Physical Sciences and Mathematics Commons^™

Age, Date Of Cutting, And Temperature As Factor Affecting Chemical Composition Of Berseem (Trifolium Alexandrinum L.), F Guessous

IGC Proceedings (1977-2023)

Chemical composition ofberseem (Trifolium alexandrinumL.), produced in winter and spring under irrigation in Morocco, was investigated in a 4-year study. Berseem was planted at various dates, and after the first cut had been harvested, samples were taken from each regrowth at weekly intervals. Total plant samples and leaf and stem samples were analyzed for dry matter

(DM), ash, crude protein (CP), and crude fiber (CF). A total of 172 samples of above-ground regrowth were analyzed and used to calculate multiple regressions of chemical composition on age and date of cutting. Date of cutting was defined as number of …

Forage Quantity And Quality Contributions From A Grass-Legume-Shrub Planting On A Semi-Arid Rangeleand, D A. Johnson, M D. Rumbaugh, G A. Van Epps

IGC Proceedings (1977-2023)

Poor grazing management has led to deterioration of vast expanses of the world's semiarid rangelands. Although contem­porary thought in range-management circles suggests that combinations of grasses, forbs, and shrubs are desirable in revegetating these areas, past revegetation mainly involved the establishment of monocultures of perennial grass. The objectives of this study were to determine the forage and protein yields of a grass-legume-shrub planting in a semiarid rangeland. The study was conducted in central Utah on a rangeland receiving 32 cm of annual precipitation. Crested wheatgrass (Agropyron cristatum) was established alone and in combination with fourwing saltbush (Atriplex canescens), alfalfa (Medicago …

Effects Of Water Stress On Herbage Quality, J R. Wilson

IGC Proceedings (1977-2023)

Uncertainty exists about whether drought is detrimental to the nutritive quality of herbage. This paper tries to resolve this uncertainty by examining the influence of soil moisture on some herbage-quality characteristics. Unpublished data from my own work and review of published literature are presented. Field plots of three tropical grasses, green panic (Panicum maximum var. trichoglume), buffelgrass (Cenchrus ciliaris), and speargrass (Heteropogon contortus), were subjected to perioqs of controlled drought, and herbage from these plots was compared with that from well-watered plots. Leaf and stem dry-matter ?igestibility of water-stressed herbage was either similar to or higher than that of unstressed …

Effects Of Climatic Zone, Topography, Land Utilization, And Soil Condition On Nutrient Composition Of Natural Grasses In Bali, I M. Nitis, K Lana

IGC Proceedings (1977-2023)

A survey based on climatic zone (zones B, C, D, E, and F), topography ( coast, hill, and higher altitude), land utilization (rice field, dry land, and plantation) and soil condition (moist and dry surface) was carried out during the wet (January to February 1979) and dry (August to September 1979) seasons in 15 districts of 8 regencies in Bali. The objective was to study the quality of the natural grass commonly fed to livestock in the mixed-farming system.

During the wet season, the crude-protein content ( on dry-matter basis) of the natural grass ranged from 7.4 % (in climatic …

Consumption Rates And Desert Grassland Herbivores, R D. Pieper

IGC Proceedings (1977-2023)

Studies were conducted on a desert grassland range in southern New Mexico for 3 years to determine relative consumption rates of the main herbivores utilizing these range areas. Consumption of some groups (cattle, pronghorn antelope, and rabbits) was determined from direct estimates of intake/individual, and density was determined from censusing procedures or known stock rates. Consumption by other groups (birds, rodents, and invertebrates) was determined from census information relating to age structure of the population and metabolic rate. Consumption by all herbivores averaged less than 5 % of the above-ground net primary productivity for the 3 years of the study. …

Pattern Of Defoliation By Cattle Grazing Crested Wheatgrass Pastures, B E. Norton, P S. Johnson

IGC Proceedings (1977-2023)

Summary Utilization of a monotypic stand of perennial grass by cattle is generally assumed to be a random process that can be ade­quately measured by counting the number of plants grazed or by comparing biomass on caged and grazed plots. At a similar level of approximation, grazing is often simulated experimentally by clipping down to a prescribed height. The purpose of our study was to examine defoliation in more detail, following grazing severity and frequency on an individual plant basis with an inter­val of only 48 hours between observations. The study was conducted on two 28-ha pastures of crested wheatgrass …

Performance Of A Subtropical Legume-Grass Pasture Under Different Grazing Management Systems, G E. Maraschin, S C. Mella, G S. Irulegui, J Riboldi

IGC Proceedings (1977-2023)

Agronomic evaluation of the dynamics of tropical legume-based pastures is relevant in assessing the response of their com­ponents within systems of grazing management. The response of tropical legume-grass mixtures to periods of rest and grazing pressure and the combinations that result in meaningful legume content in the mixture need to be known. A central composite design was used to study the performance of a Desmodium intortum (Mill.) U rb. and Paspalum gttenoarum Arech. pasture mixture to 14, 28, 42, 56, and 70daysofrestcombinedwith 2.0%, 3.5%, 5.0%, 6.5%, and 8.0% BW(i.e., kg dry matter (DM) on offer/day/100 kg body weight) as grazing …

Effects Of Treading And The Return Of Excreta On A Perennial Ryegrass - White Clover Sward Defoliated By Continuously Grazing Sheep, M L. Currl, R J. Wilkins

IGC Proceedings (1977-2023)

Grazing sheep may affect the association between grass and clover in a mixed sward by defoliation, treading, and the circula­tion of nitrogen (N) via excreta. Our objective was to examine the effect of treading and excreta on a perennial ryegrass (Lolium perenne)-white clover (Trifolium repens)sward defoliated by sheep at high and low stocking rates. Established swards of perennial ryegrass and white clover were continuously stocked from May to October with yearling wether sheep at 25 and';5() head/ha. Sward production and species composition were measured inside graze-through cages that allowed defoliation without treading and excreta return, and …

Legume Establishment In Grass-Dominant Swards: Concept And History In Kentucky, T H. Taylor, W C. Templeton Jr

IGC Proceedings (1977-2023)

Grassland farming has been practiced for 2 centuries in central Kentucky and for shorter periods in other parts of the state. Savannas and tallgrass prairies were severely grazed by domestic animals and row-cropped by early settlers, destroying most of the indigenous plant species. By the early part of the 19th century, beef cattle were being produced on bluegrass (Poa pratensis L.) pastures and driven on foot to east-coast markets. During the first century of settlement, farmers learned to top-seed legumes into grass sods, and in the course of the last hundred years development of grassland technology for establishing legumes …

Establishment Of Grasses On Cracking Clay Soils: Seedling Morphology Characteristics, L A. Watt

IGC Proceedings (1977-2023)

Although native grasses establish readily on the cracking black clay soils of northwestern New South Wales, it has proven dif­ficult to establish introduced summer grasses. Young grass seedlings were examined to see if morphological differences exist that may explain their differing capacities for establishment. It has been shown that relative differences in the primary and secondary root growth of vario1-,s species can have important ef­fects on the agronomic characteristics of those species. Low soil moisture conditions near the soil surface will restrict greatly or possibly even prevent the growth of secondary roots of young aeedlings. It is well known that …

Seed And Seedling Dynamics Of Annual Medic Pastures In South Australia, E D. Carter

IGC Proceedings (1977-2023)

Annual species of Medicago (i.e., medics) are the key to successful cereal-pasture rotations in the integrated crop-livestock farming systems on the neutral to alkaline soils of southern Australia. However, many medic stands have deteriorated in recent years. This deterioration has prompted research on the effects of grazing sheep on the seed-seedling dynamics of annual medic­based pastures in the Mediterranean environment of South Australia, aiming to quantify the impact of medic seed reserves in or on the soil upon pasture establishment and productivty.

Animal-house experiments involving the feeding of purepod and pod-chaff diets to sheep and a field experiment have been …

Mortality Of Sorghum Plants After Cutting, Y Takasaki, Y Takasaki, H Nojima

IGC Proceedings (1977-2023)

Sorghum (Sorghum spp.) is usually harvested twice a year in most of Japan but three times a year in southern Japan. Some sorghum plants die after cutting, which leads to low aftermath yield. The purpose of this study was to clarify what cultural fac­tors cause death and what plants die in the sorghum stands. Three field experiments were carried out from 1977 to 1979 to investigate the effect of sowing date, planting density, nitrogen (N) level, and cultivar on mortality rate after cutting. In 1979 the effect of high temperature on mortality was investigated. In­formation about what plants die was …

Productivity And Botanical Composition Response Of A Stabilized Pasture To Different Utilization Patterns, E Riveros, A Olivares

IGC Proceedings (1977-2023)

The effect of three different utilization patterns upon the productivity and botanical composition of typical natural pasture was studied during a year of growth. The trial consisted of cutting the swards of three plots of a natural pasture in a humid zone in the south of Chile when they reached an average height of 20 cm, leaving only a height of 5 cm. This process was carried out in three plots of 20 x 20 musing the following methods: plot 1, harvesting with bovines; plot 2, mechanized harvesting with a mower; plot 3, not harvested but sampled each time from …

Use Of Fodder-Production Models For Mineral Soils On Grassland And Arable Land, J Bochniarz, B Kaczynska, M Kasprzykowska, B Lainewska

IGC Proceedings (1977-2023)

In four regions of Poland experiments begun in 1973 and planned to last 12 years compared cutting and grazing yields of per­manent grasslands over 20-30 years old to yields of seven field fodder-production models. The models had 3-, 4- and 6-year rota­tions. The experiments were located on mineral soils with 28%-50% silt and clay and 2.1 %-3.5% humus. The water table depth varied from 44 to 170 cm in spring and from 115 to more than 175 cm in summer. Average precipitation was 375-515 mm during the growing season (April-October) and 523-658 mm annually. Average annual fertilization/ha was as follows: …

Grass And Forb Production On Sprayed And Nonsprayed Mesquite (Prosopis Glandulosa Torr.) Dunelands In South-Central New Mexico, R P. Gibbens

IGC Proceedings (1977-2023)

Production of grasses and forbs was measured for 4 years, beginning in 1976, following aerial application of 2,4,5-T to 3,634 ha of mesquite (PTosopis gl.andulosa Torr.) dunelands on the J ornada Experimental Range in south central New Mexico. Plant production was also measured on a 3,318-ha control area. The mesquite dunelands are representative of large areas in the southwestern U.S.A. where mesquite has invaded former desert grasslands. Objectives of the study were to determine forage in­creases attributable to reduced mesquite competition and to evaluate the relationships between production and precipitation. Both sprayed and control areas were grazed by cattle. Temporary …

Grass-Leguminous Mixture And Fertilization As Factors Of The Ecosystem Of Cultivated Grassland, M Mijatovic, J Pavesic-Popovic, S Katic

IGC Proceedings (1977-2023)

On degraded soils in hilly-mountain regions, natural grasslands are impoverished, low-yielding, and of low quality. While such grasslands yield 1,870 to 2,430 kg/ha dry matter without fertilization, and 6,040 to 2,430 kg/ha with N-P-K fertilization, cultivated grasslands are more productive by far. Experiments were conducted from 1971 to 1979 and from 1975 to 1980 in different ecological conditions of the hilly-

mountain part of the country. Sixteen grass and grass-leguminous mixtures were used in the establishment of cultivated grasslands. Yields of dry matter/ha .;,aried from 10,184 to 12,670 kg in hilly regions, 9,433 to 10,933 kg in transitional hilly­mountain regions, …

Basic Types Of Pasture Vegetation In The Songnen Plain, Li Chonghao, Zheng Xuanfeng, Zhao Kuiyi, Ye Juxin

IGC Proceedings (1977-2023)

In this paper, the ecological conditions of pasture vegetation, the plant constituents of the Songnen plain, and their basic types and succession are discussed. An approach is also presented on ways to improve natural steppe artificially. In this region, there are 29 lignosa associations that are suitable for grazing and 450 plant species that are suitable forages. Among them are more than 30 species of perennial gramineous and leguminous plants.

A Study Of The Ecology Of Yang-Cao (Leymus Chinensis) Grassland In Northern China, Zhu Ting-Cheng, Li Jian-Dong, Yang Dian-Chen

IGC Proceedings (1977-2023)

Lemus chinensis grasslands axe distributed over the USSR, the People's Republic of Mongolia, and the People's Republic of China. This article presents three ecological characteristics of this grassland. The canopy is diagrammed, showing the structure of the grassland; the unassimilative: assimilative and underground: above-ground biomass ratios are given; and the life-form spectrum of the plants classified. The above-ground net primary productivity (ANPP) and its relationship with the quantity of rainfall has been calculated to indicate water-use efficiency of the L. chinensis grassland. The characteristics were found to be basically the same as those of the shortgrass prairie of North …

Spatial Simulation Modeling As A Tool In Multiple-Use Management Of Renewable-Resource Systems, R C. Jump, G.M Van Dyne

IGC Proceedings (1977-2023)

A conceptual model was developed using a modified-state variable approach, which involved the recognition and suitable description of specific objectives, processes, and situations considered relevant to the simulation of ecosystem dynamics. Six primary ecosystem subsystems were selected: terrestrial abiotic, floral and fauna, aquatic abiotic and biotic, and topographic land use. These subsystems are embodied by a geographic structure defined as an ecological response unit (ERU). Subsystem characteristics of an ERU are considered homogenous, but between ER Us the characteristics may differ greatly. A set of ER Us may be arranged into any mosaic pattern, a quality that affords a unique …

Effect Of Active Roots Of Forage Grass On Soil-Aggregate Formation, H Kobayashi, I Yamane

IGC Proceedings (1977-2023)

Hipf-rotted older roots and active younger ones both are present in abundance in forage grass, and both types assist in soil ag­gregate formation in their own rhizosphere. Italian ryegrass (Lolium multiflorum Lam.) was grown in quartz sand for 12 weeks in glass boxes placed in phytotron. In experiment 1, three boxes were opened after 4, 8, and 12 weeks of growth. Root weight was measured, and quantity of sand adhering to the roots was weighed. One hundred times more sand was found adhering to roots after 12 than after 4 weeks. When converted to root basis, weights at 8 weeks …

Effects Of Maturity And Environment On Amount And Composition Of Hemicellulose In Tall Fescue, S L. Fales, D A. Holt, C.S T. Daughtry, V L. Lechtenberg

IGC Proceedings (1977-2023)

Seasonal changes in amount, compos1bon, and digestibility of fiber in vegetative tissues of forage grasses are usually associated with advancing tissue maturity. Our objective was to determine the relative effects of maturity and environment on amount and composition of hemicellulose in field-grown tall fescue (Festuca arundinacea Schreb.). Regrowth of identical chronological age was sampled weekly at different times during the growing season. Leaf samples were extracted with neutral detergent solution to isolate cell walls (NDF). The NDF was treated with 1.0 H2S0+ to remove and hydrolize hemicellulose. The hydrolyzates were analyzed for concentrations of xylose and arabinose, using …

A Descriptive Scheme For Stages Of Development In Perennial Forage Grasses, U Simon, B H. Park

IGC Proceedings (1977-2023)

A descriptive scheme of morphological stages of development in forage grasses is urgently needed for scientific investigations as well as for practical purposes. It could be used for precise timing of management measures, such as application of fertilizers and herbicides, and in harvesting with respect to a certain level of forage yield and/or quality. Existing schemes, like the Feekes scale and its modifications, were devised for cereals. They do not adequately consider the peculiar stages of development of perennial grasses grown for forage. We propose a scheme that consists of consecutive stages of the following phases of plant development: number …

Using Leaf-Area Expansion Rate To Improve Yield Of Tall Fescue, C J. Nelson, D A. Sleper

IGC Proceedings (1977-2023)

Several physiological characters have been proposed for use in breeding programs for higher yield potential. Our objectives were to evaluate recurrent restricted phenotypic selection for developing populations of tall fescue (Festuca arundinacea Schreb.) for low and high rates of leaf-area expansion (LAE). Mter four cycles, LAE was 181 and 74 mm2/day for the high (H) and low (L) populations, respectively. It appeared that LAE changes in early generations were due largely to increased leaf elongation rate (LER) of the H populations, whereas later progress was due largely to decreased leaf width (L W) of the L populations. Overall, LER had …

Photosynthesis And Dry-Matter Distribution In Altitudinal Ecotypes Of White Clover, J Noseberger, F Machler, B C. Boller

IGC Proceedings (1977-2023)

Productivity of white clover (Trifolium repens L.) is limited by plant characteristics that prevent efficient use of environmen­tal inputs. In the temperate zone, low temperature often limits growth. Comparisons of ecotypes originating from sites with cool or warm climatic conditions (low or high altitudes) can show, when plants are grown in a common environment, the degree of adaptation of processes related to net photosynthesis and the distribution of dry matter. Our objectives were to determine the photosynthetic responses to temperature in relation to the thermal regime during growth and the effects of temperature and daylength on partitioning of dry matter …

Photosynthesis Of Grass Swards Under Rotational And Continuous Grazing, B Deinum, M L. 'T Hart, E Lantinga

IGC Proceedings (1977-2023)

First-year results are presented on the photosynthesis of grass swards under intensive rotational or continuous grazing. In rotational grazing, crop photosynthesis was high in spring, declining during grazing but recovering rapidly during regrowth, possibly because of the high photosynthetic capacity of individual leaves and of the great area of active leaves left in the sward. In autumn, crop photosynthesis was rather high initially, declined rapidly during grazing, and recovered slowly during regrowth, possibly because photosynthetic capacity of the leaves was low, the decline with age was great, and the active leaf area in the stubble was small. Crop photosynthesis under …

Physiology Of Growth Of A Grazed Sward, E L. Leafe, A J. Parsons

IGC Proceedings (1977-2023)

To improve our understanding of grassland utilization under grazing, the physiology of a grazed sward was investigated. An enclosure method, infrared gas analysis, and radiocarbon were used to measure sward and single-leaf photosynthesis and assimilate utilization. Intake by sheep was also measured. Expanding and recently expanded leaves had high rates of net photosynthesis but leaf sheaths, whose projected area in a "hard" grazed sward equaled that of the lamina, had low efficiency and contributed little to canopy photosynthesis. But because high leaf efficiency did not compensate for the small leaf area, canopy photosynthesis decreased markedly as grazing intensity increased. Twice …

Leaf Growth And Grain Yield Of Wheat In North-South And East-West Rows, M B. Kirkham

IGC Proceedings (1977-2023)

Few experiments report the effect of row direction on growth of wheat in windy areas. The objective of this research was to determine the optimal row direction for winter wheat (Triticum aestivum L. em. Thell;) in the southern Great Plains of the U.S.A. for minimizing stress from wind, optimizing leaf growth (forage yield), and maximizing grain yield. During a 3-year period (1976-1979), Osage wheat was grown in north-south (NS) and east-west (EW) rows. Wind, soil water content, stomata! resistance, leaf water potential, leaf osmotic potential, elemental concentration of straw and grain, height, leaf area, and grain yield were measured. Prevailing …

Plant-Water Relationships Of Crested, Pubescent, Slender, And Western Wheatgrass, A B. Frank

IGC Proceedings (1977-2023)

Objectives were to characterize development of water stress in the field and in controlled environments; to determine stress ef­fects on transpit"ation (E), stomata} conductance (C), leaf water potential (LWP), leaf osmotic potential (LOP), and photosyn­thesis (P); and to relate measured changes to drought tolerance in crested wheatgrass (Agropyron desertorom [Fisch.] Schult.), slender wheatgrass (A. trachycaulum [Link] Malte.), pubescent wheatgrass (A. intermedium var. trichophorum [Link] Haloc), and western wheatg:rass (A. smithii Rydb. ). Both L WP and LOP decreased for all species as soil water potential decreased, but not in a 1: 1 ratio indicative of maximum osmotic adjustment. The LWP …

Responses Of Siratro (Macroptilium Atropurpureum) To Water Stress, M J. Fisher, M M. Ludlow

IGC Proceedings (1977-2023)

Experiments were conducted to seek understanding of the adaptive characters that contribute to the success of the twining tropical legume siratro (Macroptilium atropurpureum) as a component of sown pastures in the seasonally dry tropics and sub­tropics of northeastern Australia. Siratro was grown both in the field and in controlled environments and was subjected to se­quences of water stress. Measurements were made of tissue-water relations, leaf gas exchange, leaf movement, and leaf energy balance. Siratro avoids the effects of stress by maintaining its leaf-water potential greater than -20 bar, while grasses grown in associa­tion with it are about -60 to -80 …

Comparative Flooding Tolerance Of Tropical Pasture Legumes, P C. Whiteman, M Seitlheko, M E. Siregar

IGC Proceedings (1977-2023)

Growth and persistence of many tropical pasture legumes can be limited by flooding or waterlogging. Selection of tolerant species is important for pasture development in the humid lowland tropics. The aim of this project was to compare flooding tolerance of seven tropical pasture legumes and to determine whether the pot technique we developed was reproducible and rele­vant to the field situation. Plants were grown in pots and at the start of flowering were flooded to 15 cm above soil level. Water temperature and oxygen content were monitored regularly. Sets of four uniform pots were removed from flooding after 7, 14, …