Stable Transformation of Three Cultivars of Kentucky Bluegrass (Poa pratensis L.) by Particle Bombardment of Mature Seed-Derived Highly Regenerative Callus

High embryogenic calli of three cutivars of Kentucky bluegrass, Md, Bd, and Gm, were induced from mature embryos, and were proliferated on medium K3 and K5. Embryogenic calli were transformed with plamids pDM803 and pBY520 by microprojectile bombardment. Fourty-two transgenic lines had been obtained. The highest efficiency of transformation reached to 3.7% for cv. Md, 2.8% for cv. Gm, and 5 % for cv. Bd. The micro nutriment of Cupric had significant effect on transformation. The embryogenic callus cultured in dim-light condition had higher transformation efficiency than the green callus cultured in light condition for one month before transformation. The selective regime and selective pressure on the putative transgenic plants were important for obtaining the desire number of transgenic plants. It also affected the copy number of integrated genes in the genomic DNA of transgenic plants.

Growth of Kentucky Bluegrass as Influenced by Nitrogen and Trinexapacethyl

The experiment aimed to evaluate the effects of N and trinexapac-ethyl （TE） to the growth of Kentucky bluegrass. By using the method of randomized blocks design, 4 N levels, 0 （N1）, 20 （N2）, 25 （N3）, and 30 （N4） kg N ha t mon% with TE at 0 （T1）, 312.5 （T2） and 625 （T3） mL ha-1 every 10 d effect on the total height, clippings and chlorophyll concentration of Kentucky bluegrass were evaluated. Results showed that total height and total clippings of Kentucky bluegrass were reduced by treating with TE and increased by treating with N. Kentucky bluegrass treated with 312.5 and 625 mL ha ＇ per 10 d had total clippings and total height reduced 30 and 45% under different N application level. The N × TE interaction was significant for the chlorophyll concentration of Kentucky bluegrass. The chlorophyll concentration of Kentucky bluegrass treated with TE at 625 mL ha-1 every 10 d was significantly higher than that of Kentucky bluegrass treated with 312.5 mL ha-1 every 10 d at the same N level. The chlorophyll concentration of turfgrass treated with TE at 625 mL ha-1 every 10 d receiving 30 kg N ha -1 month-1 was the highest. Based on the index of turf growth and the chlorophyll concentration, turfgrass receiving 20 or 30 kg N ha-1 month-1 with 625 mL TE ha i every 10 d could balance the problem of mowing frequency and growth quickly while keeping a good quality.

Study on Classification and Genetic Diversity of Kentucky Bluegrasses by Using RAPD Markers

A total of 69 random primers were screened by using random amplified polymorphic DNA （RAPD） markers to analyze the genetic bands of 32 Kentucky bluegrass cultivars. A total of 197 bands were amplified from 46 primers, among which 195 bands were polymorphic. Each primer could amplify one to nine polymorphic bands with an average of 4.3 per primer. Based on similarity coefficient analysis of RAPD results and by using NTSYS software to cluster analyze with the average UPGMA method, the result showed that 18 cultivars of the 32 were in group 1, three cultivars were in group 2, two cultivars were in group 3, eight cultivars were in group 4, and only one cultivar in group 5.

Mowing Height and Mowing Frequency Interactions on Turf Performance of Kentucky Bluegrass

The mowing height and mowing frequency are the key factors that affect the turf quality and turfgrass growing ability. The purpose of this study was to reveal the alternative effcient interaction between mowing height and mowing frequency in Kentucky bluegrass turf management. The Kentucky bluegrass cultivar ＇Kenblue＇ （Poa pratensis L.） was used to evaluate the interactions of mowing heights （H1, H4 and H7） and mowing frequencies （F2, F5 and F8） on the performance of turfgrass and turf physiological responses under the feld condition. The results showed that the treatment of H7×F8 had perfect infuence on the turf texture, root elongation, and also enhanced soluble sugar and free proline content in plants. While, the turf quality, color, uniformity and the increasing tiller numbers were performed more superior in the treatment of H4×F5 than other treatments. In all the interacting treatments, the relation between leaf green index and number of shoots （dm2） was positively correlated, thus, it could be speculated that the proper mowing height with frequency had a strong impact on the increasing of turfgrass tillers. On the whole, the interaction of H4×F5 on turf quality was the most excellent treatment in this experiment.

Classification and Genetic Diversity of Kentucky Bluegrasses by Using RAPD Markers

Total 69 random primers were screened out through RAPD （Random Amplified Polymorphic DNA） markers to analyze the genetic bands of 32 Kentucky bluegrass cultivars. A total of 197 bands were amplified from 46 primers of them, among which 195 bands were polymorphic. Each primer could amplify one to nine polymorphic bands with an average of 4.3 being amplified from an average of primer. Based on the similarity coefficient analysis of RAPD results, NTSYS software and cluster analysis by using average UPGMA method, the result showed that 18 of 32 cultivars were in group 1, three cultivars were in group 2, two cultivars were in group 3, eight cultivars were in group 4, and there was only one cultivar in group 5, which was C2.

Development of natural treatment system consisting of black soil and Kentucky bluegrass for the post-treatment of anaerobically digested strong wastewater

To develop a sound post-treatment process for anaerobically-digested strong wastewater,a novel natural treatment system comprising two units is put forward.The first unit,a trickling filter,provides for further reduction of biochemical oxygen demand and adjustable nitrification.The subsequent soil–plant unit aims at removing and recovering the nutrients nitrogen（N）,phosphorus（P）and potassium（K）.As a lab-scale feasibility study,a soil column test was conducted,in which black soil and valuable Kentucky bluegrass were integrated to treat artificial nutrient-enriched wastewater.After a long-term operation,the nitrification function was well established in the top layers,despite the need for an improved denitrification process prior to discharge.P and K were retained by the soil through distinct mechanisms.Since they either partially or totally remained in plant-available forms in the soil,indirect nutrient reuse could be achieved.As for Kentucky bluegrass,it displayed better growth status when receiving wastewater,with direct recovery of 8%,6% and 14% of input N,P and K,respectively.Furthermore,the indispensable role of Kentucky bluegrass for better treatment performance was proved,as it enhanced the cell-specific nitrification potential of the soil nitrifying microorganisms inhabiting the rhizosphere.After further upgrade,the proposed system is expected to become a new solution for strong wastewater pollution.

Chemical and spectroscopic characteristics of humic acid from a clay loam soil in Ontario after 52 years of consistent fertilization and crop rotation

Long-term fertilization and crop rotation can influence both organic C sequestration as well as the C composition of soils and the more resistant organic C compounds contained in humic acid(HA). This study examined the effects of fertilization and cropping type(monoculture corn(MC) and Kentucky bluegrass sod(KBS) and corn-oat-alfalfa-alfalfa rotation(RC)) on the HA composition of soil from a 52-year field study in southern Ontario, Canada. Humic acid samples were extracted from soil, and elemental analysis, infrared spectroscopy, solid state 13C nuclear magnetic resonance spectra, and electron paramagnetic resonance methods were used to determine the influence of the cropping type on the characteristics of HA. Both fertilization and cropping type affected the chemical characteristics of HA. Fertilization led to a 5.9% increase in C, a 7.6% decrease in O, and lower O/C and(N + O)/C ratios in HA as compared to the corresponding non-fertilized treatments. Rotation resulted in a lower proportion of C(48.1%) and a greater(N + O)/C ratio(0.7) relative to monoculture cropping. Infrared spectroscopy analysis showed that HA contained more C-O groups in fertilized soil than in non-fertilized soil under MC and KBS. Fertilization increased the O-alkyl-C, phenolic-C, and free radical contents of HA relative to non-fertilization treatments. Rotation decreased the aliphatic and carboxyl groups and increased the O-alkyl, carbohydrate, aryl, and phenolic groups and free radicals, relative to MC and KBS. Both long-term crop rotation and fertilization dramatically modified the soil HA composition. Significant relationships were observed between the molecular composition of HA and soil organic C. Hence, humic acid characterization could be used as an indicator of the long-term sustainability of crop management practices.