Comparative effects of Varying Rates of Moringa Leaf, Poultry Manure and NPK Fertilizer on the Growth, Yield and Quality of Okra (Abelmoschusesculentus L. Moench)

The fertilizer management practices have not ensure the desired improvement in yield for okra (Abelmoschusesculentus L. Moench) due to differences in fertilizer types. The search continues for nutrient sources that would provide adequate nutrition for the crop on the season. A pot experiment was carried out at the Teaching and Research Farm, Ekiti State University, Ado Ekiti, Nigeria to evaluate the growth and fruit yield responses of okra (Abelmoschusesculentus L. Moench) to the application of air-dried milled moringa leaf (MML), poultry manure (PM) and NPK fertilizer. The MML was applied at 400, 800, and 1200 kg/ha; NPK 15-15-15 at 250 kg/ha and PM at 10 t/ha separately and in all possible combinations in completely randomized design in three replicates. The parameters measured were plant height, stem girth, number of leaves, leaf area, number of fruits and fruit weight. The single treatments differed significantly (P = 0.05) with the combinations of the treatments giving better performance. The 800 kg/ha MML + PM treatment gave the tallest plants (103.33 cm) and followed by single application of PM (102.33 cm). The application of 400 kg/ha MML + PM + NPK produced the highest number of fruits but 800 kg/ha MML + PM + NPK gave the highest fresh fruit (42.70 g) and dry fruit (20.50 g) weight. 800 kg/ha gave best growth performance among MML but 1200 kg/ha gave best yield. This suggests that MML can be used as source of nutrients to grow okra.

INTRODUCTION Okra (AbelmoschusesculentusL., Moench) is grown for fresh fruits in the tropical and subtropical regions and ranks first in terms of calorie for human consumption (Babatunde, 2007). The output of okra constituted about 4.6 percent of the total staple food production in Nigeria between 1970 and 2003 (CBN, 2004). Inadequate weed management, infertile soils, cultivation of low-yielding varieties and sub-optimal planting densities are some of the major constraints to high okra yield and production in Nigeria (Iyagba, et al., 2013) which necessitated the development of various agronomic practices the farmers can adopt to improveokra growth and fresh pod yield. The soil in Nigeria are inherently poor in fertility on account of low available nutrients and organic matter contents such that the application of organic and inorganic fertilizers would be the rule for high crop production. Inorganic fertilizers have been promoted as the panacea tothis low fertility and nutrient losses, more so as the added fertilizer nutrients become immediately availablein the soils for uptake by crops. The fresh fruit yields of okra increased with NPK fertilizer application and the recommended optimum rates had differed among the varieties (Babatola, 2006).However, the long term dependence on high rates of inorganic fertilizer has demerits: soil acidification, nutrient imbalance and trace element deficiencies especially of manganese (Mn) and zinc (Zn) (Asaduet al., 2004). These have catalyzed the identification and use of organic materials as alternative nutrient sources. Besides, the scarcity of fertilizers and resultant high prices which are beyond the reach of resource-poor farmers mean that the recommended fertilizer rates are hardly met if any at all (Rahman, 2004). Organic manures are relatively resistant to microbial degradation but are essential for enhancing soil nutrient availability and maintaining optimum soil physical conditions. Poultry manure have been reported to influence positively the growth and fruit yield of okra (Ashraf et al., 2016;Aliet al., 2013;Tiamiyuet al., 2012) which had led to the increase in the its use as nutrients sources by farmers. Poultry manure is a very cheap and effective source of nutrients, especially nitrogen (N) but ready availability remains an important issue since large amounts must be applied to give optimum yield. Also, plant residues: banana peels (Jonathan et al., 2012), Senna siamea, LeucaenaleucocephalaandGliricidiasepium (Akandeet al 2010; Olujobi and Ayodele, 2013), sea weeds (Khan et al., 2009), Moringaoleifera (Fahey, 2005) are sources of nutrients needed to improve crop production. Moringaoleifera is a good sources of green manure as it compared very well with other green manure crops such as lablab beans (Fuglie, 2008). Fuglie (2008) reported the use of moringa seedlings as green manure for crop production. Moringaoleifera was one of the green manure used by Makindeet al. (2016) in the production of fluted pumpkin who concluded that plant materias can be used as an alternative to synthetic fertilizers. Moringa leaves are rich in zeatin, a naturally-occurring cytokinin and other compounds such as ascorbates, vitamin E, and phenolics which confer on the leaf extract the status of a natural plant growth enhancer (Nagar et al., 2006). Harlinet al. (2004) advocated for the integrated use of organic manure and inorganic fertilizers to supply the nutrients required to sustain maximum crop productivity and profitability while minimizing the negative environmental impacts from nutrient use. Therefore, this study was carried out to evaluate the comparative effects of moringa leaf, poultry manure and NPK fertilizer singly and in combination on the growth and yield of okra (Abelmoschusesculentus) in Ado -Ekiti. Southwestern Nigeria.

II. MATERIALS AND METHOD Experimental Site
The experiment was conducted at the Teaching and Research Farm,Ekiti State University, Ado-Ekiti, during the 2015 cropping season. The study site lies on latitude 5°45 ′ N and longitude 8°15 ′ E and experiences tropical climate characterized by a wet and dry seasons. The long wet season is from late March to November and divided into early and late seasons by little dry season in July to August.

Collection and analysis of soil, moringa and poultry manure samples
Top soil (0-15 cm) samples were randomly collected from cultivated farm, bulked to form a composite sample, airdried and sieved using a 2mm mesh size. The routine analyses as described in Udo et al. (2009) for physical and chemical properties were carried out on the soil sample. 10 kg of the soil sample were measured into 10l plastic containers that were perforated at the base. Fresh Moringaoleifera leaves were air-dried and milled. Poultry manure was also obtained from the dump site of the Poultry House on the Farm, air-dried and finely crushed.

Experimental design
The treatments consisted of milled moringa leaf (MML) at 400, 800 and 1200 kg/ha, 10 t/ha poultry manure (PM) and 250 kg/ha NPK 15-15-15 fertilizer singly and in all possible combinations and control. The MML and PM were applied 2 weeks before planting while the NPK fertilizer was applied 2 weeks after planting (WAP). Two seeds of okra (NHAe 47-4 variety) were sowed to each pot and thinned to one seedling after emergence at 2 WAP. The experiment was laid out in a Completely Randomized Design (CRD) with three replicates. Adequate watering, weeding and pest control were carried out as required.

Data collection and statistical analysis
Data were collected on plant height, number of leaves and leaf area at intervals of two (2) weeks from 2 WAP. The leaf area was calculated as the product of leaf length and leaf breath and coefficient factor obtained with the graphical method (Pandey and Singh, 2011). Harvesting of fresh fruits begins at 9 WAP which was done in 4 days interval. The number of fruits per plant was counted while the fruit weight per plant (fresh and dry) were recorded.All data collected were subjected to analysis of variance (ANOVA) and the treatment means were separated by Fisher's Least Significant Difference (LSD) at 5% probability. Table 1 shows the pre-cropping soil properties and some chemical properties of the PM and MML. The soil was a slightly acidic (pH=6.24) loamy sand, containing 0.09%N, 1.48% organic matter and16.59 mgkg -1 available P while exchangeable K, Na, Ca, and Mg were 0.25, 0.03,2.38,1.12 cmolkg -1 respectively. The MML was slightly acidic (pH=6.37) while PM was slightly alkaline (pH=8.25). MML was higher in exchangeable K (10.40 cmolkg -1 ), total N (4.51%) and available P (7.16 mkg -1 ) than PM with 0.09 cmolkg -1 exchangeable K, 3.76% total N and 3.00 mgkg -1 available P. Table 2 shows that okra plant height increased with theMML levels and the application of NPK 15-15-15 and   Table 5 shows that PM and NPK produced the same average number of fruit per plant (4) followed by M3 (3)

IV. DISCUSSION
The pH value of the soil (pH=6.24) was within the pH range of 6 -7 considered as suitable for optimum performance of vegetables (Purselglove 1992). The total N was very low compared to the critical level of 0.1% for N in the soils of Nigeria (FMANR, 1990) suggesting the need for its increased supply in the soil to improve the growth and yield of okra.This expectation was met with the application of NPK, PM and MML singly and in all combinations which increased the selected growth parameters at all sampling occasions. Studies have shown that MML and PM are rich in nutrients (Patterson et. al., 1998;Fahey, 2005;Mark, 2010; Annette, 2012) and can thereby be used as soil amendments. Treatments with PM significantly influenced the height of okra plants. Moringa has been used as a growth enhancer (Fahey, 2005, Aluko, 2016 through foliar spray of the leaf extract but not as soil amendment. The response of okra to soil-applied MML was reflected in the growth parameters and fruit yield. Fuglie (2008) andMvumiet al. (2012 and 2013) had reported increased in the yields of crops with the application of moringa leaf extract. The increase in MML rates resulted in higher fruit yield which is similar to the observation of Aluko (2016) that the increase in concentration of moringa leaf extract as foliar spray improved pepper fruit yield. The significant increase in the growth parameters confirms the ability of plant residues to compete favorably with the inorganic fertilizers as sources of nutrients (Olujobi and Ayodele, 2013).MML and PM increased okra growth in the same magnitude as NPK 15-15-15 fertilizer and confirms that organic materials improved crop production by gradual release of nutrients (Akandeet al.,2010). The use of organic and inorganic fertilizer mixture to improve okra crop production observed by Akandeet al (2010) and Olujobi and Ayodele (2013) is similar to the response of MML + PM + NPK which would ensure steady release of nutrients, especially N that exerts the greater control on growth and yield potentialities of the soil in south western Nigeria (Olaniyi, 2006). The integrated application of NPK 15-15-15, PM and MML gave higher yield compared to the sole application of these sources. Havlinet al (2004) had advocated the integrated approach to nutrient management in crop production for better performance. Akandeet al (2010) noted that the combination of organic and inorganic fertilizer produced better yields of okra. The sole application of NPK 15-15-15 gave a better performance in terms of number of fruits and fresh fruit and dry fruit weights compared to the sole application of MML and PM. This is associated with ready availability of nutrients from NPK 15-15-15 produced in water-soluble form whereas PM would undergo microbial decomposition and mineralization through which nutrients are slowly released over a long period.

V. CONCLUSION
The results showed that the application of NPK 15-15-15, poultry manure and milled moringa leaf had significant effect on the performance of okra. The combination of NPK 15-15-15, poultry manure and milled moringa leaf gave better performance. Application of MML at different rates gave significant effect in growth characters except in number of leaves. Thus, milled moringa leaf can serve as source of nutrients for the production of okra.