Seed yield and vegetation characteristics of Cenchrus Ciliaris as influenced by fertilizer levels, row spacing, cutting height and season

Grass pasture seed production is commonly done in wet season in Tanzania with limited information on production in dry season under irrigation. Low fertility of soils and high risks of diseases are reported to affect pasture grass seed yield and viability in wet season while their demand is growing. There was a need to conduct a study to gain a practical experience on how to compromise facts on seed and forage biomass production under field conditions in sub humid agro-ecological zone of Tanzania. An experiment was conducted at Sokoine University of Agriculture farm to assess effects of different levels of Nitrogen and Phosphorus (0N 0P, 40N 20P, 60N 30P), row spacing (25, 75 and 100 cms) and cutting height (15cm, ground cut) under rain fed and irrigation in wet and dry seasons on seed yield and vegetation characteristics of Cenchrus ciliaris cv.Biloela. The study was done in two consecutive years 2012 and 2013 (March – June and June- September) for long rains and dry season respectively.

Seed yields were higher at higher rates of nitrogen and phosphorus at ground cutting (77.5 kg/ha) than at 15cm cutting height (56.7kg/ha) with a trend of decreased seed yields in the year second (77.5 to 38.4kg/ha) and (56.7 to 35.5 kg/ha) at the same levels of nitrogen and phosphorus. Row spacing of 100cm showed slightly higher seed yield (70 kg/ha) as compared to other two row spacing (25 cm and 75cm) that gave 67.2 and 69.3 kg/ha respectively. Higher seed yields were observed in dry than wet season for two consecutive years under all cutting heights (37.8 and 66.7 kg/ha 15cm cutting for wet and dry season respectively). Higher levels of nitrogen and phosphorus yielded significantly (p<0.05) higher forage biomass (13.2 tonnes nes DM/ha) and (11.1 tonnes DM/ha) from 15cm and ground cutting respectively as compared to (10.0 and 8.6 tonnes DM/ha) for low level of nitrogen and phosphorus rates. High plant density at 25cm row spacing yielded higher biomass (12.2 tonnes DM/ha) than low plant density at 100cm row spacing (11.4 tonnes DM/ha). It was concluded that, ground cutting height could be beneficial management practice for rhizomatous grass so as to obtain higher seed yields since it allows healthier ground tillers from rhizomes than profuse aerial tillers produced at higher cutting heights. Irrigation during dry season can be the best option for Cenchrus ciliaris cv. Biloela seed production when row spacing of 75cm and 100 cm are used at ground cutting height with proper rates of nitrogen and phosphorus. However, strategies for bird scaring during dry period (offseason) is highly emphasized from blooming stage to seed maturity to maximize seed yield.

Keywords: biomass irrigation, nitrogen, phosphorus, Rhizomatous grass, seed production, tillering

Introduction

Pasture seed production in Tanzania need a close technical attention of many stakeholders so as to produce more forage to support livestock sector. Rather limited information is available on pasture seed production of recommended promising pasture species under different agro ecological zones in the country. Efforts to improve management and use of established forages in Tanzania started since 1930s (MWLD 2005). On station and on-farm trials of introductions and evaluations to screen adaptability of new introduced pasture species was done. However it is apparent that little efforts were done on pasture seed production. Challenges of changing climate and arising conflicts among land users which is now apparent between livestock keepers, crop farmers and other land users is mainly due to lack of improved pastureland to support livestock and hence minimize uncontrolled livestock movements all over the country. However shortage of pasture seeds has been a major limitation to sown pasture in Tanzania (Lwoga et al 1984). According to FAO (2006), several research stations and parastatal livestock farms have been producing (uncertified) pasture seeds, but lack of funds has stifled the development and expansion of this important activity. Growing demand of grass pasture seeds in the country and neighboring countries for both grass and legume seeds necessitate researchers to respond to requirements to bring pasture seed industry to a functional level and meet the seed standards. Grass pasture seed production is commonly done in wet season in Tanzania with limited information on production in dry season under irrigation which necessitates conducting studies on grass pasture seed production in dry season using irrigation to fill the gap. Low fertility of soils and high challenges of diseases in wet season are reported to affect pasture grass seed yield and viability (Kizima et al 2013). Most soils are deficient in Nitrogen and Phosphorus which are essential nutrients for early root development, plant growth and seed maturation. Use of fertilizers in pasture establishment helps to replace and maintain soil nutrient levels for quality seed production. Pasture establishment using seed broadcasting method is commonly practiced, however growing of pasture grass seed crop in rows, rather than broadcasting is advocated for good pasture grass seed production (FAO, 1986, Kumar et al., 2005). Grass stands that are seeded in rows with reduced plant density usually produce more seeds and are easier to fertilize and weeding. Row seeded stands have also more efficient access to sunlight, nutrients, and available water than broadcast-seeded stands. Management practices of pasture swards such as cutting height are said to affect vegetation characteristics and seed yield, therefore studies on effects of cutting height is important. According to Rains et al. (1993), seed quality is variable from poor, standard to extreme high, and improves with growing professionalism by suppliers and customer discrimination.

Materials and methods

Study area

The study was conducted at Magadu Dairy farm of Sokoine University of Agriculture in Morogoro municipal, Tanzania about 526 m.a.s.l (S 6⁰ 50^I 58.80^IIE 37⁰39^I12.22^II GPS coordinates). The farm received an annual rainfall of 694.4 mm (year 2012) and 570.6 mm (year 2013)( Figures 1 and 2). During experimentation periods there was a mixture of cool and warm temperature, ranging between 15.4 to 19.9 °C for min temperature in cold dry season and max. temperature range of 28 to 36.2 °C in the warm wet season. High relative humidity (64.93%) was recorded in April during the wet season and lowest record was 39.3% in September during the dry season.

Research design

A factorial experimental design using split plot arrangement was used to evaluate effects of cutting height, row spacing and fertilizer levels in wet and dry seasons on how they affect grass seed yield and vegetative characteristics of Cenchrus ciliaris cv. Biloela. The experiment employed three treatments (Nitrogen and phosphorus levels, row spacing and cutting heights) assigned in two seasonal blocks (wet and dry season using irrigation). Three Nitrogen N and Phosphorus P levels of [ (i) 0 N: 0 P; ii) 40 N: 20 P and iii) 60 N: 30 P ], and three row spacing (sward as 25 cm row as control , 75 cm and 100 cm) replicated three times to make 27 plots of 4m x 4m, The plots were split into two subplots of 2m x 4m to accommodate two cutting heights (ground and 15cm cut) in each season.

Data collection

Soil testing was done before the experiment. Soils of experimental plots was slightly acidic pH 5.7 and had the following results (%TN = 0.15, % OC= 1.87, Phosphorus = 8.73mg/kg, Clay texture with 49%clay,13%silt and 38% sand; copper =2.42mg/kg, zinc= 2.54mg/kg, manganese =85.18mg/kg, iron= 73.02mg/kg, CEC= 31.2⁺/kg, calcium = 3.77⁺ /kg, potassium =0.55⁺ /kg , sodium= 0.30⁺ /kg).

Vegetative splits of Cenchrus ciliaris were planted 84 days before wet and dry season experiment to ensure good establishment before cutting height treatments were applied, no fertilizer was used during the establishment phase. Each season had separate experimental plots which were cut during the start of data collection. In second year, the same plots for each season were used with the same treatments. Urea fertilizer 46%N was applied after the cutting in mid March and early June followed by Triple super phosphate(TSP 46%) application after 2 weeks. Wet season experiment depended entirely on rainfall while dry season experiment used irrigation. Irrigation was done using water pipe and watering can. Watering after flowering stage was done to the basal part of vegetation to avoid wetting the inflorescence. This was done purposely to make sure the inflorescence do not contaminate with moisture which is a predisposing factor of fungal growth. Irrigation was done daily in the early stages and later at an interval of one day. Soil Moisture content in plots was monitored using digital moisture meter (VG-meter-200) at 20 cm soil depth and maintained at 40-50% moisture content by irrigation. Data were also collected on the following grass seed yield components: - total tiller/tussock, fertile tiller/tussock, tiller height (cm), tiller diameter at the third internode (mm), average number of aerial tiller per plant, inflorescence length (mm), inflorescence diameter (mm). Harvested seeds (first harvest (70 days) and second harvest(84 days)) from the same sward of each plot were air dried then yield recorded (kg /ha), visual assessment on days to 50% flowering, days to flowering, anthesis and seed maturity, measuring vegetation height to estimate forage bulk density(kgDM/m³) and forage yield (tonnes DM/ha). After second seed harvest, forage yield estimate was done and samples of forage were taken for laboratory chemical composition analysis and other samples for sorting of stem and leaf to calculate leaf to stem ration. After each season the experimental sward was cut down and left to regrow for next year trial.

Data analysis

Collected data were entered in coded excel sheets then transferred to SAS for General Linear Model procedure of Statistical Analysis System (SAS, 2000) for analysis.

Results and discussion

Growth performance

In this study it was observed that regrowth of Cenchrus ciliaris sward had already started by 3rd day for both ground and 15 cm cuttings. The regrowth vegetation took a range of 30-35 days to reach 50% blooming stage, followed by one week to reach anthesis stage of growth (Plate 1).

The sward took about 66-70 days from clean cutting to seed maturity for first harvest and an additional 14 days for second seed harvest (making a total of 84 days for the two seed harvests). Clarke et al (2004) reported that Digitaria eriantha grass take about 60 -90 days from cleaning cut to seed maturity. A study conducted by Kumar et al 2005 in India establishing Cenchrus ciliaris using seeds instead of vegetative splits observed that it took the plants 54-61 days to reach 50% flowering and 103 – 118 days to seed maturity. These results indicate that it takes relatively fewer days to produce seeds from existing stubble vegetation rather than newly established sward from seeds. By knowing number of days the grass species takes from cutting or sowing to seed maturity and weather records (e.g rainfall days); the information may assist to know when to do clean cutting and fertilizer application of existing vegetation planned for seed production so as to get better results (Figure 1 and 2)

Vegetation characteristics

Inflorescence

Mature inflorescence length varied from 8 – 13.5 cm (Table 1a and b). Large Spike length (10-13 cm) appeared in the first seed harvest and a mixture of 8-10cm and 5-8 cm were mostly harvested in second seed harvest (Plate 2).

Tillering

Higher cutting height (15cm) stimulated profuse aerial tillering (Plate 3b) as opposed to ground cutting that allowed fewer basal tillers (Plate 3a) mainly from the rhizomes that were relatively thicker in diameter (Table 1a and b) . Onyeonagu et al (2012) reported that 15 cm cutting height yielded greater number of tillers during the harvest period when Panicum maximum was subjected to cutting heights of 5,10 and 15cms. This means that high cutting height gives more profuse tillering of aerial thin tillers as opposed to lower cutting heights or ground cutting that gives fewer but thicker tillers.

Grass seed yield components

Fertilizer application significantly (p≤ 0.05) increased number of tillers per tussock from 75 to 101 for control (i.e. without Nitrogen and Phosphorus) and 60N 30P, respectively (Table 1a). Increase of optimal level of Nitrogen fertilization significantly affects the appearance of new tillers and increases the dynamics of tiller population of the pasture. These findings are supported by Mushtaque et al (2010) that Nitrogen triggers the activation of dormant buds and enhances the vegetation sward filling through the highest rate of tiller replacement, which supports a higher proportion of very active healthier young tillers for each plant .This results in higher tiller density and consequently increases seed and biomass production. Ground cutting favoured emergence of new few thicker healthier tillers from ground rhizomes (88) as compared to thinner aerial (108) total tillers per tussock for 15cm cutting height (Table1(a). Ground cutting yielded relatively longer and thicker tillers as compared to 15cm cutting that produced shorter and thinner tillers (Table 1a and b). Ground cutting produced significantly lower number of aerial tillers per plant (3-4) as compared to higher cutting height (6 and above).

Table 1(a): Mean values of Seed yield components as affected by fertilizer levels, row spacing and cutting height (year 2012)
		Fertilizer levels F0= 0 N 0P F1=40N20P F2=60N30P					Row spacing S₀= 25cm S₂=75 cm S₃=100 cm				Cutting height
	F0	F1	F2	SEM	p	S0	S2	S3	SEM	p	GND	15cm		SEM	p
Total tiller/tussock	75^b	79^b	101^a	18.8	0.0404	120^a	119^a	93^b	15.5	0.0399	88^b		108^a	13.9	0.0405
Fertile tiller/tussock	38^b	48^c	60^a	11.8	0.0189	59	57	63	5.8	0.7386	52		54	1.5	0.8442
Av.# tiller/ plant	5	5	5	1.72	0.9665	7	5	6	3.1	0.9270	4^b		7^a	2.6	0.0001
Tiller diam(mm)	2.35^b	2.6^b	3.5^a	0.55	0.0022	2.3^b	2.6^b	3.7^a	0.7	0.0085	3.0		2.7	0.2	0.7103
Tiller height(cm)	88^b	93^b	128^a	19.8	0.0012	87.0^b	96.5^c	116^a	13.5	0.0074	104.5		99.6	3.4	0.6401
Inflores. length (cm)	12	11.5	13.3	0.88	0.0648	9.0^b	11.3^ab	13.3^a	2.1	0.0495	11.5		12.1	0.4	0.2699
Inflores. diam.(mm)	13.2^b	13.8^b	16.5^a	2.0	0.0248	11.5	13.0	16.3	2.3	0.0586	14.4		13.5	0.6	0.6203
Means in rows (within the same factor) with different superscripts are different at p<0.05

Table 1(b): Mean values of Seed yield components as affected by fertilizer levels, row spacing and cutting height (year 2013)
Parameters	Fertilizer levels F0= 0 N 0P F1=40N20P F2=60N30P						Row spacing S₀= 25cm S₂=75 cm S₃=100 cm					Cutting height
	F₀	F₁	F₂	SEM	p	S0	S2	S3	SEM	p	GND	15 cm	SEM	p
Total tiller/tussock	71^b	73^b	99^a	18.9	0.0298	117^a	117^a	84^b	17.8	0.0241	87^b	103^a	8.1	0.0104
Fertile tiller/tussock	30^b	42^a	49.5^a	10.6	0.0146	51	51	53	2.0	0.6834	42	49	3.4	0.1350
Av.# tiller/ plant	5	5	5	1.6	1.000	5	5	6	2.3	0.9429	3^a	6^a	1.5	0.0001
Tiller diam(mm)	2.2	2.5	3.25	0.5	0.0503	2.1^b	2.35^b	3.4^a	0.6	0.0060	2.7	2.6	0.1	0.5791
Tiller height(cm)	88^b	89^b	122^a	17.4	0.0013	88^b	93.5^b	115^a	12.9	0.0033	102.0	98.0	2.0	0.5661
Inflores. length (cm)	9.25	11	12.6	1.7	0.1023	9	10.5	12.5	1.8	0.0865	10.1	11.5	0.7	0.0869
Inflores. diam.(mm)	11^b	13.25^ab	14.25^a	2.0	0.0307	11^b	12^b	14^a	1.5	0.0341	13.3^a	11.9^b	0.7	0.0489
Means in rows (within the same factor) with different superscripts are different at p<0.05

Seed yield

There was a significant difference on seed yield between the seasons and cutting heights and a decline of seed yield in year two (Table 2 a,b and 3).Seed yields were significantly (p<0.05) high at higher rates of nitrogen and phosphorus at ground cutting (77.5 kg/ha) than 15cm cutting height (56.7kg/ha) with a decreasing trend of seed yields in year two (77.5 to 38.4kg/ha and 56.7 to 35.5 kg/ha at the same level of fertilizer and cutting heights, respectively). Row spacing of 100cm showed slightly higher seed yield of (70 kg/ha) as compared to other two row spacing (67.2 and 69.3 kg/ha for 25 cm and 75cm respectively). These results comply with findings reported by Kumar et al (2005) in India that seed production for Cenchrus ciliaris is maximized at low plant densities when wider row spacing are used compared to narrow row spacing which result into higher plant density ( Table 1 a and b ). Ground cutting height could be beneficial management practice for rhizomatous grass so as to obtain higher seed yields since it allows healthier thicker basal tillers from rhizomes than profuse thin aerial tillers produced at higher cutting heights. Relatively higher seed yield were obtained in dry season than wet season (66.7 and 37.8 kg/ha) under cutting heights of 15cm and ground cutting (Table 3) for two consecutive years. FAO (1990) reported seed yield of 10-60 kg/ha pure clean seeds, and Kumar et al (2005) also reported a yield of 97kg/ha in India, these differences might be due to cultivar, climatic and soil fertility differences.

Table 2 (a): Seed yield (kg ha^-1) as affected by Nitrogen and Phosphorus levels, row spacing at two cutting heights (Year 2012)
	15cm cutting			Ground cutting
	1^st Harvest	2^rd Harvest	Total yield	1^st Harvest	2^rd Harvest	Total yield
F₀( 0 N 0P)	35.1	11.9	47.0^b	48.0	16.0^b	64.0^b
F₂(40N 20P)	39.0	14.0	53.0^a	49.0	16.1^b	65.1^b
F₃( 60N 30P	40.0	16.7	56.7^a	54.0	23.4^a	77.5^a
SEM	4.7	3.0	7.1	4.7	3.0	7.1
P values	0.2923	0.0987	0.0255	0.5034	0.0387	0.0254
S₀( 25cm)	39.0	13.9	53.0	50.3	16.9	67.2
S₂(75 cm )	37.5	13.6	51.2	49.8	19.5	69.3
S₃(100 cm)	37.7	15.0	53.0	50.9	19.1	70.0
SEM	4.7	3.0	7.1	4.7	3.0	7.1
P values	0.833	0.0538	0.5660	0.6744	0.0620	0.5540
Means in column within the same factor with different superscripts are different at P< 0.05

Table 2 (b): Seed yield (kg ha^-1) as affected by Nitrogen and Phosphorus levels, row spacing at two cutting heights(Year 2013)
	15cm cutting			Ground cutting
	1^st Harvest	2^rd Harvest	Total yield	1^st Harvest	2^rd Harvest	Total yield
F₀( 0 N 0P)	18.6	5.8	24.4^b	18.6	8.1	26.7^b
F₂(40N 20P)	23.2	9.4	32.6^a	19.1	10.6	29.7^b
F₃( 60N 30P	23.3	12.0	35.5^a	23.7	14.7	38.4^a
SEM	3.1	1.8	4.5	3.1	1.8	4.5
P values	0.2923	0.0345	0.0410	0.2873	0.0422	0.0380
S₀( 25cm)	24.2	8.8	33.0	21.4	10.2	31.6
S₂( 75 cm)	22.2	9.2	31.4	21.2	11.6	32.8
S₃(100 cm)	18.7	9.4	28.1	18.9	11.7	30.5
SEM	3.1	1.8	4.5	3.1	1.8	4.5
P values	0.6485	0.8829	0.7990	0.2066	0.7918	0.4450
Means in column within the same factor with different superscripts are different at P< 0.05

Table 3: The effect of season to seed yield (kg ha^-1) in two different cutting heights
Season	Year 2012		Year 2013
	15 cm cutting	Ground cutting	15 cm cutting	Ground cutting
Wet ( Rain season)	37.8^b	69.0	13.8^b	24.0^b
Dry ( Irrigation)	66.7^a	68.7	48.0^a	39.2^a
SEM	5.8	5.8	3.7	3.7
P values	0.0051	0.0649	0.0289	0.0388
Means in column within the same factor with different superscripts are different at P< 0.05

Forage biomass productivity

Rain season favoured higher forage biomass yields than dry season under irrigation (Table 4). Cutting height of 15 cm recorded higher biomass in wet season (12.6 and 12.3 tonnes /ha) as compared to dry season harvest (10.7 and 9.5tonnes DM/ha) in year one and two respectively. There was significance difference in forage biomass produced with higher level of fertilizer (13.2 tonnes DM/ha) as compared to low levels (8.0 tonnes DM/ha)(Table 4). Similar records of biomass production (13.9 tonnes DM/ha) for Cenchrus ciliaris cv.Biloela were also reported by Kusekwa et al (1987) at Mpwapwa Livestock Research Institure, Tanzania. Significance difference in biomass yields (p≤ 0.05) were observed from both higher levels of fertilizer and narrower row spacing as compared to low biomass yields from low fertilizer levels and wider row spacing respectively. These results resemble findings by Sundriyal et al (1993) who reported a decline in biomass yield at 5 cm cutting height of three grass species (Heteropogon contortus, Chrysopogon mountanus and Eulalia trispicata) as compared to increased forage biomass yield at 15 cm cutting height. Onyeonagu et al (2012) also reported that higher cutting height (15 cm) of Panicum maximum at different periods increased tiller production, which led to increased biomass as opposed to reduced cutting heights( 5 and 10 cm). Row spacing of 25cm showed significantly (p ≤ 0.05) higher forage biomass (12.2tonnes DM/ha) as compare to 75cm and 100cm (11.3 and 11.4tonnes DM/ha) respectively. This means the higher the plant density the higher the biomass productivity. Jefferson et al (1997) observed similar findings that highest harvested forage yield estimates of Psathyrostachys juncea and Agropyron cristatum were observed in the narrowest row spacing of 30 cm, when compared with other row spacing of 45, 60, 75 and 90 cm

Table 4: Total forage biomass yield (tonnes DMha^-1) as influenced by season, fertilizer levels and row spacing under two cutting heights
Factors	Year 2012		Year 2013
	15cm cutting	Ground cutting	15cm cutting	Ground cutting
Wet Season	12.6	11.8^a	12.3^a	11.0^a
Dry Season	10.7	7.9^b	9.5^b	6.7^b
SEM	0.42	0.42	0.43	0.43
P values	0.0754	0.0224	0.0255	0.0344
F₀(0N 0P)	10.0^b	8.6	9.6	8.0
F₂ (40N 20P)	11.8^ab	9.9	11.4	9.0
F₃(60N 30P)	13.2^a	11.1	11.8	9.6
SEM	0.51	0.51	0.51	0.51
P values	0.0411	0.7660	0.0622	0.7880
S₀(25cm)	12.2^a	10.0	11.4	8.8
S₂(75 cm)	11.3^b	10.3	11.1	9.6
S₃(100 cm)	11.4^b	9.3	10.4	8.1
SEM	0.51	0.51	0.53	0.53
P values	0.0100	0.5544	0.3322	0.5001
Means in column within the same factor with different superscripts are different at P< 0.05

It was apparent that wet season favoured higher biomass productivity than dry season in two cutting heights for two consecutive years (Table 5). Cutting height of 15 cm showed higher biomass than ground cutting in all seasons, fertilizer levels and row spacing. This means when Cenchrus ciliaris vegetation is cut at higher heights it allow profuse aerial tillering (plate 3b) from internodes as opposed to the vegetation cut on ground which yielded few tillers. This phenomenon might be a contributing factor towards higher forage biomass observed in 15cm as compared to ground cutting.

Table 5: Total forage biomass yield (tonnes DM ha^-1) as affected by Nitrogen and Phosphorus levels and row spacing in Wet and dry seasons
	Year 2012			Year 2013
	Wet season	Dry season (Irrigation)	Wet season		Dry season (Irrigation)
F₀(0N 0P)	11.1^b	7.4^b	11.4		6.2^b
F₂ (40N 20P)	12.2^ab	9.5^c	12.1		8.3^c
F₃(60N40P)	13.4^a	11.0^a	11.6		9.8^a
SEM	0.51	0.51	0.53		0.53
P values	0.04322	0.0255	0.6550		0.0310
S₀( 25cm)	12.1	10.2^a	11.2		9.0^a
S₂( 75 cm)	12.1	9.5^ab	12.4		8.3^ab
S₃(100 cm)	12.6	8.2^b	11.5		7.0^b
SEM	0.51	0.51	0.53		0.53
P values	0.0768	0.0441	0.1088		0.0331
Means in column within the same factor with different superscripts are different at P< 0.05

Forage bulk density

It was observed that bulky density was significantly (p≤ 0.05) higher (11.14 KgDMm^-3) in higher rates of fertilizer than in control treatment (8.91 kgDMm^-3) and narrow spacing had significantly higher (p ≤0.05) biomass per unit volume (10.87kgDMm^-3) than wider row spacing (9.49 kgDMm^-3)(Table 6) . This was probably due to higher tiller density which led to higher biomass accumulation in narrow row spacing and higher cutting height than in wider and ground cutting treatments. Butler (2007) reported a low bulk density of 6.89 kg/m³ of aboveground biomass of herbaceous plants in American great plains when used the same technique of sampling of clip and weigh using quadrat sampling unit area in relation to vegetation height. The study findings may be higher probably because of differences in species and soil fertility. Forage bulk density in the field can be used as a good indicator in estimating how much biomass is available for grazing or for harvest. Higher bulk density indicate larger amount of forage available in smaller area. This means good management practices may increase vegetation height and biomass yield per area hence higher forage bulkiness per unit volume in the field.

Table 6: Bulky density (kg DMm^-3) of Cenchrus ciliaris as affected by fertilizer levels, row spacing, cutting heights and seasons.
Factors	Year 2012		Year 2013
	15cm	Ground	15cm	Ground
F₀(0N 0P)	8.91^b	7.19	8.49	6.68
F₂ (40N 20P)	9.89^ab	8.12	9.56	7.37
F₃(60N 40P)	11.14^a	9.03	9.94	7.78
SEM	0.49	0.49	0.51	0.51
P values	0.0140	0.0647	0.0976	0.1539
S₀(25cm)	10.87^a	8.58	10.05^a	7.58
S₂(75 cm)	9.58^ab	8.13	9.36^ab	7.61
S₃(100 cm)	9.49^b	7.63	8.58^b	6.63
SEM	0.49	0.49	0.51	0.51
P values	0.0676	0.0508	0.0015	0.2011
Wet season	10.16	8.91	9.60	8.31
Dry (irrigation)	9.80	7.32	9.06	6.24
SEM	0.40	0.40	0.42	0.42
P values	0.5836	0.3185	0.8650	0.0654
Means in column within the same factor with different superscripts are different at P< 0.05

Leaf to Stem ratio

There was no significant (p ≥0.05) difference between the treatments in terms of leaf to stem ratio.. Wet season showed relatively high leaf to stem ratio as compared to dry season (Table 7). Slightly higher ratios of leaf to stem ratio were also observed in wider row spacing as compared to narrow row spacing. Ground cutting showed lower leaf to stem ratio than 15cm cutting height. This may be due to profuse tillering which allowed growth of leafy biomass as opposed to ground cutting (table 1a and b) which yielded few healthier tillers with relatively large stem diameter and few aerial tillers. Nisa et al (2006) reported lower leaf to stem ratio (0.63) for Cenchrus ciliaris when vegetative splits were planted and clipped after two months. This difference might be due to cultivar differences.

Table 7: Leaf to stem ratio as affected by fertilizer levels, row spacing and season.
Factor	Year 2012	Year 2013
F₀(0N 0P)	0.71	0.70
F₂ (40N 20P)	0.73	0.71
F₃(60N 40P)	0.77	0.72
SEM	0.02	0.02
P values	0.1487	0.1344
S₀(25cm)	0.72	0.72
S₂(75 cm)	0.75	0.72
S₃(100 cm)	0.75	0.73
SEM	0.02	0.02
P values	0.6572	0.6320
Wet season	0.76	0.73
Dr season	0.72	0.72
SEM	0.02	0.02
P values	0.0678	0.0667
Ground cutting	0.72	0.71
15 cm cutting	0.76	0.69
SEM	0.02	0.02
P value	0.0788	0.0782

Chemical composition analysis

Higher level of fertilizer increased % CP content (5.161 to 7.062 and 3.940 – 6.528) in dry and wet season samples respectively (Table 8). These CP figures were closer to minimum (7% ) required to sustain rumen functionality in beef cattle (NRC 1996). García-Dessommes (2007) reported higher mean CP% (8.7) of Cenchrus ciliaris hybrid and five genotypes. Digestible crude protein (DCP %) also increased with fertilizer levels both in the dry and wet season. Dry season samples showed slightly higher DCP as compared to wet season samples, this might be due to the fact that continued irrigation allowed continuous sprouting of the vegetation which was a bit fresh even during harvest of forage biomass.

Table 8: Chemical composition analysis of Cenchrus ciliaris hay harvested after seed harvest
	Fertilizer level	Cutting height	%DM	%DDM	%CP	%DCP	ADF%	%NDF	%TDN	ME
DRY SEASON	F₀ (0N 0P)	15 cm	90.7	47.5	5.2	3.5	53.1	82.4	42.0	0.69
	F₀ (0N 0P)	Ground	89.6	48.2	5.5	3.9	52.3	80.6	42.9	0.705
	F₂(40N 20P)	15 cm	90.8	47.7	4.8	3.3	52.9	79.1	42.2	0.693
		Ground	90.7	47.2	5.3	3.7	53.6	82.2	41.5	0.681
	F₃ (60N 40P)	15 cm	90.5	49.3	7.1	4.9	50.9	82.1	44.5	0.732
		Ground	90.5	48.0	6.6	4.5	52.5	83.7	42.7	0.701
WET SEASON	F₀ (0N 0P)	15 cm	90.6	43.0	4.8	3.0	58.9	89.8	35.4	0.581
		Ground	90.5	43.9	5.2	3.4	57.8	87.0	36.7	0.602
	F₂(40N 20P)	15 cm	91.3	42.7	4.1	2.7	59.3	88.4	34.9	0.573
		Ground	90.5	43.0	3.9	2.6	58.9	88.5	35.4	0.581
	F₃ (60N 40P)	15 cm	91.0	45.4	6.5	4.3	55.9	87.2	38.8	0.638
		Ground	91.2	45.1	4.3	4.0	56.2	88.5	38.4	0.631

Use of irrigation for seed production during the dry season

The results from this study showed that it is practically possible to produce high yields of Cenchrus ciliaris seeds in Morogoro during the dry period (June – October, about 120 days) by of use irrigation as compared to wet season period (Table 2 a, b). This advantage of favourable dry season weather conditions for grass seed production may however be utilized with precautions of birds threat (Plate 4).

Since there are no other ripe crops in the field, dry season pasture grass seed production faces the threat of invasion of big groups of small birds (Lonchura cucullata) which feed on grass seeds from the milky stage to maturity. Without protection these birds can attack the irrigated field of grass seeds and wipe up small farms before harvest time. According to Andersen et al (2000), Lonchura cucullata - are described as prolific small birds (about 9 cm length) moving in groups. Small flocks of these birds are said to be found in a variety of habitats, where there are suitable seeds and often sit huddled together on grasses and bushes wheezing chik, chik, chik. Those birds are commonly found in the coast regions of Tanzania and commonly known as tonnes gobofu in Swahili and as Utonnes gwa in Luguru language in Morogoro. Hiring manpower to scare these birds is inevitable during the dry season and thus increases cost of seed production.

Conclusion and recommendations

Acknowledgement

The authors are very grateful to the Ministry of Livestock and Fisheries Development for funding this study. Acknowledgement is also extended to staff members of Magadu dairy farm of the Department of Animal Science and production of Sokoine university of Agriculture for their cooperation during the two years of this field trial.

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Seed yield and vegetation characteristics of Cenchrus Ciliaris as influenced by fertilizer levels, row spacing, cutting height and season

J B Kizima, E J Mtengeti¹ and S Nchimbi-Msolla²

Abstract

Introduction

Materials and methods

Study area

Research design

Data collection

Data analysis

Results and discussion

Growth performance

Vegetation characteristics

Inflorescence

Tillering

Grass seed yield components

Seed yield

Forage biomass productivity

Forage bulk density

Leaf to Stem ratio

Chemical composition analysis

Use of irrigation for seed production during the dry season

Conclusion and recommendations

Acknowledgement

References

Seed yield and vegetation characteristics of Cenchrus Ciliaris as influenced by fertilizer levels, row spacing, cutting height and season

J B Kizima, E J Mtengeti1 and S Nchimbi-Msolla2

Abstract

Introduction

Materials and methods

Study area

Research design

Data collection

Data analysis

Results and discussion

Growth performance

Vegetation characteristics

Inflorescence

Tillering

Grass seed yield components

Seed yield

Forage biomass productivity

Forage bulk density

Leaf to Stem ratio

Chemical composition analysis

Use of irrigation for seed production during the dry season

Conclusion and recommendations

Acknowledgement

References

J B Kizima, E J Mtengeti¹ and S Nchimbi-Msolla²