Evaluation of improved lowland sorghum (Sorghum Bicolor (L.) Moench) varieties in Southern Ethiopia

Abstract In Ethiopia, there are several sorghum production constraints, among which shortage of high yielding varieties is the major one. The objective of this experiment was to select superior lowland sorghum varieties in Basketo special and Melokoza districts. An experiment was conducted in the 2017 main cropping season with seven improved varieties (Teshale, Melkam, Dekebe, Meko, Seredo, Gubiye, 76T1#23) and one local check arranged in randomized complete block design with three replications. The result of the study revealed that the effect of variety was significant for all the measured traits. Among the varieties, the highest average grain yield (2945 kg ha-1) was obtained from Teshele variety. Thus, this variety would be recommended for further demonstration and pre-scaling up in Melokoza and Basketo special districts and other similar agro ecologies.


Introduction
Sorghum (Sorghum bicolor (L.) Moench) grows in a wide range of agro ecologies most importantly in the drought-prone parts where other crops can least survive (Adugna, 2007). This makes sorghum preferable by farmers in drought-prone areas due to its tolerance to drought and harsh environments. It is one of the important indigenous food crops and is only second to tef as injera (leavened local flatbread) making cereal. Sorghum is the fifth most important cereal crop in the world (FAO (Food and Agricultural Organization), 2005).

ABOUT THE AUTHOR
Selamawit Markos is researcher in Arbaminch agricultural research center of South Agricultural Research Institute (SARI), Ethiopia. She has conducted several research activities related to plant breeding. She has also an experience in collaborating research with national projects mainly focusing on sorghum and rice breeding. She has an interest in conducting further research in plant breeding.

PUBLIC INTEREST STATEMENT
In Ethiopia, sorghum grows in a wide range of agro ecologies most importantly in the droughtprone parts. However, there are several sorghum production constraints, among which shortage of high yielding varieties is the major one. Before dissemination of different released varieties, conducting adaptation trail is vital due to variation in environmental factors from region to region. Seven sorghum varieties adaptation trail was conducted in Basketo special and Melkoza districts. From these varieties, Teshele variety is high yielder and recommended for the study area.
In Ethiopia, sorghum is the third most important cereal crop after tef and maize in terms of area coverage and total production (CSA (Central Statistical Authority), 2018). It accounts for 18.53% of the total area allocated to cereals and it also accounts for 19.3% of the area covered by cereals (CSA (Central Statistical Authority), 2018). Likewise, sorghum is the dominant crop in the low land areas of southern Ethiopia. It ranks fourth in area cultivated (12%) and in total production (12.69) among cereals (CSA (Central Statistical Authority), 2018). In spite of the importance of the crop to the farmers in the target area, lack of improved varieties, non-adoption of improved technologies, diseases and pests are major series production constraints in the study area. Some varieties of sorghum were released by different national and regional research centers. However, most of them were not evaluated in Basketo special and Melokoza district of Southern Ethiopia. Therefore, the objective of this study was to evaluate and select better performing lowland sorghum varieties in the study area.

Description of study area
An experiment was conducted at Basketo special district (Angla-3 and Angla-4 in 2017) and Melokoza district (Mender −1 and Mender-3 in 2018) during the main cropping season (March to July) (Table 1).

Experimental design and procedures
An experiment was conducted by using seven sorghum varieties namely; Gubiye, Seredo, Teshale, Meko, 76T1#23, Melkam and Dekeba from Melkessa Agricultural Research Centers and one local check. The field experiment was arranged in a randomized complete block design with three replications. During planting, the seeds were manually drilled at a seed rate of 10 kg/ha. The plot with 5 m long and 4.5 width was used. Six rows with inter-row spacing of 75 cm and 20 cm spacing between plant were used. Fertilizer, 100 kg/ha of NPS was applied at the time of planting (as basal application) and 50 kg/ha urea was applied in the form of split application; half of it at planting and the rest as top dressing before heading. Hand weeding was used.

Data collection and analysis
Data were collected on plant and plot basis for different traits. For the data collection on plot bases, five plants from the four central rows of each plot were randomly tagged and plant height, spike length and tiller number per plant were recorded. All plants from the four central rows of each plot were subjected to yield evaluation. Analysis of variance (ANOVA) was computed using statistical packages and procedures outlined by Gomez and Gomez (1984) to randomized complete block design using Genstat computer software (Genstat 16th edition). Mean separation was made by Least Significant Difference (LSD) for the comparison among the experimental varieties at 5% probability level.

Results and discussion
Combined analysis of variance was computed for the locations, genotypes and location by genotype interaction for the traits studied. Accordingly, combined analysis of variance indicated there were significant (P < 0.05) differences among genotypes, locations and location by variety interaction for plant height, spike length, tiller number and grain yield (Table 2). Firew., Mekbib, and Asfaw (2016) and other authors also reported considerable variation in plant height, panicle length, tiller number and grain yield of different sorghum varieties which coincides with the current result.
At mender-3, angla-4 and angla-3, Teshele was better yielder than the check and other varieties ( Table 3). The highest grain yield over the locations was obtained from variety Teshele (2945kg/ha) ( Table 3) with yield advantage of 28.6% over the local check in the study area. From these, it could be suggested that the use of improved sorghum varieties had brought a proportional yield increment than the local check. The current result was in line with Fuad Abduselam, Tegene, Fikadu, Alemayehu, and Taye (2018) and Yoseph and Zemach (2014) who reported significant difference for grain yield in sorghum varieties.
Variety, Teshele had better average spike length than the other varieties which is positively related to high yield (Table 4)

Conclusion and recommendation
Sorghum (Sorghum bicolor (L). Moench) grows in a wide range of agro ecologies most importantly in the drought-prone areas. The studied varieties were significantly different for most studied traits. From the tested varieties, the highest grain yield (2945kg/ha) was recorded for Teshele over the local check in the study area. Thus, it could be demonstrated before large-scale production in the study areas and area with similar agro ecologies.