HOW IS IT, HOW TO USE IT AND WHERE?
Use of Grama Rhodes.
Write: Monti, Delgado y Jozami.
Source Engormix
The term comes from pasture Pasture Megatérmicas that require high temperatures for growth, basically were developed and adapted to tropical and subtropical regions, in temperate zones offer their production during the summer period.
1. Introduction
Until the 80s prevailed in the Pampas agricultural production systems-livestock, with the emergence of new technologies and forms of agricultural production coupled with agricultural potential and a lower relative price of beef was generated process agriculturization that overall capitalization resulted in a loss of cattle stock and improvements such as fencing, watering facilities, and rural housing.
During the early ’90s, Eye Vdo INTA proposes a model of production for agricultural fields CBI called for the purpose of increasing production of breeding herds and sustain farming in the south Santafesino, despite the excellent physical results and economic trends established in the previous decade was enhanced.
The Ministry of Production in the Province of Santa Fe offers a program called Meat Santafesinas to transfer technologies to producer groups.
One strategy to improve productivity is to increase the forage value within PCS participants found that 42% performed the livestock on purely agricultural environments and conformed to the IWC proposal, the remaining 58% performed partial livestock or entirely in non-agricultural grasslands are occupied by (1).
Natural grasslands in the region are usually degraded and / or are of low productivity, constrained by the presence of salts and / or alkalinity and water logging in some cases temporary.
To the extent that deepened the process of agriculturization, the forage resource is called Natural Golf (CN) gained more importance since it was the place where the property is concentrated during the summer season, hence the possibility of increasing productivity in this period potentially increase the load means.
We initially tried to improve them with wheatgrass, this forage to suit non-agricultural areas has its peak production in autumn and spring, the summer is in the reproductive stage thus decreases the rate of growth but particularly quality declines, whereas the use of species Megatérmicas gives the ability to leverage the higher growth rate and quality during the summer.
Depending on the strategy in November 2008, the establishment of Christian Soljan – PCS Group Chovet featuring advice from Vet Med Guillermo Delgado Grama Rhodes was introduced cv Pioneer in a batch setting, given their excellent performance tested other varieties and species in 2009 was tested with cv Tolga, Callide and Panicum var coloratum green Klein, in 2010-11 was sown cv Katambora y Toro. The proposal was quickly accepted and was able to follow in the region to different lots of producers, also led to perform the I Congress of Megatérmicas pastures for temperate zones “(2)
From this perspective the inclusion of Rhodes Grass in the feed chain can maintain high load during the summer on non-agricultural areas and during the cold seasons can be used for conventional feed resources temperate areas as stubble, soiling or temperate grassland with a growth fall-winter-spring (OIP) (3).
So from the point of view these pastures provide strategic solutions to the feed chain structure while maintaining high quality for supply to cattle-breeding farm areas.
2. Using Megatérmicas Pastures in temperate
The term comes from pasture Pasture Megatérmicas that require high temperatures for growth, basically were developed and adapted to tropical and subtropical regions, in temperate zones offer their production during the summer period.
The International Research Center for Agricultural Development of the Government of Australia (4) determines that the area which develops varieties of Rhodes Grass (GR) is from latitude 30 ° S to 30 ° N. It is important to note that GR varieties used in the region are mostly of Australian origin.
In Argentina until 2003 was respected in the catalogs of seeds latitude 30 ° S as the limit for the planting of Chloris gayana (Rhodes Grass) and was quoted by Bavera in the year 2006 (5).
In this paper recommends some tropical grasses Digitaria eriantha, Panicum coloratum, pubescens and Eragrostis curvula Antephora to be implanted in the pampas subhumid / semi-arid climate characterized by warm, loose, sandy soils, and rainfall less than 800 mm .
In the humid pampas are used long megatérmicas annual grass species such as maize (Zea maize) and sorghum (Sorghum spp), Moha (Setaria italica), Millet (Panicum milleaceum), and are also known as annual species considered weeds honey grass (Paspalum dilatatum), Barnyardgrass (Echinochloa crus-galli), Queues fox (Setarias viridis), or perennials such as Bermudagrass (Cynodon dactylon) and Johnson grass (Sorghum alepense) (6).
Many of them have high forage value and annual species are used for grazing (forage sorghum and millet), silage (maize and sorghum) or hay (Millet and Moha).
In the case of the species considered weeds for crops consumed in the stubble when control of the same was inefficient or there is strong pressure from weeds that are manifested when lifting the crop harvest.
While the use of GR in the temperate region recognizes various backgrounds, their inclusion in pastoral systems of south Santa Fe began to spread massively from the new experiences from the PCS (2-3).
3. Morphological, physiological and chemical differences between forage species and meso megatérmicas
a. Photosynthesis
The process of photosynthesis allows plants to produce sugars from the capture of CO 2 in air, water, nutrients, solar energy and the presence of chlorophyll. This process depends on internal factors and external to the plant. Among the external factors we can mention the availability of solar energy, water, concentration of CO 2 and O 2 , nutrients, humidity and temperature. Internal factors that influence photosynthesis are chlorophyll availability, degree of senescence of leaves and the activity of the enzyme Rubisco.
The enzyme Rubisco (ribulose-1 ,5-bisphosphate carboxylase-oxygenase) is responsible for setting the CO 2 catalyzes a key reaction in photosynthesis: assimilation and fixation of CO 2 in the biosynthesis of carbohydrates. If the concentration of CO 2 is low, it functions as oxidase, and instead of help fixing deCO 2 the oxidation of carbohydrates to CO 2 and H 2 O, and the process known as photorespiration (not to be confused with cellular respiration).
This enzyme is considered a very inefficient catalyst for two reasons, firstly has low substrate turnover rate (the amount of substrate which binds per unit time). Their catalytic activity is slow: Rubisco catalyzes the condensation of three molecules of CO 2 per second, while the majority of enzymes together about a thousand molecules of substrate per second, and on the other hand catalyzes two competing reactions: the carboxylation (fixing carbon) and the oxygenation of RuBP (ribulose-1, 5 – bisphosphate). Hence its name: carboxylase / oxygenase. Ribulose (RuBP) is the molecule which is incorporated into CO 2 from the air.
Photosynthesis The process has two phases:
- Phase photochemical or Hill reaction where solar energy is converted into chemical energy in the presence of chlorophyll, the obtained products are ATP and NADPH 2 , as a byproduct we obtain O 2 from water.
- Calvin cycle is to reduce the CO 2 and turn it into sugars, the enzyme Rubisco is located at the beginning of this cycle. This cycle is common in any process of photosynthesis.
In higher plants recognize three different types of CO2 uptake pathways:
1 – Calvin cycle or C3 account for 85% of higher plants, some representative species are oats, wheat, rice, tomatoes, potatoes, etc.
2 – Via Hacht-Slack or C4 correspond to species and tropical, among the most commercially important are maize, sorghum, sugar cane, etc..
3 – Acid Metabolism or CAM crassulacean as the cactus, pineapple, orchids, aloe vera, etc.. They are usually species adapted to conditions of stress water.
Unlike C3, C4 plants and CAM having an additional enzyme, PEP carboxylase, which is capable of fixing CO2 without being inhibited by the presence of O2 (as with the rubisco) enabling it to form a 4-carbon intermediate (called oxaloacetate) is transported to cells in the face of the sheath where it releases CO2 and finally determined by the Rubisco ushering Calvin cycle (7).
b. Characterization of C3 and C4 species
Physiological and morphological differences between species of grass called C4 and C3 result in differences in growing season, biomass production and quality, water use efficiency and nitrogen, etc..
C4 plants are characterized by high growth rates under high temperature and light, perfectly adapted to tropical weather conditions in subtropical and temperate behave markedly with summer growth.
c. Morphological
C4 plants have a spatial separation between the primary fixation of PEP carboxylase and Rubisco final, producing leaves in an array of different tissues.
The vascular bundles in C4 plants are surrounded by a radial layer of mesophyll cells, instead of C3 in these mesophyll cells are located in two layers, the superficial shape of the innermost palisade and spongy.
The arrangement of the mesophyll cells, called Kranz structure would facilitate gas exchange and transfer of photosynthates. On the other hand have a thickened cell wall and forming a package suberizada very close with a higher content of sclerenchyma and vascular tissue that prevent easy mechanical disruption and degradation by rumen bacteria reducing their digestibility (9).
d. Forage quality
Forage quality of a pasture is affected by the digestibility and the concentration of protein, digestibility is limited by the presence of substances such as hard to digest lignocellulosic compounds or enhanced when a high proportion of easily digestible substances such as carbohydrates soluble cell present in the juices.
These ratios are related to the dynamic development of the cell wall is strongly influenced by environmental factors such as temperature, light, moisture, nitrogen and defoliation but in the case of C4 grasses is magnified by the combination of factors morpho-physiological.
4. Environments and cultivars
The environments of a region defined by its topography, soil type and its limitations, reaction to extreme climate events.
The size of these environmental units may allow different agronomic management, and sometimes forced to manage their scale batches are not homogeneous.
The parameters that define the suitability of an online environment are general relief, groundwater depth, presence of salts, exchangeable sodium percentage (% PSI), pH, organic matter, presence of compacted layers or thaptos, coverage, type of vegetation susceptibility to natural flooding.
The first classification of environments that is done is by its suitability for agricultural or nonagricultural then its main limitation in low alkaline, saline, saline-alkali, candy, etc.. Rhodes grass is usually well suited to these types of environments although there are differences between them.
The varieties that show photoperiod sensitivity have better forage quality because it is maintained for a longer period in a vegetative state while maintaining a high leaf stem.
The diploid strains show a greater tolerance to salinity and alkalinity that the tetraploid, although the latter is being made tolerant varieties. The same behavior occurs with frost resistance (10).
Photosynthetic optimum is obtained with temperatures of 35 ° C, and average temperatures below 15 ° begin to produce the asimilatos formed gradually accumulates in the chloroplasts and affect the rate of uptake and translocation of metabolites, may cause physical damage to the apparatus photosynthetic will limit the growth of pastures.
5. Implementation of Rhodes Grass in temperate zones.
a. Preparing the ground
Although the GR does not require a very fine seed bed, need to be in close contact with the ground and get some light to trigger germination, management issues is also desirable planting an area of level ground, no further is very good competitor with weeds and grasses that his presence tends to decrease the production of tillers and stolons making it difficult to cover the ground.
When ground conditions permit can be sown direct in the form so the site preparation is a chemical fallow in order to achieve adequate control of the natural vegetation.
When that happens not required to assess type and amount of natural vegetation. There are situations where the vegetation is so abundant that it can not effectively use a disk so you can resort to burning of natural vegetation or move a roller knife.
In environments of low there is usually great difficulty in achieving good coverage and accumulation of organic matter, therefore eliminating it through the burning is a desirable practice, but sometimes may become necessary. Then the roller knife does a very good job when you have time to flip and cut the vegetation allowing you to keep some coverage and breaking the surface compaction if any.
When there is abundant coverage can work with disk harrow and roller.
All work performed by mechanics are appropriate in winter when the greatest amount of vegetation is dry, and waiting for the checks with herbicides in early spring. Since the most common natural vegetation in these environments are chacho hair (Distichlys spicata) and Bermudagrass (Cynodon dactylon) is required to make two applications before planting, in the case of Bermudagrass is appropriate that the first application is in the fall.
b. Sowing
The seed of the GR is very small and light, unprocessed semila 1 kg of seeds has approximately 4,000,000 (11), their viability is generally low, around 20-25%. For better distribution is desirable that the seed is peleteada, in that case, a good quality seed must have at least 500,000 bacteria per kg of seed.
Stocking density ranges from 4-5 kg / ha for tetraploid varieties and 8 kg / ha for diploid varieties.
Seeding should be shallow and well distributed, for it can be broadcast planting it with air, fertilizer, seeder drums or conventional drills with hoses outside the body of implantation. In all cases it is convenient to pass a roller to ensure intimate contact between seed and soil. In the event that takes place under direct seeding should find that the seed is discovered.
Germination starts with a soil temperature of 13-14.8 ° C, although the optimum temperature is 31 ° C and the maximum temperature is 46.5 to 48.4 ° C. The units of heat that needs to accumulate to initiate germination is 36 to 40 ° (12)
The optimum planting date is after the soil temperature exceeds 15 ° C it begins to occur from late October to November. While there have been successful with planting of December.
As we delay the date of planting reduces yield potential and the possibility of using it in the first year.
c. Stages of growth from sowing
The phases of growth of the GR from planting are:
– Birth
– Slow growth phase (implementation)
It is a slow growth phase that lasts a short time to reach the 4 th leaf unfolded.
– Beginning of tillering and elongation of stolons
It is the beginning of active growth and where he quickly begins to cover the ground surface.
Tropical pastures have a direct dependence on the rate of leaf appearance with temperature (13).
It was found that the phyllochron for cv Callide for the test conditions was approximately 120 ° C (14).
– Elongation of the pseudostem
This is the stage that has the highest quality forage
– Stem elongation and flowering
Forage quality is diminished by low leaf / stem ratio, although the accumulated MS is maximized.
– Maturation
Forage quality is very low, full of seeds that fall favors the installation of a seed bank that will assure natural reseeding.
6. Production results
From 2008-09 to 2010-11 production measurements are made in rural Chovet District-Santa Fe – Argentina, in the establishment owned by Mr. Cristian Soljan, located at latitude 33 ° 34’59 “S and longitude 61 º 33’16 “O.
The landscape corresponds to a plano-concave area with small runoff roads, temporary ponds and lagoons. Soil is a complex and Co175 Co174 undifferentiated (INTA, 1984). Presents alkalinity around the horizon with impeded drainage for runoff and very slow permeability, these aspects are favored by the trace of a north-south channel, on the west side of the lot to prevent water accumulation on the surface.
Measurement of the production takes place in a performing cuts Pioneer cv exclusion cages that were placed in different representative areas.
The average annual production in the last 3 evaluations was 7827 kg DM with a coefficient of inter-annual variation of 4%, however the coefficient of variation between cages was 12% which suggests within the test conditions the existence of greater influence on soil physicochemical conditions of interannual climate variations.
As cuts were made between 22 to 87 days (annual average 45 days) depending on time of year due to strong seasonal growth data were modeled to obtain the curve of average monthly percentage distribution, this information is of paramount useful for budgeting forage.
7. Production-climate interaction
When analyzing the yield curve between cuts, one can observe a different distribution for each year and attributed to climatic influence.
The average seasonal average temperature is relatively stable and benign, its standard deviation was 0.7 ° C and never got more than 1 ° C, whereas precipitation have a high variability between production, the coefficient of variation is 41% mean 399.2 mm. The year 2010-11 was a year girl and the lowest rainfall in the series, unlike the year 2011-12 it rained 1408 mm.
Comparing the growth curve and monthly climate variables shows that the highest correlation between temperature and production (0.83) than between production and rain (0.64).
Of the three analyzed temperature is the mean monthly minimum temperature that most of the production condition (0.86) than average (0.84) or high (0.80), these values are interannual differences.
The 2010-11 season despite the low rainfall there was a very low correlation (0.61) with production as opposed to existing temperatures (0.93-0.94-0.95), allowing to infer that the 616 mm of the campaign were sufficient to express their potential.
Although cv Pioneer is sensitive to low temperatures in their growth period is also shown tolerance to low temperatures and frost in times of rest.
8. Interaction-quality heat summation
The quality analysis of the last two years show that the average is 62.5% digestibility and the average content of protein is 8.1%.
Taking digestibility as a benchmark of quality can be seen a difference in behavior is linked to interannual heat summation during the cutting interval.
The heat summation determines the rate of leaf growth and its lifetime, GR is a species in your life as you go up in them mean leaf NDF and indigestible NDF to generate its supporting structure (15).
The correlation between thermal sum and digestibility is very high and negative, in 2009-10 was -0.91 and for the year 2010-11 was -0.92.
9. Range of use
To achieve an appropriate balance between quality and forage supply agreement exists that harvesting should be done when the heat summation (Average Temperature – Temperature base) is 400 ° C.
That heat summation between the months of December to February is obtained with a time of rest between 30-35 days grazing in the pasture last fall is very important to leave a quantity to sustain coverage that protects the growing points of frost winter.
The demonstration plant morphological managed to accumulate the required temperature is the existence of 3 leaves unfolded per tiller.
10. Final Thoughts
Rhodes grass is an excellent choice for improving low forage value. By concentrating its production during the summer season is required to supplement the feed chain with temperate species and reserves.
Growth rate and rapid loss of quality after the optimum point requires a set management in order to avoid them.
Forage quality is generally lower than in temperate species but with proper management is achieved levels consistent with the stringent requirements of the breeding herd.
Literature
1 – Monti, Mario. 2007. Livestock subsystems South of the Province of Santa Fe – Meat Program Santafesinas Ministry of Production-Santa Fe
2 – Monti, M et al. 2009. Megatérmicas introduction of forage species in livestock production systems in southern province of Santa Fe – Argentina.“Technical Disclosure XI Scientific Conference 2010” at the National University of Rosario – Faculty of Veterinary Science – Department of Science & Technology
3 – Congress Megatérmicas Pastures in Temperate Zones. Melincue 28-29 August 2008. Ministry of Production delegation Rufino, INTA Venado Tuerto, Faculty of Veterinary Science, UNR, APROCARSA. Santafesinas Meat Program – Intensive cattle breeding.
4 – Tropical forages. Australian Centre for International Agricultural Research. Australian Government. http://www.tropicalforages.info/index.htm
5 – Bavera, G.. 2006. Collection. Approximate area of adaptation of subtropical pastures. Beef Cattle Production Courses FAV UNRC. 2pag
6 – Red DANAC – Index agriculture. http://www.danac.org.ve/indice//malezas.php?letra=Y&listado=t&ps=22
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9 – Melo O. 2009. Subtropical pasture management. Congress Subtropical Pastures in temperate zones. Melincue. Santa Fe
10 – del Pozo Rodríguez, Pedro Pablo. 2004. Ecophysiological basis for management of tropical grasses – Part I. Agrarian University of Havana, Cuba
11 – Suttie, JM 2003. Hay and straw conservation for small farmers and pastoral conditions. Collection FAO Plant Production and Protection No. 29
12 – Noe Puga et al. 2011. Cardinal temperatures for seed development in stage 11-emergence of forage grasses. Journal of Livestock Science. 2011, 2 (3) :347-357.
13 – Look, J, Herrero, M. 2002. Functional attributes of the forage plants and their implications on Pasture Management. Institute of Ecology and Resource Management, University sof Edinburgh, West Mains Road, Edinburgh EH9 3JG. England
14 – Borrajo, CI and McLean, GD 2010. Leaf morphogenesis in tropical grasses. AAPA.
15 – Agnusdei, MG, Nenning, FR, Di Marco, ON and Aello, MS2009. Changes in nutritional quality during vegetative growth of grasses Megatérmicas length of various sizes and folia (Chloris gayana and Digitaria decumbens). Journal of Animal Production Argentina Vol 29 (1): 13 – 25 (2009)
