Effect of different levels of fertilizer and plant spacing on yield of taro (Colocasia esculenta L.) under Marathwada conditions

Introduction

Taro (Colocasia esculenta L.) is a highly nutritious crop, particularly valued for its corms, which contain 63-85%water and are rich in essential nutrients. The corms provide 1.3-4.0% protein, 13-29% carbohydrates, 0.6-1.2% fiber and 2.0-4.0% fat with the starch content ranging between 13-30%. Notably, taro has higher protein content than yam, cassava, and sweet potato, making it a valuable protein source despite its relatively low fat content. The quality of taro corms and cormels is influenced by their acridity and fiber content, and the small size of their starch granules contributes to their excellent digestibility, with an estimated digestibility rate of 98.9%. It is also a good source of vitamins A and C with essential amino acids like leucine and phenylalanine. It is also rich in potassium, calcium, phosphorus, iron, riboflavin, thiamine, niacin, Furthermore; all parts of the taro plant, including the corms, cormels, rhizomes, petioles, leaves, and flowers are edible and contain significant nutritional value. Even after boiling, the tender petioles and leaves remain a rich source of iron and vitamin C, making taro an excellent food for a variety of dietary needs. Two main determining variables for any crop's optimum growth and production are nutrient management and spacing. To increase growth and yield, wise and appropriate application of fertilizers and spacing is necessary. While too high or too low plant spacing can lead to relatively low yield and quality, appropriate plant spacing can produce the best potential production (Akther et al, 2016) [1] . In view of this, the present investigation was conducted to find out optimum dose of fertilizer and appropriate spacing for obtaining higher yield in taro.

Twenty-one distinct taro genotypes were evaluated in previous year among which PBNT-1 genotype was found best in respect to quantitative and qualitative parameter under Marathwada conditions hence, the said selected genotype was used in the present investigation for estimation of optimum dose of fertilizer and spacing. Subsequently the uniform sized healthy, disease free corms weighing 30-40 g were used for planting at three different spacings viz., S1= 60 x 45 cm S2= 60 x 60 cm S3= 60 x 30 cm with the application of different levels of fertilizers viz., F1= 80:60:60 kg NPK/ha (100% RDF) F2=100:75:75 kg NPK/ha (125% RDF) F3= 60:45:45 kg NPK/ha (75% RDF). The other cultivation practices were followed as per recommendations and observations of various yield parameters were recorded periodically and data was statistically analyzed as per standard methods.

Results and Discussion

The data pertaining to number of corms per plant, corm length, corm diameter and weight of corms per plant under various treatments have been statistically analyzed and presented in Table 1. The maximum number of corms per plant (2.03) was recorded in treatment F 2 [125% of the recommended NPK dose (100:75:75 kg/ha)] whereas, the minimum (1.48) was observed in treatment F 3 [75% of the recommended NPK dose (60:45:45 kg/ha)]. The results in respect to number of corms might be due to the higher fertilizer levels generally increase the number of corms per plant by providing essential nutrients that promote growth and development. Das et al. (2018) [4] reported similar result in number of corms per plant in taro. The plant spacing plant spacing S 2 (60 cm x 60 cm) produced maximum number of corms per plant (1.92) while the minimum number of corms per plant (1.56) was obtained in S 3 (60 cm x 30 cm). The greater number of corms per plant produced at wider spacing likely due to less competition among the plants for nutrients, water and space. These results are in accordance with Dhar (1989) [5] . The highest number of corms per plant was recorded in the F 2 S 2 combination [125% RDF (100:75:75 kg/ha) with 60 cm x 60 cm]. The lowest number of corms per plant (1.31) was recorded in F 3 S 3 combination [75% of RDF (60:45:45 kg/ha) with 60 cm x 30 cm]. Akther et al. (2016) [1] and Bhatt et al. (2019) [2] reported similar result in number of corms per plant of taro. The highest corm length (8.20 cm) was recorded in F 2 [125% of recommended dose of NPK (100:75:75 kg/ha)] followed by F 1 [100% recommended dose of NPK (80:60:60 kg/ha)], (7.34 cm) while lowest (7.26 cm) was recorded in F 3 [75% of recommended dose of NPK (60:45:45 kg/ha)] and the highest corm length (8.00 cm) was obtained in the plant spacing of S 2 (60 cm x 60 cm) followed by plant spacing of (S 1 -60 cm x 45 cm) i.e. 7.43 cm. The S 3 (60 cm x 30 cm) recorded lowest corm length (7.37 cm). Adequate fertilization provides essential nutrients that support robust growth and development. Proper levels of nitrogen, phosphorus and potassium promote healthy corm development leading to longer corms. Similarly increase in corm length might be due to proper spacing reduces competition for resources such as light, water and nutrients. When plants are closely spaced, they compete for these resources which can limit corm growth and result in shorter corms. Similar results were reported by reported by Mannan et al. (1988 [6] and Dhar (1989) [5] . The highest corm length was observed in the F 2 S 2 combination [125% of RDF (100:75:75 kg/ha) with 60 cm x 60 cm] averaging (8.93 cm). The lowest (6.62 cm) was obtained from F 3 S 3 combination [75% RDF (60:45:45 kg/ha) with 60 cm x 30 cm]. These are in accordance with the findings of Akther et al. (2016) [1] and Bhatt et al. (2019) [2] .

The maximum corm diameter (6.17 cm) recorded in F 2 [125% of recommended dose of NPK (100:75:75 kg/ha)] followed by F 1 [100% recommended dose of NPK (80:60:60 kg/ha)] i.e. 4.75 cm and the minimum corm diameter (4.69 cm) was recorded in F 3 [75% of recommended dose of NPK (60:45:45 kg/ha)]. This increment in diameter might be due to the application of higher dose of fertilizer, the similar findings are in line of Verma et al. (2012) [8] and Das et al. (2018) [4] . In respect to the plant spacing treatment S 2 (60 cm x 60 cm) recorded maximum corm diameter (5.64 cm) which was followed by S 1 (60 x 45 cm) i.e. 5.09 cm whereas, minimum corm diameter (4.88 cm) was observed in treatment S 3 (60 cm x 30 cm). The increase in corm diameter with wider spacing was also reported by Dhar (1989) [5] and Akther et al. (2016) [1] . Wider plant spacing usually results in larger corm diameter as it reduces competition for resources and allows more favorable condition for corm development. The interaction of plant spacing and fertility levels had a significant effect on corm diameter. The highest corm diameter (6.66 cm) was observed in the F 2 S 2 combination [125% of RDF (100:75:75 kg/ha) with 60 cm x 60 cm], the lowest (4.04 cm) was recorded in F 3 S 3 combination [75% of RDF (60:45:45 kg/ha) with 60 cm x 30 cm]. Akther et al. (2016) [1] and Bhatt et al. (2019) [2] reported similar result about corm diameter in taro. The highest average corm weight (228.95 g) was recorded in F 2 [125% of recommended dose of NPK (100:75:75 kg/ha)] which was followed by F 1 [100% recommended dose of NPK (80:60:60 kg/ha)], (219.44 g) while the lowest (188.39 g) was noticed in F 3 [75% of recommended dose of NPK (60:45:45 kg/ha)] which was significantly inferior to rest of other treatments. Increased fertilizer levels typically lead to greater corm weight per plant by supplying more nutrients that support robust growth. Similarly, the maximum corm weight (236.73 g) was obtained in treatment S 2 (60 cm x 60 cm) which was followed by S 1 (60 cm x 45 cm) i.e. 200.54 g and minimum (199.51 g) was observed in S 3 (60 cm x 30 cm). Wider plant spacing typically enhances corm weight per plant by minimizing competition for nutrients and light (Akther et al. 2016) [1] . The interaction of plant spacing and fertility levels had significant effect on the weight of corms per plant at the final stage. The highest weight of corms per plant was observed in the F 2 S 2 combination [125% of RDF (100:75:75 kg/ha) with 60 cm x 60 cm] averaging (289.55 g). The lowest weight of corms per plant (175.17 g) was obtained in F 3 S 2 [75% of RDF (60:45:45 kg/ha) with 60 cm x 60 cm]. Bhatt et al. (2019) [2] reported similar results in weight of corm per plant in taro. The data pertaining to number of cormels plant -1 revealed that the maximum number of cormels per plant (32.89) was found in F 2 [125% RDF (100:75:75 kg/ha)] followed by F 1 [100% of RDF (80:60:60 kg/ha)] i.e. 30.53 whereas, the minimum (21.10) was recorded in F 3 [75% of RDF NPK (60:45:45 kg/ha)]. Higher levels of fertilizer generally increase the number of cormels per plant by providing essential nutrients that support additional growth. Conversely, lower fertilizer levels often result in fewer cormels due to limited nutrient availability. The maximum number of cormels plant -1 (31.20) was obtained in plant spacing of S 2 (60 cmx60 cm) which was followed by plant spacing S 1 (60 cm x 45 cm) i.e. 27.10 whereas, minimum number of cormels plant -1 (26.22) was observed in the plant spacing of S 3 (60 cm x 30 cm). An increase in plant spacing the corresponding increase in number of cormels plant -1 was also reported by Mannan et al. (1988) [6] and Dhar (1989) [5] . Different levels of fertilizer in combination with spacing had a significant effect on the number of cormels plant -1 at the final stage. The highest number of cormels plant -1 (41.90) was recorded in the F 2 S 2 combination [125% of RDF (100:75:75 kg/ha) with 60 cm x 60 cm] which was significantly higher than the other treatments. The lowest number of cormels plant -1 (19.31) was obtained from the F 3 S 1 [75% RDF (60:45:45 kg/ha) with 60 cm x 45 cm]. These results are in accordance with the findings of Mannan et al. (1988) [6] and Dhar (1989) [5] . The treatment F 2 [125% of RDF (100:75:75 kg/ha)] recorded highest cormel weight (323.53 g) and it was followed by F 1 [100% of RDF (80:60:60 kg/ha)] i.e. 294.80 g while treatment F 3 [75% of RDF (60:45:45 kg/ha)] recorded lowest cormel weight (227.08 g plant -1 ). The similar results were also reported by Verma et al. (2012) [8] and Akther et al. (2016) [1] . The maximum average cormel weight (306.06 g plant -) was obtained in the plant spacing of S 2 (60 cm x 60 cm) followed by S 1 (60 cm x 45 cm) i.e. 271.62 g and minimum average cormel weight (267.73 g plant -) was observed in treatment S 3 (60 cm x 30 cm) which was significantly inferior to rest of other treatments. Wider plant spacing typically leads to greater cormel weight per plant by reducing competition for resources and allowing for more extensive growth (Dhar 1989) [5] . The highest weight of cormels plant -1 351.59 g was recorded in F 2 S 2 [125% of RDF (100:75:75 kg/ha) with 60 cm x 60 cm] followed by F 1 S 2 (325.43 g plant -1 ), (F 2 S 3 317.50 g plant -1 ) whereas, the lowest weight of cormels plant -1 213.53 g was observed in F 3 S 3 combination [75% of RDF (60:45:45 kg/ha) with 60 cm x 30 cm]. This is in agreement with the results of Mannan et al. (1988) [6] and Dhar (1989) [5] . The maximum cumulative herbage yield 120.88 q/ha was recorded in treatment F 2 [125% of RDF (100:75:75 kg/ha)]. However, the minimum 93.48 q/ha herbage yield was recorded in treatment F3 [75% of RDF (60:45:45 kg/ha)].

The highest herbage yield 125.36 q/ha was obtained in plant spacing of S 3 (60 cm x 30 cm) which was significantly higher than rest of all other treatments. The lowest cumulative herbage yield 83.67 q/ha noticed in plant spacing of S 2 (60 cm x 60 cm). The interaction effect of different levels of fertilizer and plant spacing had significant effect on cumulative herbage yield at 120 days. The highest herbage yield 144.31 q/ha was recorded in F 2 S 3 combination [125% of RDF (100:75:75 kg/ha) with 60 cm x 30 cm] which was significantly higher than other treatments. This was at par with F 1 S 3 [100% of RDF (80:60:60 kg/ha) with 60 cm x 30 cm] (128.06 q/ha). The lowest herbage yield 75.28 q/ha was recorded in F 1 S 2 combination [100% RDF (80:60:60 kg/ha) with 60 cm x 60 cm]. Shellikeri et al.

(2019) [7] documented similar data on herbage yield. Interaction effect of fertilizer levels and plant spacing on herbage yield (g/plant) in taro significantly influences overall productivity.

In respect to the total corm + cormel yield, the maximum (233.10 q/ha) was recorded in treatment F 2 [125% of RDF (100:75:75 kg/ha)]. However, the minimum corm + cormel yield was recorded (127.47 q/ha) in treatment F 3 [75% of RDF (60:45:45 kg/ha)]. The influence of plant spacing on the total corm + cormel yield was also noticed as the highest corm + cormel yield (192.26 q/ha) was obtained in plant spacing of S 3 (60 cm x 30 cm) which was significantly higher than rest of all other treatments. The lowest total yield (184.58 q/ha) was obtained in S 2 (60 cm x 60 cm). High fertilizer levels combined with closer plant spacing generally result in the more corm + cormel yield as plants receive optimum nutrients and more plant population per unit area. The interaction of plant spacing and fertility levels showed a significant effect on corm + cormel yield (q ha -1 ). The highest corm + cormel yield (263.22 q/ha) was observed in the F 2 S 3 combination [125 of% RDF (100:75:75 kg/ha) with 60 cm x 30 cm] while the lowest corm (144 q/ha) was recorded in the F 1 S 2 combination [100% RDF (80:60:60 kg/ha) with 60 cm x 60 cm]. Several researchers, including Choudhary et al. (2013) [3] , Shellikeri et al. (2019) [7] and Bhatt et al. (2019) [2] reported similar findings.

Conclusion

In view of the findings and results presented above, it may be concluded that the treatments F2

References

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