Performance of yield attributes , yield and economics of teff ( Eragrostis tef ) influenced by various row spacing , nitrogen and phosphorus fertilizers

Teff [Eragrostis tef (Zucc.)] is the most important cereal crop of Ethiopia, occupying 31% area and 20% production of the total cereal crops. However, its productivity is almost stagnant, with a national average yield of meager 1.46 tonnes ha -1 mainly due to inadequate modern agronomic practices and technologies in the present production system. The urgent necessity for its higher production and productivity as a staple food of the country is increasing year after year. Therefore, in order to investigate the effect of three levels of rows spacing, four levels of nitrogen and phosphorus fertilizer rates and their interaction on growth and yield attributes as well as yield of teff, a field experiment was conducted on kora variety of teff. The response of growth parameters to the treatments were significant in all parameters, except lodging percentage due to main effect of rows spacing. The highest increments recorded were 317, 49.09 and 28.18% in effective tillers, panicle length and plant height plant -1 , respectively in their interaction effects in treatments of 80/80 and 70/70 kg of N/P2O5 ha -1 with 10 cm over the lowest result recorded from treatment of 50/50 kg of N/P2O5ha -1 with 30 cm spacing. While, the response of yield and yield components were found significant and the highest result in interaction effects were an increment of 113.21, 35.28, 55.45 and 41.7% kg ha -1 for grain yield, straw yield, biomass yield and harvest index, respectively from 80/80 kg of N/P2O5 with 10 cm spacing over the lowest result reported from 50/50 kg of N/P2O5 ha -1 with 30cm spacing. Economic partial budget analysis of the study depicted that at row spacing of 10 cm with 80/80 kg of N/P2O5 ha -1 fertilizer dose resulted in maximum relative net return of ETB 50178 ha -1 followed by ETB 48017 ha -1 for 70/70 kg of N/P2O5 ha -1 . The study concluded that, higher productivity and net economic return can be achieved for kora variety of teff by applying 80/80 kg of N/P2O5 ha -1 with 10 cm row spacing as compared to the other treatments.

Teff [Eragrostis tef (Zucc.)] is the most important cereal crop of Ethiopia, occupying 31% area and 20% production of the total cereal crops.However, its productivity is almost stagnant, with a national average yield of meager 1.46 tonnes ha -1 mainly due to inadequate modern agronomic practices and technologies in the present production system.The urgent necessity for its higher production and productivity as a staple food of the country is increasing year after year.Therefore, in order to investigate the effect of three levels of rows spacing, four levels of nitrogen and phosphorus fertilizer rates and their interaction on growth and yield attributes as well as yield of teff, a field experiment was conducted on kora variety of teff.The response of growth parameters to the treatments were significant in all parameters, except lodging percentage due to main effect of rows spacing.The highest increments recorded were 317, 49.09 and 28.18% in effective tillers, panicle length and plant height plant -1 , respectively in their interaction effects in treatments of 80/80 and 70/70 kg of N/P 2 O 5 ha -1 with 10 cm over the lowest result recorded from treatment of 50/50 kg of N/P 2 O 5 ha -1 with 30 cm spacing.While, the response of yield and yield components were found significant and the highest result in interaction effects were an increment of 113.21, 35.28, 55.45 and 41.7% kg ha -1 for grain yield, straw yield, biomass yield and harvest index, respectively from 80/80 kg of N/P 2 O 5 with 10 cm spacing over the lowest result reported from 50/50 kg of N/P 2 O 5 ha -1 with 30cm spacing.Economic partial budget analysis of the study depicted that at row spacing of 10 cm with 80/80 kg of N/P 2 O 5 ha -1 fertilizer dose resulted in maximum relative net return of ETB 50178 ha -1 followed by ETB 48017 ha -1 for 70/70 kg of N/P 2 O 5 ha -1 . The study concluded that, higher productivity and net economic return can be achieved for kora variety of teff by applying 80/80 kg of N/P 2 O 5 ha -1 with 10 cm row spacing as compared to the other treatments.

INTRODUCTION
Teff [Eragrostis tef (Zucc.)] is the most important staple food crop in Ethiopia, occupying 31% area and 20% production of the total cereal crops (CSA, 2014).Teff grain and straw has good demand and fetch relatively  higher price as compared to other cereal crops.Moreover, teff has excellently adapted to the changing agro-climatic conditions in Ethiopia; thus, reduces production risks.
The major limitation for teff production in the country has been its low productivity.Teff has the lowest yield per hectare as compared to other major cereals, as the national average yield is meager, 1.46 tonnes ha -1 (CSA, 2014).One of the reasons for the low yield is ineffective traditional sowing methods and inadequate application of nitrogen (N) and phosphorus (P 2 O 5 ) fertilizers.Most farmers practice the traditional broadcasting method of sowing, which leads to excess crop density and increases competition among plants for nutrients, water, sunlight and CO 2 .Further, broadcasting methods requires additional seed rate as compared to row sowing method hence increases cost of production of teff.
Therefore, present cultivation system of teff is unable to satisfy the consumers demand, due to the fact that most Ethiopian farmers practice traditional farming system.Production system is not efficiently supported by modern technology due to research gap in choosing most feasible modern technology.The research gaps in most effective sowing methods and most appropriate amount of N/P 2 O 5 fertilizers has been identified as significant constraints for the low productivity of teff in West Showa zone among others.The above modern agronomic practices and technologies have the potential to substantially enhance teff productivity to ensure food security in West Showa zone.The experiment was conducted with the objectives to study the effect of three levels of rows spacing, four levels of N/P 2 O 5 fertilizer rates and their interaction on growth parameters, yield components and yield.

MATERIALS AND METHODS
A field experiment was carried out at the experimental plots in Ambo University Research Site, Ambo.Ambo is located 114 km away from Addis Ababa towards the west of the country.The research was done on 'Kora' variety of teff during the main cropping season of 2015 on Vertisols of Ambo district in West Shoa Zone, Western Oromia, Ethiopia.
The experiment was laid out in randomized complete block design with three replications.The treatments were: 10, 20 and 30 cm row spacing and 50/50 kg of N/P2O5 ha -1 , 60/60 kg of N/P2O5 ha - 1 , 70/70 kg of N/P2O5ha -1 and 80/80 kg of N/P2O5ha -1 with application of di-ammonium phosphate (DAP) as basal dose and urea 21 days after sowing.Each harvestable plot had an area of 1.6 m by 1.25 m (2 m 2 ) with 0.5 m spacing between plots and 1 m between blocks.The treatments were assigned to plots by randomization method.

RESULTS AND DISCUSSION
The results of analysis of the observations revealed that the highest number of tillers plant -1 (10.9) were recorded from the treatment combination of 80/80 kg of N/P 2 O 5 ha -1 with 10 cm row spacing, followed by 10.1 from 70/70 kg of N/P 2 O 5 ha -1 with 10 cm, respectively.However, the lowest number of tillers (2.6) was recorded from the combination of 50/50 kg of N/P 2 O 5 ha -1 with 30 cm rows spacing (Table 1).The highest number of tillers was recorded from the treatment of 10 cm rows spacing with 80/80 kg of N/P 2 O 5 ha -1 and 70/70kg of N/P 2 O 5 ha -1 may be due to less plant density which creates favorable environment for plant tillering.The effective number of tillers was increased by 240.6% in plots treated with 80/80 kg of N/P 2 O 5 ha -1 with 10 cm rows spacing as compared to the lowest result obtained from the treatment combination of 50/50 kg of N/P 2 O 5 ha -1 with 30 cm space between the rows.As the number of productive tillers plant -1 increased, the yield per hectare also increased.Therefore, analysis of effective number of tillers counted at 90% physiological maturity of teff was significantly (p<0.001)affected between 12 treatments of rows spacing and the combination of N and P 2 O 5 fertilizer rates (Table 1).Debebe (2005) reported that productive  tiller numbers were affected by plant densities and available nutrients in his study on teff.
Likewise, the analysis of plant heights measured at 90% physiological maturity of teff were significantly (p<0.001)affected among 12 treatments of row spacing and combination of N/P 2 O 5 fertilizer rates (Table 1).The highest plant height plant -1 (111.0 cm) was recorded from the combination of 80/80 kg of N/P 2 O 5 ha -1 with 20 cm, followed by 104.3 cm from 70/70 kg of N/P 2 O 5 ha -1 with 10 cm row spacing and 106.1 cm from 80/80 kg of N/P 2 O 5 ha -1 with 30 cm row spacing, respectively.However, the lowest (86.6 cm) was recorded from the combination of 50/50 kg of N/P 2 O 5 ha -1 with 10 cm row spacing (Table 1).The highest mean value of plant height of the treatment was significantly taller by 28.18% over the shortest plant height.This might be due to a series of intra-row competition for nutrients such as N/P 2 O 5 ha -1 , which retarded elongation of stems.Legesse ( 2004) also reported that, as applied N rates increased, the grain uptake also increased which also reflected in the plant height, yield and yield components like panicle length, grain yield, straw yield and biomass yield.
Further, the grain yield ha -1 was significantly (p<0.001)affected among 12 treatments of row spacing and combination of N/P 2 O 5 fertilizer rates (Table 2).The highest grain yield (3766.67kg ha -1 ) was recorded from the combination of 80/80 kg of N/P 2 O 5 ha -1 with 10 cm rows spacing followed by 3633.4 kg ha -1 from 70/70 kg of N/P 2 O 5 ha -1 with 10 cm rows spacing.While, moderate grain yield of 3050, 2933 and 3036.7 kg ha -1 were recorded from 80/80 kg of N/P 2 O 5 ha -1 with 20 cm row spacing, 70/70 kg of N/P 2 O 5 ha -1 with 20 cm row spacing and 60/60 kg of N/ P 2 O 5 ha -1 with 10cm spacing between the rows, respectively.However, the lowest grain yield of 1766.6 kg ha -1 was recorded from the combination of 50/50 kg of N/P 2 O 5 ha -1 with 30 cm rows spacing (Table 2).Kassahun (2001) reported that adequate nitrogen fertilization had substantial influence on yield and related traits of teff.
Similarly, the highest mean value of grain yield was increased by 113.22 and 105.67% in the treatments of 80/80kg of N/P 2 O 5 ha -1 with 10 cm rows spacing and 70/70 kg of N/P 2 O 5 ha -1 with 10 cm row spacing, respectively as compared to 50/50 kg of N/P 2 O 5 ha -1 with 30 cm row spacing.This might be due to the fact that plants supplied with adequate amount of N/P 2 O 5 fertilizers had better ability for absorbing nutrients and water which enhanced vegetative growth and grain filling as compared to plants grown under lower fertilizer rates.Tekalign and Teklu (2000) reported yield improvement due to effective management of soil fertility and plant nutrition in their research conducted on teff.
Further, analysis of the harvest index of teff was significantly (p<0.001)affected by 12 treatments of rows spacing and combination of N/P 2 O 5 fertilizer rates (Table 2).The highest harvest index (34%) was recorded from the combination of 80/80 kg of N/P 2 O 5 ha -1 with 10 cm row spacing.The moderate harvest index (33, 32 and 32%) was recorded from the combination of 80/80 kg of N/P 2 O 5 ha -1 with 20 cm row spacing, 70/70 kg of N/P 2 O 5 ha -1 with 20 cm row spacing and 60/60 kg of N/P 2 O 5 ha -1 with 10 cm row spacing, respectively, which were statically at par with each other.On the other hand, the lowest harvest index (24%) was recorded from the combination of 50/50 kg of N/P 2 O 5 ha -1 with 30 cm row spacing.Plots treated with 80/80 kg of N/P 2 O 5 ha -1 with 10 cm and 70/70 kg of N/P 2 O 5 ha -1 with 10 cm row spacing showed the harvest index increment of 41.7 and 41.7%, respectively as compared to 50/50 kg of N/P 2 O 5 ha -1 with 30 cm.Liben et al. (2004) reported higher harvest index with adequate nitrogen fertilizer rate in teff.

Assessment of the benefit
Cost ratio associated with different treatments, the partial budget technique of CIMMYT was applied on yield and straw yield.Based on this technique, the highest net Where, RS= Row Spacing, *Sale of grain = ETB 15.5 kg -1 and Sale of straw = ETB 1.5 kg -1 .*Variable costs = Cost from land preparation to yield and straw yield transportation (ETB 15125) + cost of seed (ETB 375) were equivalent for all treatments.Where, GY kg/ha (in kilo gram/hectare) = Grain yield, AGY = adjusted grain yield, SY = straw yield, GR Birr/ha= grain revenue in Birr/hectare, SR Birr/ha = straw revenue in Birr/ha, TR Birr/ha = total revenue in Birr/ha, TVct Birr/ha= total variable cost in Birr/ha, NB Birr/ha = net benefit Birr/ha, MRR%= marginal return rate in percentage.
return was estimated from 80/80 kg/ha of N/P 2 O 5 with 10 cm (Table 3).The partial budget analysis estimated that the treatment of 10 cm row spacing with 80/80 kg of N/P 2 O 5 ha -1 fertilizer rate resulted in maximum relative net return of ETB 50178 ha -1 followed by ETB 48017 ha -1 for 10 cm row spacing with 70/70 kg of ha -1 and ETB 38121 ha -1 for 10 cm row spacing with 60/60 kg of N/P 2 O 5 ha -1 fertilizer rate, respectively (Table 3).Similar higher net return was also reported by Tefera and Ketema (2001).
It can be concluded that from the present study, application of 80/80 kg of N/P 2 O 5 ha -1 with 10 cm rows spacing followed by 70/70 kg of N/P 2 O 5 ha -1 with 10 cm row spacing with the same amount of 25 kg ha -1 of seed rate resulted in better economical return with maximum grain yield production for kora variety of teff in the field experiment.Further, the research also suggests that there is potential to conduct future studies under varying amounts of seed rate below 25 kg ha -1 with the studied N/P 2 O 5 fertilizer rate and rows spacing.
same letter along columns and rows are not significantly different.
same letter along columns and rows are not significantly different.

Table 1 .
Main and interaction effects on plant height at 90% physiological maturity plant -1 and effective tiller number plants -1 .

Table 2 .
Main and interaction effects on teff grain yield in kg ha -1 and harvest index (%).

Table 3 .
Partial budget analysis for variable cost on mean yield of grain and straws.