The Potentials of Rhodes Grass (Chloris Gayana Kunth) as Drought Resistant Perennial Forage Grass in Nigeria

Rhodes grass, abyssinian Rhodes grass, Callide Rhodes grass, common Rhodes grass [English]; chloris, herbe de Rhodes [French]; capim de Rhodes [Portuguese]; grama de Rodas, pasto de Rodas, pasto Rhodes, zacate gordura [Spanish]; rhodesgras [Afrikaans]; koro-korosan [Philippines/Tagalog]. Rhodes grass is a perennial or annual tropical grass. It is a leafy grass, 1-2 m in height, highly variable in habit. The culms are tufted or creeping, erect or decumbent, sometimes rooting from the nodes. The roots are very deep, down to 4.5 m. The leaves are linear, with flat or folded glabrous blades, 12-50 cm long x 10-20 mm wide, tapering at the apex. The seed head has an open hand shape and encompasses 2-10 one-sided or double-sided racemes, 4-15 cm long. The inflorescences are light greenish brown (rarely yellow) in colour and turn darker brown as they mature [1]. The spikelets (over 32) are densely imbricated and have two awns. The fruit is a caryopsis, longitudinally grooved [1-5].

The low nutritive quality of the forage during the growth period is mainly due to environmental stresses such as high temperatures [6], infertile soils [7] and poor management [8]. In recent years, there has been several attempts to improve the nutritive quality of the forage resources through propagation of improved species with high nutritive value [9], which requires establishment of suitable sown pasture and feed lots to meet the higher nutritional needs of more productive animals [10].
Rhodes grass (Chloris gayana Kunth) being one of the improved pasture species in Nigeria has been increasingly cultivated over the last few years in the country due to its high dry matter yield, favourable economics of cultivation, and superiority over other perennial forage grasses [11].
In order to improve the availability of good quality pasture feed, a fast growing, high yielding and qualitative forage species are required for the development of sown pastures (via pasture agronomy) that are to be sustained under intensive systems of management. Intensive pasture production make use of forage species that prove their superiority in terms of bulk productivity (dry matter yield per unit area), palatability, chemical composition, nutrient availability, persistence under defoliation regimes and inclement climatic conditions, competition and compatibility with other forages in the pasture ecosystem (Muhammad and Abubakar, 2004). Therefore there is need to evaluate the growth and herbage yield of the newly introduced pasture species such as Rhode grass (Chloris gayana Kunth) while subjecting it to some management practices for optimum growth, yield and nutritive value to increase the availability of good quality feed for improved livestock production. areas under natural pastures or by increasing yields per unit land area through intensive production of improved pasture species.
With the present trend of competitive land use in Nigeria, increasing pasture feed production through expansion of land area under natural pasture is hardly feasible as a result of the demographic changes. The only viable option therefore remains the production of improved species of grasses and legumes for intensive livestock production due to their high forage yield and nutritive value [13][14].
More so, pasture management techniques such as fertilization and spacing are utilized in order to secure a desirable balance for high productivity [15,16]. Therefore, evaluation of growth and herbage yield of Rhodes grass (Chloris gayana Kunth) as affected by nitrogen fertilizer and inter row spacing in Sokoto sound justifiable.
The major objective of this paper is to evaluate the potentials of Rhode grass (Chloris gayana Kunth) in Nigeria.

Origin and Distribution
Chloris gayana is a native of South Africa and was named Rhodes after the famous Cecil Rhodes, who popularized it [17].
Rhodes grass is now widespread in tropical and subtropical areas worldwide. It was introduced into India, Pakistan, Australia and the USA. In Australia, it was introduced by soldiers returning from the Boer wars at the beginning of the 20th century. In Western Australia, Rhodes grass has become one of the most widely sown subtropical grasses since year 2000 [4]. The species was introduced in India through USA and later in Karnataka in 1920. Being drought resistant, Rhodes grass is found in semi-arid region and other lowlying areas [17].

Botany
Rhodes grass is a perennial or annual tropical grass. It is a leafy grass, 1-2m in height, highly variable in habit. The culms are tufted or creeping, erect or decumbent, sometimes rooting from the nodes. The roots are very deep, down to 4.5m. The leaves are linear, with flat or folded smooth blades, 12-50cm long x 10-20mm wide, tapering at the apex. The seed head has an open hand shape and encompasses 2-10 one-sided or double-sided racemes, 4-15cm long. The inflorescences are light greenish brown (rarely yellow) in colour and turn darker brown as they mature [1]. The spikelets (over 32) are densely arranged in an overlapping manner and have two awns. The fruit is a caryopsis, longitudinally grooved [1][2][3][4][5]. It has a straw coloured on ripening. It produces profuse amount of seeds. Seed count 7250000 to 9500000/kg [17].

Adaptation
Rhodes grass is a spring and summer-growing grass found in open woodlands and grasslands, in road margins, disturbed sites and riverbanks. It is cultivated as sown pastures in irrigated terraces [1,3]. Chloris gayana thrives in places where annual temperatures range from 16.5°C to above 26°C, with maximum growth at 30°C/25°C (day/night temperature). Optimal annual rainfall is about 600-750mm with a summer-rainfall period [1,4,18]. Rhodes grass can survive in areas where annual rainfall ranges between 310mm and 4030mm and where temperature extremes are 5°C and 50°C [1,5]. Due to its deep roots, Rhodes grass can withstand long dry periods (over 6 months) and up to 15 days of flooding [1,2]. Seasonal water logging over 30cm kills the plant [2]. Rhodes grass grows on a wide range of soils from poor sandy soils to heavy clayey alkaline and saline soils (more than 10 dS/m). This salt tolerance is particularly valuable in irrigated pastures where it can be cultivated without problem. Rhodes grass does better on fertile, well-structured soils and it prefers soil pH between 5.5 and 7.5. Establishment on acidic soils is difficult. It is tolerant of Li but not of Mn and Mg [1]. Chloris gayana is a full sunlight species which does not grow well under shade [1,2,18].

Land preparation
The land should be cleared from weeds and trees before ploughing [19]. The land should be ploughed two to three times to get a fine and leveled seedbed. As the Rhodes grass seed is very small it needs a well-prepared seedbed [20]. The seedbed should be ploughed and prepared well. A well-prepared seedbed favours seed germination, seedling emergence and growth [21].

Planting time
Planting should be done at the start of the main rainy season when the soil has received sufficient moisture to support germination and establishment. Seed germinates within 7 days after planting [1]. Sowing too deeply will result in failure or poor germination. Rhodes grass seed will germinate under slightly cooler conditions than most summer growing grasses [21].

Seed rate and planting methods
Rhodes grass can be established vegetatively (root splits) or from seed. Seed rate varies depending on seed quality (germination and purity), sowing method, environmental conditions and land preparation. Generally, the seed rate should be from 3 -15kgha -1 considering the previous factors. High seed rate is usually important in cooler and high-altitude areas. Seed should be sown on the surface no deeper than 2cm [1]. Rhodes grass can be row sown or broadcasted. For broadcasting seed can be mixed with soil or sand. After sowing it should be covered with light soil by using tree branches. Alternatively, sowing the seed and light packing by driving animals before and after sowing is also another option.
However, if the labour is available, it can be planted in rows. In this case, the spacing between rows should be 20cm [22]. Planting should be conducted when the soil gets moist and care has to be taken to uniformly apply/drill the seeds over the prepared land [21].

Fertilizer application
Rhodes grass is productive in moderate to high fertile soils.
If the soil is infertile, applying nutrients to the soil is essential.
Applying nitrogen and phosphorus fertilizers is recommended.
Applying DAP fertilizer at the rate of 100kgha -1 at planting and urea at the rate of 50kgha -1 after establishment and at every cut is essential. Some literatures recommend applying 100kgha-1 nitrogen after each cut. If available, applying manure is another option. Manure can be applied at the rate of 5 -10 tonsha -1 [19].
In general, grasses have a high requirement for N, P and K. These nutrients should be applied after each cut or grazing. Generally, it is recommended that annual maintenance nutrient requirements for N, P and K is 50 -300kgha -1 , 10 -20kgha -1 and 25 -50kgha -1 , respectively [19]. In addition to biomass improvement, fertilizer application enhances both nutritive value and yield. Rhodes grass gives an increased response to phosphorus in some areas and usually a spectacular linear response to nitrogen in the presence of adequate phosphorus and potassium, both in yield and in crude protein content. Split applications after each cut or after grazing cycles are better than one basic application with the usual rate of 275 to 400kgha -1 . Generally, cut and carry system requires more maintenance inputs than the grazing system. If sown pastures are well-utilized and maintained with fertilizers, they will continue to provide high herbage yield for up to five years and start to decline thereafter. The usual productive life of Rhodes grass is three years; this can be extended by optimum fertilization [21].

Weed, insect pest and disease control
The newly established pasture should be free from weeds.
Removing weeds by hand is essential thus, removing weeds reduces competition when the grass is weak, and it also minimizes the chances of further perpetuation of weeds by seed. Weed removal at early stage of Rhodes grass production is crucial as the plant is weak at this stage removing weeds makes establishment easier and enhances further survival. Weeding twice after planting at monthly intervals during establishment is recommended. Harvesting the grass and weeds together using sickle when there is vigorous growth is another alternative to control weeds. Using herbicide like 2-4-D is also effective to remove young broad-leaved weeds [22]. CASCAPE (2015) [21] reported that there are no insects observed on Rhodes grass but common pests such as armyworm may attack Rhodes grass pasture. There are no diseases observed on Rhodes grass production during CASCAPE project interventions in different districts of north-western Ethiopia. Diseases are more severe with legumes than with grasses.

Harvesting, threshing and post-harvest handling
To obtain high quantity and quality feed, the Rhodes grass should be harvested at 50% flowering stage. Harvesting Rhodes grass at early stage will ensure higher levels of Crude Protein (CP) in the harvested material. As the harvesting time gets late the crude protein level of the grass gets low. The newly established pasture through seed sowing can be utilized within 3 -5 months after sowing. The harvested material can be fed to livestock as fresh or it can be made hay for later feeding. If root split is used as a planting material, first harvest can be done from two to three months provided that there is adequate moisture and fertilizer application. Burning is applicable in Rhodes grass as the grass is fire tolerant [21].

Nitrogen Fertilizer and its Effect on Plant Growth and Yield
High crop responses in terms of growth, tiller production, and tissue concentration of elements, and yield have been associated with application of nitrogen fertilizer [23]. The nutritive value of crops is also increased as a result of nitrogen fertilization. [24] reported that applied nitrogen (0, 84, and 168 kgNha -1 ) in guinea grass increased dry matter yield of total herbage (5840, 8460 and 12400kgha -1 respectively) [25]. also reported increase in the dry matter yield of guinea grass with increasing nitrogen fertilizer application and recommended a dosage of 400kgNha -1 per year for guinea grass in Cuba. Application of nitrogen fertilizer was found to significantly increase the number of tillers per plant, total herbage yield of guinea grass grown in Nsukka, Nigeria [26,27]. Observed that the dry matter and crude protein yields on guinea grass sward depended largely on the level of N fertilizer applied. [28] reported that nitrogen fertilization increased the crude protein of Rhodes grass by 15% at the early stage of growth.

Effect of Nitrogen Fertilizer on Rhodes Grass (Chloris gayana) Production
Fertilizer is the most important input that improves yield, growth and also the quality of annual forage plants. It has been observed that Rhodes grass responded well to nitrogen (N) fertilizer after a basic pre-plant phosphorous (P) application [29][30][31][32]. Moreover, response of Rhodes grass was remarkable when nitrogen fertilizer was applied in a separate split dose [29,31,33,34].
Leaf area and leaf to stem ratio of Rhodes grass also increase by increasing nitrogen fertilizer [35]. Fertilizers treatment had a very significant effect on fodder yield both fresh and dry [35,36]. Thus, nitrogen and phosphorous fertilizers play very important role to enhance the fodder production both in quality and quantity of Rhodes grass [29].

Effects of Spacing on Plant Growth and Yield
It is always good to follow the recommended crop spacing guidelines since overcrowding of crops may reduce yields and it may also lower quality of the fruits produced because of competition for light and soil nutrients. If crops are planted too close to one another, it may be hard for the farmer to walk about in the garden weeding, spraying pesticides or doing crop inspection [37]. Appropriate spacing enables the farmer to keep appropriate plant population, avoid over and under population in a given plot of land which has negative effect on yield and quality [38]. Nadaf et al. Research Institute Shika, Zaria [39,40]. Reported that the wider the inter row and intra row spacing of 75cm and 100cm respectively produced the highest dry matter yield with Vigna unguicuata L. var.  [41,42]. Reported that data on growth performance of Rhodes grass generally ranges from 7 -25 tonsDMha -1 per year, depending on variety, soil fertility, environmental conditions and cutting frequency [1,2122]. Reported that on average, the herbage yield of Rhodes grass based on a study conducted on farmers' fields in the central highlands of Ethiopia was from 8.74 to 9.1 tons DMha -1 per year on rain-fed conditions. Based on several studies, the dry matter yields of [41,42,45] also reported that the herbage yield of Rhodes grass varies generally with type of cultivar, age of the plant and other environmental factors. Table 1

Methods of Growth and Herbage Yield Estimation
Generally, the weight of herbage material is expressed on the dry matter basis rather than on the fresh (green) basis. This is because dry matter (DM) is a solid substance that is not subjected to daily fluctuation of its content, unlike fresh weight (FAO, 1980) [46]. reported that weight of herbage produced is one of the most important characteristics of the range plants and it is probably the best single measure of growth. Biomass is the weight of organic matter per unit area and the organic matter might include weight of new growth herbage above ground, wild animals, roots, dead organic matter or mature trees. In vegetation studies this is usually done based on unit area measurement, which is square centimeter or square meter. In measuring biomass, the herbage is clipped to constant weight in the laboratory and then weighed. The herbage biomass for the larger area is then found through multiplication [47,48]. Reported that there may by three general methods of One of the merits of this method is that it reduces the cost of labour and time involved in cutting, weighing and drying of samples.

Factors Affecting Growth and Herbage Yield
Agro-ecological factors: According to [21], Rhodes grass (Chloris gayana) is a stoloniferous perennial grass that grows in a wide range of climates (rainfall and temperature) and soil types.
Rhodes grass grows better in areas where annual rainfall is above 600mm and altitude ranges from 1400 -2400 masl. Rhodes grass grows on a wide range of soils. It grows well on well drained moderate to high fertility soils. It can also survive on infertile soils although it is unproductive and may eventually die out particularly if grazed regularly. It is not tolerant to water logging. Rhodes grass has some establishment problems on very acidic soils, but it is tolerant to saline conditions. Generally, Rhodes grass is a poor shade tolerant forage crop. Once well-established, Rhodes grass recovers well after fire due to its vigorous fibrous root system.
Rhodes grass is moderately drought resistant. In addition, due to its vigorous horizontal root (stoloniferous) growth and extensive roots, Rhodes grass has great contribution in soil binding and soil erosion control [63][64][65][66].

Conclusion and Recommendation
Based on the result obtained from this study, it is recommended that Rhodes grass should be cultivated with 120KgNha -1 and 30cm inter row spacing in the study area.