- Email: [email protected]
Indigenous grass species with potential for maintaining rangeland and livestock feeding in Oman
Agriculture, Ecosystems and Environment 95 (2003) 623–627
Indigenous grass species with potential for maintaining rangeland and livestock feeding in Oman Ali El-Kharbotly a,1 , Osman Mahgoub b,∗ , Ali Al-Subhi a , Abdullah Al-Halhali b a
b
Department of Crop Sciences, College of Agriculture, Sultan Qaboos University, P.O. Box 34, Al-Khod 123, Oman Department of Animal and Veterinary Sciences, College of Agriculture, Sultan Qaboos University, P.O. Box 34, Al-Khod 123, Oman Received 30 October 2001; received in revised form 9 September 2002; accepted 16 September 2002
Abstract This study aimed at identifying plant species with potential for rangeland conservation and to provide livestock feed in Oman. A survey was carried out in Al-Khod region near Muscat (Oman) to identify potential grass species. Samples were collected from various sites during the rainy season (November–April) to study the morphology and chemical composition of selected grasses. Cenchrus and Pennisetum species were the most promising grasses in terms of livestock feeding. The yield of pasture dominated by Cenchrus was higher than that reported for the species in other countries with a similar arid environment and comparable to grasses grown in Oman under irrigation. Relevant meteorological records indicated that the grasses had good potential to withstand shortage of water. The germination test on burs and seeds showed high dormancy reflecting ability to survive under uncertain rainfall and potential for survival under rangeland conditions. Storage of seeds for a period of 1 year improved their germination up to 66%. Variation in morphological traits indicated the suitability of grasses to develop varieties for commercial use under farm or rangeland conditions. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Oman; Cenchrus; Pennisetum; Rangeland; Arid zones; Climate
1. Introduction Few plant species are currently used for livestock feeding in Oman and most of them are not native. Non-native plants have a limited level of adaptation to the Omani climatic and environmental conditions, which reduces their ability to produce sufficient animal feed. The shortage of livestock feeding is an important factor for animal production in the country. ∗ Corresponding author. Tel.: +968-515233; fax: +968-513418. E-mail addresses: [email protected] (A. El-Kharbotly), [email protected] (O. Mahgoub). 1 Present address: Plant Production Research Center, Ministry of Agriculture and Fisheries, Sultanate of Oman, P.O. Box 445, Al-Khod 132, Oman. Tel.: +968-893131x223; fax: +968-893097.
Serious environmental problems affect grassland cover in Oman, including salinity and over-grazing. The majority of edible forage species in rangeland are grassy species that need improvement through selection and breeding. Similar approaches have been used under similar natural conditions in India and Zimbabwe based on native grasses including Cenchrus and Setaria species, which are well adapted to low rainfall and arid conditions (Rao et al., 1996). Some preliminary surveys identified native grass species in Oman (MAF, 1982; Ghazanfar, 1990) but their economic potential has not been evaluated. This study aimed to identify grass species with potential for re-introduction in natural habitat or mass production under farming conditions in the Al-Khod region of Al-Batina plains (Sultanate of Oman).
0167-8809/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 - 8 8 0 9 ( 0 2 ) 0 0 1 7 9 - 2
624
A. El-Kharbotly et al. / Agriculture, Ecosystems and Environment 95 (2003) 623–627
2. Materials and methods A survey was conducted in Al-Khod region to collect plant samples for identification and chemical analysis. Samples were collected in January (midrainy season) and April (end of rainy season) 1998 from seven sites selected randomly along small wadis (seasonal water runoffs) and natural water catches in the Al-Khod region. Detailed observations were made on one site where water stayed for a few days after rain. This site is protected from animal grazing throughout the year. Climatological data were obtained from Seeb International Airport, Muscat. Seedlings collected in November were planted the same day in 25 cm pots filled with a common medium based on soil from the site, and kept in a shade house. Watering was done as required but no fertilizer was added. Foliage was cut in April and a second time in August of the same year. Some specimens were collected with roots and kept in plastic bags for identification based on the Herbaria of the Department of Biology, College of Science, Sultan Qaboos University and references on Gulf flora (Migahed, 1978; Al-Rawi, 1987; Webster, 1987; Ghazanfar, 1990; Wood, 1997). Four abundant grass species were studied. Lots, each of 25 plants, were used to record total weight (g), length (mm), inflorescence length (mm) and number of internodes. Each plant was then separated into inflorescence, main stem, leaf blade and leaf sheath that were pooled and oven-dried in paper bags at 70 ◦ C for 72 h, for chemical analyses. Plants in the water catchment were harvested at the flowering stage using a rotary motor grass cutter (STIHL FS 74R) to assess yield and observe regeneration under natural conditions. Ten 1 m2 quadrants were harvested to determine the fresh weights and to estimate yields. Seeds were collected at the end of the rainy season
for further investigation. Samples were pooled and analyzed in terms of dry matter (DM), crude protein (CP), fat (ether extract), crude fiber and ash according to the standard methods of AOAC (1990). A germination test was carried out using four replicates each of 25 burs containing seeds. Three treatments were applied in a complete random design. Treatments were (1) untreated, (2) soaked in water for one week (water changed twice a day), and (3) treated with giberellic acid (GA3) 200 ppm for 15 min. Burs were placed in 20 cm Petri dishes on wet filter paper and kept in an incubator at 23 ◦ C in the dark for 1 month. Observations were made daily to detect germination. After 1 month, burs were left to dry and stored under dry conditions. The same test was repeated on the same batch of seeds twice after a period of 4-month storage each. Another batch of 1-year-old burs was included in the third test. Ungerminated burs were checked for the presence of seeds. Another test was carried out using two batches of seeds after threshing, one batch from burs stored for 1 year, the other freshly collected. These batches were tested for germination without any pre-treatment. ANOVA (SAS, 1991) and correlation analyses were carried out to study relationships between traits.
3. Results Over the last 25 years, meteorological records of the Seeb International Airport, the weather station of the study area, showed that temperature and relative humidity might reach 43.3 ◦ C and 91% during summer, 15.4 ◦ C and 13.0% during winter, the mean minima and maxima being 17.3 ◦ C and 40.4%, 42 ◦ C and 68.2%, respectively. The mean annual rainfall was 86.2 mm with only 3.7, 2.4 and 1.3 mm in 1980,
Table 1 Chemical composition of some fresh samples of grassy species with agricultural potential in Oman (in g/100 g DM) Grass species
Dry matter (%)
Crude protein
Ether extract
Crude fiber
Ash
Cenchrus ciliaris (vegetative stage) C. ciliaris (late vegetative stage) C. ciliaris (flowering stage) Aristidia sp. (vegetative stage) Cymbopogon sp. (vegetative stage) Cymbopogon sp. (late vegetative stage)
24.258 31.246 45.459 58.888 43.368 66.327
11.58 6.852 9.445 9.866 7.745 4.199
1.76 1.678 1.135 ND 1.504 1.531
26.059 27.861 26.882 ND 28.704 31.373
16.315 11.865 8.342 9.979 7.078 9.209
ND: not determined.
Chemical component
Plant part
Grass
S.E.
Cenchrus ciliaris (white)
Cenchrus ciliaris (purplish)
Cenchrus setigerus
Pennisetum macruorum
90.96 90.48 91.501 90.37
91.86 90.22 60.982 76.89
87.99 82.19 83.861 85.42
96.94 91.39 86.591 86.28
DM
Stem Leaf sheath Leaf blade Inflorescence
Crude protein (g/100 g DM)
Stem Leaf sheath Leaf blade Inflorescence
1.96a 4.86b,1,2 7.89c,1 4.80b,1
2.98 3.701 4.702 4.151
Ash (g/100 g DM)
Stem Leaf sheath Leaf blade Inflorescence
7.18a,1,2 13.38b,1,2 17.67b,1,2 7.62a
8.331,2 16.672 18.412 10.18
1.88 4.511,2 7.411 5.691,2 5.671 9.991 13.321 7.53
Significant (probability) Component
Replicate
Plant part
Component part
5.85
0.038
0.8726
0.055
0.2185
2.95 6.102 8.131 6.682
0.65
0
0.0371
0
0.1077
10.402 14.412 14.141 9.57
1.51
0
0.6999
0
0.427
Means followed with the same letter or numbers are not different (P > 0.05). Numbers in superscript (1, 2) for rows and letters in superscript (a, b) for columns within same chemical components.
A. El-Kharbotly et al. / Agriculture, Ecosystems and Environment 95 (2003) 623–627
Table 2 Chemical composition of plant parts of some Cenchrus and Pennisetum species sampled in Oman
625
626
A. El-Kharbotly et al. / Agriculture, Ecosystems and Environment 95 (2003) 623–627
1984, 1985, respectively. Rainfall followed a certain pattern of heavy showers (10–60 mm) mainly in winter months (November to April) except for 1979, 1980, 1984 and 1985 where rainfall ranged between 0.5–8.3 mm during the winter season. However, more than 10 mm rain was recorded in May 1981, October 1987, August 1994 and July 1995. The survey period September 1997 to August 1998 showed the same pattern as the 25-year climate chart. Eighteen species and several varieties with potential as animal feed and conservation of land were identified from the survey carried out in Al-Khod region. These included Aristidia (three spp.), Cenchrus (two spp., three varieties), Lascirius (one sp.), Echinochloa (two spp.), Panicum (two spp.), Octochloa (two spp.) Cymbopogon (one sp.), Pennisetum (one sp.), and Cyprus (one sp.). Pennisetum macruorum Trin. was found in many places but showed very vigorous growth in one site with abundant water supply. Aristidia spp. Ochtochloa compressa (Forssk.) Hilu., and Cyprus conglomeratus, Rottls. were found along Al Hail coastal line. The most abundant grass species were C. ciliaris (white), C. ciliaris (purplish), C. setigerus and P. macruorum. The number of internodes in these species appeared to have little effect on plant height as shown by the low correlation coefficient values (r = 0.336). Average plant height was 680, 626, 489, 644 mm for C. ciliaris (white), C. ciliaris (purplish), C. setigerus and P. macruorum, respectively, the differences being highly significant (P < 0.001) between all species. There was a low correlation between different traits, which indicated that plant length, inflorescence length and number of internodes were not linked. Fresh yield of natural range pasture dominated by Cenchrus spp. at the water catchment location was estimated to 5612 kg/ha (S.E. = 0.068). Tables 1 and 2 reflect the chemical composition of plants sampled. Germination using seeds in burs never exceeded 1% for all grasses under all treatments. Pre-treatment had no stimulatory effect whereas threshing increased germination significantly in both 1-year-old and freshly collected seeds. Germination levels in fresh C. setigerus, purplish C. ciliaris and white C. ciliaris seeds were 24% (±5.3), 34% (±4.5) and 29% (±4.6) whereas in 1-year-old seeds they were 63.3% (±4.5), 64% (±5.3) and 66% (±6.4), respectively. No signif-
icant differences in germination rate were observed between the three grasses (C. setigerus, purplish C. ciliaris and white C. ciliaris).
4. Discussion and conclusion Rainfall is a limiting factor in arid lands as seed germinate only after heavy showers and the plants are able to complete their life cycle on the soil moisture and the showers that follow. In the current study, the most vigorous growth (over 1 m) was observed in areas protected by thorny bushes of Acacia and those closed to animal grazing. Regeneration of grasses from underground rhizomes was observed within a week after rainfall at the start of the rainy season, germination being uniform at different locations. Grazing of seedlings resulted in inability of grasses to reach the flowering stage. Plants that escaped grazing were able to produce tillers, reached flowering stage and shed seeds half way through the rainy season. No germination was observed in areas where seeds were scattered on the soil surface without cover whereas it occurred in areas where the soil had been disturbed by machinery, animals, between stones or along roadsides. Ochtochloa compressa on the coast showed stunted growth probably because of salinity and Cy. conglomeratus appeared to be very useful for coastal conservation as new rhizomes and maximum growth were being observed during winter. Cenchrus spp. seemed promising for animal feed because of height, branching and leaf size, regeneration ability after cutting, and ability to survive the dry season. The species were identified as C. ciliaris and C. setigerus, two varieties of the former being found, one with purplish (Wood, 1997), the other with white inflorescence (Migahed, 1978). The species are very palatable when young and remain so at maturity (Sherman and Riveros, 1990). They have been introduced to northern Australia and are being cultivated in permanent pastures in East and Central Africa and Northern Australia; they form one of the most important natural hay grasses in India, Mexico and the US (Whyte et al., 1975). Yield of grasses dominated by Cenchrus spp. from the catchment was higher than in the arid zone of India with or without fertilizer (1785 and 942 kg/ha, respectively) (Rao et al., 1996).
A. El-Kharbotly et al. / Agriculture, Ecosystems and Environment 95 (2003) 623–627
Vigorous growth of C. ciliaris as well as other grasses was observed under Acacia trees, probably due to the provision of shade and nitrogen. Such conditions may be adapted for management of rangeland grasses under Omani conditions. High protein and low fiber content of Cenchrus make it superior to Rhodes grass commonly grown in Oman (Mahgoub and Lodge, 1994). Natural rangeland grasses should be utilized early in the season for early grazing and subsequent regeneration and seed production. Selection of grasses with more internodes could increase the total crude protein and ash contents. Both variations and absence of link are promising in terms of breeding grass with economical value. The extremely low germination rate indicates strong dormancy, which is useful for the plants to survive, but hinders quick breeding programs. Selecting for short or no dormancy should facilitate the domestication of these grasses but at the same time is likely to lower their survival rate. Two separate breeding programs for seeds with long or short dormancy should therefore be carried out to produce grasses for natural rangeland and for use under irrigation. All species collected grew well under irrigation in the shade house and reached flowering stage at the same time as in their natural habitat. All plants regenerated after harvesting. Growth of plants was slow during the June/July period. Cenchrus spp. produced flowers in April and again in August. Several crops per year may hence be obtained from these grasses after cutting under irrigation. Repeated cutting could also provide higher yields per area of animal feed that may be preserved as hay or silage.
627
Acknowledgements The authors would like to thank Ms Amina Al-Farsi of the Department of Biology, College of Science, Sultan Qaboos University for assistance with identification of grass species. This paper is published as paper #291000. References Al-Rawi, A., 1987. Flora of Kuwait. Compositae and Monocotyledonae, vol. II. Kuwait University, Kuwait. AOAC, 1990. Official Methods of Analysis, 15th ed. Association of Official Analytical Chemists, Virginia, USA. Ghazanfar, S.A., 1990. An Annotated Catalogue of the Vascular Plants of Oman. Department of Biology, College of Science, Sultan Qaboos University Press, Muscat, Oman. MAF, 1982. Survey of Grazing Lands for Livestock. Final Report. Ministry of Agriculture and Fisheries, Muscat, Oman. Mahgoub, O., Lodge, G.A., 1994. Growth and body composition of Omani local sheep. 1. Live-weight growth and carcass and non-carcass characteristics. Anim. Prod. 58, 365–372. Migahed, A.H., 1978. Migahed and Hammouda’s Flora of Saudi Arabia. Monocotyledons, vol. II, 2nd ed. Riyadh University Publication, Riyadh, Saudi Arabia. Rao, A.S., Singh, K.C., White, G.R., 1996. Productivity of Cenchrus ciliaris in relation to rainfall and fertilization. J. Range Manage. 49, 143–146. SAS, 1991. SAS for Windows, Version 6.0. SAS Institute, Cary, NC. Sherman, P.J., Riveros, F., 1990. Tropical Grasses. FAO, Rome. Webster, R.D., 1987. The Australian Paniceae (Poaceae). J. Cramer, Berlin, Germany. Whyte, R.O., Moir, T.R., Cooper, J.P., 1975. Grasses in Agriculture. FAO Agricultural Studies, Rome. Wood, J.R.L., 1997. A Handbook of the Yemen Flora. Royal Botanic Gardens, Kew.
Indigenous grass species with potential for maintaining rangeland and livestock feeding in Oman Ali El-Kharbotly a,1 , Osman Mahgoub b,∗ , Ali Al-Subhi a , Abdullah Al-Halhali b a
b
Department of Crop Sciences, College of Agriculture, Sultan Qaboos University, P.O. Box 34, Al-Khod 123, Oman Department of Animal and Veterinary Sciences, College of Agriculture, Sultan Qaboos University, P.O. Box 34, Al-Khod 123, Oman Received 30 October 2001; received in revised form 9 September 2002; accepted 16 September 2002
Abstract This study aimed at identifying plant species with potential for rangeland conservation and to provide livestock feed in Oman. A survey was carried out in Al-Khod region near Muscat (Oman) to identify potential grass species. Samples were collected from various sites during the rainy season (November–April) to study the morphology and chemical composition of selected grasses. Cenchrus and Pennisetum species were the most promising grasses in terms of livestock feeding. The yield of pasture dominated by Cenchrus was higher than that reported for the species in other countries with a similar arid environment and comparable to grasses grown in Oman under irrigation. Relevant meteorological records indicated that the grasses had good potential to withstand shortage of water. The germination test on burs and seeds showed high dormancy reflecting ability to survive under uncertain rainfall and potential for survival under rangeland conditions. Storage of seeds for a period of 1 year improved their germination up to 66%. Variation in morphological traits indicated the suitability of grasses to develop varieties for commercial use under farm or rangeland conditions. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Oman; Cenchrus; Pennisetum; Rangeland; Arid zones; Climate
1. Introduction Few plant species are currently used for livestock feeding in Oman and most of them are not native. Non-native plants have a limited level of adaptation to the Omani climatic and environmental conditions, which reduces their ability to produce sufficient animal feed. The shortage of livestock feeding is an important factor for animal production in the country. ∗ Corresponding author. Tel.: +968-515233; fax: +968-513418. E-mail addresses: [email protected] (A. El-Kharbotly), [email protected] (O. Mahgoub). 1 Present address: Plant Production Research Center, Ministry of Agriculture and Fisheries, Sultanate of Oman, P.O. Box 445, Al-Khod 132, Oman. Tel.: +968-893131x223; fax: +968-893097.
Serious environmental problems affect grassland cover in Oman, including salinity and over-grazing. The majority of edible forage species in rangeland are grassy species that need improvement through selection and breeding. Similar approaches have been used under similar natural conditions in India and Zimbabwe based on native grasses including Cenchrus and Setaria species, which are well adapted to low rainfall and arid conditions (Rao et al., 1996). Some preliminary surveys identified native grass species in Oman (MAF, 1982; Ghazanfar, 1990) but their economic potential has not been evaluated. This study aimed to identify grass species with potential for re-introduction in natural habitat or mass production under farming conditions in the Al-Khod region of Al-Batina plains (Sultanate of Oman).
0167-8809/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 - 8 8 0 9 ( 0 2 ) 0 0 1 7 9 - 2
624
A. El-Kharbotly et al. / Agriculture, Ecosystems and Environment 95 (2003) 623–627
2. Materials and methods A survey was conducted in Al-Khod region to collect plant samples for identification and chemical analysis. Samples were collected in January (midrainy season) and April (end of rainy season) 1998 from seven sites selected randomly along small wadis (seasonal water runoffs) and natural water catches in the Al-Khod region. Detailed observations were made on one site where water stayed for a few days after rain. This site is protected from animal grazing throughout the year. Climatological data were obtained from Seeb International Airport, Muscat. Seedlings collected in November were planted the same day in 25 cm pots filled with a common medium based on soil from the site, and kept in a shade house. Watering was done as required but no fertilizer was added. Foliage was cut in April and a second time in August of the same year. Some specimens were collected with roots and kept in plastic bags for identification based on the Herbaria of the Department of Biology, College of Science, Sultan Qaboos University and references on Gulf flora (Migahed, 1978; Al-Rawi, 1987; Webster, 1987; Ghazanfar, 1990; Wood, 1997). Four abundant grass species were studied. Lots, each of 25 plants, were used to record total weight (g), length (mm), inflorescence length (mm) and number of internodes. Each plant was then separated into inflorescence, main stem, leaf blade and leaf sheath that were pooled and oven-dried in paper bags at 70 ◦ C for 72 h, for chemical analyses. Plants in the water catchment were harvested at the flowering stage using a rotary motor grass cutter (STIHL FS 74R) to assess yield and observe regeneration under natural conditions. Ten 1 m2 quadrants were harvested to determine the fresh weights and to estimate yields. Seeds were collected at the end of the rainy season
for further investigation. Samples were pooled and analyzed in terms of dry matter (DM), crude protein (CP), fat (ether extract), crude fiber and ash according to the standard methods of AOAC (1990). A germination test was carried out using four replicates each of 25 burs containing seeds. Three treatments were applied in a complete random design. Treatments were (1) untreated, (2) soaked in water for one week (water changed twice a day), and (3) treated with giberellic acid (GA3) 200 ppm for 15 min. Burs were placed in 20 cm Petri dishes on wet filter paper and kept in an incubator at 23 ◦ C in the dark for 1 month. Observations were made daily to detect germination. After 1 month, burs were left to dry and stored under dry conditions. The same test was repeated on the same batch of seeds twice after a period of 4-month storage each. Another batch of 1-year-old burs was included in the third test. Ungerminated burs were checked for the presence of seeds. Another test was carried out using two batches of seeds after threshing, one batch from burs stored for 1 year, the other freshly collected. These batches were tested for germination without any pre-treatment. ANOVA (SAS, 1991) and correlation analyses were carried out to study relationships between traits.
3. Results Over the last 25 years, meteorological records of the Seeb International Airport, the weather station of the study area, showed that temperature and relative humidity might reach 43.3 ◦ C and 91% during summer, 15.4 ◦ C and 13.0% during winter, the mean minima and maxima being 17.3 ◦ C and 40.4%, 42 ◦ C and 68.2%, respectively. The mean annual rainfall was 86.2 mm with only 3.7, 2.4 and 1.3 mm in 1980,
Table 1 Chemical composition of some fresh samples of grassy species with agricultural potential in Oman (in g/100 g DM) Grass species
Dry matter (%)
Crude protein
Ether extract
Crude fiber
Ash
Cenchrus ciliaris (vegetative stage) C. ciliaris (late vegetative stage) C. ciliaris (flowering stage) Aristidia sp. (vegetative stage) Cymbopogon sp. (vegetative stage) Cymbopogon sp. (late vegetative stage)
24.258 31.246 45.459 58.888 43.368 66.327
11.58 6.852 9.445 9.866 7.745 4.199
1.76 1.678 1.135 ND 1.504 1.531
26.059 27.861 26.882 ND 28.704 31.373
16.315 11.865 8.342 9.979 7.078 9.209
ND: not determined.
Chemical component
Plant part
Grass
S.E.
Cenchrus ciliaris (white)
Cenchrus ciliaris (purplish)
Cenchrus setigerus
Pennisetum macruorum
90.96 90.48 91.501 90.37
91.86 90.22 60.982 76.89
87.99 82.19 83.861 85.42
96.94 91.39 86.591 86.28
DM
Stem Leaf sheath Leaf blade Inflorescence
Crude protein (g/100 g DM)
Stem Leaf sheath Leaf blade Inflorescence
1.96a 4.86b,1,2 7.89c,1 4.80b,1
2.98 3.701 4.702 4.151
Ash (g/100 g DM)
Stem Leaf sheath Leaf blade Inflorescence
7.18a,1,2 13.38b,1,2 17.67b,1,2 7.62a
8.331,2 16.672 18.412 10.18
1.88 4.511,2 7.411 5.691,2 5.671 9.991 13.321 7.53
Significant (probability) Component
Replicate
Plant part
Component part
5.85
0.038
0.8726
0.055
0.2185
2.95 6.102 8.131 6.682
0.65
0
0.0371
0
0.1077
10.402 14.412 14.141 9.57
1.51
0
0.6999
0
0.427
Means followed with the same letter or numbers are not different (P > 0.05). Numbers in superscript (1, 2) for rows and letters in superscript (a, b) for columns within same chemical components.
A. El-Kharbotly et al. / Agriculture, Ecosystems and Environment 95 (2003) 623–627
Table 2 Chemical composition of plant parts of some Cenchrus and Pennisetum species sampled in Oman
625
626
A. El-Kharbotly et al. / Agriculture, Ecosystems and Environment 95 (2003) 623–627
1984, 1985, respectively. Rainfall followed a certain pattern of heavy showers (10–60 mm) mainly in winter months (November to April) except for 1979, 1980, 1984 and 1985 where rainfall ranged between 0.5–8.3 mm during the winter season. However, more than 10 mm rain was recorded in May 1981, October 1987, August 1994 and July 1995. The survey period September 1997 to August 1998 showed the same pattern as the 25-year climate chart. Eighteen species and several varieties with potential as animal feed and conservation of land were identified from the survey carried out in Al-Khod region. These included Aristidia (three spp.), Cenchrus (two spp., three varieties), Lascirius (one sp.), Echinochloa (two spp.), Panicum (two spp.), Octochloa (two spp.) Cymbopogon (one sp.), Pennisetum (one sp.), and Cyprus (one sp.). Pennisetum macruorum Trin. was found in many places but showed very vigorous growth in one site with abundant water supply. Aristidia spp. Ochtochloa compressa (Forssk.) Hilu., and Cyprus conglomeratus, Rottls. were found along Al Hail coastal line. The most abundant grass species were C. ciliaris (white), C. ciliaris (purplish), C. setigerus and P. macruorum. The number of internodes in these species appeared to have little effect on plant height as shown by the low correlation coefficient values (r = 0.336). Average plant height was 680, 626, 489, 644 mm for C. ciliaris (white), C. ciliaris (purplish), C. setigerus and P. macruorum, respectively, the differences being highly significant (P < 0.001) between all species. There was a low correlation between different traits, which indicated that plant length, inflorescence length and number of internodes were not linked. Fresh yield of natural range pasture dominated by Cenchrus spp. at the water catchment location was estimated to 5612 kg/ha (S.E. = 0.068). Tables 1 and 2 reflect the chemical composition of plants sampled. Germination using seeds in burs never exceeded 1% for all grasses under all treatments. Pre-treatment had no stimulatory effect whereas threshing increased germination significantly in both 1-year-old and freshly collected seeds. Germination levels in fresh C. setigerus, purplish C. ciliaris and white C. ciliaris seeds were 24% (±5.3), 34% (±4.5) and 29% (±4.6) whereas in 1-year-old seeds they were 63.3% (±4.5), 64% (±5.3) and 66% (±6.4), respectively. No signif-
icant differences in germination rate were observed between the three grasses (C. setigerus, purplish C. ciliaris and white C. ciliaris).
4. Discussion and conclusion Rainfall is a limiting factor in arid lands as seed germinate only after heavy showers and the plants are able to complete their life cycle on the soil moisture and the showers that follow. In the current study, the most vigorous growth (over 1 m) was observed in areas protected by thorny bushes of Acacia and those closed to animal grazing. Regeneration of grasses from underground rhizomes was observed within a week after rainfall at the start of the rainy season, germination being uniform at different locations. Grazing of seedlings resulted in inability of grasses to reach the flowering stage. Plants that escaped grazing were able to produce tillers, reached flowering stage and shed seeds half way through the rainy season. No germination was observed in areas where seeds were scattered on the soil surface without cover whereas it occurred in areas where the soil had been disturbed by machinery, animals, between stones or along roadsides. Ochtochloa compressa on the coast showed stunted growth probably because of salinity and Cy. conglomeratus appeared to be very useful for coastal conservation as new rhizomes and maximum growth were being observed during winter. Cenchrus spp. seemed promising for animal feed because of height, branching and leaf size, regeneration ability after cutting, and ability to survive the dry season. The species were identified as C. ciliaris and C. setigerus, two varieties of the former being found, one with purplish (Wood, 1997), the other with white inflorescence (Migahed, 1978). The species are very palatable when young and remain so at maturity (Sherman and Riveros, 1990). They have been introduced to northern Australia and are being cultivated in permanent pastures in East and Central Africa and Northern Australia; they form one of the most important natural hay grasses in India, Mexico and the US (Whyte et al., 1975). Yield of grasses dominated by Cenchrus spp. from the catchment was higher than in the arid zone of India with or without fertilizer (1785 and 942 kg/ha, respectively) (Rao et al., 1996).
A. El-Kharbotly et al. / Agriculture, Ecosystems and Environment 95 (2003) 623–627
Vigorous growth of C. ciliaris as well as other grasses was observed under Acacia trees, probably due to the provision of shade and nitrogen. Such conditions may be adapted for management of rangeland grasses under Omani conditions. High protein and low fiber content of Cenchrus make it superior to Rhodes grass commonly grown in Oman (Mahgoub and Lodge, 1994). Natural rangeland grasses should be utilized early in the season for early grazing and subsequent regeneration and seed production. Selection of grasses with more internodes could increase the total crude protein and ash contents. Both variations and absence of link are promising in terms of breeding grass with economical value. The extremely low germination rate indicates strong dormancy, which is useful for the plants to survive, but hinders quick breeding programs. Selecting for short or no dormancy should facilitate the domestication of these grasses but at the same time is likely to lower their survival rate. Two separate breeding programs for seeds with long or short dormancy should therefore be carried out to produce grasses for natural rangeland and for use under irrigation. All species collected grew well under irrigation in the shade house and reached flowering stage at the same time as in their natural habitat. All plants regenerated after harvesting. Growth of plants was slow during the June/July period. Cenchrus spp. produced flowers in April and again in August. Several crops per year may hence be obtained from these grasses after cutting under irrigation. Repeated cutting could also provide higher yields per area of animal feed that may be preserved as hay or silage.
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Acknowledgements The authors would like to thank Ms Amina Al-Farsi of the Department of Biology, College of Science, Sultan Qaboos University for assistance with identification of grass species. This paper is published as paper #291000. References Al-Rawi, A., 1987. Flora of Kuwait. Compositae and Monocotyledonae, vol. II. Kuwait University, Kuwait. AOAC, 1990. Official Methods of Analysis, 15th ed. Association of Official Analytical Chemists, Virginia, USA. Ghazanfar, S.A., 1990. An Annotated Catalogue of the Vascular Plants of Oman. Department of Biology, College of Science, Sultan Qaboos University Press, Muscat, Oman. MAF, 1982. Survey of Grazing Lands for Livestock. Final Report. Ministry of Agriculture and Fisheries, Muscat, Oman. Mahgoub, O., Lodge, G.A., 1994. Growth and body composition of Omani local sheep. 1. Live-weight growth and carcass and non-carcass characteristics. Anim. Prod. 58, 365–372. Migahed, A.H., 1978. Migahed and Hammouda’s Flora of Saudi Arabia. Monocotyledons, vol. II, 2nd ed. Riyadh University Publication, Riyadh, Saudi Arabia. Rao, A.S., Singh, K.C., White, G.R., 1996. Productivity of Cenchrus ciliaris in relation to rainfall and fertilization. J. Range Manage. 49, 143–146. SAS, 1991. SAS for Windows, Version 6.0. SAS Institute, Cary, NC. Sherman, P.J., Riveros, F., 1990. Tropical Grasses. FAO, Rome. Webster, R.D., 1987. The Australian Paniceae (Poaceae). J. Cramer, Berlin, Germany. Whyte, R.O., Moir, T.R., Cooper, J.P., 1975. Grasses in Agriculture. FAO Agricultural Studies, Rome. Wood, J.R.L., 1997. A Handbook of the Yemen Flora. Royal Botanic Gardens, Kew.