Determination of Optimum Plant Density on Yield and Yield Components of Potato (Solanium tubersom L.) in Debub Ari District, Southern Ethiopia

Copyright @ Corresponding author: Biruk Gezahegn 139 Global Journal of Research in Agriculture & Life Sciences ISSN: 2583-4576 (Online) Volume 05 | Issue 05 | Sept.-Oct. | 2025 Journal homepage: https://gjrpublication.com/gjrals/ Research Article Determination of Optimum Plant Density on Yield and Yield Components of Potato (Solanium tubersom L.) in Debub Ari District, Southern Ethiopia *Biruk Gezahegn Southern Ethiopia Agricultural Research Institute, Jinka Agricultural Research Center, P.O. Box 96, Jinka, Ethiopia ORCID: https://orcid.org/0000-0001-8622-8273 1. Introduction The potato crop was introduced to Ethiopia around 1858 by Schimper, a German botanist (Pankhurst, 1964). Among African countries, Ethiopia has possibly the greatest potential for potato production; 70 percent of its arable land mainly in highland areas above 1500 m is believed suitable for potato. Since the highlands are also home to almost 90 percent of Ethiopia's population, the potato could play a key role in ensuring national food security (FAO, 2008). However, the current area cropped with potato about 0.16 million hectares and the national average yield is about 7.2 t/ha, which is very low as compared to the world’s average production of 16.8 t/ha (Adane et al., 2010). The crop yield in Ethiopia is lower than that of most potato producing countries in Africa like South Africa and Egypt, which produce 34.0 and 24.8 t/ha, respectively (FAO, 2008). At present, potatoes are still widely regarded as a secondary crop, and annual per capita consumption is estimated at just 5 kg. However, potato growing is expanding steadily: FAO estimates that production has increased from 280 000 tones in 1993 to around 525 000 tones in 2007 and 280 million tons in 1993 to around 329,556,000 tons in 2009 in Ethiopia and World respectively (FAOSTAT, 2010). The highlands of Ethiopia are the most populated areas of the country containing the majority of the agricultural work force required for the sector. With the continuing increase in population and decline in size of farm land holdings, the major labor force has to move to the labor intensive cropping system to sustain rural development and food production (MoARD, 2006). The optimizing of plant density is one of the most important subjects of potato production management, because it affects seed cost, plant development, yield and quality of the crop (Bussan et al., 2007). In practice, plant density in potato crop is manipulated through the number and size of the seed tubers planted (Allen and Wurr, 1992). Thus, the studies have been conducted to create the optimal combination of seed size and planting distance for a certain environment (Bussan et al., 2007). The yield of increased as increasing plant density whereas percentage of large tubers decreased. Though, the optimal planting density differed depending on the environmental conditions and cultivars. The possibility of securing high yield depends much upon maintenance of optimum number of plants per unit area and their spatial arrangement in the field (Endale and Gebremedhin, 2001). The optimum intra-row and inter-row spacing in potato production plays a great role on yield and yield components. Rahemi et al. (2005) also reported that intra-row spacing was significant on yield of potatoes and the 20 cm intra-row Abstract The aim of the study was to determine optimum plant population on yield and yield components of potato in Debub Ari district of south Omo zone, Southern Ethiopia. The study was carried out from 2018 to 2019 cropping season. Three inter-rows spacing (70, 80 and 90 cm) and three intra-rows spacing (30, 40 and 50 cm) were arranged in a randomized complete block design with three replications. Use of 30 cm intrarow spacing and 80 cm inter-row spacing is superior in potato tuber yield (33.40 t ha-1). However, use of 30 cm intrarow spacing and 80 cm inter-row spacing produced optimum tuber yield for potato production in the study area. Keywords: Intra-row spacing, inter-row spacing, potato tuber yield. Global J Res Agri Life Sci. 2025; 5(5), 139-143 @ 2025 | PUBLISHED BY GJR PUBLICATION, INDIA 140 spacing in comparison with 30 cm spacing showed 13.9, 59.8 and 30.39% increase in yield. Intra-row distance of 20 cm increased total tuber number and weight, and tuber weight per plant and the marginal return rate increased by 13% when intra-row distance decreased from 35 to 25 cm. In Ethiopia, many production problems accounted for the low yield of potato. Among them, lack of proper planting material, inappropriate agronomic practices, absence of proper pest and disease management practices and unavailability of proper transport, storage and marketing facilities are the prominent ones (Bereke, 1994). Low soil fertility is also one of the factors limiting the productivity of crops, including potato (Bergaet al., 1994). Similarly, Bekele (2001) suggested that the annual total production is very low due to the acute shortage of good quality seed-potatoes, poor production and yielding capacities and high susceptibility to late blights. Traditionally, farmers maintain or improve the fertility of farmland soils either by practicing fallowing, use of farmyard manure, intercropping and/or crop rotation. The use of some of these cultural practices as a means of maintaining or improving soil fertility is limited to a great extent due to small land holdings of farmers. The optimization of plant density is one of the most important subjects of potato production management, because it affects seed cost, plant development, yield and quality of the crop (Bussan et al., 2007). When potatoes are grown for quality and higher yield production, agronomic practices need to be used in order to maximize the production of seed size tubers and decrease the yield of large tubers. There is still much to learn about even the simple interrelationships of haulm and tuber growth and the interference between branches. An understanding of these inter-relationships should allow the crop to be managed so as to provide a wide range of responses, such as radiation interception and influence of climate variation in maturity, earlier tuber formation and control of the number and sizes of tubers at maturity (Koomanet al., 1996). Most of the Debub Ari woreda farmers are planting with inappropriate row spacing or blanket recommendation due to lack of awareness appropriate planting row spacing and improved varieties. So, in order to minimize this constraint there is need to found standard-seeding rates or spacing for seed sizes to confirm ideal yield. Therefore, the objective of this study was conducted to evaluate the optimal plant population (Inter and Intra-row planting methods) for potato that would enhance growth and productivity. 2. Materials and Methods 2.1 Description of the Study Area On farm experiment conducted at Senegal kebele, Debub Ari woreda South Omo Zone during 2018/19 cropping season. The sites are situated at 036O 40’ 59.3” E longitude and 05O 50’ 07.6” N latitude with 1400-2300 m.m and 22 0C and 110C mean annual rainfall and temperature, respectively. The altitude of the areas 1918 m.a.s.l. 2.2 Experimental Treatments and Procedures Field experiment conducted using 9 treatments and laid in randomized complete block design in 3 replications. The treatments included three intra row spacing (30, 40 and 50 cm) and three inter row spacing (70, 80, 90 cm) with factorial combination. The experiment design was Randomized Complete Block Design (RCBD) with three replications. 2.3 Data collection Plant height, number of tuber per plant, total tuber yield, marketable tuber yield and unmarketable tuber yield were taken. Plant height (PH): height of five randomly selected plants was measured from the base of the stem to shoot apex at flowering. Number of tuber per plant: The average tuber number of was recorded from five randomly selected plants. Total tuber yield (t/ha): The sum of marketable and unmarketable tuber yields. Marketable tuber yield (t/ha): was recorded at harvest by weighting tubers which are healthy and greater than 20 mm diameter. Unmarketable tuber yield (t/ha): was recorded at harvest by weighting tubers which are rotten, greened and less than 20 mm diameter. 2.4. Statistical Analysis Analysis of variance was carried out using SAS-statistical software (SAS Version 6.12, 1997). Significantly differing means were separated using the least significance difference (LSD) test at 5% level of significance as per the procedure described by Gomez and Gomez (1984). Global J Res Agri Life Sci. 2025; 5(5), 139-143 @ 2025 | PUBLISHED BY GJR PUBLICATION, INDIA 141 3. Result and discussion 3.1 Plant height Interaction effect of inter-row spacing with intra-row spacing showed significant effect on plant height of potato (Table 1). The highest plant height (100.9 cm) was recorded in the treatment combination of 70 cm inter-row and 30 cm intrarow spacing. The results of this experiment indicated that the combinations of narrow inter and intra-row spacing resulted was maximum plant height. On the contrary, the lowest plant height (90.8 cm) was recorded in the treatment combination of 90 cm between row and 30 cm between plant spacing and it was significantly different from the other treatment combinations. This might be due to the fact that plants at narrow spacing practiced high competition for growth resources such as light and grow more vegetative whereas, plants that exhibit intense competition increased in height. The result of this investigation opposes with the finding of Zamil, et al. (2010) who reported that the widest spacing gave the tallest plant which was significantly different from the closest spacing. Endale and Gebremedhin (2001) also reported that significant effect of spacing (spatial arrangement) on plant height. This might have resulted due to the availability of growth factors in the wider inter and intra-row spacing. In contrary Ahmed et al. (2010) reported that intra-row spacing had no significant effect on plant height. 3.2 Number of tuber per plant The highest number of tubers per plant (14.87) was recorded at the wider inter and intra row spacing of 90*50cm whereas the lowest number of tubers per plant (11.82) was obtained at the narrow inter and intra row spacing of 70*30 cm (Table 1). In the wider intra and inter row spacing there could be minimum competition among plants for space and resources and also better plant exposure for high radiation interception that increased the photosynthetic efficiency of the plant and finally resulting in increased number of tubers per plant. In line with this result, Leyla and Halis (2009) reported that closer spacing reduced tuber number per hill, average tuber weight, tuber yield per hill and percentages of large and medium size tubers. Table 1: Interaction effect of inter and intra row spacing on Plant height, Number of tuber per plant, Tuber yield and Marketable tuber yield of combined result Treatments PH (cm) NTPP TY (t ha-1) MTY (t ha-1) 70*30 100.9a 11.82d 30.93b 27.22b 70*40 98.50c 12.68cd 27.56c 24.23c 70*50 93.83f 14.12ab 21.88e 19.82e 80*30 99.20b 13.18bc 33.40a 30.97a 80*40 96.67d 12.23cd 24.32d 22.68d 80*50 92.68h 14.07ab 17.97f 16.60f 90*30 95.97e 11.83d 25.42d 22.63d 90*40 93.30g 13.72b 20.95e 19.42e 90*50 90.80i 14.87a 17.46f 16.68f LSD 5% 0.486 0.984 1.523 1.425 CV (%) 4.40 16.36 15.35 11.50 3.3 Tuber yield The analysis of data revealed significant difference due to interaction effects on tuber yield (Table 1). The highest mean tuber yield (33.40 t ha-1) was obtained from 80*30 cm inter and intra row spacing, while the lowest mean tuber yield (17.46 t ha-1) was obtained from the wider inter and intra row spacing 90*50 cm. The present result is in agreement with the finding of Sultana and Siddique (1991) who reported that the yield of tubers per hill increased significantly with increase in plant spacing but the yield of tuber per hectare did not follow the same trend. 3.4 Marketable tuber yield The analysis of data revealed significant difference due to interaction effects on marketable tuber yield (Table 1). The highest mean marketable tuber yield (30.97 t ha-1) was obtained from 80*30 cm inter and intra row spacing, while the lowest mean tuber yield (16.60 t ha-1) was obtained from the wider inter and intra row spacing 80*50 cm. Global J Res Agri Life Sci. 2025; 5(5), 139-143 @ 2025 | PUBLISHED BY GJR PUBLICATION, INDIA 142 Table 2: Effect of intra and inter row spacing on unmarketable tuber yield of combined result Treatments UMTY (t ha-1) Intra row spacing (cm) 30 3.33 40 2.98 50 1.38 LCD (5%) NS Inter row spacing (cm) 70 2.78 80 2.07 90 1.63 LCD (5%) NS CV (%) 30.90 3.5 Unmarketable tuber yield The analysis of data revealed a non-significant difference due to main and interaction effects on unmarketable tuber yield (Table 2). The highest mean unmarketable tuber yield (3.33 and 2.78 t ha-1) was obtained from 30 cm intra row spacing and 70 cm inter row spacing. This result is in agreement with Khalafalla (2001) who reported unmarketable tuber number per hill increased with decreased intra-row spacing. 4. Conclusion and recommendation From the present study it is possible to conclude that both intra and inter row spacing affect yield and yield related traits of potato. 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