Ball Clover Research Articles

Quantifying soil health in a topographically diverse warm-season perennial pasture over-seeded with a mix of cool-season annuals

Over-seeding cool-season annual forages in pastures in the southeastern US provides increased grazing opportunities for livestock and reduces the amount of hay needed during winter. The constant presence of vegetation can benefit soil health, the biological aspect of which has only received cursory investigation to date. Since 2009, a commercial cattle grazing operation located in south Mississippi has been over-seeding a diverse mixture of oats (Avena sativa L.), triticale (X Triticosecale Wittmack), annual ryegrass (Lolium multiflorum Lam.), hairy vetch (Vicia villosa Roth), radish (Raphanus sativus L.), turnips (Brassica rapa L. subsp. rapa), red clover (Trifolium pratense L.), ball clover (Trifolium nigrescens Viv.), and crimson clover (Trifolium incarnatum L.) into pastures dominated by bahiagrass (Paspalum notatum Flüggé). Soil health properties were assessed across a heterogeneous landscape from soils collected immediately prior to seeding and following increased spring productivity of cool-season annuals from 2015 to 2017. Samples were collected across a topographic sequence to a depth of 15 and 30 cm. Three samples per site were collected from summit, backslope, and footslope locations. Soil chemical assessments included macronutrients, pH, soil organic matter (SOM), total carbon (TC), and total nitrogen (TN). Fatty acid methyl ester analysis and enzyme assays were used to determine soil microbial community structure and activity. While TC and TN did not change with time (20.5 and 2.4 g kg−1, respectively), SOM increased by 6% from 2015 to 2017. Nitrate-N decreased by 82% from 2015 to 2017. N-acetyl-β-glucosaminidase activity increased by 32%, while β-glucosidase remained constant. Total microbial abundance did not change with time; however, Gram positive bacteria and actinomycetes decreased by 51% and 43%, respectively, from fall to spring. Arbuscular mycorrhizal fungi increased from fall to spring by an average of 45%. This pasture management technique of over-seeding a diverse mix of winter annuals may have resulted in a steady state of TC and TN, while SOM increased and inorganic nitrogen decreased with time, and enhanced the total soil microbial community particularly fungi and their potential enzyme activity. Despite some biological indications of system stability, soil properties potentially limiting to plant growth were identified for some sites, but these limitations were not closely related to topographic position as expected.

Development of Plant-Parasitic Nematode Populations on Forage Crops under Field Conditions

The continuous increase in cost and scarcity of mineral fertilizers resultingfrom the use of high-cost energy sources has renewed interests in organic recyclingand biological nitrogen-fixation to improve soil fertility and productivity. Foragelegumes can fix nitrogen from atmosphere which has the merit to offer nitrogen forboth crop production and soil fertility. However, plant-parasitic nematodes (PPNs)interactions with leguminous crops can be agronomically damaging under variousconditions. The present study examined population development of each of thePPN genera Meloidogyne spp., Paratrichodorus spp., Criconemella spp.,Pratylenchus spp., Tylenchorhynchus, and Tylenchus spp. on fourteen legumecultivars (i.e. 'Florida' red clover, 'Nolin' red clover, 'Kenland' red clover, 'Kenstar'red clover, 'Tibbee' crimson clover, 'Dixie' crimson clover, 'Mt. Barker' Subterraneanclover, 'Amclo' arrowleaf clover, 'FL - 77' alfalfa, 'Abon' persian clover, 'Wood ford'big flower vetch, 'Seqrest' ball clover, 'Kondinin' rose clover, and 'Chief' crimsonclover). The nematode initial and final populations varied considerably among thelegume cultivars. Therefore, we adjusted for the rate of nematode multiplication byusing analysis of covariance. However, we could not use one of the statisticalmultiple comparison methods because each treatment had different mean ofsquares for the experimental error. Consequently, a matrix was designed to test thesignificance of nematode populations on the cultivars using the t-test. Using acomputer program, the exact (numerical) level of statistical significance fornematode densities among the cultivars could be established. Relatively lowerpopulations of the nematode genera were found on 'FL-77' alfalfa plants.

Tolerance of Three Clovers (Trifoliumspp.) to Common Herbicides

Clover inclusion may increase the sustainability of certain low-maintenance turfgrasses. However, selective weed control within mixed turfgrass–clover swards proves problematic because of clover susceptibility to herbicides. Research was conducted to identify common turf herbicides that are tolerated by threeTrifoliumspecies, including white clover, ball clover, and small hop clover, within low-maintenance turfgrass. Leaf and flower density, as well as plant height, were measured 4 wk after treatment as indicators of clover response to 14 herbicides. The threeTrifoliumspp. were moderately tolerant of bentazon (< 35% decrease in leaf density, height, or flowering). Simazine was well tolerated by white clover (< 5% decrease in all response variables), yet moderate injury to ball clover and small hop clover was observed (> 32% decrease in leaf density and > 27% decrease in flower density). Pronamide was well tolerated by white and ball clovers, with no effect on measured response variables; however, pronamide decreased small hop clover height and flower density (38 and 42%, respectively). Imazethapyr and imazamox were moderately well tolerated by white clover and small hop clover (< 39% decrease by all response variables), yet ball clover may be more susceptible to these herbicides than was anticipated based on previously reported tolerance. The herbicides 2,4-DB, halosulfuron, and metribuzin were well tolerated by white clover, with no effect on measured response variables; however, results suggest ball and small hop clovers were less tolerant. Clopyralid, 2,4-D, glyphosate, imazaquin, metsulfuron-methyl, and nicosulfuron resulted in varying degrees of injury across clover species and response variables, but, in general, these herbicides may not be viable options when attempting to maintain any of the three clover species tested. Further research is needed to quantify long-term effects of herbicide application on sward composition and clover succession.

Introgression of reproductive traits from Trifolium nigrescens increases the seed yield of white clover (T. repens)

AbstractInterspecific hybrids between white clover and the annual, profuse flowering ball clover have been developed as a strategy to improve the potential seed yield of white clover. The seed yield and seed yield components of advanced white clover × ball clover hybrids were compared with white clover in replicated field experiments over two harvest years. The backcross 3 hybrid had more reproductive nodes per stolon than the control variety ‘AberHerald’ which was reflected in more inflorescences per unit area but inflorescences with fewer florets and seeds. The hybrid had a greater potential seed yield than the control variety in 2002 but not 2001. Backcross 3 hybrids have also been produced across the range of leaf size categories. Medium and large leaved hybrids produced significantly more inflorescences and a higher potential seed yield than control varieties of comparable leaf size in both harvest years. The small leaved hybrid was not significantly greater than the control variety ‘AberDale’ in either inflorescence production or seed yield.

Forage yield and persistency of Trifolium repens × Trifolium nigrescens hybrids under rotational sheep grazing

AbstractIntrogression of reproductive traits from the annual, profuse flowering, ball clover (Trifolium nigrescens Viv.) into white clover (Trifolium repens L.) is one breeding strategy to improve seed yields of T. repens that must be achieved without sacrificing agronomic performance and persistency under grazing. The yield and persistency of hybrids between white clover and T. nigrescens were compared under rotational sheep grazing over three harvest years. The hybrids included the backcross (BC) 2 and 3 generations produced using white clover as the recurrent parent. The large‐leaved T. repens variety Olwen, medium‐leaved varieties AberDai and Menna and the small‐leaved variety S184 were sown as controls. Hybrids and control varieties were sown with a perennial ryegrass companion; between April and the end of October in each harvest year the plots were rotationally grazed with sheep with clover and perennial ryegrass (DM) yield and the proportion of clover present measured over the growing season. The clover and total DM yields of the BC2 and BC3 were generally comparable with the small‐ and medium‐leaved varieties within the experiment and significantly greater than the yields of the large‐leaved variety Olwen. Throughout the 3 years of the experiment the BC2 maintained a clover content above 0·30 and comparable with the small‐leaved varieties, while the clover content of the BC3 was comparable with the small‐ and medium‐leaved varieties in the first and third harvest years. No significant difference in perennial ryegrass production was observed when grown with the backcrosses or the control varieties. Differences in stolon and growing‐point density were observed at the end of the experiment with the density of the BC2 and BC3 less than the small‐leaved variety S184 but, in common with the medium‐leaved varieties, greater than the large‐leaved variety Olwen. The implication of these results for the use of this material in future experiments and in the white clover breeding programme is discussed.

Forage quality of Trifolium repens L. × T. nigrescens Viv. hybrids

AbstractInterspecific hybridization with the close relative Trifolium nigrescens Viv. (Ball clover) is a possible strategy to increase the seed yield potential of white clover (T. repens L.). Fertile F1 plants have been used as the basis for several generations of backcrossing using T. repens as the recurrent parent. Forage quality of the parental species and backcross hybrids when grown in mixtures with perennial ryegrass (Lolium perenne L.) was compared in field plots over three harvest years. The dry‐matter digestibility (DMD) and crude protein (CP) concentration of the legume fraction was greater than that of perennial ryegrass, but the water‐soluble carbohydrate (WSC) concentration of the legume components was lower than that of perennial ryegrass. Differences in forage quality between T. repens and the backcross hybrids were relatively small. The WSC concentration of the backcrosses was less than T. repens but the CP concentration was greater. Significant differences in the forage quality of the companion grass were observed when grown with the parental species and the hybrids; however, these differences were attributed to the plots with T. nigrescens and the F1 plants, where the clover content was low. Few differences in the forage quality of the grass were measured when grown with T. repens and the backcross hybrids. The impact of these results on the use of these hybrids in cultivar development programmes is discussed.

Forage yield and persistency of Trifolium repens × Trifolium nigrescens hybrids when sown with a perennial ryegrass companion

Abstract Introgression of reproductive traits from ball clover (Trifolium nigrescens Viv.) into white clover (Trifolium repens L.) is one breeding strategy to improve seed yields of T. repens that must be achieved without sacrificing agronomic performance and persistency. The yield and persistency of hybrids between white clover and the annual, profuse flowering species T. nigrescens were compared under a cutting regime over three harvest years. The hybrids included the F1 and the backcross (BC) 1, 2 and 3 generations produced using T. repens as the recurrent parent. Parental species and hybrids were sown with a perennial ryegrass companion; clover and perennial ryegrass dry‐matter (DM) yield and the proportion of clover present were measured over the growing season. In the third harvest year, a portion of each plot was grazed. Differences were observed between T. nigrescens, the F1 and the backcross hybrids and T. repens. In the first and second harvest years, clover DM yield, the proportion of clover present and total DM yield of the backcross hybrids were similar to T. repens, whereas that of the T. nigrescens and the F1 hybrid were negligible. No significant difference in perennial ryegrass production was observed between the parental species and the hybrids when grown, respectively, in combination with these species and hybrids. In the third harvest year, clover DM yield and the proportion of clover present with the BC3 was lower than with T. repens. Throughout the growing season the DM production of T. repens and the backcross hybrids was similar. In the third harvest year, under cutting, DM yield of T. repens was greatest and that of the BC3 lowest, but under grazing, the yields of the BC1 and BC3 were greater than T. repens and the BC2. The implication of these results for the future development of these hybrids is discussed.

Uptake of Selected Nutrients by Temperate Grasses and Legumes

Temperate forages are used throughout the southeastern USA to provide feed for livestock when tropical and subtropical grasses are dormant and as a hay source. Long‐term utilization of broiler litter as a fertilizer in some areas of the region has elevated soil levels of P and micronutrients. Our objective was to compare P, Cu, and Zn uptake among temperate forage species from a Savannah fine sandy loam soil (fine‐loamy, siliceous, semiactive, thermic Typic Fragiudult) amended with litter under a single‐harvest system. Dry weight of ryegrass (Lolium multiflorum Lam.) herbage was greater than all other species except ball clover (Trifolium nigrescens Viv.) in 1997 and oat (Avena sativa L.) in 1998. Clovers were susceptible to Sclerotinia crown and stem rot (Sclerotinia trifoliorum Erikss.) that reduced plant density, vigor, and dry herbage weight. Although forage P concentration of all species was similar to or greater than ryegrass, only crimson clover (T. incarnatum L.) had P uptake equal to ryegrass during both years (mean of 23.4 kg ha−1). This was attributed to the high correlation between dry herbage weight and P uptake (r = 0.95 and 0.89 in 1997 and 1998, respectively). Legumes typically had greater Cu and Zn concentrations than ryegrass, but only crimson clover and hairy vetch (Vicia villosa Roth) had comparatively greater Cu and Zn uptake during both years. The combination of desirable agronomic traits and nutrient uptake capacity make annual ryegrass a superior temperate forage species for use in southeastern pastures fertilized with broiler litter.

Growth and reproductive characteristics in backcross hybrids derived from Trifolium repens L. x T. nigrescens Viv. interspecific crosses

Interspecific hybridisation with the close relative, Trifolium nigrescens (Ball clover) is a possible strategy to achieve increased reproductive potential of white clover (Trifolium repens). Fertile F1 plants have been used as the basis for two generations of backcrossing to T. repens as the recurrent parent. F1 and backcrossed plants were assessed in both glasshouse and field for a range of morphological traits, including inflorescence production, and the level of water soluble carbohydrates in the stolons. Plants resulting from two generations of backcrossing had an increased allocation of dry matter to inflorescence production in comparison with T. repens. Variation within these plants for agronomic traits (e.g. stolon length, dry weights etc.) suggests that selection for these traits is feasible and in combination with increased inflorescence production offers a potentially valuable approach to germplasm improvement in white clover.

Allelopathic Effects on Germination and Seedling Growth of Clovers by Endophyte‐Free and ‐Infected Tall Fescue

Reports of allelopathy by tall fescue (Festucarundinacea Schreb.) on Trifolium species are inconsistent. Many tall fescue plants are infected with a fungal endophyte (Acremonium coenophialum Morgan‐Jones & Gams), which may account for some of the inconsistencies. My objective was to investigate the allelopathic effect of extracts of endophyte‐free (TF − E) and ‐infected (TF + E) tall fescue seeds the seed germination and seedling growth (shoot, root, and root‐hair length and root‐hair density) of five Trifolium species (ball clover, T. nigrescens Viv.; crimson clover, T. incarnatum L.; red clover, T. pratense L.; subterranean clover, T. subterraneum L.; and white clover, T. repens L.). Extracts were prepared by passing 50 g of seed through a pulverizing mill, soaking the milled seed in 500 mL of deionized water, filtering, and sterilizing the solution. Differences among allelopathic effects for seed germination were attributed to legume species. Although the presence of fungal endophyte had no effect on seed germination, germination of ball, crimson, and red clover seed was significantly reduced in extracts of tall fescue seed. Differences among allelopathic effects for shoot and root lengths were attributed to legume species. Seedling shoot length was significantly increased and root length was significantly decreased for clover seedlings grown in tall fescue extracts. Differences among allelopathic effects for root‐hair length and density were attributed to species and substrate (TF − E vs. TF + E) differences. There was a 34% reduction in root‐hair length and a 45% reduction in root‐hair density for clover seedlings grown in seed extracts compared with seedlings grown in water. Seed germination and seedling shoot and root lengths inadequately expressed the subtle allelopathic effects of the fungal endophyte. Micromorphological characters, such as root hairs, may be more sensitive in detecting allelopathic effects.

Oviposition Preference of Darkwinged Fungus Gnats (Diptera: Sciaridae) Among Trifolium Species

We examined the oviposition preference of darkwinged fungus gnats, Bradysia spp., on 14 Trifolium cultivars representing seven species and seedling mortality following fungus gnat larval feeding. Variation in fungus gnat oviposition preference was detected for interspecific Trifolium cultivars but not for intraspecific cultivars. In a replicated free-choice greenhouse test, subterranean clover, T. subterraneum L., was preferred significantly over other tested species, followed by crimson clover, T. incarnatum L.; arrow leaf clover, T. vesiculosum Savi; red clover, T. pretense L.; kura clover, T. ambiguum Bieb.; white clover, T. repens L.; and ball clover, T. nigrescens Viv. All Trifolium species were susceptible to feeding by fungus gnat larvae; we have also observed the death of 20 white clover seedlings by as few as six fungus gnat larvae. Fungus gnats may pose a serious threat to cool-season pasture legumes. Field surveys and population studies are needed to determine the importance of fungus gnat feeding in reducing the pasture persistence of cool and warm-season forage legumes.

Phytotoxicity of Plant Materials on Seed Germination of Crownvetch, Coronilla varia L.1

AbstractPhytotoxic potential of six crop and four weed species was determined on crownvetch. Water extracts of Virginia pepperweed, evening primrose, crabgrass, and crownvetch were most toxic to seed germination. Tall fescue and weeping lovegrass were least toxic. Extracts from aerial portions were more inhibitory than those from roots. Crown vetch was less tolerant of high osmotic pressure than was crimson clover, but this did not explain the strong inhibition of the former species by certain plant extracts. Pepperweed residues incorporated into soil for 10 weeks were toxic to crownvetch seed germination. Kobe lespedeza residues incorporated into soil did not affect percent germination but decreased seedling growth.Pepperweed extract inhibited seed germination of tall fescue, ball clover, sericea, and Kobe lespedeza. It was toxic to crownvetch at a dilute concentration of 1:150 (w/v). The toxic substance occurred in all parts of the plant and was not affected by drying temperature. Pepperweed extract was toxic to five fungi. The phyto‐ and fungitoxicity of pepperweed may be of significance in competition with other plant species.

Natural Selection of Ball Clover Ecotypes in Reseeding Pastures1

Local ecotypes of ball clover developed in fields reseeding for 5 to 9 years. Ecotypes originating in southern Alabama made more rapid autumn growth, considerably more winter forage, and bloomed slightly earlier than those from further north in the State.