of this study is to obtain cold-resistant somatic mutants from the seed of eminent Chinese native centipedegrass selection E-126by induction and screening at low temperature. The callus induced by seeds of centipedegrass was cultivated at the low temperature of0℃for twenty-six days during the process of subculture and two pieces of survival callus tissues were obtained. Strain1and Strain2were obtained after survival callus subculture proliferation, differentiation, rhizogenesis as well as transplantation. No significant differences were found in leaf color, lamellar hair, leaf length and leaf width among Strainl, Strain2and the control. LT50of Strainl and Strain2were-6.646℃and-6.546℃, respectively, which was significantly lower that of control (LT50=-5.351℃), no significant differences were demonstrated between LT50of Strain1and Strain2. The results of sequence related amplified polymorphism (SRAP) markers demonstrated that there were identical characteristic bands at110bp,230bp and240bp of centipedegrass Strain1and Strain2obtained through low temperature induction, however, no characteristic bands at110bp,230bp and240bp were found in control plant, which indicated that the somatic mutants of centipedegrass were genetically stable comparing with that of the control plant on molecular level. Strain1and Strain2could be utilized as the identical strain.The new selection of E-126was used to respectively study the effect of carbamide (0,5,10,15and20g/L), NaH2PO4(0,2,4,8and12g/L), KNO3(0,2.5,5,7.5and10g/L), EDTA-Fe (0,1,5,10and15ml/L),6-BA(0,5,10,15and20mg/L) and B9(0,1,3,5and7g/L) on the coldness and green period of centipedegrass during the cold season. The result showed:(1) the relative electrical conductivity and chlorophyll decomposition of centipedegrass were reduced, whereas the content of soluble sugar and proline in centipedegrass leaf were obviously increased under the treatment compared with the check, which means that the treatment could improve the coldness and performance of centipedegrass during the cold season.;(2)10g/L carbamide,8g/L NaH2PO4,7.5g/L KNO3,10ml/L EDTA-Fe,10mg/L6-BA and1g/L B9respectively treated resulted in the best result and could respectively prolong the green period by11-12,16,12-13,15,16-17 and4-5days compared with the check. The result with10mg/L6-BA treatmented was the best in all treatments and prolong the green period by16-17days compared with the check. |
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