Spectral Parameters of Nd^(3+)∶Sr_6YSc(BO_3)_6

The crystal Nd 3+∶Sr 6YSc(BO 3) 6 was grown by the top-seeded solution growth method from a Li 6B 4O 9 flux. The s pectral properties of Nd 3+∶Sr 6YSc(BO 3) 6 crystal were investigated. Using Judd-Ofelt theory to ana lyze the optical strength measured in absorption spectrum, the following spectr al parameters were obtained: parameters of oscillator strengths Ω λ are Ω 2=1.194×10 -20 cm2, Ω 4=4.186×10 -20 cm2 and Ω 6=3.3 51×10 -20 cm2. The radiative lifetime is 322 μs, and the fluorescence b ranch ratios were calculated: β 1=0.465, β 2=0.453, β 3=0.079 and β 4=0.004. The results indicate that Nd 3+∶Sr 6YSc(BO 3) 6 c rystal seems to be a potential high-efficient laser material.

Genetic Parameters for Yields and Reproductive Traits of Chinese Holstein Cows in Heilongjiang Province

[Objective] This study aimed to estimate the genetic parameters for milk yield, fat percentage, fat yield and age at first freshening of Chinese Holsteins first lactation cows in Heilongjiang under frigid-temperature and temperature zone. [Method] Records of yield and reproduction from 8 868 Chinese Holstein first lacta- tion cows from 21 herds were utilized to evaluate genetic parameters for Hei- Iongjiangs＇ Chinese Holsteins. Restricted maximum likelihood （REML） method was used with an animal model. [Result] The heritabilities were 0.16 to 0.34 for yields and fat percentage, 0.38 for reproduction （age at the first freshening）, which were similar to estimates for temperate areas from similar methods, except for constituent percentage. Also, the estimates of genetic correlation were high between milk yield and fat yield （0.97）, but were low between milk yield and fat percentage （-0.24）, age at the first freshening （-0.29） and generally antagonistic. [Conclusion] Thus, es- timates of genetic parameters in this frigid and frigid-temperate environment did not differ appreciably from those that occur in temperate dairy areas.

Development and Age Structure of Ramets of Kalimeris integrifolia Populations in the Songnen Plains, Northeast China

Kalimeris integrifolia Turcz. is a root sucker form perennial herb of Compositae. In die late period of growing season, fresh fleshy radicels grow up above the soil surface to develop root-borne buds, which in turn grow into ramets and taproot. On the basis of observation on numerous samples, methods to classify the age of ramets and buds for the root sucker herbaceous plant population and to estimate the ages of taproots were established according to their morphology. The age of ramets was classified based on the regeneration times of taproot buds. Ramets developed from new root sucker buds were classified as 1 a. After 1 a ramets died, the ramets reproduced from the taproots were 2 a, and so on. New buds from a root sucker were 0 a buds, other age classes of buds were consistent with that of ramets, i.e. buds produced from taproots of I a ramets were 1 a buds, and so on. In the hay clipping meadows of the Songnen Plains, for K. integrifolia population, there are three age classes of ramets, representing a steady age structure. The maximal age of taproots of ramets is 4 a. Among all age classes, the population productivity of 2 a ramets was the highest, and that of I a ramets was the lowest. The ramet productivity increased with ramet age. During the early period of growing season, the productivity of 3 a ramets was the highest, but after the middle of growing season, I a ramets showed the greatest relative growth rate. The population size and age structure in the next year could be accurately forecasted by the number of fresh roots with budlet and present population in late autumn. The potential population in the bud banks was more than two times of the present population, which may provide sufficient substitution in the future.

Phenotypic Plasticity in Response to the Heterogeneous Water Supplyin the Rhizomatous Grass Species, Calamagrostis epigejosin the Mu Us Sandy Land of China

Calamagrostis epigejos (L.) Roth. is a perennial grass with slender and long rhizome segments between interconnected neighbor ramets. To investigate the phenotypic plasticity in response to the heterogeneous soil water supply, ramet pairs of the species were subjected to heterogeneous water supply by which either mother ramets or daughter ramets were in high or low soil water supply, respectively, in the Maowusu (Mu Us) Sandy Land of Nei Mongol. The results showed that the phenotypic characteristics of the individual ramets of C epigejos were greatly influenced by the heterogeneous water supply. The ramets treated with high water supply significantly produced more new rhizomes and more offspring (ramets), and accumulated more shoot biomass, and allocated more biomass to their shoots than those treated with low water supply. In comparison with the daughter ramets in homogeneous soil water supply, phenotypic characteristics, in terms of new rhizome growth, the production of new offspring, and the biomass allocation pattern, of the daughter ramets within the pairs of the species were not significantly changed, no matter that high or low soil water supply to mother ramets. The phenotypic responses of mother ramets to soil water supply were similar to those of daughter ramets. From these results, it is inferred that the interconnected ramets of C epigejos response phenotypically to their local soil water rather than to the soil water experienced by the interconnected ramets. The interconnected ramets of C epigejos might be independent of each other in water relationship, although they are physically interconnected with rhizome segments. The physiological independence of interconnected ramets might facilitate the risk spreading and thus enhance the genet survivorship under the frequent drought stresses in Mu Us Sandland.

Evaluation of Extracts of Native and Non-Native Plant Species for the Suppression of Cogongrass （Imperata cylindrica L.）

Effects of the extracts of muhly grass （Muhlenbergia capillaries Lam.）, chenopodium （Chenopodium ambrosioides L.） and black walnut （Juglans nigra L.） on the growth of cogongrass （Imperata cylindrica L.） were studied. None purified extracts from these plant species were used to evaluate survival, shoot and root growth of cogongrass. Results of plant species extracts on the production of roots, shoot and rhizomes of cogongrass genets and ramets were determined on a weekly basis. The extracts significantly reduced the growth and survival of cogongrass when compared to the control. Results indicated that for the in vivo studies, chenopodium extracts, black walnut and muhly grass extracts reduced growth, root and shoot biomass of cogongrass by 50 %, 30 % and 41% respectively, compared to control at 8 weeks after planting. These studies indicated plant species with potential for the biological control of cogongrass, an invasive species in the Gulf Coast States.

Growth and production characters of elymus cylindricus in different shortening heading time

Ramet modules in a certain population differ in terms of functions,which accounts for different contributions of the same ramets.Shortening heading time brings about different contributions of such modules.Ramets heading one after another were treated as a continuum in respective cohorts of Elymus cylindricus aged two.The reproductive ramets that head earlier were marked with tags every four days during the whole heading stage from the beginning to the end,after which all the labeled ramets at the maturity period were gathered.The results showed that,the height and biomass of ramets,the length and biomass of inflorescences,percentage of inflorescence length to ramet height,percentage of inflorescence biomass to ramet biomass,the number and biomass of seeds,seed-setting rate,and percentage of seed biomass to ramet biomass declined with the increasing intensity of heading time shortening as displayed with linear or quadratic function.Ramet characteristics weakened remarkably when shortened heading time added up to 17 days.The biomass distribution in relation to inflorescence and seed maintain a stable rate at the early heading stage and dwindled quickly at the near-end stage,but the biomass of ramets remain constant throughout the entire heading stage.The ramets with earlier heading time make greater contribution to the survival of population than the shortened heading time in this species of bunchgrass.

DNA Sequence-Based Markers for Verification of Ramet-to-Ortet Relationship in Oil Palm (<i>Elaeis guineensis</i>Jacq.)

Since oil palm (Elaeis guineensis Jacq.) does not breed true, tissue culture-derived material is the resource of choice for achieving oil palm homogeneity in terms of growth and yield. Currently, no genomic tagging method is available with which one could verify the ortet (tissue donor oil palm) from which the clonal planting material (ramets) origi-nated, particularly in cases of unsatisfactory performance. Thus, Sime Darby Plantation used 10 genomic microsatellite markers to genotype 8 sets of 5 ramets +1 ortet and 2 single ortets. The average genetic distance (D) among oil palms from the same set of ramets and ortet was 0.0000 with the exception of sets containing off-type ramets (D = [0.0834 - 0.1505]). The dendrogram showed that the ramets and their ortet of origin formed a sub-cluster, confirming their simi-larity. The 10 microsatellite markers were valuable to Sime Darby as tools for verification of ramet-to-ortet relation-ships and for the identification of off-types. Furthermore, the set of 10 markers revealed a high expected heterozygosity (He = 0.634) that is a high expected heterosis effect on which yield depends.

Ramet Population Structure of Fargesia nitida （Mitford） Keng f. et Yi in Different Successional Stands of the Subalpine Coniferous Forest in Wolong Nature Reserve

Forest structure and succession in Wolong Nature Reserve is influenced by the understory dwarf bamboo population. However, less is known about how the forest succession affects the dwarf bamboo population. To examine the bamboo ramet population growth of Fargesla nitida （Mltford） Keng f. et Yi and to determine how ramet population structure varies along the succession of coniferous forest, we sampled ramet populations of F. nitida from the following three successional stages： （i） a deciduous broad-leaved （BL） stand; （ii） a mixed broad-leaved coniferous （MI） stand; and （ill） a coniferous （CF） stand. We investigated the population structure, biomass allocation, and morphological characteristics of the bamboo ramet among the three stand types. Clonal ramets, constituting the bamboo population, tended to become short and small with succession. The ramet changed towards having a greater mass investment in leaves, branches and underground roots and rhizomes rather than in the culm. With respect to leaf traits, individual leaf mass and area in the BL stand were markedly bigger than those In both the MI and CF stands, except for no significant difference in specific leaf area. The age distribution showed that the bamboo population approached an older age with succession. The results demonstrate that the ramet population structure of F. nitida is unstable and its growth performance is inhibited by succession.

Clonal integration affects growth and sediment properties of the first ramet generation,but not later ramet generations under severe light stress

Clonal integration benefits clonal plants by buffering environmental stress and increasing resource extraction efficiency.However,the number of connected ramet generations that benefit from clonal integration in a clonal system has received relatively little attention.A pot experiment was conducted to evaluate the extent of physiological integration within the clonal system of Vallisneria natans consisting of a mother ramet and three sequentially connected offspring ramets.Mother ramets were grown in full sunlight,and offspring ramets were heavily shaded with limited light availability.Stolons between mother ramets and offspring ramets were severed or connected,but connection among the three offspring ramets remained.The photosynthetic ability of unshaded mother ramets of V.natans was significantly enhanced,but their biomass accumulation was greatly reduced when connected to shaded offspring ramets.Clonal integration significantly increased biomass accumulation,C and N availabilities,extracellular enzyme activities and microbial biomass of the first ramet generation(adjacent ramet),but not later ramet generations.Our results indicate that support from the mother ramet of V.natans may be limited to the adjacent offspring ramet in a clonal system under severe light stress,implying an effect of ramet generation.Our results contribute to a better understanding of the hierarchy and segmentation of clonal plants.These findings suggest that the extent of clonal integration plays a vital role in ecological interactions of the ramet population.