GROWTH AND YIELD OF OKRA (ABELMOSCHUS ESCULENTUS) IN RESPONSE TO TREE LEGUME MANURE AND UREA FERTILIZER By

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1 Olujobi O. J. 1 and Ayodele O. J. 2 GROWTH AND YIELD OF OKRA (ABELMOSCHUS ESCULENTUS) IN RESPONSE TO TREE LEGUME MANURE AND UREA FERTILIZER By Olujobi O. J. 1 and Ayodele O. J Department of Forestry, Wildlife and Fisheries Management, Ekiti State University, P.M.B. 5363, Ado-Ekiti, Nigeria 2. Department of Crop, Soil and Environmental Sciences, Ekiti State University, P.M.B. 5363, Ado-Ekiti, Nigeria Correspondence Author: olujobioj@yahoo.com Abstract Out of the nutrients required for adequate nutrition and high yield of okra (Abelmoschus esculentus, L. Moench), nitrogen (N) is the most critical. Unfortunately, N deficiency is widespread in Nigeria on account of low available soil N and organic matter content. This study examined the growth and fruit yield responses of okra to organic leaf mulch and inorganic fertilizer (urea) application during the rainy season of There were five treatments consisting of leaf residues of three tree legumes: Senna siamea, Leucaena leucocephala and Gliricidia sepium each applied at 5 MT.ha - 1, urea fertilizer to supply 60 kg Nha -1 and control (no soil additive). The treatments were replicated three times and allocated to plots in a completely randomized design. Okra (variety NHAe 47-4) was established in 2.80x1.20 m beds and data on morphological characters taken at 2, 4, 6 and 8 weeks after planting. There were significant differences (P < 0.05) in plant height, leaf length and width due to application of tree legume leaf residues while number of leaves was not significantlly different. Okra in Gliricidia sepium leaf residue treatment, performed best in term of fruit yield at harvest. Therefore, application of tree legumes leaf residue (especially Gliricidia) to the soil in okra growth cycle is recommended for adoption by farmers in the study area for improved okra productivity. Key words: Okra, tree legume, urea fertilizer, growth and yield. IJAFS 4, 2013, 12: Accepted for publication, June, Cite as IJAFS 4 (1&2), Pp Introduction As the society develops in size and complexity, demand for resources increases both in intensity and diversity. The increase in population of developing countries has influenced the production, supply and demand for goods and services, especially in urban areas. Shortage of food in most of these countries is a function of population explosion and rural urban migration, environmental hazards (drought, flood etc), low level of technology, attitude of people towards farming (some people believed that farming is meant for poor people), land hunger and widespread soil infertility (Olujobi and Oke, 2005). Low and declining soil fertility is a serious problem, particularly in the humid lowland of Western Nigeria where farmers had traditionally relied on natural bush fallows for nutrient and soil organic matter build-up (Nye and Greenland, 1960). This fallow system is gradually collapsing under the pressure of increasing population such that farmers increasingly practice a more or less sedentary agriculture on small land area (Kadeba, 1999). The success of sedentary agriculture depends on the ability of farmers to maintain or improve the quality of the basic element of the natural resources base (soil). Soil productivity maintenance is a major constraint of tropical agriculture. 502

2 Growth And Yield Of Okra (Abelmoschus Esculentus) In Response To Tree Legume Manure And Urea Fertilizer Tropical soils are adversely affected by sub-optimal fertility and erosion, causing deterioration of the nutrient status and changes in soil organism populations (Economic Commission for Africa, 2001). The use of inorganic fertilizers can improve crop yields and soil ph, total nutrient content, and nutrient availability, but its use is limited due to scarcity, high cost, nutrient imbalance and soil acidity. The use of organic manure as a means of maintaining and increasing soil fertility has been advocated (Smil, 2000). Nutrients contained in manures are released more slowly and are stored for a longer time in the soil, ensuring longer residual effects, improved root development and higher crop yields (Abou El Magd et.al., 2005). Out of the nutrients required for adequate nutrition and high yield of okra (Abelmoschus esculentus, L. Moench), nitrogen (N) is the most critical. Unfortunately, N deficiency is widespread in Nigeria on account of low available soil N and organic matter contents, while the coarse-textured nature of top soils and rainfall patterns favour high nitrate losses through leaching (Ayodele, 1993). The present blanket fertilizer recommendation of 200 kg/ha of NPK fertilizer for vegetable crops in Ekiti state has not yielded the expected result because it not based on systematic studies for respective nutrients availability in the soils of the state (Ayodele, 1993). Moreover the high input approach to soil maintenance through inorganic fertilizer has not been successful in the region because of the unfavourable socio-economic and agroecological conditions. During the past decade, there has been a great deal of discussion and debate about the use of organic fertilizer in tropical region to improve soil fertility and thus increase crop yield. In this circumstance, a low cost management strategy becomes necessary to maximize yields and fruit quality of vegetable crops. To this effect, the use of organic residues has been emphasized. Therefore, this study was carried out to evaluate the effects of multipupose tree legume residue and inorganic fertilizer application on the growth performance and yield of okra (NHAe 47-4 variety). Materials and Methods The study was conducted at the Teaching and Research Farm, Ekiti State University Ado-Ekiti, in South West Nigeria ( lat N, long E, 25 m above sea level, subhumid tropical climate). The soil was classified as Oxic Tropudalf - well drained with moderate fertility. Experimental plot measuring 10 x 12 m was cleared and divided into fifteen plots of 2.80 m x 1.20 m with buffer of 1 m in-between the plots. Five different treatments namely: (1) Senna siamea leaf residue; (2) Leucaena leucocephala leaf residue; (3) Gliricidia sepium leaf residue; (4) Urea fertilizer and (5) control (no soil additive). Each plot area was made into flat bed, and each plant leaf biomass was applied at the rate of 5 MT. ha -1. Average nitrogen content in the leaf sample of the three legume species (Senna siamea 3.23%; Leucaena leucocephala 3.59%; Gliricidia sepium 3.42%) was used as basis for determining the quantity of leaf biomass to be added to supply equivalent amount of 70 kg N ha -1 (Oyun, 2006). The experiment was laid out in Completely Randomized Design (CRD) replicated three times. After 7 days of application, viable seeds of okra were sown directly into the soil at 3 seeds per hole at a depth of 2 cm with the spacing of 70 x 30 cm. giving rise to fourteen stands per bed. After 6 days of germination, the seedlings were thinned to one per stand, and urea fertilizer was applied at the rate of 60 kg N.ha -1 to the seedlings in the inorganic fertilizer treatment. 503

3 Olujobi O. J. 1 and Ayodele O. J. 2 Two weeks after planting (WAP), one stand of okra per treatment was uprooted and plant height, leaf number, leaf length and leaf width were measured. Plant from each treatment was divided into root, stem and leaf. Fresh weight of each component part was determined on a scale on the field. Sub-sample of each component part was oven dried at 70 o C for 48 hours to constant weight to determine the dry matter yield. The same procedure was repeated at 4, 6 and 8 WAP respectively. At maturity, okra fruit of the remaining ten plants in each treatment were harvested twice in a week for a period of three weeks. The yield was determined on a scale. Statistical Analysis Growth and yield parameters were analyzed for differences using analysis of variance (ANOVA) techniques based on statistical analysis system (SAS) package (2000) at 5 % level of significance. The means were separated with New Duncan s Multiple Range Test. Results Characteristics of the experimental soil The soil of the experimental plot is slightly acidic, with ph value of The organic cabon and total nitrogen are relatively low. Available phosphorus and potassium are very low. Mechanical analysis indicated that the soil is loamy sand (Table 1). Effect of inorganic and organic residue application on growth of okra Okra plant height was not significantly different for all the treatments at 2WAP (Table 2). At 4 WAP, okra in Leucaena leucocephala leaf biomass treatment has significantly higher height value (27.48 cm). Plant heights of okra are not significantly different in Gliricidia sepium, Senna siemea and urea treatments. At maturity (6-8 WAP), Gliricidia sepium leaf biomass treatment has the highest plant heights (31.04 cm and respectively), however the values are not significantly different (P< 0.05) from that of urea and Leucaena leucocephala. Okra plant in the control treatment has the least height throughout the growth period. Leaf length revealed that at 2 WAP okra in the control treatment plot has the significantly (P< 0.05) least value (3.96 cm). At 4WAP, okra in urea and Leucaena leucocephala treatments has the highest value of leaf length (11.10 cm), however, the values are not significantly different (P< 0.05) from that of Senna siemea and Gliricidia sepium treatments (Table 3). The control treatment has the least value and it is significantly different from the other treatments. At 6WAP, Gliricidia sepium leaf biomass treatment has significantly higher leaf length (16.24 cm), while the control has the least value of leaf length (13.26 cm). At 8WAP the result shows that okra leaf length in Gliricidia sepium and Senna siemea leaf biomass treatments are significantly higher (15.70 cm and cm respectively) (Table 3). Table 1: Physical and chemical properties of the experimental soil Soil properties Measured values ph ((H 2O) 5.90 Organic Carbon (%) 1.19 Nitrogen (%) 0.13 Available phosphorus (ppm) 3.45 Potassium (meg/100g) 0.24 Calcium (meg/100g) Magnesium (meg/100g) 2.35 Mechanical analysis (%) Sand 78.4 Clay 4.8 Silt

4 Growth And Yield Of Okra (Abelmoschus Esculentus) In Response To Tree Legume Manure And Urea Fertilizer Table 2: Height (cm) of okra during growth cycle Means with the same superscript in each column are not significantly different at P < 0.05 Weeks after Planting Gliricidia sepium 8.90 a b ab a Senna siemea 8.60 a b c a Leucaena leucocephala 8.94 a a ab a Urea 8.76 a b ab a Control 8.08 a c d b Table 3: Leaf length (cm) of okra during growth cycle Means with the same superscript in each column are not significantly different at P < Weeks after Planting Gliricidia sepium 5.24 a a a a Senna siemea 5.22 a ab bc a Leucaena leucocephala 4.70 a a b b Urea 5.16 a a c b Control 3.96 b 9.74 b c b Table 4 revealed that okra leaf width was not significantly different for all the treatments at 2WAP. At 4WAP, Gliricidia sepium leaf biomass treatment gave the highest leaf width, however, the values was not significantly different (P < 0.05) from Senna siemea, Leucaena leucocephala and urea. At 6WAP, Gliricidia sepium leaf biomass treatment has the highest okra leaf width and it was not significantly different (P < 0.05%) from Senna Siemea and Leucaena leuocephala treatments. At 8WAP, the result shows that width of okra leaves are not significantly different for all the treatments except in the control treatment which has the least value (11.44 cm). Leaf number of okra was not significantly different (P < 0.05) for all the treatments throughout the growth period (Table 5). 505

5 Olujobi O. J. 1 and Ayodele O. J. 2 Table 4: Width (cm) of okra leaf during growth cycle. Means with the same superscript in each column are not significantly different at P < 0.05 Weeks after Planting Gliricidia sepium 5.92 a a a a Senna siemea 5.74 a ab a a Leucaena leucocephala 5.92 a ab ab a Urea 5.96 a ab b a Control 5.26 a c c b Table 5: Number of okra leaf during growth cycle Weeks after Planting Gliricidia sepium 3.80 a 4.20 a 4.20 a 3.60 a Senna siemea 3.60 a 4.40 a 3.40 a 3.80 a Leucaena leucocephala 3.80 a 5.00 a 4.00 a 3.80 a Urea 4.00 a 4.20 a 4.40 a 4.20 a Control 3.40 a 3.40 a 4.40 a 3.80 a Means with the same superscript in each column are not significantly different at P < 0.05 Effect of inorganic and organic residue application on yield of okra Okra yield was highest in treatment with Gliricidia sepium leaf biomass (49.91 g) followed by Leucaena leucocephala, (48.34 g) and Senna siemea (47.70 g) treatments. However, okra yield was not significantly different for all the organic residue treatments (table 6). Leucaena leucocephala leaf biomass treatment has the highest dry matter (5.07 g) for okra leaf. Though the value was not significantly different from that of urea, it was however significantly different from that of Gliricidia sepium and Senna siemea leaf biomass treatments (P < 0.05). Stem dry matter was not significantly different for all the treatments. Root dry mater was not significantly different for all the organic residue treatments (P < 0.05), but significantly different from that of urea and control treatments (Table 7). 506

6 Growth And Yield Of Okra (Abelmoschus Esculentus) In Response To Tree Legume Manure And Urea Fertilizer Table 6: Fruit yield (g) of okra at harvest Yield of Fruit Gliricidia sepium a Senna siemea Leucaena leucocephala Urea Control a a a b Means with the same superscript in each column are not significantly different at P< 0.05 Table 7: Dry matter (g) of okra plant during growth cycle. Leaves Stem Root Gliricidia sepium Senna siemea Leucaena leucocephala Urea Control 5.05 b 4.80 b 5.07 a 4.27 ab 2.52 b 6.80 a 6.75 a 7.67 a 6.62 a 5.00 a 5.37 ab 5.35 ab 6.72 a 6.32 b 4.25 b Means with the same superscript in each column are not significantly different at P<0.05 Discussion Significant higher growth advantage exhibited by okra with application of tree legume leaf residues and inorganic fertilizer over okra without application of manure (Control) throughout the growth period, had proved that there is better growth performance in okra when there is addition in form of organic residue or inorganic fertilizer to improve soil nutrient. This result confirms the findings of Ghanbarian et. al., (2008), Uddin et. al., (2009), and Akande et. al. (2010) that application of organic material could ameliorate soil nutrient to improve crop production. The observed greater value in height and leaf size recorded for okra with application of tree legume leaf biomass treatments over okra with application of inorganic fertilizer (urea) in this study (Tables 2, 3, and 4) might largely be due to the available higher organic matter which increases the humus contents of the soil for better aggregation of the loose soil particles. This situation enhanced the moisture holding capacity of the soil and at the same time reduces nutrient loss due to leaching. On the other hand, the sandy nature of the experimental soil (Table1) allowed for rapid leaching of the applied urea fertilizer, which hitherto affects the growth of the okra plant in the urea treatment. This assertion corroborates the report of Owen (2003) that the nutrient use efficiency of crops is better with organic manure than inorganic fertilizer; as the nutrient seems to be more available in tree legume leaf treated plot due to the aggregation of the soil particle than inorganic fertilizer, treated plot. Also the release of nutrient from tree legume leaf biomass is gradual such that there is a synchrony between the nutrient release and nutrient uptake of okra plant for effective utilization. Similar result have been reported on pegeon pea residue and maize (Olujobi and Oyun, 2012). 507

7 Olujobi O. J. 1 and Ayodele O. J. 2 Differences observed in growth parameters of okra with different tree legume leaf biomass residue in tables 1, 2 and 3 could be attributed among other things to the quality of the litter. For instance, the higher growth values obtained for okra in Leucaena leucocephala leaf biomass treatment plot at the early stage of growth over that of Gliricidia sepium and Senna siemea leaf biomass treatments could be due to rapid mineralization of Leucaena leucocephala leaf biomass. The soft nature and small size of Leucaena leucocephala leaf enhanced its rapid decomposition to release plant nutrient, especially N for plant growth. Akande et.al (2010) has made similar observation in an organic and inorganic fertilization of okra experiment. Significant increase in the fruit yield of okra with tree legume leaf residue and inorganic fertilizer (Table 5) compared to the yield in the control treatment could be due to influence of sufficient nutrient supply to okra during growth. Although there are no significant differences in okra yield among the three tree legume leaf residue treatments, and also between tree legume leaf residue and inorganic fertilizer treatments, the apparently higher fruit yield obtained for Gliricidia sepium leaf biomass treatment over that of Leucaena leucocephala and Senna siemea leaf biomass treatments might be due to synchronization between nutrient release by Gliricidia sepium leaf biomass and nutrient demand by okra at the fruiting stage. Higher dry matter yield obtained for leaf, stem and root of okra grown with application of tree legume leaf biomass in this study revealed that organically cultivated crops had higher dry matter content than those grown conventionally (Magkos et.al, 2003). The highest dry matter value in leaf, stem and root of okra in Leucaena leucocephala leaf biomass treatment might be due to the faster decomposition and mineralization of leucaena leaf to supply sufficient nutrient to okra at the early growth stage which led to vigorous vegetative development and dry matter acumulation. Similar performance has been reported in the case of dry matter yield of maize grown in soil improved with legume litter (Myers et.al., 1997; Michael et. al., 2010). Conclusion and Recommendation The results from this study have shown that application of tree legume leaf residue and inorganic fertilizer (urea) positively affects growth performance and fruit yield of okra. Also, okra grown in soil amended with tree legume leaf biomass exhibited a more vigorous growth and better yield than those grown with inorganic (urea) fertilizer and those without addition. It is therefore recommended that low cost base organic farming be adopted by okra farmers in the study area instead of high cost inorganic farming. Also, Gliricidia sepium leaf biomass is recommended for high fruit yield of okra in the study area. References Abou El-Magd, M. M. Hoda, A. Mohammed and Fawzy, Z. F.:Relationship, growth and yield broccoli with increasing N, P or K ratio in a mixture of NPK fertilizers. Annais Agriculture Science Moshtohor, Vol. 43 (2) (2005), pp Akande M. O., Oluwatoyinbo F. I., Makinde, E. A., Adepoju A. S. and Adepoju I. S.: Response of Okra to organic and inorganic fertilization. Nature and Science Vol.8 (11), (2010), pp Ayodele, O. J.: Yield Response of Okra (Abelmoschus esculentus (L) Moench) to N P K Fertilization. Research Bull. 13. National Horticultural Research Institute, Idi-Ishin, Ibadan. (1993 ) 9 pp. 508

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