Agronomy Journal 93:1249-1256 (2001)
© 2001 American Society of Agronomy
FORAGES
Performance of Annual Medic Species (Medicago spp.) in Southeastern Wyoming
Michael J. Walsh*,a,
Ronald H. Delaneyb,
Robin W. Grooseb and
James M. Krallb
a WAHRI, Faculty of Agric., Univ. of Western Australia, Nedlands, WA 6907, Australia
b Dep. of Plant Sci., Univ. of Wyoming, Laramie, WY 82070
* Corresponding author (mwalsh{at}agric.uwa.edu.au)
Received for publication April 26, 2001.
 |
ABSTRACT
|
|---|
Annual medic (Medicago spp.) pastures that produce high levels of good quality forage are well suited to grazing and are used extensively throughout dryland farming regions of the world. In these regions, they are normally an integral component of cropping rotations because they allow for reductions in weed and disease problems in addition to increasing soil N levels for subsequent crops. The objective of this research was to investigate the performance of 17 annual medic cultivars and experimental lines for their potential use as self-regenerating annual pastures in the dryland cropping region of southeastern Wyoming. Dry matter and seed production capabilities were recorded over three seasons, 1996 to 1998. Growth phase development following different emergence times was evaluated in two seasons, and the forage quality was assessed for medic cultivars and lines grown in the 1997 season. Results revealed that the M. rigidula (L.) All. line, SA10343, consistently produced the greatest level of dry matter, with more than double the amount of forage than nearly all other cultivars. Dry matter production was related to the period of growth and development where higher yielding cultivars showed extended periods of vegetative growth. In general, the southeastern Wyoming climate substantially reduced the growth and development periods of medic cultivars bred in southern Australia. Given the overall performance of all cultivars, it was determined that the M. rigidula species had the greatest potential for further development in this environment.
|
INTRODUCTION
|
|---|
THE SYSTEM of integrated crop and livestock production known as ley farming was developed in the semiarid dryland farming regions of southern Australia. The ley-farming system is based on the rotation of cereal crops with annual legume pasture phases that regenerate from seed (self regenerating) at the start of each pasture phase. These pastures typically use annual medics as the legume pasture component (Crawford et al., 1989). The establishment of this system relies on the effectiveness of the pasture phase of the rotation in producing large amounts of high quality forage for grazing. Additional requirements are that these pasture phases allow for the control of weeds and diseases while improving the structure and fertility of the soil. An additional criterion for these pastures is that they need to maintain a sufficiently high seedbank level to allow regeneration from seed at the start of each pasture phase. Annual medic pastures have been used for these purposes with considerable success for many years in Australia's dryland cropping regions (Puckridge and French, 1983). In these regions, annual medics are highly suited as a productive pasture phase despite harsh environmental conditions. The resulting reductions in weed and disease problems along with improved soil fertility and structure have led to a stable wheat (Triticum aestivum L.) production system.
As there are appropriate soil types and sufficient precipitation levels, it is believed that an annual medic based ley-farming system can be developed for use in southeastern Wyoming. Developing this farming system for this region relies on the inclusion of an annual medic pasture that is effective in producing increased levels of high quality forage over a summer growing season. Both the amount of N fixed and the additions to soil organic matter levels are directly related to dry matter production levels (Crawford et al., 1989). Additionally, seed production and, therefore, seedbank establishment for regeneration are also linked to the level of dry matter produced (Puckridge and French, 1983).
The differences in environmental conditions between a Mediterranean winter growing season and the summer growing season of southeastern Wyoming are likely to affect the growth and development of annual medics. There are several environmental factors, including temperature, moisture stress, and photoperiod that have been found to affect the growth and development of annual medics (Aitken, 1955; Clarkson and Russell, 1975, 1976; Van Heerden, 1984). These studies suggest that with longer photoperiods and higher temperatures, the development periods of annual medics are likely to be reduced in a summer growing season. Regardless, annual medics have proven to be highly adaptive to a wide range of environments and locations (Crawford et al., 1989).
Annual medic pasture regeneration depends on the establishment and maintenance of a viable seedbank throughout all stages of a ley-farming rotation. A productive medic stand has regenerating plant densities between 200 to 400 plants m-2 (Carter, 1981). In order to achieve this density, a viable seedbank of about 200 kg ha-1 (approximately 4000 seed m-2) is needed. There can be considerable losses from the seedbank mainly due to germination during nonpasture phases of the rotation but also from seed death and predation. Therefore, it is essential that there is sufficiently high seed production during the annual medic pasture phase to allow for any losses before the commencement of the next pasture phase.
The objective of this study was to evaluate the performance of a number of annual medic cultivars and experimental lines for their potential as legume pasture phases over three summer growing seasons at Archer in southeastern Wyoming. The performance of cultivars and experimental lines was primarily assessed on the basis of dry matter and seed production as well as plant establishment and forage quality. It is envisaged that annual medic pastures will replace all or at least part of the fallow phase of the widely used fallow–wheat rotation. Therefore, to assess the appropriate period for medic pasture production, the effects of differing emergence times on medic growth and development were determined. These criteria will be used to determine the overall suitability and potential of annual medics for use in annual pastures in southeastern Wyoming.
|
MATERIALS AND METHODS
|
|---|
Field Trial Location, Seasonal Conditions, and Planting Procedures
All field experiments reported in this paper were conducted at the University of Wyoming's Archer Research and Extension Center located at Archer in southeastern Wyoming (41°09'N, 104°39'E; elevation 1803 m). The soil type was a fine sandy loam mixed mesic Pachic Arguistoll (Dalrymple et al., 1993). Soil pH was 6.3, and P and K (0–10 cm) were approximately 12 and 200 kg ha-1, respectively, at the experimental site.
Seventeen cultivars and experimental lines of the genus Medicago were evaluated over the 1996, 1997, and 1998 summer growing seasons (Table 1). Nine of the lines are commercial cultivars developed for use in south Australian dryland cropping zones. Five of the lines have some frost tolerance and are being developed for use in cooler dryland farming climates. The remaining three lines, two experimental lines from the South Australian Research and Development Industry and ‘George’ developed for the Northern Great Plains of the USA, also have some frost tolerance (R. Groose, personal communication, 1998).
Sites were located on areas that were cropped the previous year with winter wheat and prepared by cultivating with a rototiller to a depth of approximately 15 to 20 cm just before planting. Medic seed were scarified by hand using sandpaper before inoculation with the appropriate Rhizobium strain. Seed of M. littoralis Rohde ex Lois. and M. rigidula were inoculated with the R. meliloti strain WSM 826, M. rigiduloides seed were inoculated with R. meliloti strain M18, and seed of the remaining medic cultivars and experimental lines were inoculated with R. meliloti strain WSM 688 immediately before planting. In 1996, 100 germinable seed (pure live seed at 100% germination) were planted in 1-m-long rows while in 1997 and 1998, 500 germinable medic seed were sown by hand-spreading the seed on the soil surface of 1.0-m2 plots. In each trial, the seed were covered with approximately 1 to 2 cm of soil by raking. The respective planting and germination dates for each season are listed in Table 2. In 1997 and 1998, two additional plantings were conducted for evaluating medic performance following different times of emergence over three growing seasons (Table 2). The development of new cultivars and the availability of seed for evaluations resulted in some differences in the medic cultivars used in each of the three seasons (Table 1). Plots were maintained weed free throughout each of the growing seasons by hand weeding.
Data Collection and Sample Processing for Field Experiments
The date of seedling emergence (appearance of open cotyledons) of each of the medic cultivars and experimental lines was recorded following each planting date. These dates were subsequently used as the commencement of the growth and development period (Table 2). Plant establishment counts were recorded for the entire plot when medic plants had reached or passed the three-leaf stage. Days from seedling emergence to flowering were determined by noting the date of the first fully emerged flower in each plot. Dry matter sampling was conducted at plant maturity by removing all aboveground plant material from half of the plot area. Plant samples were oven-dried at 60°C for 2 d before weighing. Harvest dates were noted for calculating the number of days from emergence to harvest (growth and development periods) for each plot. Plant samples from the 1997 harvest were prepared for quality analysis by grinding with a Wiley mill to pass through a 1-mm screen. Medic seed production levels were recorded by vacuuming pods from the soil surface and by collecting pods still attached to plant material present in the remaining half of the plot. These were collected when plants had completed senescence. Plants of the SA10343 line survived the 1997–1998 winter in two of the three replicates following the third time of emergence. These plants then flowered and produced pods the following spring. For these plots, pod collection took place in late spring 1998. Pod numbers were recorded for each treatment, and then a subsample of 100 pods was threshed and seed collected for determining total seed production. Viable seed numbers were determined by placing 100 scarified seed on moistened paper in germination boxes, which were placed in darkness at 20°C for 14 d. After this period, viable seed were determined as seed that had germinated, imbibed but not rotted, or were unaffected.
Plant samples from the 1997 growing season were retained to investigate potential forage quality differences between cultivars and experimental lines. Crude protein levels were determined using the methods described by AOAC (1980). To compare forage quality levels of these cultivars and experimental lines to other forages, levels of neutral and acid detergent fiber were measured to calculate relative feed values. Levels of neutral and acid detergent fiber were determined according to the methods described by Goering and Van Soest (1970). Relative feed values were calculated according to the method of Casler (1990).
Experimental Design and Analysis
Medic plots were sown in a randomized complete block design in each of the three growing seasons. In 1997 and 1998, there were three planting times, and the medic cultivar and planting times were randomized within each replicate in a randomized complete block design with three replicates. Medic plant establishment counts, dry matter yield, and seed production were analyzed in a randomized complete block design with three replicates in 1996. Medic cultivar and experimental-line comparisons were conducted for each time of emergence for all measurement variables in the 1997 and 1998 experiments. This is because there were strong interaction effects between emergence time and the performance of medic cultivar and experimental lines (P < 0.01). The variances of the treatment means of all factors and their interactions were tested for equality using Hartley's F-test (Pearson and Hartley, 1966), and a univariate analysis was conducted on the residuals to determine if they were normally distributed. Medic cultivars were compared for each of the variables measured using Tukey's Honest Significant Difference Test. All analyses were conducted using the SAS statistical package (1992). All tests for significance were conducted using 
= 0.05.
|
RESULTS
|
|---|
Precipitation
The total monthly precipitation levels were highly variable, with large differences between these values for each of the three growing seasons. Precipitation levels for the May through September growing season were 339, 489, and 248 mm for 1996, 1997, and 1998, respectively (Fig. 1)
. Additionally, in some instances, there were variations in monthly totals >100 mm between seasons. These variations in precipitation levels indicate that there would have been large differences in the amount of moisture available for plant growth in these three seasons. In general, the wetter 1997 season would have provided increased soil moisture levels for longer periods compared with the 1996 and 1998 growing seasons. The 1998 season was particularly dry, with below-average precipitation levels throughout the growing season.
View larger version (35K):
[in this window]
[in a new window]
|
Fig. 1. Average, 1996, 1997, and 1998 monthly precipitation values for Archer Research and Extension Center (Wyoming Agric. Stat. Serv., 1998).
|
|
Growth and Development
The average number of days from emergence to flowering over the 1997 and 1998 seasons was 55 d for the first two times of emergence, decreasing to around 40 d for the third time of emergence in the 1997 season. In 1998, there was no medic production from the third time of emergence due to the dry seasonal conditions. This delay in development from the third time of emergence resulted in many of the cultivars being killed by frost at the end of the growing season. The number of days from emergence to flowering was consistently greater in the 1998 growing season than the 1997 season for nearly all medic cultivars and lines (Table 3). For the 12 medic species evaluated in both of these seasons, average flowering times were 9 d later at the first time of emergence and 6 d later at the second time of emergence in 1998.
View this table:
[in this window]
[in a new window]
|
Table 3. Days from emergence to flowering for annual medic cultivars and lines emerging following different planting dates over the 1997 and 1998 growing seasons, Archer, WY.
|
|
The response of medic cultivars and experimental lines to environmental conditions is indicated by their time to flowering following differing times of emergence. The days to flowering recorded over three seasons and at different times of emergence within these seasons were, in most instances, substantially less than values recorded for these species grown under south Australian conditions (Table 4). Apart from Manesty (M. aculeata) and SA10343 (M. rigidula), the earliest flowering times for medic species grown at Archer were about half of those recorded in Australia (Crawford et al., 1989). ‘Paraponto’ (M. rugosa Desr.), Sava [M. scutellata (L.) Mill.], and Harbinger (M. littoralis) flowered more than 20 d earlier than the shortest recorded period in Australia. For the remainder of the species, the longest periods to flowering recorded at Archer only slightly overlapped with the shortest recorded periods in Australia.
The total growth and development periods of the annual medic cultivars and experimental lines were generally prolonged in the 1998 growing season compared with the 1997 growing season (Table 5). In 1998, the number of days from emergence to harvest increased by a mean of 25 and 16 d from the first and second emergence times, respectively, compared with the 1997 season. In both seasons, later emergence times resulted in shorter growth and development periods for all cultivars and lines. The mean time to harvest decreased by 6 d from Time 1 to Time 2 and by a further 12 d from Time 2 to Time 3. Thus, the total available growth and development period had been reduced by 18 d by the third time of planting.
View this table:
[in this window]
[in a new window]
|
Table 5. Days from emergence to harvest for annual medic cultivars and lines emerging at different times over the 1997 and 1998 seasons, Archer, WY.
|
|
There were large variations in the mean plant counts for all medic species at the three times of emergence in 1997 and at both times of emergence in 1998 (Table 6). The mean plant density in 1998 was only 57 plants m-2 compared with a mean of 165 plants m-2 for the 1997 growing season. Within the 1997 growing season, the last time of emergence produced on average 20 and 50 plants m-2 more than the first and second times of emergence, respectively. Similarly, the second time of emergence in 1998 established almost 50 plants m-2 more than the first time of emergence.
View this table:
[in this window]
[in a new window]
|
Table 6. Plant establishment counts for annual medic cultivars and lines from different times of emergence in three seasons, 1996–1998, Archer, WY.
|
|
The establishment of individual medic cultivars and experimental lines following the various emergence times was highly variable in all three seasons, with very few consistent performances that were identifiable (Table 6). However, it was noticeable that ‘Sava’ generally established lower plant densities than all other medic cultivars despite a uniform seeding density. This was a surprising result considering the larger seed size and potentially increased seedling vigor of this species. Another poor performer was George, which in most instances, produced very low plant densities. Cultivars of M. truncatula Gaertn. generally established increased plant densities and appeared to be less affected by differing seasonal influences.
Production Levels
The high dry matter production of the Tifton burclover experimental line SA10343 indicates that this species is potentially well suited to production in the southeastern Wyoming climate (Table 7). SA10343 produced substantially more dry matter than all other cultivars and lines. The only instance when this cultivar did not produce the maximum recorded yield was at the third time of emergence in 1997. In all other instances, SA10343 produced significantly more dry matter than all other cultivars and lines evaluated. The average yield of this line was 7.1 t ha-1, which was almost double the next highest average yields of 4.0 and 3.8 t ha-1 for ‘Paraggio’ and SA3601, respectively. The majority of the remaining cultivars failed to produce average yields >2.0 t ha-1.
View this table:
[in this window]
[in a new window]
|
Table 7. Dry matter production for annual medic cultivars and lines emerging at different times in three seasons, 1996–1998, Archer, WY.
|
|
Increased dry matter yields of annual medic cultivars and experimental lines appeared to be more closely related to extended growth and development periods. Over all emergence times, the three highest-yielding cultivars and lines, SA10344, Paraggio, and SA3601, had mean periods of 120, 91, and 110 d, respectively, from emergence to harvest. There are, however, exceptions to this. For example, George produced a substantially lower mean yield of 2.5 t ha-1 despite averaging a growth and development period of 114 d. In this particular case, poor plant establishments may have reduced the yield potential. It is possible that individual cultivars and experimental lines will have different plant establishment and growing period requirements for achieving maximum yields.
The crude protein levels of the medic cultivars and experimental lines were apparently related to their growth and development periods as well as their time of emergence (Table 8). The higher average crude protein levels were recorded for the two experimental lines, SA10343 and SA3601, as well as for George and ‘Herald’. Apart from Herald, these cultivars and lines all had extended growth and development periods >100 d. There was also a substantial increase in crude protein levels across all cultivars and experimental lines for the third time of emergence. Similarly, relative feed values were also increased for two of the longer season medics, SA10343 and George, and also for all medic cultivars and lines at the third emergence time in this season. According to the USDA classification scheme (Linn and Martin, 1989), forage quality increased from good for Planting Time 1 and 2 to supreme for Planting Time 3. Mean viable seed production for most cultivars and experimental lines was sufficiently high to ensure the establishment of a seedbank for subsequent pasture regeneration. In particular, Herald and ‘Santiago’ (M. polymorpha L.) produced exceptionally high levels of >20000 seed m-2. This was more than double the amount of seed produced by most of the other cultivars evaluated (Table 9). The amount of seed produced by these two cultivars would ensure that they established an excellent seedbank for regeneration. Cultivar Herald recorded the maximum seed production for three of the five growth periods in which it was evaluated.
View this table:
[in this window]
[in a new window]
|
Table 8. Crude protein levels and relative feed values for annual medic cultivars and lines emerging at three different times over the 1997 growing season, Archer, WY.
|
|
View this table:
[in this window]
[in a new window]
|
Table 9. Viable seed production for medic cultivars and lines emerging at different times in three seasons, 1996–1998, Archer, WY.
|
|
|
DISCUSSION
|
|---|
The production of high levels of quality forage by some of the cultivars and experimental lines evaluated in this study indicates the potential for growing annual medic pastures in southeastern Wyoming. Although experimental lines and cultivars developed for southern Australia were evaluated, the overall performance of the annual medics was encouraging for the further development of this group of pasture species for this region. The highest average yields of medic dry matter from these experiments (Table 7) were far superior to those reported by other researchers (Koala, 1982; Zhu et al., 1996) for annual medic production in summer growing seasons in Montana and Minnesota. In particular, the markedly higher yield of the Tifton burclover experimental line SA10343 was more typical of yields recorded in higher precipitation climates in southern Australia (Puckridge and French, 1983). Over two seasons, with large differences in precipitation levels, this line consistently yielded >7.0 t ha-1 when given an adequate growth and development period. This at least indicates that SA10343 is able maintain a high level of production over a range of environmental conditions. Along with increased yields, the forage quality levels were also high. In particular, crude protein levels recorded for the Time 3 treatment were comparable to levels reported elsewhere in higher precipitation climates (Zhu et al., 1996; Denny et al., 1979). The assessments of forage quality (Table 8) suggest that the majority of the annual medic cultivars evaluated would be highly suited for livestock production (Linn and Martin, 1989).
The level of seed production by the majority of the annual medic cultivars and lines evaluated appeared to be adequate for establishment of a viable seedbank that would allow regeneration at the start of subsequent pasture phases. The exceptionally high seed production level of Herald and Santiago of approximately 1.0 t ha-1 virtually guarantees future establishment of productive medic pastures (Table 9). This level of seed should be sufficient to ensure pasture regeneration for a number of years given typical levels of hardseededness and dormancy release (Carter, 1981). The remaining cultivars, apart from Sava and Paraponto, produced more than 4000 seed m-2 (approximately 200 kg ha-1), which is the proposed minimum level for a viable annual medic seedbank (Carter, 1981). The reduced seed production by all cultivars from the later emergence times (Time 3 in 1997 and Time 2 in 1998) indicates that conditions at the end of the growing season were not favorable for seed production. As a consequence, management practices of planting time, cultivar selection, and grazing need to be planned to avoid this period for seed production.
The dry matter yield potentials of most cultivars were generally limited by the short summer growing season and later times of emergence in the southeastern Wyoming climate. Results from three growing seasons demonstrated that the growth and development periods of cultivars adapted to south Australian conditions in particular were substantially reduced in this climate compared with a typical Mediterranean climate (Crawford et al., 1989) (Table 4). Although there was some flexibility in the Australian annual medic cultivars evaluated, the overall effect of this climate was a shorter growth and development period and a reduced yield potential. Similarly, the yields of all cultivars were lower when the amount of available growing season was reduced following the third time of emergence.
The high dry matter levels produced by some cultivars and lines were achieved despite low plant establishment numbers recorded throughout this study. This indicates that plant densities <200 plants m-2 may be sufficient for forage production in southeastern Wyoming. It was only at the third time of emergence in 1997 that several medic cultivars and lines uniformly achieved the desired density of 200 plants m-2. This seedling density is widely accepted in southern Australia as being the level required for a productive pasture with a maximum potential for forage yield and weed competition (Carter, 1981). However, in this study, consistently high dry matter production was recorded from seedling densities considerably lower than 200 plants m-2.
Given the overall value of elevated levels of forage production in defining the performance of an annual medic pasture phase, these studies have identified the experimental line SA10343, and therefore, M. rigidula in general, as having the greatest potential for development and use in southeastern Wyoming. The extended growth and development periods displayed by SA10343 significantly increased its potential for forage production above that of the other cultivars and lines. There were also indications that SA10343 had some degree of winter hardiness and may potentially be grown over the late fall through spring period. This growth period would allow an annual medic pasture phase to commence immediately following a wheat crop and be completed in time for a short fallow period before a subsequent wheat crop. This flexibility further emphasizes the suitability of this species for further development in southeastern Wyoming.
|
REFERENCES
|
|---|
- Aitken, Y. 1955. Flower initiation in pasture legumes: III. Flower initiation in Medicago tribuloides Desr. and other annual medics. Aust. J. Agric. Res. 6:258–264.
- AOAC. 1980. Official methods of analysis. 12th ed. AOAC, Washington, DC.
- Carter, E.D. 1981. Seed and seedling dynamics of annual medic pastures in South Australia. p. 447–450. In A. Smith and V. Hays (ed.) Proc. Int. Grassl. Congr., 14th, Lexington, KY. 15–24 June 1981. Westview Press, Boulder, CO.
- Casler, M.D. 1990. Cultivar and cultivar x environment effects on relative feed value of temperate grasses. Crop Sci. 30:722–728.[Abstract/Free Full Text]
- Clarkson, N.M., and J.S. Russell. 1975. Flowering responses to vernalization and photoperiod in annual medics (Medicago spp.). Aust. J. Agric. Res. 26:831–838.
- Clarkson, N.M., and J.S. Russell. 1976. Effect of water stress on the phasic development of annual Medicago species. Aust. J. Agric. Res. 27:227–234.
- Crawford, E.J., A.W.H. Lake, and K.G. Boyce. 1989. Breeding annual Medicago species for semiarid conditions in southern Australia. Adv. Agron. 42:399–437.
- Dalrymple, A.W., S.D. Miller, and K.J. Fornstrom. 1993. Soil water conservation and winter wheat yield in three fallow systems. J. Soil Water Conserv. 48:53–57.
- Denny, G.D., J.P. Hogan, and J.R. Lindsay. 1979. The digestion of barrel medic (Medicago truncatula) hay and seed pods by sheep. Aust. J. Agric. Res. 30:1177–1184.
- Goering, H.K., and P.J. Van Soest. 1970. Forage fiber analysis: Apparatus, regents, procedures, and some applications. USDA Agric. Handb. 379. U.S. Gov. Print. Office, Washington, DC.
- Koala, S. 1982. Adaptation of Australian ley-farming to Montana dryland cereal production. M.S. thesis. Montana State Univ., Bozeman.
- Linn, J.G., and N.P. Martin. 1989. Forage quality tests and interpretation. AG-FO-2637. Minnesota Ext. Serv., Minneapolis.
- Pearson, E.S., and H.O. Hartley. 1966. Biometrika tables for statistics. Vol. 1. Cambridge Univ. Press, Cambridge.
- Puckridge, D.W., and R.J. French. 1983. The annual legume pasture in cereal–Ley-farming systems of southern Australia: A review. Agric. Ecosyst. Environ. 9:229–267.
- SAS Institute. 1992. Proprietary software release 6.09 TS044. SAS Inst., Cary, NC.
- Van Heerden, J.M. 1984. Influence of temperature and daylength on the phenological development of annual Medicago species with particular reference to M. truncatula, cv. Jemalong. S. Afr. J. Plant Soil 1:73–78.
- Wyoming Agricultural Statistics Service. 1998. Wyoming agricultural statistics annual bulletin. Wyoming Agric. Stat. Serv., Cheyenne, and College of Agric., Univ. of Wyoming, Laramie.
- Zhu, Y., C.C. Sheaffer, and D.K. Barnes. 1996. Forage yield and quality of six annual Medicago species in the north-central USA. Agron. J. 88:955–960.[Abstract/Free Full Text]
This article has been cited by other articles:
|
|
|
|
 
J. R. Bow, J. P. Muir, D. C. Weindorf, R. E. Rosiere, and T. J. Butler
Integration of Cool-Season Annual Legumes and Dairy Manure Compost with Switchgrass
Crop Sci.,
July 1, 2008;
48(4):
1621 - 1628.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
J.M. Krall, R.W. Groose, M.J. Walsh, V. Nayighugu, J. Cecil, and B. Hess
Registration of 'Laramie' Annual Medic
Journal of Plant Registrations,
May 1, 2007;
1(1):
32 - 33.
[Full Text]
[PDF]
|
|
|
|
|
|
|
B. TIVOLI, A. BARANGER, K. SIVASITHAMPARAM, and M. J. BARBETTI
Annual Medicago: From a Model Crop Challenged by a Spectrum of Necrotrophic Pathogens to a Model Plant to Explore the Nature of Disease Resistance
Ann. Bot.,
December 1, 2006;
98(6):
1117 - 1128.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
C. M. Cherr, J. M. S. Scholberg, and R. McSorley
Green Manure Approaches to Crop Production: A Synthesis
Agron. J.,
February 7, 2006;
98(2):
302 - 319.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
M. K. Sledge, P. Pechter, and M. E. Payton
Aluminum Tolerance in Medicago truncatula Germplasm
Crop Sci.,
August 26, 2005;
45(5):
2001 - 2004.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
P. M. Carr, W. W. Poland, and L. J. Tisor
Natural Reseeding by Forage Legumes following Wheat in Western North Dakota
Agron. J.,
July 13, 2005;
97(4):
1270 - 1277.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
P. M. Carr, W. W. Poland, and L. J. Tisor
Forage Legume Regeneration from the Soil Seed Bank in Western North Dakota
Agron. J.,
March 1, 2005;
97(2):
505 - 513.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
J. P. Muir, W. R. Ocumpaugh, and T. J. Butler
Trade-Offs in Forage and Seed Parameters of Annual Medicago and Trifolium Species in North-Central Texas as Affected by Harvest Intensity
Agron. J.,
January 1, 2005;
97(1):
118 - 124.
[Abstract]
[Full Text]
[PDF]
|
|
|
TOP
ABSTRACT
INTRODUCTION
