Floral Properties of Different Lucerne Varieties and Their Effects on Bee Visitation

Lucerne( Medicago sativa L.) is a plant of strict allogamy,and its pollination relies on bees mainly. Genetic variations of lucerne floral properties,including receptacle diameter,coronary length,number of flowers per raceme,number of racemes per twig,number of flowers per square metre,percentage of tripped flowers,nectar production,sugar concentration in nectar and contents of sucrose,fructose and glucose in nectar,have been studied with morphological markers,and floral properties of ten lucerne cultivars were also investigated to determine their role in number of visiting bees and to provide a basis for the evaluation of mutant flowers for visitation by bees. The results showed CV( coefficient of variation) of floral properties was from 0. 80% to 92. 30%,of which the content of glucose was the most significant one with variation from 0. 01 to 0. 53 μmol /L( P 【 0. 05),and the sugar concentration was the most insignificant one( P 】 0. 05). The significant order of floral properties affecting the number of visiting bees was that the nectar production per square metre( r = 0. 93,P 【 0. 01) was in the first place,followed by the number of flowers per square metre( r = 0. 92,P 【 0. 01),sucrose concentration of nectar sugar( r = 0. 82,P 【 0. 05),coronary length( r = 0. 77,P 【 0. 05) and nectar production per flower( r = 0. 71,P 【 0. 05).

Buick十年后的重逢 2006款别克Lucerne

全新的Lucerne是别克品牌意义重大的里程碑车型,我们为这款车搭载了新的V8引擎,Lucerne是近 10年来第一台采用V8引擎的轿车, 对于这款车,我们充满信心。——通用公司总经理John

Seasonal patterns in water uptake for Medicago sativa grown along an elevation gradient with shallow groundwater table in Yanchi county of Ningxia,Northwest China

Lucerne （Medicago sativa L.） is a deep-rooted perennial leguminous forage with high evapo-transpiration rate exceeding the annual precipitation in semi-arid areas of Northwest China. Groundwater might be the potential water sources of lucerne in the area with shallow groundwater table. In this study, stable isotopic compositions of oxygen and hydrogen （6180 and 8D） of different water sources and xylem sap were analyzed to determine the seasonal （April, June, July and August） and topographic （three slope positions） variations in water sources for lucerne growing in Ningxia eastern semi-arid area adjacent to Mu Us Desert characterized by shallow groundwater table. IsoSource software was used to calculate the probable contribution of different water sources to the total plant water uptake. Stomatal conductance, stem water potential, carbon isotope discrimination （A13C） of whole plant were also determined for evaluating the water status of lucerne growing at different slope positions. The results showed that soil water content increased as the elevation decreased. Oxygen compositions of soil water in the 0-40 cm profile fluctuated considerably. Soil water 8180 values in deep profile （〉3.5 m） were similar to those in groundwater, implying the recharge of groundwater to this soil layer. Highest water utilization rate from deep soil profile （below 350 cm） was recorded for lucerne grown at the slope position 1 （groundwater table depth of 3.5-3.9 m） in April, June and July. The lucernes at slope position 2 （groundwater table depth of 5.8-6.4 m） and slope position 3 （groundwater table depth 7.1-8.3 m） mostly used water from deep soil layers （below 350 cm） during dry period, and turned to use water from superficial soil layer in wet period. Higher yield, A13C value of whole plant and stomatal conductance were observed for lucerne grown at the slope position 1 than those at other slope positions. These results indicated that groundwater is a significant water source for transpiration of lucerne grown in Ningxia semi-arid area with shallow groundwater table where lucerne grassland is suggested to be established so as to obtain better yield performance.

Effect of Soil and Water Conservation Measures on Selected Soil Physical and Chemical Properties and Barley （Hordeum spp.） Yield

A study was conducted in 2007/2008 at Absela locality, Banja Shikudad District of the Amhara National Regional State, Ethiopia to evaluate the effects of soil bunds stabilized with vetiver grass （IT. zizanioides） and tree lucerne （C. palmensis） on soil physical and chemical properties, bund height, inter-terrace slope and barley （Hordeum vulgare L.） yield. Data were analyzed using one-way analysis of variance （ANOVA） and mean values for the treatments were separated using Duncan＇s Multiple Range Test. Results indicated that the non-conserved fields had significantly （p 〈 0.05） lower organic carbon and was found to contain 66% less OM from the average of the conserved treatment. 9-year old sole soil bund, the 9-year old soil bund stabilized with tree lucerne, the 9-year old soil bund stabilized with vetiver, and the 6-year old soil bund stabilized with tree lucerne had 71.20, 68.56, 52.30, and 36.12%, respectively higher percent OM than the control treatment. The trend was similar for total nitrogen. The non-conserved treatment had a higher bulk density when compared to the conserved fields. Fields with soil bunds stabilized with vetiver grass had the highest bund height and the lowest inter-terrace slope than fields treated with the rest of remaining conservation measures. Barley grain yields were significantly （P 〈 0.05） greater in both the soil accumulation and loss zones of the conserved fields than the non-conserved （control） treatment. Practicing soil conservation measures and curtailing causes of land degradation could improve the soil physical and chemical properties thereby increase land productivity of the conserved land.

Distribution and Productivity of Naturalized Alfalfa in Mixed-Grass Prairie

Alfalfa (Medicago sativa L.) is an important forage and conservation crop in North America but occurrences of naturalized alfalfa in rangelands are rare. A naturalized population of yellow-flowered alfalfa in mixed-grass prairie on the Grand River National Grassland in South Dakota has potential agricultural value for the region. Despite this value, the distribution pattern of this alfalfa among and within native plant communities in the northern Great Plains is unknown. Field studies were conducted from 2003 through 2006 along topographic positions at two sites where yellow-flowered alfalfa was naturalized to evaluate the relationships of yellow-flowered alfalfa on biomass production, cover, species diversity, and alfalfa seedbank distribution characteristics. High yellow-flowered alfalfa cover (>50%) was associated with increased total biomass and occurred exclusively in swales and toeslopes that had silty loam soils. However, species diversity and non-alfalfa biomass were reduced when yellow-flowered alfalfa cover was high. Yellow-flowered alfalfa cover was lower and species richness was higher on backslopes and shoulder areas where sandy loam soils were present. A strong positive linear association existed between yellow-flowered alfalfa cover and alfalfa seedbank density (r values ranged from 0.76 to 0.82, P < 0.0001). Greater than 99% of the seeds were viable but germination rate was only 4%, indicating a high percentage of hard seed in this alfalfa population. Naturalized yellow-flowered alfalfa was a dominant component of a stable, low diversity plant community composed of mainly introduced species in rich soils of swales/toeslopes that contributed to forage production and quality in mixed-grass prairie in the northern Great Plains.

Validation of a Technique for Estimating Alfalfa (Medicago sativa) Biomass from Canopy Volume

Determining biomass production of individual alfalfa (Medicago sativa L.) plants in space planted evaluation studies is generally not feasible. Clipping plants is time consuming, expensive, and often not possible if the plants are subjected to grazing. A regression function (B′ = 0.72558 + 0.11638 × V′) was developed from spaced plants growing on rangeland in northwestern South Dakota near Buffalo to nondestructively estimate individual plant biomass (B) from canopy volume (V). However, external validation is necessary to effectively apply the model to other environments. In the summer of 2015, new data to validate the model were collected from spaced plants near Brookings, South Dakota. Canopy volume and clipped plant biomass were obtained from ten alfalfa populations varying in genetic background, growth habit, and growth stage. Fitted models for the model-building and validation data sets had similar estimated regression coefficients and attributes. Mean squared prediction errors (MSPR) were similar to or smaller than error mean square (MSE) of the model-building regression model, indicating reasonable predictive ability. Validation results indicated that the model reliably estimated biomass of plants in another environment. However, the technique should not be utilized where individual plants are not easily distinguished, such as alfalfa monocultures. Estimating biomass from canopy volume values that are extrapolations (>2.077 × 106 cm3) of the model-building data set is not recommended.

Estimation of alfalfa fall dormancy using spaced plant and sward trials across multiple environments

Background:Alfalfa is a globally important forage crop.Cultivars are characterized by fall dormancy(FD).FD affects biomass yield and winter survival and is used to identify appropriate growing regions of cultivars.It has historically been assessed by measuring the natural height of regrowth in autumn of spaced plants in the field.Because commercial alfalfa is normally grown as a solid planted sward,FD could be different if plants were grown under real production conditions.The objective of this experiment was to assess whether FD ratings obtained from swards were similar to those obtained on spaced plants.Methods:We evaluated 20 alfalfa cultivars in field trials established in 2015 at five locations in the United States.We harvested the trials in early autumn and measured regrowth plant height approximately 3 weeks later in 2015 and 2016.Results:Autumn plant height responded as expected for the established check cultivars in all locations.Fall dormancy ratings for cultivars under both management systems were highly correlated.Conclusions:Estimating FD from spaced plant height measurements in autumn is very robust,and using height data from sward plots gives equivalent results to that measured in spaced plant nurseries.This finding has many practical advantages.

DISCIPLINE SYSTEM OF ALFALFA BIOLOGY: FROM MULTIOMICS TO BIOLOGICAL BREEDING

Alfalfa(Medicago sativa)is the main leguminous forage crop with great ecologic and economic value.The research of alfalfa in various fields has exploded,but has not been included in a systematic framework.This paper summarizes the status of global alfalfa research over the past 10 years,raise the subject concept of alfalfa biology,and review the recent advances from the perspective of discipline system as germplasm resources,multiomics and biotechnology,environmental biology,symbiotic nitrogen fixation,biological breeding and cultivation.This paper proposes the key unsolved scientific and technical issues in alfalfa biology,and hope to appeal the research interest of more plant scientists and to promote the development of alfalfa industry.