Published on International Journal of Food & Nutrition
Publication Date: June 10, 2019
Ogunleye, T. A., Lawal, B. A., Akanbi, W.B. & Kolawole, G. O.
Department of Crop production and Soil Science, Ladoke Akintola University of Technology
Ogbomoso, Oyo State, Nigeria
Commercial production of Orange-Fleshed Sweet Potato (Ipomea batatas Lam) (OFSP) is limited by shortage of planting materials and poor soil fertility. This study was therefore conducted to determine the effects of number of nodes on vine cuttings and fertilizer types on the performance of OFSP. Field experiments were conducted at Fadama site at Ikose and Teaching and Research Farm, Ladoke Akintola University of Technology, Ogbomoso (under rainfed) in 2016. Treatment factorial combinations consisted of three ranges of number of nodes on vine cuttings and four fertilizer types laid out in a Randomized Complete Block Design replicated five times. Data collected on percentage sprouting, tuber yield and tuber nutritional content were subjected to analysis of variance. Means were compared using Duncan’s Multiple Range Test at 5% significant level. Number of nodes on vine cuttings significantly influenced (p<0.05) percentage sprouting and tuber yield, but fertilizer types only significantly influenced the nutritional contents of OFSP tuber. At Ogbomoso, percentage sprouting (53.07%) for 2-3 nodes was significantly higher than others. Tuber yield (79.45 t/ha) was significantly higher with 2-3 nodes while 4-6 nodes gave the least (35.39 t/ha). Carotenoid (155.71 mg/kg) was significantly higher (p<0.05) with 4-6 nodes while application of 10 t/ha tithonia compost produced the highest carotenoids (157.05 mg/kg). Cuttings with 4-6 nodes produced tuber with the highest tuber vitamin A (3505.44 mg/kg) which was significantly higher than others. At Ikose, the highest percentage sprouting (45.52%) was obtained from 7-10 nodes cuttings and this was significantly higher than others. Tuber yield (22.89 t/ha) harvested from 7-10 nodes cuttings was significantly higher than others. Significantly highest carotenoids (155.40.mg/kg) was observed on 4-6 nodes cutting while combine application of 200 kg NPK + 5 t/ha tithonia compost produced the highest carotenoids (155.84 mg/kg) which was significantly higher than other fertilizer types. The study concluded that the use of 2-3 nodes vine cuttings and application of 400 kg NPK was the best agronomic practices for OFSP production in Ogbomoso while 7-10 nodes vine cutting and application of 200 kg NPK + 5 t/ha tithonia compost gave the best result at Ikose.
Keywords: Orange flesh sweet potato,vitamin A,nodes number inr vine, NPK and Tithonia compost.
Sweet potato (Ipomoea batatas L.) belongs to family Convolvulaceae (Oggema et al. 2007 and Mekonnen et al., 2015). It isoften produced by small scale farmers in marginal soils, using low inputs (Amare et al. 2014). It is an important staple food crop in most parts of tropical and subtropical regions of the world (FAO, 2004). It is among the world’s most important versatile and underutilized food crop grown generally for its storage roots (FAO, 2004). Sweet potato is the third most important crop after potato and cassava in the world and one of the root and tuber crops largely grown in East Africa as staple for rural communities (Laban et al., 2015). Sweet potato production in Africa has doubled from 1.0 to 2.0 million tons per year between 2002 and 2012 (FAO, 2017).Sweet potatoes are rich sources of antioxidant, vitamins A, D and E and mineral elements of dietary and health importance (Laban et al., 2015).As a result of the high nutrient contents, its production on large scale becomes inevitable (Okpara et al., 2011).
Yields of sweet potato could be improved by the use of good planting materials in terms of nodes number in the vine cuttings (Essilfie et al. 2016). The numberof nodes on cuttings used as planting material may be an important aspect of yield variability (Essilfie et al. 2016). Yield of sweet potato could be improved by the use of good planting materials which bring about a higher tuber yield.The increase in the length of the vine cutting used and a length of about 30 cm is recommended (Essilfie et al. 2016). It was reported by Anakweze (2011) that cuttings of greater length than this tend to be wasteful of planting material, while shorter cuttings establish more slowly, and give poor yields . It was observed that vine cuttings of 30 cm length with six nodes which were prepared from the healthy stem of each OFSP varieties (Nwankwo et al. 2014) increases the production of healthy vines.
The application of fertilizer is one of the most important input for increasing the productivity of crops (Adediran et al. 2004). Generally, nutrient deficiency has been shown to account for low yields in the production of sweet potato (Njoku et al., 2001 and Okpara et al., 2011). Despite common low-input cultivation practices, sweet potato shows a large yield response to nutrient input application via fertilizer and manure (Agbede and Adekiya, 2010). Fertilizer application could also increase yield of orange fleshed sweet potato by at least 32 % under poor soil condition and nearly double (83.93%) under better condition (Stathers et al. 2005). Better sweet potato root quality was observed at optimum amount of nitrogen supply especially through organic sources (Nedunchezhiyan et al., 2003). There is a dearth of information in south western Nigeria on appropriate fertilizer type and number of nodes on vine cutting for the production of OFSP. This is required to fine tune the production technology required for large scale production of this crop. This study was conducted to evaluate the effects of number of nodes per vine cuttings and fertilizer types on the performance of OFSP.
2. MATERIALS AND METHODS
Field experiments were carried out between 2016 and 2017 at Ikose and LAUTECH Ogbomoso. Ikose lies on latitude 8º111N and longitude 4º121E while Ogbomoso lies on latitude 8º101N and longitude 4º161E, the temperature ranges from 28-33oC with a relative humidity of about 75%. This`study involved two locations Ogbomoso (under rainfed) and Ikose (under irrigation). The Ikose trial was carried out between October 2016 and March 2017 while the Ogbomoso trial was carried out between April and September 2017. The treatment consisted of three number of nodes (2-3 ,4-6 and 7-10 nodes) and four fertilizer combinations (0, 400 kg NPK 15-15-15/ha, 10 tons/ha compost, and 200 kg NPK 15-15-15/ha + 5tons/ha compost). The factorial combination of the two factors gave 12 treatments laid in Randomized Complete Block Design replicated five times. The gross experimental area was 1034 m2 and was divided into five replicates each measured 47 m x 3.6 m Each replicate was subdivided into 12 plots making a total of 60 plots. The plot size was 3 m x3.6 m and contained 55 plants spaced out at 90 cm x 30 cm. Data collection commenced 4 weeks after planting (WAP). Three plants per plot were tagged for measurement of growth, tuber yield and nutritional qualities. Parameters assessed are percentage sprouting, vine length, number of secondary vine, leaf area, number of flowers, tuber weight/hectare and tuber nutritional qualities. Data collected were subjected to analysis of variance and treatment means were separated using Duncan Multiple Range Test at 5% probability level.
The results showed that number of nodes and fertilizer types significantly influenced growth, yield and yield traits across the study area. The highest percentage sprouting (53.07%) from Ogbomoso recorded from 2-3 nodes planted potato was not significantly different from sprouting from others (Table 1). However, the least percentage sprouting in Ikose (29.99%) obtained from 2-3 nodes planted potato was significantly lower than others. Length of primary vine and leaf area at both locations were not significantly influenced by number of nodes and fertilizer type except at 4 WAP (Table 2 and 3). Fertilizer types had significantly influenced the number of flowers at 8 WAP with the highest average of 1.60 recorded from plants that received 200 kg NPK 15:15:15 + 5 ton/ha Compost treatment in Ikose (Table 4). The treatment maintained the lead at 12 WAP (4.64) while the least number of flowees was obtained from plants treated with no fertilizer. However, across the weeks in Ogbomoso, both number of nodes and fertilizer types have no significant influence on number of flowers.
Tuber yield from Ogbomoso were significantly higher than yields from Ikose (Figure 1). The highest tuber yield (79.45 ton/ha) harvested from 2-3 nodes planting materials in Ogbomoso was significantly higher than tuber yield from others. The highest tuber yield obtained from 4-6 nodes planting materials in Ikose was significantly higher than yields from others while 18.32 ton/ha harvested from application of only NPK was not signicantly higher than yields from application of other fertilizer type except control treatment where no fertilizer was applied. However, in Ogbomoso, among the fertilizer types, compost application produced the highest yield of 60.89 ton/ha which was not significantly higher that yield harvested from other sources. Dry Matter Content (DMC) was significantly influenced by number of nodes and fertilizer combination (P≤0.05) across the location. Planting materials with 4-6 nodes produced the highest DMC across the locations (57.28 and 57.21 mg/kg in Ogbomoso and Ikose respectively) which were significantly higher than others, with the least obtained from 2-3 nodes planting materials (Table 5). Application of 400 kg NPK 15-15-15/ha produced tubers with significantly higher DMC (56.65 and 56.67 mg/kg in Ogbomoso and Ikose respectively). Number of nodes on planting materials and fertilizer type applied also influenced Carbohydrate contents in the tuber significantly but protein content was not siginifantly influenced by either of the factors (Table 5).
The highest carotenoids contents (155.71 and 155.40 mg/kg from Ogbomoso and Ikose respectively) obtained from tubers produced by 4-6 nodes vine were not significantly different from values from yields of other nodes. However, in both location, fertilizer type influenced carotenoids contents (Figure 2). Application of 10 ton/ha compost influenced the carotenoids content most (157.05 and 155.84 mg/kg from Ogbomoso and Ikose respectively). Carotenoids content where compost was combined with NPK were not significantly different compared with sole compost application but was significantly different compare with sole NPK and control. Vitamin A contents of tuber produced by 4-6 nodes vine were significantly higher than contents in others while application of sole NPK produced tubers with significantly lower vitamin A contents (Figure 3).
Better sprouting of vines of potato observed in Ogbomoso compared with Ikose was in accordance with the reports of by Matimati et al. (2003) and Essilfie et al. (2016) that the survival of sweet potato is majorly attributed to the soil, weather conditions and that sweet potato will sprout beter under a rainfed condition. In 2004, Ebregt et al. observed that
the survival of sweet potato is more related to the agro-ecological condition which may cause planting materials failure to take off and also that sweet potato does not have the ability to resist dryness. This is in agreement with findinds of Yeng et al. (2012) that fresh planting materials from dividing portions of the vine, with good land preparation ensures good sprouting of vines. None significant growth parameters response of sweet potato was in agreement with the findings of Janssens (2001) and Mukhtar et al. (2010) which was attributed to innate quality of the crop itself because sweet potato can colonize maginal soils, due to its ability to produce adventitious roots and trailing vine as observed in this finding. In the report of Puran and Ronell (2014), vine cuttings with 3 to 5 nodes was reported to survive with higher opportunity to sprout and develop due to presence of more nodes and higher carbohydrate reserve. Even, higher number of nodes of seven was repoted by Anakweze (2011) as against 2-3 nodes observed in this trial to have sprouted better than other higher number of nodes.
Potato grown without application of fertilizer was repoted to have less dry matter yield (Nedunchezhiyan et al. 2010) comprared with report of Jarvan and Edesi (2009) that dry matter content increased with application of manure and mineral fertilizer. This can explain why significantly lower dry matter was obtained from potato treated with no fertilizer.
Carbohydrate content was least with the application of 400 kg NPK 15:15:15 as against the report of Vosawai et al. (2015) that application of increased mineral fertilizer gave the highest carbohydrarte content. Vosawai et al. (2015) reported that application of inorganic fertilizer produced the highest carotenoid content in sweet potato. Naikwade et al. (2011) reported that beta carotene content was significantly increased in response to the type and the level of nitrogen fertilizer applied. The highest carotenoid obtained from sweet potato treated with sole NPK 15:15:15 was in agreement with report of Albert (2015) that sole application of NPK gave the highest carotenoid content of OFSP.
The study concluded that 2-3 nodes with the application of 10 t/ha compost exhibited the best performance for growth parameters and 4-6 nodes with application of 400 kg NPK 15:15:15 produced the best result for tuber nutritional content at Ogbomoso. 7-10 nodes vine cuttings and application of 200 kg NPK + 5 t/ha Tithonia compost gave the best result at Ikose.