RESEARCH NOTES

Short communication of practical oriented research or relevant information in agriculture or seed technology are presented in this section.

Seed Production of Indigenous Rangeland Forage Species in the Sultanate of Oman by S. K. Nadaf, S.M. Al-Farsi and S.A. Al-Hinai

Bulk seed multiplication of two rangeland forage species viz. Cenchrus ciliaris L (UAE Accession No. MAF-120) and Coelachyrum piercei Benth (UAE Accession No. MAF-116) was entrusted to the Seed and Plant Genetic Resources Laboratory during November 1999 under Phase II of the Arabian Peninsula Research Program (APRP) of ICARDA. Initially 6 g of Cenchrus ciliaris L and 8 g of Coelachyrum piercei Benth were received for seed production. Seed multiplication was carried out at the Agriculture Research Station in Sohar under drip irrigation from March 2000 to February 2002. Total seed yield collected through six harvests was 13.6 kg and 12.6 kg, respectively for C. ciliaris and C. piercei in a span of 600 days. It has been observed that both forage crops produced comparatively more seed yield in summer than in winter season. The studies clearly indicated that seed production of Cenchrus and Coelachyrum is possible throughout the year in Oman. Non-synchronous formation of panicles and early shattering of seed were the problems encountered during seed harvesting in both grass species. New experiments have been initiated to further investigate these problems.

Introduction
The Sultanate of Oman has a large area of rangelands in the Arabian Peninsula especially in Dhofar Jabal areas in the southern part of the country. The indigenous forage species play an important role in the long-term sustainability of rangelands because of their adaptation to the environment. They could be alternative feed resources compared to exotic or imported forage species with high demand for scarce water resources. However, the availability of seed of indigenous forage species is a major limiting factor. More than 60 germplasm accessions of different indigenous forage species have been collected under Phase I of APRP (ICARDA) from 1998-2001. The collections represent part of the genetic diversity of rangeland forage species used by grazing animals. However, few forage species (e.g. C piercei) have been investigated and found capable to emerge under adverse conditions and produce good quality forage as compared to Rhodes grass. The seed of indigenous rangeland forage species have to be multiplied in large quantities before they are evaluated for forage productivity under the existing irrigation system or for reseeding in degraded rangelands.

Large-scale seed production of perennial forages such as Rhodes grass, Kikiyu grass, Prairie grass etc. is carried out under sprinklers in countries like Australia, Canada and the United States. In India, seed production of grass species is carried out under rainfed conditions in established crop stands. In Oman all forage seed of grass species were hitherto imported from abroad. There was no research conducted to assess the possibility to produce seed of any forage species. Therefore, the program was initiated to explore the prospects of seed production of two indigenous rangeland grass species viz. C. ciliaris and C. piercei under the hot arid climatic conditions of Oman.

Materials and Methods
Seed multiplication of two rangeland forage species viz; C. ciliaris (UAE Accession No. MAF-120) and C. piercei (UAE Accession No. MAF-116) were entrusted to the Seed and Plant Genetic Resources Laboratory in November 1999 under Phase II of APRP of ICARDA. Accordingly, 6 and 8 g of C. ciliaris and C. piercei, respectively were supplied to Seed and Plant Genetic Resources Laboratory where seed multiplication was carried out at the Agriculture Research Station in Sohar under drip irrigation from March 2000 to February 2002.

The experiment was planted in loam soil (sand (48.3%), silt (31%), clay (19.7%) and pH of 7.7. The soil has soluble cations (med./100g) of 8.8, 9.8, 1.7 0.6 and 20.9, for Ca, Mg, Na, K and SEC, respectively. The soluble anions (med.100 g) was 0.05, 31.6 and 0.1 for N%, av. (PPM) and av. (med./100g).

From each species, one to two seeds were sown at 2.5 cm depth in loam soil at drip points spaced at 50 cm distance in lines spaced at 50 cm apart. Each species had 20 drip lines with 50 drip points to accommodate 1000 plants in an area of 250 m2. About 10 to 15 granules of systemic insecticide, carbofuran (Furadan) were scattered around each hill to protect the seed from ants. The crop was fertilized with 150 kg each of N, P2O5 and K2O ha^-1 year^-1 in the form of urea, triple super phosphate and potassium sulphate, respectively. The entire amount of phosphorous and potassium fertilizers were applied after seedling establishment while 1/3 of N was applied in two split doses i.e. 1/2 N with P and K or after each harvest and the remaining 1/2 N at flag leaf emergence.

The crop was initially irrigated very lightly with water of about 0.8 dS/m (15 minutes/day) until germination. The duration of irrigation was increased by 5 minutes every week for one month. Afterwards the crop was irrigated daily for 20 to 30 minutes.

Although the initiation of germination was noticed in few hills from the fourth day, in most of the hill points germination was observed only during the second week after sowing. The panicle initiation started first in C. piercei. The two species took about 15 days to attain 50% heading from the day of panicle initiation. The crops were physiologically mature in about three months i.e. during the last week of June 2000. The mature seeds were manually harvested from each plant by grasping the panicles from 4 to 15 July 2000, when the first cut was made at a height of 10 cm from ground level. The second crop came to heading within 25 to 30 days and was harvested during the second week of October 2000. The two species appeared to produce tillers continuously and they were harvested for seed whenever the species showed more than 70% maturity. The data on seed yield (collected) was recorded after cleaning the harvested produce.

Results and Discussion
The details of germination, plant stand, days to 50% heading and maturity, and seed yield (collected with husk) in each harvest for C. ciliaris and C. piercei are given in Tables 1 and 2, respectively. In the first harvest, the highest seed yield was collected from C. ciliaris (2.8 kg) followed by C. piercei (2.2 kg). Subsequent seed harvests were of low magnitude but consistent with plant stand with respect to indigenous grass collections (Tables 1 and 2). Germination of 0 to 4% was observed in each species in the initial test carried out using husked seed immediately after harvest while it was between 27 and 40% after four months of storage indicating seed dormancy.

In a span of about 600 days, the total seed yield was 13.6 kg and 12.6 kg for C. ciliaris and C. piercei, respectively. It has been observed that summer crops produced comparatively more seed yield than in the winter season in both grass species. These studies clearly demonstrated that seed of grass species such as Cenchrus and Coelachyrum can be produced throughout the year in the Gulf climate of Oman.

Problems encountered during seed multiplication
Both grass species are non-synchronous in panicle initiation of tillers. Moreover, shattering of seed from panicles of earlier tillers was high before panicles from late tillers reach maturity. It was difficult to assess a proper harvesting period for panicles of all tillers at one time. Therefore, harvesting has to be started either when earlier formed panicles attain maturity showing signs of shattering (which would indirectly delay cutting time) or all at one compromising time losing some immature seed of late emerging panicles. Furthermore, some mechanism should be developed to collect the shattered seed from the ground.

Although shattering of earlier panicles was less noticed in C. piercei, tillering appeared to be continuous throughout the growing period with no sign of cessation. This made it very difficult to decide the optimum harvesting time.

Future aspects of research in seed multiplication
The seed multiplication exercise was successful in raising the crops and producing satisfactory amounts of seed from two rangeland forage grass species which are germplasm of UAE collections. It has been planned to carry out the following activities with main objectives to:
• Investigate the effect of irrigation systems (drips or sprinklers) to decide which system to be used in commercial seed production of indigenous rangeland forage species
• Extend large scale seed production in different sites under an appropriate irrigation system based on activity (1) for each indigenous rangeland forage species
• Distribute seed of selected indigenous rangeland forage species for performance testing in the farmers' fields (on-farm trials)
• Distribute the seed of selected indigenous rangeland forage species for reseeding in the degraded rangelands

Experiments were already initiated in March 2003 under Phase II of APRP-ICARDA to investigate the appropriate stage of maturity for harvesting seed of such rangeland forage species.