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a Agric. and Nat. Resour. Dep., Delaware State Univ., 1200 N. Dupont Hwy., Dover, DE 19901
b Crop and Soil Sci. Dep., The Pennsylvania State Univ., University Park, PA 16802
c USDA-ARS Pasture Syst. and Watershed Manage. Res. Unit, Bldg. 3702 Curtin Rd., University Park, PA 16802-3702
* Corresponding author (mlabreveux{at}desu.edu).
Received for publication May 13, 2003.
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ABSTRACT |
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 TOPNOTES ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONCONCLUSIONSREFERENCES |
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Abbreviations: DM, dry matter • Sev, severe (treatment) • Sev/Mod, severe–moderate (treatment)
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INTRODUCTION |
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TOPNOTESABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONCONCLUSIONSREFERENCES |
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Chicory was first reported as having excellent forage value under rotational grazing in the late 1970s (Lancashire, 1978). The cultivar Grasslands Puna was released in 1985 and has been frequently used in the USA where good summer productivity has been reported (Jung et al., 1996; Volesky, 1996). Chemical analyses indicate that Puna chicory is a high quality feed, and animal performance tests suggest that high liveweight gains and voluntary feed intake are obtainable in deer (Cervus elaphus), sheep (Ovis aries), and cattle (Bos taurus) (Rumball, 1986; Kusmartono et al., 1996; Barry, 1998).
Plantain (a.k.a. English plantain, narrow-leaf plantain, buckhorn plantain, ribwort, and ribgrass) has a broad distribution in grasslands throughout the temperate world (Fraser and Rowarth, 1996), and naturally occurring populations of plantain appear to have considerable tolerance to drought and summer heat (Sagar and Harper, 1964). Animal performance tests performed in New Zealand suggest liveweight gain of lambs grazing plantain to be about 100 g animal–1 d–1 and 1 kg ha–1 d–1 greater than that of lambs grazing ryegrass (Lolium perenne) pastures (Moorhead et al., 2002). Plantain establishes rapidly, grows on a wide range of agricultural soils, and during dry years, the species may attain DM yields similar to orchardgrass (Stewart, 1996). Two forage cultivars are available commercially, Grasslands Lancelot and Ceres Tonic. Grasslands Lancelot was selected for its bushy growth habit and the ability to tiller strongly under close grazing by sheep (Rumball et al., 1997). Ceres Tonic was selected for erect growth habit and large leaves (Stewart, 1996).
Forage chicory has greater potential yields than plantain under clipping (Sanderson et al., 2003), but the latter grows on a wider range of agricultural soils than chicory. Consequently, the utilization of these two species for pasture purposes could improve forage availability during the summer over a wide range of soil conditions. While some reports on the productivity and quality of chicory under nongrazing situations have been generated in the northeastern USA (Belesky et al., 2001, 2000; Holden et al., 2000; Jung et al., 1996), most available information on grazed chicory pastures comes from climatic conditions different than those observed in this region (Collins and McCoy, 1997; Li et al., 1997a, 1997b; Stewart, 1996; Belesky et al., 1996; Ruiz-Jerez et al., 1991). Information on plantain and its adaptability to the conditions of the northeastern USA is scarce (Sanderson and Elwinger, 2000; Sanderson et al., 2003).
The use of forage chicory and plantain to improve annual and summer availability of forage is considered in this paper. Our objectives were to evaluate and compare with orchardgrass seasonal productivity of different cultivars of chicory and plantain under grazing, and, if appropriate, to suggest grazing guidelines for the region.
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MATERIALS AND METHODS |
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TOPNOTESABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONCONCLUSIONSREFERENCES |
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Experiment 1
Chicory cultivars Forage Feast, Grasslands Puna, and INIA LE Lacerta; plantain cultivars Grasslands Lancelot and Ceres Tonic; and Pennlate orchardgrass were seeded in pure stands in May 1997. A Hege 1000 series (Hege Maschinen, Waldenburg, Germany1) plot drill planter adjusted to seeding rates of 4.5 kg ha–1 for chicory and 11 kg ha–1 for plantain and orchardgrass was used for planting. Seeding depth was 
1 cm. Soil tests to a 150-mm depth in March 1998 indicated a pH of 6.3 and 93, 489, and 256 kg ha–1 P, K, and Mg, respectively. No fertilizer was added at planting. Nitrogen, in the form of urea, was applied on 10 April and 15 June 1998 at a rate of 50 kg ha–1. A total of 60 and 120 kg ha–1 P and K, respectively, was applied in April. Mowing controlled weeds during the year of establishment.
A randomized complete block (four replicates) design with a split-plot arrangement of treatments was used with cultivars randomly assigned to subplots within the grazing treatment main plots. Subplot size (cultivars within grazing treatment) was 12 by 14 m, resulting in a main plot size of 72 by 14 m and a block size of 72 by 56 m. The grazing treatment consisted of combinations of frequency (3- and 5-wk rest period) and intensity (50- and 150-mm stubble residue) of grazing. Guidelines for the treatments were derived from results obtained for forage chicory by Li et al. (1997a) in New Zealand and Volesky (1996) in Oklahoma where rest periods of 4 and 5 wk were more productive than those 1 or 2 wk long. Paddocks were grazed frequently and severely (3 wk and 50 mm), frequently and lightly (3 wk and 150 mm), infrequently and severely (5 wk and 50 mm), or infrequently and lightly (5 wk and 150 mm). All cultivars (subplots) within a grazing treatment (main plot) and block were grazed at the same time. The number of animals per paddock at each grazing event (12 to 14 cow-calf pairs) was adjusted to minimize the grazing period and avoid pasture damage. The approach resulted in periods no longer than 36 h. Grazing began on 5 May and ended 9 Sept. 1998. Herbage mass was collected before grazing from four 0.1-m2 quadrats cut to ground level with electric shears. All material was oven-dried at 55°C for 48 h and weighed. Plant and tillers were counted on 1 Oct. 1997, 1 Apr. and 12 Oct. 1998, and 4 May 1999. Plants of chicory and plantain were counted once per subplot in a 0.6- by 0.6-m quadrat area, whereas orchardgrass tillers were counted inside a 0.1-m2 quadrat on three randomly assigned areas within the subplot.
Data were analyzed using the MIXED procedure of SAS Institute (1998). Results for DM yield were separated into spring (from May to July) and summer (July through September) seasons and compared within each season. Preplanned orthogonal contrasts were used for mean separation (Steel et al., 1997). Cultivars were evaluated using Pennlate orchardgrass as the control. Planned cultivar comparisons were Forage Feast chicory vs. Pennlate orchardgrass, Lacerta chicory vs. Pennlate orchardgrass, Puna chicory vs. Pennlate orchardgrass, Ceres Tonic plantain vs. Pennlate orchardgrass, and Lancelot plantain vs. Pennlate orchardgrass. Grazing treatment by cultivar means were compared for the effect of grazing treatment within each cultivar (e.g., yields of infrequently and severely grazed Puna chicory vs. infrequently and lightly grazed Puna chicory). The overall grazing treatment effect was also compared.
Experiment 2
In 1999, due to the loss of a great number of plants in all plots (see Stand Density section), a new experiment was planted. The most productive cultivar of chicory (Grasslands Puna) and most persistent plantain (Grasslands Lancelot) were sown. The number of grazing treatments was reduced following the results obtained in Exp. 1 while paddock size was increased, requiring a different layout and experimental design.
Based on results from Exp. 1, Puna chicory, Lancelot plantain, and Pennlate orchardgrass were seeded in August 1999 at the same location and on similar soils. Preplanting soil tests indicated a pH of 6.5 and 89, 325, and 205 kg ha–1 P, K, and Mg, respectively. The soil was tilled during the spring of 1999, but seeding was delayed because of dry conditions. Before seeding, weeds were controlled with 1.1 kg a.i. ha–1 of glyphosate [N-(phosphono-methyl) glycine]. A no-till drill was used at seeding rates similar to Exp. 1. Mowing controlled weeds during the year of establishment. Nitrogen fertilizer in the form of urea was applied each year in May and August at a rate of 40 kg N ha–1. The experimental site was approximately 2.2 ha. A split-block design (four replicates) with species and grazing treatments as factors was applied. Each experimental unit was approximately 0.09 ha.
Grazing treatment guidelines followed the results obtained for Exp. 1, in particular the effect of grazing intensity during summer. Visual assessments of canopy structure taken during 1998 were also considered when establishing target intensity of grazing. Grazing treatments consisted of leaving two postgrazing stubble heights during summer but only one intensity of grazing (50 mm) during the spring to prevent development of reproductive structures. The severe (Sev) treatment plots were grazed to an average canopy height of 50 mm during the entire season of growth while the severe–moderate (Sev/Mod) plots were grazed to a 50-mm stubble height in the spring and 100 mm in the summer. Canopy height was monitored biweekly, and time to grazing was determined according to these results. Height monitoring was done with a meter stick, and height was defined as that of the first vegetative leaf (standing and not trampled in the case of postgrazing measurements) touching the measuring device. Twenty-five readings were made on each plot.
Grazing began when canopy height reached 250 mm on orchardgrass and chicory plots and 200 mm on plantain plots. The number of animals per paddock at each grazing event was adjusted to limit the grazing period to no longer than 36 h to minimize pasture damage. In 2000, profuse rainfall during May delayed the date to first grazing; consequently, many reproductive structures remained after grazing, and plots had to be mowed to a height of 100 mm. For consistency purposes, this procedure was repeated in 2001. In general, between 7 and 10 beef cow-calf pairs were used to graze the plots to a 100- and 50-mm stubble, respectively. Total time for grazing the entire experiment (rotation time) was approximately 10 d. Plant counts were made in May, August, and October. Herbage samples were taken before grazing. At each sampling date, two 1.6-m2 areas were cut to ground level; 0.53 m2 was kept for separation into components, oven-dried at 55°C for 48 h, and weighed. The rest of the sample was immediately weighed, and a 300-g sample was drawn, oven-dried, and reweighed for DM estimation.
Data were analyzed using the mixed-model procedure of SAS Institute (1998) with repeated-measures analysis over years. A compound symmetry (CS) covariance structure was selected as the one that best fit the experimental data. Replicates (blocks) and interactions with replicates were considered to be random effects while years were considered as fixed effects. Guidelines for analysis of data were based on Steel et al. (1997) and Littel et al. (1996)(1998). Results for DM yield were separated into spring (first two grazing cycles that ran between May and mid-July) and summer (remaining grazing cycles that ran from mid-July through September) seasons and compared within each season. Treatment means of yields were separated using planned orthogonal contrasts (Steel et al., 1997). Cultivar comparisons were made using Pennlate orchardgrass as the control. Planned contrasts for cultivar comparisons were Puna chicory vs. Pennlate orchardgrass and Lancelot plantain vs. Pennlate orchardgrass. Grazing effect was tested over the summer, applying the contrasts Sev vs. Sev/Mod treatments. Planned contrast for year comparison was 2000 vs. 2001.
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RESULTS AND DISCUSSION |
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Results of this 1-yr experiment showed that, during the spring, chicory and plantain cultivars could be grazed at either 3- or 5-wk grazing frequencies (Table 3) without negatively affecting yields. During the summer, a longer rest period was required to achieve maximum yields. However, in either season of study, minimum yields were obtained when cultivars were grazed to a 50-mm stubble height every 3 wk. Energy for regrowth, if sufficient regrowth buds are present, is either provided by photosynthetically active tissue or it is derived from reserves (Briske, 1996). In grasses, regrowth arising from reserves has a slower initial DM accumulation rate, and consequently, a longer resting period is required to achieve maximum accumulation (Davies, 1988). When grazing some types of orchardgrass such as Pennlate, leaving a 100-mm stubble height to prevent depletion of reserves and productivity losses such as those observed in 1998 has been suggested (Carlassare and Karsten, 2002). In this study, severely grazed plants may have been forced to remobilize reserves for regrowth, and a 3-wk rotation may not have sufficed to achieve maximum DM accumulation. There is little or no information regarding the regrowth rates and reserve allocation and remobilization requirements for either chicory (Li et al., 1998) or plantain cultivars, and these topics may be an aspect for future study.
Published reports (Volesky, 1996; Li et al., 1997a; Belesky et al., 1999; Sanderson et al., 2003) suggest the use of a 5-wk cutting or grazing interval to attain maximum yields of Puna chicory or other chicory and plantain cultivars. Results after this first year of study support the possibility of reducing the rest period during the spring to 3 wk. A reduction in the rest period during the spring limits partitioning of DM into reproductive structures. In the case of chicory, a taller stubble can lead to a nondesirable canopy structure, with regrowth occurring from buds left on the flower stalk instead of those coming from the crown (Li et al., 1998). During the summer, the suggested 5-wk rest period could be restored to ensure maximum DM yields.
Dry Matter Yields in 2000 and 2001—Experiment 2
The average DM yield of Puna chicory during the spring of 2000 and 2001 was 61 and 57% greater than that of Pennlate orchardgrass during the same seasons (Table 4). Lancelot plantain had a 50% greater DM yield than Pennlate orchardgrass in spring 2000 (P < 0.05), and a year later, the spring DM productivity of these cultivars did not differ.
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Drier weather conditions during 2001 (Table 1) had an effect on the length of the regrowth period (Table 5). On average, it took Puna chicory and Pennlate orchardgrass 27.5 and 37.5 d to regrow in 2000 and 2001, respectively. Puna chicory showed stunted growth from 28 June until 20 August, the second and third grazing dates, respectively. Fifty-three days elapsed between these two grazing events, 21 d longer than the regrowth period registered for Pennlate orchardgrass. However, Pennlate orchardgrass showed signs of stress, possibly due to dry weather between the third and forth grazing cycle when its regrowth period was extended to 48 d.
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Although the differential potential ability of Pennlate orchardgrass and Puna chicory to improve summer productivity was not expected to arise from the length of grazing season, it cannot be overlooked. Faster growth at lower temperatures should be a characteristic to consider when breeding chicory cultivars for the northeastern USA.
Summer DM yield of Lancelot plantain was similar to that of Pennlate orchardgrass in 2000 (Table 4) but more than three times lower in the summer of 2001 (P < 0.05). This disparity in productivity between years, however, is primarily attributed to plant density losses observed on Lancelot plantain plots. Low persistence and productivity losses of Lancelot plantain under various growing conditions have been reported by Sanderson et al. (2003), Labreveux (2002), and Skinner and Gustine (2002).
Some aspects of the grazing strategies applied during this experiment should be considered in the overall analysis of productivity. As opposed to the conventional fixed-term grazing schedule utilized in Exp. 1, the height-based grazing strategy applied in Exp. 2 allowed to control the stress imposed to plants over the summer and potentially reduce plant stand losses. However, it may be beneficial to adopt differential target heights depending on the environment, the seasons, or the weather conditions. In a separate study, when Puna chicory was grown under simulated drought stress and clipped every 3 and 5 wk, water shortage did not affect the amount of DM produced (Labreveux, 2002). A reduction in leaf area expansion was observed during that study, which was most likely related to the shortage of water and its role in cell elongation (Van Volkenburgh, 1994). Based on these results, it could also be assumed that the height of expanded leaves in a canopy would be affected by drier weather conditions as well.
Stand Density
Plant density during 1998 of Exp. 1 declined regardless of the grazing treatment applied (Fig. 1)
. Puna and Forage Feast chicory and Lancelot plantain losses ranged between 25 and 45% of their initial stand. The highest losses were observed in Lacerta chicory, with an 80% density reduction, while Ceres Tonic plantain lost only 20%. Nevertheless, plant counts taken after the winter of 1999 showed that Ceres Tonic plantain had the lowest plant density. While winter may have killed 50% of Lancelot plantain stand, Ceres Tonic plantain lost 95% of the plants, making it a less suitable plantain cultivar for use in perennial pastures in northeastern USA. When developing Ceres Tonic plantain, breeders used genotypes from the Mediterranean region of Portugal (Stewart, 1996). Mediterranean ecotypes, when grown in temperate regions, can have greater autumn yields but low persistence, presumably related to lower winter dormancy. For example, continental ecotypes of tall fescue (Festuca arundinacea Schreb.) have been reported to be more winter hardy than their Mediterranean relatives (Robson, 1967).
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During 2000 and 2001 of Exp. 2, the strategy was changed to grazing only when the plots reached a defined canopy height, as proposed by Bircham and Hodgson (1983). The number of Puna chicory plants lost was much lower than during Exp. 1 (Fig. 2) . For this entry, losses during 2000 did not exceed 8% and were not affected by the intensity of grazing during the summer. Lancelot plantain plots, however, did not perform as well. Plant density of Lancelot plantain was reduced between 50 and 60% during 2000. Similar losses were found in a clipping study (Sanderson et al., 2003), reinforcing the observations in this study and suggesting that Lancelot plantain has less-than-desirable survivability rates in the northeastern USA.
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Plant density of Puna chicory at the beginning of the first-year grazing season in Exp. 1 (April 1998) and Exp. 2 (May 2000) was approximately 100 plants m–2. After a year, plant density in Exp. 1 dropped to 50 plants m–2, whereas in Exp. 2, the average density remained the same (100 plants m–2). This difference suggests that grazing strategy influences the survival rate of Puna chicory in a 2-yr-old pasture.
Losses at the end of the second grazing season in Exp. 2 were 35%, leaving an average density of 69 plants m–2, well above the minimum requirement of 25 plants m–2 proposed by Li et al. (1997b) to maintain productivity. Estimates made by Stevens et al. (2000) suggest that the addition of chicory to a pasture improvement program could double the profitability over a 5-yr period of sheep production in New Zealand when compared with an improved pasture program without this species. However, the estimates assumed a constant DM contribution by chicory over the 5-yr period, which may not be feasible in the northeastern USA unless persistence of the species under the region's weather conditions is improved.
In Exp. 1, tiller density of Pennlate orchardgrass from April 1998 to April 1999 was, on average, 50% lower (Fig. 1). In Exp. 2, tiller density fluctuations throughout the 2-yr study appear to follow an expected seasonal pattern (Fig. 2). Changes in tiller density of Pennlate orchardgrass and plant density of Puna chicory together with visual observations of weed invasion (data not shown) were taken as a measure of stress imposed by each grazing strategy. The comparison of experiments suggests that a canopy-height–based strategy, as opposed to a fixed rotation schedule, allows for better control of the stress imposed and, consequently, improves the persistence of these species.
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CONCLUSIONS |
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TOPNOTESABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONCONCLUSIONSREFERENCES |
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ACKNOWLEDGMENTS |
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NOTES |
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TOPNOTESABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONCONCLUSIONSREFERENCES |
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1 Mention of a trademark does not imply endorsement. 
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TOPNOTESABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONCONCLUSIONSREFERENCES |
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 M. Labreveux, M. A. Sanderson, and M. H. Hall Forage Chicory and Plantain: Nutritive Value of Herbage at Variable Grazing Frequencies and Intensities Agron. J., February 7, 2006; 98(2): 231 - 237. [Abstract] [Full Text] [PDF]
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d) of grazing season after the first grazing of Puna chicory, Lancelot plantain, and Pennlate orchardgrass during 2000 and 2001.
