Determination of Efficient Methods and Appropriate Time of Seed Harvesting for Panicum coloratum at Teppi Agricultural Research Center, Southwester Ethiopia

The aims of this study were to determine appropriate time and efficient techniques of harvesting methods for Panicum Coloratum forage. The experiment was designed in randomized complete block design (RCBD,) in 4x4 factorial combinations of harvesting methods (mowing, sweating, shaking and sweeping) and time harvesting (14 th , 21 th , 28 th and 35 th days) after full anthesis. The experiment was replicated four times. The Results revealed that the mean number of inflorescences per M s , number of racemes per inflorescence, number of spikelet per raceme f were significantly different across the years. Seed yield and seed germination percentage were affected by different harvesting methods and time of harvesting and also influenced by their interactions. The sweating method gave more seed yield 633 and 618kg/ha on the 28 th and 35 th days of harvesting with 66 and 64 germination percentages respectively. In conclusion, smallholder farmers or commercial seed producers can produce optimum seed yield and quality by sweating method at 28 or 35 days of harvesting after full anthesis.

Proper choice of harvest time is important. It is also important that choosing of the method of harvest and care should be required for purity standards and with minimum wastage of seed and time.
With knowledge of seed-production requirements, potential seed producers from the private or public sector can decide whether such an enterprise would be technically and economically viable.
Thus, studies on appropriate forage seed harvesting management techniques help fully exploit the seed potential of cultivated forage varieties. Choosing an appropriate time and method of seed harvest is crucial in pasture seed husbandry of sown pastures. In the current study, different methods of seed harvesting and appropriate time of harvest were examined for Panicum coloratum grass species to determine the optimum.

Description of the study area
The experiment was carried out during 2016, 2017 and 2018 main cropping season at Teppi Agricultural Research Center. The center is located at 7° 08' latitude 35° 18' longitude about 610kms south west of Addis Ababa at the elevation of 1200 meters above sea level. The average annual temperature is 23 °C with mean minimum and maximum of 15 °C and 30 °C, respectively. The area has an annual average rainfall of 1630mm, of which the majority falls during May-October [6]. The major farming system is mixed crop-livestock production mainly with perennial cash crops like Coffee, Spices and Chat (Catha edulis). The major livestock raised in the study area are cattle, sheep, goats and poultry. Maize, Sorghum, Enset (Ensete ventricosum) and horticultural crops are the main food crops grown in the study area [7].

Experimental design, treatment and establishment
The experiment was arranged in randomized complete block design (RCBD) in factorial combinations of four harvesting methods and four harvesting times for panicum coloratum replicated four times. The harvesting methods were considered as main-plot and consists

Data collection
Data collected were components of seed yield (number of inflorescence/m 2 , number of raceme per inflorescence, number of spikelet per raceme, seed yield and 1000 seed weight) and seed viability (germination percentage) and defined as:

E.
Thousand seed weight (g): The weight of seed obtained from thousand seeds measured with sensitive electronic balance and carried out when seed moisture content (determined by testing a small seed sample by moisture meter) was approximately 12%.

Seed germination test (%):
The maximum germination potential of the seed out of 100 seeds.

Data analysis
Data were analyzed using general linear model of statistical Eijk=Random error

The number of inflorescence, racemes and spikelet
The  Means bearing different superscript letter along the column differ significantly (P<0.05).
In agreement with study done by Assefa et al.  (Table 2). Seed yield was significantly (P<0.001) different when it was harvested by the four different methods across years. However, it was also showed significant (P<0.001) interaction effect with methods and times of harvesting. The overall mean seed yield obtained from sweating method (467) was higher than mowing (400), shaking (311) and sweeping (238).
The higher seed yield from sweating might be due to efficiency of the harvesting method. The sweating method probably results in minimum seed loss. In agreement with Abebe et al. [11] total seed yield harvested from Andropogon gayanus grass significantly affected by harvesting method. In contrast to this, Mengistu et al. [5] reported that direct mowing is more efficient harvesting method for seed recovery for Panicum grass species. The mean seed yield of panicum coloratum obtained in different methods of harvesting in the present study was higher than 145kg/ha, which was reported by Assefa et al. [8].

Seed yield, thousand seed weight and germination percentage of Panicum coloratum harvested at different times
The current study showed that the effect of harvesting times significantly affected the seed yield ( Table 2). The overall seed yield (kg/ha) obtained on the 35 th days (493) and on the 28 th days (481) were the highest values and statistically similar. On the contrary, the lowest seed yield (153) was produced on the 14 th days of harvesting after full anthesis.

Copyright © Gezahegn Mengistu
MCDA.000644. 6(4).2020 In contrast to harvesting methods, harvesting times significantly affected thousand seed weight. The maximum 1000-seed weight was recorded on 35 th and 28 th (1.98) days, whereas the lowest minimum 1000-seed weight attained on 14 th days of harvesting (1.84). Time of harvesting affected germination percentage. The best germination percentage and recovery of good quality seed was attained on 28 th (72) and 35 th (74) days of harvesting after peak anthesis. The lowest germination percentage was on 14 th day harvest after peak anthesis and this would indicate seed immaturity and low viability.

Interaction effect harvesting methods and time of harvesting on seed yield of Panicum coloratum
There was a significant interaction between different harvesting methods and time of harvesting of Panicum coloratum ( Table 3).
The overall mean result indicated that highest seed yield (633kg/ ha) was obtained by sweating over other harvesting methods at 28 th days and the value was also statistically similar with the 35 th harvesting days (61kg/ha).This was followed by sweeping by 35 th days (570) and then by mowing method. The lowest seed yield (133.33kg/ha) was attained at the 14th days of harvesting by sweeping. The sweeping method appeared to be the least efficient even if harvesting time is undertaken at different weeks. This could be associated with loss of seeds in the cracked experimental plot. Abebe et al. [11] suggested that low seed yield of Andropogon gayanus a harvested by sweeping could be due to losses of seed by wind and small insects before harvesting. Lowest seed yield obtained on the 14 th days harvesting time might be due to the immaturity stage of Panicum coloratum so that small amount of seeds were recovered the maturity stage.

Interaction effect of harvesting methods and time of harvesting on 1000-seed weight of Panicum coloratum
There was a significant interaction effect of 1000-seed weight (P<0.01) between different harvesting methods and time of har-

Copyright © Gezahegn Mengistu
MCDA.000644. 6(4).2020 vesting of Panicum coloratum ( Table 4). The maximum 1000-seed weight (2.11g) was obtained by sweating over other harvesting method at the 28 th days whereas the lowest value (1.73g) was on 14 th days by sweeping method after full anthesis. days of harvesting by sweeping method of harvesting. Simon et al. [12] reported that immature seeds had higher initial seed moisture content, less developed, lighter, and as a result less viable than mature seeds [13]. The germination percentages observed by different harvesting methods (sweating, mowing and shaking) harvested at 28 th and 35 th days of harvesting times were higher than other country acceptable standards 60% [8].

Conclusion
Harvest methods and time of harvesting affected both seed yield and seed germination percentage in this study. Among dif-ferent methods and times of harvesting, the sweating method attained the best seed yield 633 and 618kg/ha when it was harvested at 28 th and 35 th days of harvesting after full anthesis, respectively.
The study also showed that high germination percentage was obtained by shaking and sweating with no significant variation observed. Hence, harvesting Panicum coloratum by sweating method of seed harvesting at 28 th days of harvesting time gave better seed yield with optimum seed quality (germination percentage). This is valuable information for forage seed producers in this country.

Data Availability
The data sets used to support the findings of this study are available from the corresponding author up on request.