Field Evaluation of Crown Rust in Annual Ryegrass Populations

Crown rust (Puccinia coronata [Pers.] Cda.) is the most prevalent disease found on annual ryegrass (Lolium multiflorum L.) of the southeastern USA. Determination of crown rust resistance is difficult because of the erratic nature of infections at most locations. As crown rust is present at Gainesville, FL each year, a rust nursery was designed to evaluate rust resistance and susceptibility of annual ryegrass. Evaluation consists of periodic rust ratings of the seed crop and regrowth of part of each plot after cutting. Nursery results indicate the buildup of rust, including at the date of 90% heading (start of flowering), and rust on regrowth under high rust spore load for all ryegrass genotypes. A rust index based on rust ratings at the 90% heading date for two or more growing seasons is proposed to distinguish highly-resistant, resistant, susceptible and highlysusceptible ryegrass cultivars

Evolutionary Recurrent Selection Develops Adapted Annual Ryegrass

Seed companies find having their own annual ryegrass breeding program in the southeastern USA, unprofitable. The annual ryegrass breeding program at the University of Florida provides new annual ryegrass (Lolium multiflorum) cultivars with disease resistance and adaption. The evolutionary recurrent selection breeding uses large nurseries, roguing of diseased and unthrifty plants and selection of best plants to provide seed for the next generation. Current commercial cultivars developed are named along with some of their characteristics

Tall Tropical Grasses and Leucaena as Energy Crops for Lower South USA

The tropical leguminous shrub/tree, leucaena (Leucaena spp. mainly leucocephala), and perennial tropical tall grasses such as elephantgrass (Pennisetum purpureum), sugarcane, and energycane (Saccharum spp.) are well adapted to the long growing seasons and high rainfall of humid lower South. In much of the area the topgrowth is killed by frost during winter and plants regenerate from underground parts in spring. Selected accessions from a duplicated 373 accession leucaena nursery had an average annual woody stem dry matter production of 31.4 Mg ha-1 and four seasons growth of 78.9 Mg ha-1. The tall perennial grasses have linear growth rates of 18 to 27 g m-2d-1 for long periods (140 to 196 d and sometimes longer) each season. Oven dry biomass yields of tall grasses have varied from 19 to 45 Mg ha-1 in mild temperate locations to over 60 Mg ha- 1yr-1 in warm subtropics of lower Florida peninsular

Influence of Maturity on Quality and Agronomic Characteristics of Energycane

As fossil fuel supplies decline and become cost prohibitive, biomass must be exploited as a renewable energy source, Energy yield from biomass tends to vary among species and different parts of the same plant, The purpose of this research was to determine change in percentage dry matter (DM), DM yield and quality (crude protein (CP), in vitro organic matter digestion (IVOMD)) of green leaves (GL), dead leaves (DL) and stems (S) of L79-1002 energycane (Saccharum spp. L.) harvested at 0.6 m increments from 0.6 to 4,2 m. As plant height at harvest increased from 0.6 to 4.2 m, GL quantity decreased 87% and S increased 69% on DM basis. CP reduction in GL, DL and S was 50, 59 and 75%, respectively, as plant height increased from 0,6 to 4.2 m. IVOMD of GL decreased from 61% (0.6 m) to 41 % ( 4.2 m) and S decreased from 62% (0.6 m) to 33% (4.2 m). The IVOMD of GL dropped at a faster rate than S as plant height increased until late maturity (3.6-4.2 m). Plant quantity and quality of energycane changed drastically as plant height increased

Effect of continuous gamma-ray exposure on performance of learned tasks and effect of subsequent fractionated exposures on blood-forming tissue

Sixteen monkeys trained to perform continuous and discrete-avoidance and fixed-ratio tasks with visual and auditory cues were performance-tested before, during, and after 10-day gamma-ray exposures totaling 0, 500, 750, and 1000 rads. Approximately 14 months after the performance-test exposures, surviving animals were exposed to 100-rad gamma-ray fractions at 56-day intervals to observe injury and recovery patterns of blood-forming tissues. The fixed-ratio, food-reward task performance showed a transient decline in all dose groups within 24 hours of the start of gamma-ray exposure, followed by recovery to normal food-consumption levels within 48 to 72 hours. Avoidance tasks were performed successfully by all groups during the 10-day exposure, but reaction times of the two higher dose-rate groups in which animals received 3 and 4 rads per hour or total doses of 750 and 1000 rads, respectively, were somewhat slower

Fertilizer versus legume nitrogen for tropical grass-legume associations.

the effects of fertilizer nitrogem and legume nitrogem on yield and quality of three tropical grasses, a legume and grass-legume associations was evaluated in 1984 and 1985. The grasses were of "Pensacola" bahiagrass (Paspalum notatum flugge.), tifton "Hybrid-81" bermudagrass [Cynodon dactylon(L.) Pers.], and "Survenola" digitgrass (Digitaria X umfolozy Hall) and the legume was "Florigraze" rhizoma peanuts (Arachis glabrata Benth.). Nitrogem ferlization resulted in increased yields of hidh quality forage in pure stands of tropical grasses. The association of tropical grasses with rhizoma peanuts resulted in encreased crude protein content of the grass componenr and increased yields of higher quality forage inthe associations. The ability of tropical grasses to compete with rhizoma peanuts was substantially increased by N fertilization, resulting in balanced associations of the legume with bermudagrass and digitgrass

Rhizoma Peanut: More Than a ‘Lucerne’ for Subtropical USA

Rhizoma peanut (Arachis glabrata) was introduced to Florida from South America in the 1930s. Selections \u27Arb\u27 (PI 118457) and \u27Arblick\u27 (PI 262839) were released in the 1960s, but their use was very limited due to slow establishment and low productivity. The University of Florida released \u27Florigraze\u27 (PI 421707) in 1978 and \u27Arbrook\u27 (PI 262817) in 1986. These cultivars produced much higher dry matter yields. Thereafter, rhizoma peanut began to gain commercial acceptance. These cultivars are used throughout the Gulf Coast region of the USA for commercial hay production, pasture, creep grazing, silage, balage, and living mulch (French et al., 1994). It is estimated that circa 8 Kha of rhizoma peanut have been planted (Quesenberry, 1999). \u27Ecoturf\u27 (PI 262840), an A. glabrata introduction that is gaining wide spread acceptance as a low maintenance turf or ornamental, is the latest development with rhizoma peanut breeding at the University of Florida. In 2002, perennial peanut was selected as the Plant of the Year by the Florida Nurserymen and Growers Association. Current estimates are that rhizoma peanut sales (mainly hay, but also includes planting material and ornamental production) exceed $7M USD