THE EFFECTS OF GOAT MANURE AND SUGARCANE MOLASSES ON THE GROWTH AND YIELD OF BEETROOT ( BETA VULGARIS L)

: A pot experiment was conducted to study the effect of goat manure and sugarcane molasses on the growth and yield of beetroot ( Beta vulgaris L. ) in sandy regosol. The experiment was laid out in a completely randomized design (CRD) with six treatments. The treatments included inorganic fertilizer (T1), 10 t/ha of goat manure alone (T2) and also 10 t/ha of goat manure and 50% triple superphosphate (TSP) with 1–4 t/ha of sugarcane molasses (T3-T6). The results showed that plant growth parameters (leaf length, leaf petiole length, leaf width, leaf number, fresh weight and dry weight of leaves) were significantly varied among the treatments. There was a significant difference in the diameter of beetroot among the treatments. Significant differences (P<0.05) were observed in fresh weight of beetroot and total plant among the treatments. Fresh weight of root yield and total yield of beetroot per plant were increased in 10 t/ha goat manure, 2 t/ha sugarcane molasses and 50% TSP (T4) and 10 t/ha goat manure, 3 t/ha sugarcane molasses and 50% TSP (T5) when compared to the control treatment (T1). The total yield of beetroot per m 2 was 1,792.62 g in T4 and 1,402.68 g in T1. The root yield of beetroot was increased in T4 in comparison to T5. It can be concluded that 10 t/ha of goat manure with 2 t/ha of sugarcane molasses and 50% TSP could be applied for obtaining a high yield of beetroot in sandy regosol.


Introduction
Beetroot (Beta vulgaris .L) belongs to Chenopodiaceae family. It is grown widely in Sri Lanka. Beetroot is good for health as it contains minerals, vitamins, fiber and medicinal properties. This crop is one of the most noteworthy vegetables with regard to antioxidant properties, primarily owing to the presence of betatains (Ullah and Khan, 2008;Nahla et al., 2018). In some countries, beetroot pigment is commercially used as red food dye in diverse products. Beta vulgaris var. rubra has considerable anticancer properties (Kapadia et al., 1996). Beetroot is an annual vegetable crop grown for its root, and commonly grown beet varieties are detroit dark red and crimson globe. In Sri Lanka, it is grown in all agroecological regions but effectively cultivated in Nuwara Eliya, Badulla, Kandy and Matale districts. Beets prefer well-drained fertile sandy loams to silt loams with high organic matter for better root development.
Inorganic fertilizers release nutrients quickly, therefore, farmers widely use it to supply nutrients for vegetable crops to obtain a high yield, but excessive use of these fertilizers is toxic to human health and causes nutrient loss, groundwater contamination and a decrease in effective microbial communities (Chen, 2006). On the other hand, the use of organic manure improves soil physical and chemical properties and provides favorable conditions for crop growth with less environmental impact (Suthamathy and Seran, 2009). The application of organic manures can increase crop yield and soil fertility more than chemical fertilizer (Murmu et al. 2013). Hence, the residual effects of organic manure or compost application increased crop production for at least one growing season (Eghball et al., 2004;Imthiyas and Seran, 2017).
The use of locally available organic manures with a reduced level of inorganic fertilizers could give a greater seed yield than inorganic fertilizers alone (Seran, 2016;Raveenthira and Seran, 2020). Ojeniyi and Adegboyega (2003) reported that the application of goat manure remarkably increases nitrogen (N), phosphorous (P), potassium (K), calcium (Ca) and magnesium (Mg) in the leaf of celosia plant. Sugarcane molasses are ones of the economically important agricultural crops grown in tropical regions, and they are produced annually in large amounts (De la Rosaa et al., 2019). They are a byproduct of sugar industries which have been used in agriculture as an organic source of fertilizer. It contains sugar, minerals, vitamins, ash and polyphenols (Takara et al., 2007;Jain and Venkatasubramanian, 2017;De la Rosaa et al., 2019). The use of sugarbeet molasses in crop cultivation accelerates nutrient uptake efficiency and soil biological activity (Samavat and Samavat, 2014). The application of organic manures improves the water holding capacity of soil and supplies both macro and micro plant nutrients for achieving better crop yield. Therefore, this experiment was aimed to determine the effect of the combined application of goat manure and sugarcane molasses with a reduced level of phosphorus (P) inorganic fertilizer on the growth and yield of beetroot and also to find out the optimum rate of molasses with 10 t/ha of goat manure as a basal application for a high yield of beetroot in sandy regosol. The finding is useful to beetroot growers for obtaining high yield with less use of inorganic fertilizer.

Materials and Methods
A pot experiment was carried out in the Crop Farm of Eastern University, Sri Lanka in 2018-2019. This area comes under the agroecological zone of the low country dry zone. The annual rainfall ranges from 1800 to 2100 mm. The annual mean temperature is 32±3˚C and the humidity level nearly 60%-80%. The type of soil is sandy regosol. A pot experiment was laid out in a completely randomized design (CRD) with six treatments and ten replications. Treatments included in this experiment are as follows.
Sugarcane molasses were collected from the Galoya Plantation (Pvt) Ltd, Hingurana, Ampara, Sri Lanka and goat manure was obtained from Animal farm, Eastern University, Sri Lanka. According to the treatments, goat manure (1.73% N, 0.47 P 2 O 5 , 1.67% K 2 O) and sugarcane molasses (0.53% N, 0.043 P 2 O 5 , 1.48% K 2 O) were taken and mixed with soil to prepare the soil mixture. The polybags (30 cm height and 30 cm diameter) were filled with soil mixture, and holes were made at the side and base of each polybag to facilitate the drainage of water.
Seeds of beetroot cv. crimson globe were collected from the Department of Agriculture, Nuwaraeliya, Sri Lanka. Two seeds were placed in each polybag, but only one healthy seedling was maintained in each polybag one week after seedling emergence. Inorganic fertilizers as basal (165 kg/ha urea, 270 kg/ha tripe superphosphate, 125 kg/ha muriate of potash) and top dressing (165 kg/ha urea, 125 kg/ha muriate of potash) were applied to control treatment (T1) as recommended by the Department of Agriculture, Sri Lanka. Other treatments, that is, T2-T6, 10 t/ha goat manure and 0-4 t/ha sugarcane molasses with half dosage of recommended tripe superphosphate (TSP) were applied as described above. Irrigation was done twice a day in the morning and evening by using a watering can. Weeding was done manually.
In this experiment, leaf, root and yield parameters in all treatments were collected at harvesting time. Plant height was measured using a meter scale in each plant. The number of leaves per plant was counted. Length and width of leaf, petiole length and edible root length (cm) were measured with the aid of a ruler while the diameter of the edible root was measured with the aid of a vernier calliper. The chlorophyll content of leaves was measured using a chlorophyll meter (SPAD 502 plus). The shoot (above-ground level plant part) and edible root portion of each plant in all treatments were separated and their fresh weights (g) were measured. These materials were cut into small pieces, separately dried at 105 0 C for 1 hour in an oven, and their dry weight (g) was recorded using an electronic balance. Harvesting was done at 75 days after planting. Total crop yield (g/m 2 ) and marketable root yield (g/m 2 ) were calculated. All the collected data for each parameter were analyzed by analysis of variance using the SAS 9.1 statistical software package. The treatment mean was compared by the Tukey's test at the 5% significance level.

Results and Discussion
Plant height Figure 1 shows the average plant height of the beetroot crop in each treatment. There was a significant variation (P<0.01) in plant height among the treatments. Plants treated with T5 (10 t/ha of goat manure, 3 t/ha of sugarcane molasses and 50% of TSP) exhibited maximum plant height (27.4 cm), whereas T1 (inorganic fertilizers as control) had a minimum value of 19.36 cm among the treatments. A significant variation in plant height was observed between T1 and T5, but the difference between T2 (10 t/ha of goat manure alone) and T5 was not significant. Among the treatments, the shortest plant was observed in the control (T1) treatment where NPK inorganic fertilizers were applied at the recommended rate. In addition to primary nutrients, sufficient amounts of secondary macronutrients such as calcium, magnesium and sulfur are important for plant growth. Ojeniyi and Adegboyega (2003) have stated that goat manure also releases essential micronutrients to the soil, and it was found to significantly increase the leaf growth of celosia. The growth and yield of beetroot as influenced by goat manure and sugarcane molasses 325 The maximum plant height recorded in T5 may be probably due to favorable application of goat manure and molasses which contain potassium and other nutrients. Nitrogen (N), phosphorus (P) and potassium (K) are the major nutrients essential for plant growth and yield. The high concentration of these primary nutrients is necessary for plants as any deficiency of the essential nutrients will preclude healthier plant growth (Gholizadeh et al., 2009). T6 treatment (10 t/ha of goat manure, 4 t/ha of sugar masses and 50% TSP) produced significantly shorter plants as compared to T5. This may be due to excess potassium ion availability from the high concentration of K fertilizer applied. This result is supported by the findings of Taiz and Zeiger (2006), who suggested that excess ions in nutrient solutions decreased plant growth. Shaibur et al. (2008) reported that potassium ions reduced calcium and magnesium concentrations in rice seedlings.

Number of leaves
There was no considerable difference (P>0.05) in an average number of leaves produced per plant. The minimum value of 6.4 was obtained in T2, while the maximum number of leaves (9.2) was recorded in T5 ( Figure 2). This may be due to the high nutrient supply, particularly nitrogen and potassium in the combined application of goat manure and molasses. In this study, the number of leaves per plant was increased by increasing potassium supply to a certain limit then declined as observed in the lower number of leaves in T6 compared to T5. Molasses supply the ion at a higher rate. Serio et al. (2001) mentioned the lower rate of lettuce leaf production under the higher electrical conductivity value in soilless conditions. The leaf surface area is important for the physiological activity of the plant.

Leaf length
Statistically analyzed data revealed that there was a remarkable difference (P<0.0001) in the length of the 1 st leaf of the plant among the treatments (Table 1). This ranged from 9.20 cm to 13.36 cm, whereas it was 8.90 cm -10.30 cm for the length of the 2 nd leaf. These lengths were higher in T5 compared to other treatments. The application of molasses may provide the plant nutrients probably potassium for the leaf growth. The result obtained in this study was in agreement with the findings of Shabala (2003) and Fromm (2010), who have mentioned that potassium serves a vital role for osmoregulation, cell expansion, stomatal movements and photosynthesis. In the other study, the increasing potassium fertilizer application resulted in decreased phosphorus (Baghour et al., 2001;Lin and Yeh, 2008) and Ca and Mg concentrations in leaves (Sabreen and Saiga, 2004;Lin and Yeh, 2008). The inadequate primary nutrient supply reduces photosynthesis, leaf production and plant growth (Zhao et al., 2005), which is an indication that the plant requires a balanced supply of plant nutrients for better leaf growth.

Leaf petiole length
There was a substantial variation (P<0.05) in the petiole length of the beetroot plant among the treatments. Petiole lengths of the 1 st leaf (13.80 cm) and the 2 nd leaf (12.10 cm) were the longest in T5 compared to other treatments (Table 1). Potassium is identified as the dominant osmoticum (Shabala et al., 2000), and it is important for cell enlargement and stomatal function (Shabala, 2003). Plants make use of calcium ion for strengthening cell walls (Hepler, 2005). In addition to N, P and K nutrients, the application of goat manure also supplies Ca, Mg and other micronutrients to soil for plant growth as stated by Ojeniyi and Adegboyega (2003).

The growth and yield of beetroot as influenced by goat manure and sugarcane molasses 327
Leaf width A significant difference (P<0.001) was observed in the average leaf width of the plant among the treatments. The higher value of 6.24 cm was attained in T5, and a lower value of 5.04 cm was noted in T6 (Table 2). Leaf width was considerably higher (P<0.05) in the T5 treatment than in other treatments except for T4. This finding was supported by the result of Shabala et al. (2000), who stated that potassium plays a role in cell enlargement and leaf expansion. The T6 treatment had a lower value of leaf width than T5. A high potassium concentration may cause a deficiency of calcium and magnesium (Nguyen et al., 2017). As a result of low calcium availability, a decrease of plant height, leaf area and plant growth was observed by Leal and Prado (2008).

Shoot weight of the beetroot plant
Fresh and dry weights of the shoot (above-ground level plant part) per plant are given in Table 2. Significant differences in both fresh (P<0.01) and dry (P<0.05) weights of the shoot were observed among the treatments. The values of fresh (17.55 g) and dry (3.02 g) shoot weights obtained in T5 were higher than those in other treatments while lower values (10.55 g and 1.62 g respectively) were recorded in T2. The T1 treatment using inorganic fertilizers alone produced 14.27 g of fresh and 2.42g of dry shoot weights. A similar shoot weight was recorded between T1 and T2. It may be due to potassium availability to plants. Potassium performs significant roles in the physiological processes, such as photosynthesis, translocation of photoassimilates, transportation of water and nutrients, nutrient balance, etc., in plants (Marschner, 2012;Hasanuzzaman et al., 2018).

Chlorophyll content
There was a significant variation (P<0.05) in the chlorophyll content of leaves, as shown in Figure 3. The leaf chlorophyll content ranged from 35.40 (T2) to 45.17 (T5) and a notable difference (P<0.05) was observed between T2 and T5 treatments. This difference may be due to the required amount of nutrients received by plants. Chlorophyll is necessary for photosynthesis to produce essential carbohydrates as a food source for the plants (Hynninen and Leppakases, 2002). Guo et al. (2019) have stated that increased potassium supply interferes with the uptake of the other nutrients, particularly nitrogen and potassium uptake, and optimal potassium enhances the nutritional function of NO 3 − in wheat plants. Figure 3. The effect of goat manure, molasses and 50% TSP application on the average chlorophyll content of beetroot leaves.

Diameter of the edible root
The diameter value of the edible root (beetroot) in each treatment is shown in Table 3. According to the statistical analysis, there was a considerable difference (P<0.01) in the diameter of beetroot among the treatments. A high average value (4.04 cm) of the root diameter was attained in T4 (10 t/ha of goat manure, 2 t/ha of sugar molasses and 50% TSP). This value, however, was statistically similar to those in T1 and T5 treatments.
The reason may be due to the sufficient amount of potassium supplied by molasses for increasing the diameter of the beetroot grown in sandy regosol soil. The potassium fertilizer application increased the total sugar in beetroot plants grown in sandy calcareous soil (Abdel-Motagally and Attia, 2009). In this study, T5 and T6 treatments showed lower values of the root diameter than the value The growth and yield of beetroot as influenced by goat manure and sugarcane molasses 329 obtained in T4. A higher rate of potassium provides the adverse effect on calcium (Leal and Prado, 2008), but calcium is very important for fundamental physiological functions in plant structure and signalling (Gilliham et al., 2011). Domingues et al. (2016) reported that the dry mass of the shoot and root was high in plants grown with high calcium concentrations.

Fresh weight of the edible root
The fresh weight of the edible root (beetroot) per plant is indicated in Table 3. There was a remarkable difference (P<0.0001) in the fresh weight of the beetroot among the treatments. The fresh weight of the root ranged from 22.29 g to 37.28 g. The combined application of 10 t/ha of goat manure, 2 t/ha of sugar molasses and 50% TSP significantly (P<0.05) had a higher value of beetroot than the other treatments except for T5. The lowest fresh weight was recorded in T2. Romheld and Kirkby (2010) mentioned the positive effect of the potassium fertilizer application on the yield of sugar beet. Mg deficient plants are less competent to translocate sucrose to the root via the phloem (Hermans et al., 2006;Farhat et al., 2016). Potassium nutrient accumulates more in roots than in the shoot of the beetroot plant (Granjeiro et al., 2007). Chen et al. (2018) reported that magnesium deficiency did not influence the dry weight of the shoot but reduced the dry weight of the root. The application of farmyard manure with reduced inorganic fertilizers improves soil fertility and crop yield (Seran, 2016).

Fresh weight of the beetroot plant
There was a significant variation (P<0.0001) in the total fresh weight of the plant among the treatments. The total fresh weight of the beetroot plant in each treatment is shown in Table 3. The maximum value of 53.83 g was recorded in T4, whereas a minimum value of 32.84 g was attained in T2. Abdel-Motagally and Attia (2009) stated that the fresh weight of beetroot was increased with increasing potassium rates. A similar result was reported by Chandraju et al. (2008), who noted that the application of molasses enhances the primary nutrient uptake and yield of leafy vegetables. In plants grown with a low ion level of magnesium, total biomass is lower than that of plants with sufficient magnesium ions (Cakmak and Kirkby, 2008), and potassium deficiency results in a severe reduction in photosynthetic CO 2 fixation and use of photosynthates (Cakmak, 2005). The application of goat manure with EM could give a higher yield of vegetable cowpea (Seran and Shahardeen, 2012).

Beetroot yield
Marketable root yield (g/m 2 ) and total crop yield (g/m 2 ) of beetroot are given in Figure 4 and Figure 5, respectively. According to the statistical analysis, there were remarkable differences (P<0.0001) in root yield and total crop yield among the treatments. The highest root yield (1241.51g) and total crop yield (1792.62 g) of beetroot were obtained in the T4 treatment. These values, however, were not different from T5. Plants treated with T1 (control treatment) gave significantly lower values of the crop and root yields than plants treated with T4 and T5. This result supported the findings of Çakmak (2005) and Hermans et al. (2006), who have indicated that potassium and magnesium have important functions in photosynthesis and biomass distribution among the plant parts. Magro et al. (2015) have observed that the use of organic compost increases root production.
Plants treated with T1 (control treatment), T2 (10 t/ha of goat manure alone) and T3 (10 t/ha of goat manure, 1 t/ha and 50% TSP) gave significantly lower values (P<0.05) of root yield and crop yield than those in T4. Mohammadi and Brimvandi (2009) reported that the application of molasses increased available potassium and total nitrogen but reduced available phosphorus in soil. The excess potassium application may influence calcium and magnesium deficiency (Nguyen et al., 2017). In this study, goat manure, molasses and triple superphosphate provide essential macro and micronutrients for the growth and yield of beetroot in sandy regosol. Further, we suggest that naturally available phosphate fertilizer can be used in crop cultivation as a substitute for triple superphosphate (inorganic fertilizer) as stated by Sithamparam and Seran (2014). Figure 5. The effect of goat manure, molasses and 50% TSP application on the total yield of the beetroot crop.

Conclusion
The results revealed that the application of 10 t/ha of goat manure, 2-3 t/ha of sugarcane molasses and 50% TSP significantly increased marketable root yield and total crop yield of beetroot when compared to the recommended NPK inorganic fertilizers. Marketable root yield was high (1241.51g) in the T4 treatment (10 t/ha of goat manure, 2 t/ha of sugarcane molasses and 50% TSP) followed by T5 (10 t/ha of goat manure, 3 t/ha of sugarcane molasses and 50% TSP). The marketable root yield and total yield of the beetroot crop in T4 were increased by 33.8% and 27.8% respectively as compared to those in the control treatment. The result proves that goat manure combined with sugarcane molasses and TSP is a suitable source of nutrients for improving soil fertility and the yield of beetroot. This study concludes that the combined application of 10 t/ha of goat manure with 2 t/ha of sugarcane molasses and 50% TSP is more suitable for sandy regosol to obtain a high yield of beetroot than the recommended chemical fertilizer. Moreover, it can be suggested that organic or natural phosphorus resources can be used as a replacement for inorganic phosphorous fertilizer since organic manure is ecofriendly. A further study is necessary to evaluate the quality of beetroot.