Published on International Journal of Agriculture & Agribusiness
Publication Date: September, 2019
Fikadu-Lebeta W. & Refisa-Jebessa G.
Department of Horticulture, College of Agriculture and Veterinary Sciences, Ambo University
P.O. Box 19, Ambo, Ethiopia
The experiment was conducted to study the effect of different rates of cow dung application on growth and yield of carrots (Daucus carrota L.) of Nantes variety during 2015 at Ambo University College of Agriculture and Veterinary Sciences. Cow dung were applied at four levels; T1 (control), T2 (5 t ha-1), T3 (10 t ha-1) and T4 (15 t ha-1). The experiment was laid out in a randomized complete block design with three replications. The result showed that no significant differences were obtained for parameters; plant height, leaf number, root length & root diameter due to treatments. Root fresh weight and root dry weight were significantly affected by different rates of cow dung application. The highest yield was recorded by 15 t ha-1 cow dung application which was better for promoting carrot root development. In this finding, it is recommended that the experiment should be repeated at more location and years to confirm the obtained result.
Keywords: Carrot, Cow dung, vegetables, organic fertilizers, growth and yield.
Carrot (Daucus carrota L.) is one of the most important root vegetable classified under the family of Apiaceae. It is a cool season vegetables and growth is optimal when temperature is maintained between the ranges of 150c to 240c. The crop needs well drained soil with organic fertilizers incorporated to the soil (Manosa, 2011; Zeleke & Derso, 2015). Carrot is an important source of carotenoids, flavonoids, vitamins (A, B & C), sugars and minerals, which are used for both food and health benefits. It is very helpful to maintain eyes health and also serve as antioxidant (Baranski et al., 2010; Dias, 2014). Chemoprotective compounds are the products of carrots that protect the body against many diseases of civilization (Bystricka et al., 2015).
Although carrot is very important vegetable crops, its production continues to be constrained by a number of biotic and abiotic factors that can reduce productivity. Among the various factors contributing for potential yield, fertilizer management is of great importance (Emana et al., 2015). Literatures have reported that organically produced fruits and vegetables fetch premium price on the international market (Oberholtzer et al., 2005). Organic fertilizer application for carrot crop production is very best with specific recommendation over inorganic fertilizers which are not ecofriendly. It is recommended to improve the growth and yield of carrots when compared to plants not received any fertilizer (Mbatha, et al., 2014).
Cow dung is very important source of organic fertilizer which is ecofriendly. It maintains soil health and can improve crop productivity by increasing soil fertility. Using cow dung effectively can contribute to reduce environmental degradation and reduce greenhouse gas concentration (Raj et al., 2014). Accordingly Ali (1998) reported that cow dung manure improves physical and chemical properties of the soil.
Amos et al. (2015) found that cattle manure application for maize vegetable at 15 ton ha-1 has increased plant height (140.4cm) by 24% over the control. In addition, it produces the overall increase in all parameters. Similarly, Dawuda et al. (2011) reported that application of chicken manure at 15 t ha-1 improves vegetative growth, root yield and give more income for carrot crop production. Mehedi et al. (2012) also stated that 15 t cow dung ha-1 application to carrot showed the better gross and marketable yield (38.13 t ha-1 and 30.42 t ha-1, respectively).
The lower productivity of carrot in Ethiopia cannot be ascribed to the lack of high yielding cultivars; rather, the main cause of low yielding is suboptimal uses of fertilizers like cow dung. To omit these problems, several attempts have been done to increase the yield potential of carrots crops. But, they have concerned with inorganic fertilizers. The literature pertains that the use of organic fertilizers in vegetable crops production particularly in carrot is very much limited (Ahmed et al. 2014; Emana et al., 2015). Therefore, the experiment was undertaken to study the effect of cow dung application on growth and yield of carrot (Daucus carrota L.).
2. MATERIALS AND METHODS
2.1. Description of the Study Area
The experiment was conducted under irrigation from March 2015 to June 2015 at Ambo University College of Agriculture and Veterinary Sciences, Main Campus, which is found in West Shewa zone, Ethiopia. The research site was under field condition, horticulture garden of the University. Ambo University is geographically located at about 8057’N latitude and 38007’E longitude. The area was located in altitude of 2195 m.a.s.l and 126km away from Addis Ababa. The average rain fall is 1150 mm and average temperature is 18.50c. The soil of the experimental area was characterized by well drained vertisols (Ambo Woreda Agricultural Office Annual Report, 2014, unpublished).
2.2. Experimental Materials
The experiment was conducted using carrot seed of Nantes variety and cow dung manure. Nantes variety of carrot is one of the potential carrot varieties in West Shewa. It is being cultivated widely and has been accepted by farmers due to its high yielding ability, consumers’ preference, wider adaptation and relatively resistance to disease compared to other improved carrot varieties growing in the area. Dried and decomposed cow dung manure was obtained from Ambo University dairy farm.
2.3. Experimental Procedures
Suitable site was selected and the land was cleaned (unwanted materials and vegetables were removed). The area was measured by using trigonometric theorem (3, 4, 5). Land digging and plot preparation according to the length and width recommended to carrot production was undertaken in accordance with a standard practice locally used. Different levels of Cow dung were incorporated to the soil at the time of land preparation. Carrot seed of Nantes variety was brought from Holeta Agricultural Research Center. The seed was sown according to recommended space at the rate of 5 kg ha-1 and drilled in rows in each plot uniformly and thinned back to the recommended space after emergence (Zeleke and Derso, 2015). All agronomic practices were applied uniformly to all plots. Data were collected accordingly at harvest.
2.4. Treatments and Experimental Design
For this experiment, Randomized Complete Block Design (RCBD) was used with three replications and it consists of a single factor (cow dung application). The cow dung were applied at four rates; treatment one (T1) control, treatment two (T2) 5 ton ha-1, treatment three (T3) 10 ton ha-1 and treatment four (T4) 15 ton ha-1. Treatments were assigned randomly to experimental plots within the block. Plots were consisted of four rows at 25 cm distance apart and 5cm distance between plants. Each plot was comprised of 1.5m×2m, total of 3m2. Space between plots and blocks were 0.5m and 1m respectively.
2.5. Data Collected
Ten plants were selected randomly from each plots on different parameters such as, plant height, leaf number, root length, root diameter, fresh mass and dry mass of carrot root crop. The data were collected at harvest.
Plant Height (cm): Plant height was recorded from base of the root to the tip of the plant at harvest and average plant height were taken.
Leaf Number: The leaf number was recorded in ten randomly selected plants from plots at harvest and average leaf number was expressed in number.
Root Length (cm): The length of root was measured in ten randomly selected plants from each plot at harvest from the base of the root to the top of the root and average length was expressed in cm.
Root Diameter: The diameter of ten roots selected randomly was measured by using caliper at basal portion and the average root diameter was expressed in cm.
Fresh Weight of the Root (g): The weight of ten roots selected randomly at harvest was recorded with the help of beam balance and the average root weight was expressed in gram.
Dry Mass of the Root (g): The fresh mass of the root was chopped and dried by oven dry at 75oC temperature for 48 hours at harvest and recorded with the help of beam balance and the average root weight was expressed in gram.
Gross Yield per Hectare: Ten plants during harvesting were weighted and converted to yield per hectare.
2.6. Data Analysis
All parameters under investigation were subjected to Analysis of Variance (ANOVA) for statistical analysis and LSD at 5% was used to compare the mean difference between treatments (Gomez & Gomez, 1984).
3. RESULT AND DISCUSSION
3.1 Growth Parameters: Measured growth parameters were not significantly affected by application of different rates of cow dung. A general increase in plant height and leaf number was observed, although the difference was not significant. The highest plant height (39.95 cm) and leaf number (16.18) was recorded from 15 ton ha-1 cow manure application, while the lowest 34.99 cm and 14.37 was from control respectively (Table 1). Probably, this may be due to low Nitrogen levels to facilitate the growth and development of foliage parts of the plant. This finding is in correspondence with the findings of Mehedi et al. (2001) who stated that the application of high rate of cow dung at 20 ton ha-1 was increased the percentage of branched root and rotten roots which reduced the yield and favors the growth parameters (leaf number and plant height), lower rates of cow dung application increased the yield rather than growth parameters. This result was also coincide with the investigation of Gudugi (2013) who stated that application of cow dung led to significant increase in growth and yield of okra plant over the control. Application of cow dung at the rate of 15 to 20 t ha-1 significantly improved the performance of Okra plant. However, the effect of cow dung on number of leaves per plant was not significant.
Table 1. The effect of cow dung rates on growth parameters of carrot
CV= Coefficient of variance, LSD = Least significant difference, NS = not significantly different at LSD (0.05) level of probability.
3.2 Yield Parameters: The measured yield parameters of carrots were significantly affected due to different levels of cow dung application except root diameter and root height. Although root diameter and root height were not responded a significant difference, the mean value measured was showed that the general increase in both parameters as the rate of cow dung application increased (Figure 1). This is in correspondence with the report of Ahmed et al. (2014) who stated that application of organic manure had no significant effect on carrot root diameter. However, according to this investigation, the rates of cow dung application were significantly affected root fresh weight and root dry weight. With an increase in the rate of cow dung, the root fresh weight was increased. The highest root fresh weight (145.06 g plant-1) was recorded from the plot treated with 15 ton ha-1 of cow dung application and the lowest (76.86 g plant-1) was recorded from the plot treated with 5 ton ha-1 of cow dung rate (Figure 2). This finding is agreed with the finding of Abduallha-Al-Noman (2015) who conducted the experiment to see the effect of cow dung, zinc and boron on carrot. He found that the maximum root fresh weight (160.70 g), dry matter of root (12.35 %) and yield ha-1 (59.67 t) was recorded from 15 t ha -1 cow dung application. Similarly, Mazed et al. (2015) stated that maximum root fresh weight of (146.50 g) was recorded from 25 t ha-1 cowdung application and the lowest (123.96 g) from no treatment. Jeptoo et al. (2012) also stated that application of bio-slurry manure at 7.8 t ha-1 increased yield of carrots by 23.5% over control. Increased response of root fresh weight might be due to the increasing level of fertility status of the soil. This is in line with the finding of Awodun (2008) who reported cow dung is very best in improving soil fertility particularly for growing vegetable crops. Similarly, Audu and Aliyu (2013) found that cow dung is a good fertilizing material that can be used to maintain soil fertility status and improve crop production.
The effect of different rates of cow dung application on root dry weight and gross yield per hectare were significantly affected both parameters. The mean comparison at LSD 5% probability level showed that maximum root dry weight was recorded from the plot treated with 15ton/ha of cow dung while minimum root dry weight was recorded from the plot treated with 5 ton ha-1. The highest root dry weight (81.47g plant-1) was recorded from the plot treated with 15 ton ha-1 of cow dung application and the lowest (43.17g plant-1) was from the plot treated with 5 ton ha-1 of cow dung rate (Figure 2). In the case of gross yield ha-1, maximum amount of yield (40.63 ton ha-1) was obtained from plots treated with 15 ton ha-1 while minimum amount (21.53 ton ha-1) was obtained from application of 5 ton ha-1 of cow dung rate (Figure 3). This finding is in correspondence with the finding of Mehedi et al. (2012) who stated that 15 t cow dung ha-1 application to carrots showed the better gross and marketable yield (38.13 t ha-1 and 30.42 t ha-1, respectively).
Figure 1. The effect of cow dung rates on root diameter (a) and root height (b).
Mean values followed by the same letters are not significantly different at LSD (0.05) level of probability
Figure 2. The effect of cow dung rates on root fresh weight (a) and root dry weight (b).
Mean values followed by the same letters are not significantly different at LSD (0.05) level of probability
Figure 3. The effect of cow dung rates on Gross yield ha-1.
In this study we investigate that the effects of different rates of cow dung application on growth and yield of carrot crop. The result revealed that the maximum root fresh weight (145.06g), root dry weight (81.47g) and gross yield ha-1 (40.7 ton) were recorded from the plot treated with 15 ton ha-1 of cow dung rate, while the minimum 76.86g, 43.17g and 21.53 ton ha-1 respectively were recorded from the plots treated with 5 ton ha-1 of cow dung. Application of cow dung to carrot crop with the rate of 15 ton ha-1 was obtained significant difference for parameters; root fresh weight, root dry weight and gross yield per hectare. As the rate of cow dung application increased the yield per hectare also increased. The low rate of cow dung application led to small root fresh weight, root dry weight and gross yield ha-1. Different rates of cow dung application for root diameter, plant height and leaf number was not showed significant difference. Therefore, low rate of cow dung application cause yield reduction, so it is recommended that the experiment should be repeated at more location and years to confirm the obtained result.
First and for most, we would like to thank Almighty God for giving us health and strength to conduct this experiment. Also we would like to thank Ambo University College of Agriculture and Veterinary Sciences for developing this course in the BSc curriculum of Horticulture. Finally we express our gratitude to Ambo University department of horticulture laboratory workers for their technical assistance.