Morphological and chemical characteristics of 11 warm season pasture weed species were defined. Goldenrod (Solidago altissima L.) was significantly taller and common ragweed (Ambrosia artemisiifolia L.) had the largest canopy diameter of the 11 species studied. Species ranged from 14 to 134 cm in height with canopy diameters of 25 to 70 cm. No direct correlation was found between individual leaf size and total leaf area. Macro- and micromineral content varied widely among species but all values obtained were considered high enough to meet the requirements of ruminant animals. Redroot pigweed (Amaranthus retroflexus L.) and horsenettle (Solanum carolinense L.) contained potentially toxic levels of nitrate. Five of the 11 species contained sufficient crude protein for ruminants and six of the 11 species were more than 50% digestible. Digestible energy values averaged 1.9 Mcal/kg for the 11 weeds evaluated.

Each year approximately 150,000 to 200,000 ha of tall fescue (Festuca arundinacea Schreb.) are havested for seed in the United States. The majority of this hectarage is utilized for fall and winter grazing as well as seed production in the spring. The objectives of this study were to examine the effects of N level and date of last forage harvest in the spring on the forage and seed yield and seed quality of tall fescue. A sward of ‘Kenwell’ tall fescue was grown under three levels of N and five defoliation regimes at Mississippi State, Miss. on a Leeper silty clay loam (fine, montmorillonitic, nonacid, thermic Vertic Haplaquept). Nitrogen rates of 0, 67, and 134 kg/ha applied as NH4NO3 were applied in February of 1967 and 1968. Plots were harvested zero, one, two, three, or four times at 15 day intervals prior to seed harvest. The five defoliation treatments, by date of last forage harvest prior to seed harvest were no harvest, 15 and 30 March and 15 and 30 April. Following seed harvest the aftermath was harvested for forage. Variables measured were dry matter yield, seed yield, panicles/ m2, spikelets/panicle, and florets/spikelet. Seed quality characteristics measured included germination, seedling weight, and shoot and radicle length. Dry matter and seed yields were decreased significantly in plots defoliated later than 30 March. Reductions in seed yield appeared to be the result of decreased tiller density and the number of spikelets per panicle. Early spring defoliation (15 March) resulted in some damage to fertile tillers in the 1st year as evidenced by a reduced number of spikelets/panicle, although there was no effect on seed yield or tiller density. Seed quality was reduced for all plots defoliated after 30 March. Dry matter and seed yields increased with increasing rates of N. Maximum forage and seed yields were attained at 134 kg/ha of N while maximum seed quality was attained with 67 kg/ha of N. Results of this study indicate that tall fescue seed fields which are to be grazed or cut for hay should not be defoliated in the spring after tillers commence to elongate and become erect if maximum production is to be realized. Higher rates of N were required to maximize dry matter and seed yields than to maximize seed quality.

A series of experiments was conducted during 1978,1979, and 1980 to screen selected cultivars of grasses and legumes for their adaptation and performance under a multiple harvest system in a shaded environment. Acceptable stands of all species except Unioh sessiliflora Michx. were obtained under each shade treatment. The most shade tolerant species were 'Nangeela' subclover (T#olium subternzneum L.), ryegrass (Lolium mul@7orium Lam.), Per&n clover (Trifolium resupinatum L.) and crimson clover (Trifolium incarnatum L.). Shade reduced the height of species with an upright growth habit while decumbent type species (subclover) showed less reduction. Nitrogen content was not affected by shade while potassium and phosphorus levels increased for all species under 5% shade. In separate field experiments the yield, stand density, and persistence of sericea lespedexa [Lespdeza cuneata (Dumont) G. Don) decreased with increasing shade although crude protein content was not affected. Cultivars of 4 species, ('Mt. Barker' subclover, 'Tibbee' crimson clover, 'Kentucky 31' tall fescue (Festuca arundinacea Schreb.), and 'Gulf ryegrass), had acceptable stands and yields under 50% shade in a multiple harvest regime. These results demonstrate that several forage species are sufficiently shade tolerant to warrant consideration for use in forested environments.

No abstract

Bermudagrass (Cynodon dactylon L. Pers.) is the major warmseason perennial forage crop used for beef production in the Southeast. Seedhead production is irregular and consequently cannot be used as an index of age or quality. Chronological age is, therefore, important in making management decisions. Since bermudagrass production and quality may vary with season and year, ‘Coastal’, ‘Alicia’, ‘Callie’, and common bermudagrass harvested at 2‐, 4‐, 6‐, and 8‐week intervals were evaluated over 2 years in northeast Mississippi on a Leeper fine sandy loam (fine, montmorillonitic, nonacid, thermic Vertic Haplaquept) soil. During the 1975 growing season rainfall was generally adequate and total dry matter yields of Coastal, Alicia, and common bermudagrass harvested at the four intervals were similar. Forage yields of Callie, however, averaged 20% higher than the other grasses because of higher production during July and August. In 1976, rainfall was especially low during August (2.0 cm) and total yield of the hybrid bermudagrasses were similar averaging 72% higher than that of common. Lower total season yields of common were reflected in less regrowth during July and August. Averaged over the grasses, total forage yields harvested at 4‐, 6‐, and 8‐ week intervals were 2.6 metric tons/ha lower in 1976 than in 1975 and were related in general to higher early‐season (June to July) forage yields in 1975 and limited regrowth in August and September 1976. Crude protein (CP) was higher for Callie and common both years of the study. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) varied little among grasses or harvest intervals. The increase in CP (3.4 units) and decrease in NDF (3.8 units) observed in 1976 appeared related to rainfall patterns, variation in regrowth potential among the grasses, and possible changes in the proportion of leafstem fractions. Averaged over years, Callie was higher in CP (11.9 vs. 10.3%) and digestible dry matter (55.3 vs. 53.0%), and lower in lignin (5.2 vs. 5.7%) than the other grasses. Results suggest that selection of hybrid bermudagrasses over common should be based mainly on their potential to produce significantly more dry matter when moisture is limiting.