Effect of different levels of fertilizer and plant spacing on growth of taro (Colocasia esculenta L.) genotype 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. These 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 rich in potassium, calcium, phosphorus, iron, riboflavin, thiamine, niacin, vitamins A and C along with dietary fiber. Taro is also a good source of essential amino acids like leucine and phenylalanine. 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 vigorous growth in taro.

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., S 1 = 60 x 45 cm S 2 = 60 x 60 cm S 3 = 60 x 30 cm with the application of different levels of fertilizers viz., F 1 = 80:60:60 kg NPK/ha (100% RDF) F 2 =100:75:75 kg NPK/ha (125% RDF) F 3 = 60:45:45 kg NPK/ha (75% RDF). The other cultivation practices were followed as per recommendations and observations of various growth parameters were recorded periodically and data was statistically analyzed as per standard methods.

Results and Discussion

The data pertaining to days to sprouting, percent sprouting and days to first leaf emergence under various treatments have been statistically analyzed and presented in Table 1. The least number of days for sprouting (6.99 days) was recorded in F 2 [125% of recommended dose of NPK (100:75:75 kg/ha)], which was considerably superior among rest of the treatments, whereas the maximum number of days for sprouting (12.10 days) were recorded in F 3 [75% of recommended dose of NPK (60:45:45 kg/ha)]. The minimum number of days to sprouting (7.44 days) was recorded in the plant spacing of S 2 (60 cm x 60 cm) while S 3 (60 cm x 30 cm) recorded maximum number of days to sprouting (10.38 days). The interaction between different levels of fertilizer and plant spacing had a significant effect on the number of days to sprouting. The shortest sprouting time was observed in the F 2 S 2 combination recording (5.27 days), which was significantly superior among all other treatment combinations. This might be due to application of higher level of fertilizer fulfill the nutritional requirement which promotes early sprouting. Nutrients like NPK enhance soil fertility and corms vigor, thereby improving sprouting conditions similarly, plant spacing can influence the days to sprouting primarily by affecting soil conditions and resource availability. Adequate spacing ensures that corms have enough room to access light, water and nutrients, which can promote even and timely sprouting. Crowded conditions may lead to competition for these resources, potentially delaying sprouting or causing uneven growth. Proper spacing helps optimize conditions for each corm, potentially leading to early and more uniform sprouting (Sagoe et al. 2018) [8] . The highest sprouting rate (100%) was achieved in F 2 [125% of recommended dose of NPK (100:75:75 kg/ha). This was significantly superior among rest of the treatments and the lowest sprouting (88.18%) was obtained in F 3 [(75% of recommended NPK dose (60:45:45 kg/ha)]. Proper fertilization can enhance germination rates, as phosphorus, for example, is crucial for root development. However, over fertilization can harm seeds by increasing soil salinity, while insufficient fertilization might limit growth. Additionally, soil conditions and the specific nutrient needs of different seeds play a role in how effectively fertilizers influence sprouting. The plant spacing of S 2 (60 cm x 60 cm) had the highest sprouting (94%) while S 3 (60 cm x 30 cm) recorded lowest sprouting (92.93%). Plant spacing can impact the percent sprouting of tubers, though its effects are often more pronounced during the later stages of plant growth. Proper spacing allows each seedling to access adequate light, nutrients and water, which can promote healthy growth and better establishment. Conversely, overcrowding can lead to competition for resources, potentially reducing sprouting rates and overall plant health. Similar results were reported by Khandekar et al. (2000) [4] and Ndon et al. (2003) [6] in taro. The interaction of different levels of fertilizer and plant spacing was showed non-significant effect on percent sprouting. The minimum days to first leaf emergence (8.35 days) was recorded in F 2 [125% of recommended dose of NPK (100:75:75 kg/ha)] which was significantly superior over rest of the treatments and treatment F 3 [(75% of recommended dose of NPK (60:45:45 kg/ha)] took maximum days (16.93 days) to first leaf emergence. In respect to the plant spacing, treatment S 2 (60 cm x 60 cm) recorded minimum days (11.14 days) to first leaf emergence however, S 3 (60 cm x 30 cm) took maximum days to first leaf emergence (14.02 days). Application of optimum fertilizer dose and appropriate plant spacing leads to quicker and more uniform leaf emergence by optimizing the plant's growth environment (Shellikeri et al. 2019) [9] . The interaction of plant spacing and fertility levels was showed non-significant effect on days to first leaf emergence. [2] . Similarly, the optimal spacing ensures that taro plants have enough space to develop fully leading to increased height and overall better growth. The result observed here is in agreement with (Kumar et al. 2016) [5] . The interaction effect of different levels of fertilizer and plant spacing showed significant impact on plant height at 120 DAP. The highest plant height (86.70 cm) was recorded in the F 2 S 2 combination which was significantly higher than the other treatments whereas, the lowest (55.87 cm) was recorded in the F 3 S 3 combination. [3] . Plant spacing significantly affects the number of leaves on taro plants. Wider spacing allows each plant more access to light, water and nutrients which can enhance leaf production and lead to a higher number of leaves. With ample space taro plants can grow more robustly and develop a full canopy (Kumar et al.

2016) [5] . The F 2 S 2 combination produced highest number of leaves (6.30) which was significantly greater than other treatments and found to be statistically at par (5.70) with F 2 S 1 whereas, treatment combination F 3 S 2 recorded lowest number of leaves (4.71). The similar results are in accordance with the findings of Akther et al. (2016) [1] and Bhatt et al. (2019) [2] . The maximum number of suckers per plant (6.86) was obtained in treatment 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)]. However, the minimum number of suckers per plant (4.77) was observed in treatment F 3 [75% of recommended dose of NPK (60:45:45 kg/ha)]. The maximum number of suckers per plant (5.79) was recorded in S 2 (60 cm x 60 cm) plant spacing, which was statistically at par with S 1 (60 cm x 45 cm), (5.62). The minimum number of suckers per plant (5.55) was observed in plant spacing S 3 (60 cm x 30 cm).

Fertilizer application significantly influences the number of suckers in taro plants. Adequate fertilization provides essential nutrients that support overall plant growth and vigor which can lead to increased sucker production. Specifically, balanced levels of nitrogen, phosphorus and potassium promote robust growth and help the plant to produce more suckers. Nitrogen is particularly important for vegetative growth and can enhance sucker development.

Proper spacing ensures that each taro plant has enough room to grow and produces higher number of suckers. Therefore, optimizing plant spacing is essential for maximizing sucker production and overall plant growth in taro cultivation. Kumar et al. 2016 [5] and Das et al. 2018 [3] reported similar results in taro.

The maximum leaf area (524.66 cm [9] . The interaction effect of different levels of fertilizer and plant spacing had significant effect on leaf area. The highest leaf area (673.33 cm²) was recorded in the F 2 S 2 combination which was statistically at par with F 1 S 1 (563.47 cm²). The lowest leaf area (349.52 cm²) was recorded in the F 3 S 3 combination. Similar findings are in agreement with Akther et al. (2016) [1] and Bhatt et al. (2019) [2] . The maximum petiole length (77.63 cm) was observed in treatment F 2 [125% of recommended dose of NPK (100:75:75 kg/ha)] whereas, minimum petiole length (54.64 cm) was observed in treatment F 3 [75% of recommended dose of NPK (60:45:45 kg/ha)]. Petiole length also showed significant differences at different plant spacing in this context the maximum petiole length (66.51cm) was recorded in S 2 (60 cm x 60 cm) while the minimum petiole length (59.11 cm) was measured in S 3 (60 cm x 30 cm). The increase in petiole length in this treatment might be due to the fact that use of adequate levels of NPK which promotes healthy development and lead to longer petioles as nitrogen stimulates vegetative growth including petiole elongation. Further, wider plant spacing avails better exposure to light and in turn more benefit of lights thus better petiole growth was observed. The observation here is in agreement with Verma et al. (2012) [10] and Ogbonna et al. (2015) [7] . The interaction effect of different levels of fertilizer and plant spacing had significant effect on petiole length (cm). The highest petiole length (79.90 cm) was recorded in F 2 S 2 combination which was statistically at par with F 2 S 3 combination (77.07 cm). The lowest petiole length (31.33 cm) was recorded in F 3 S 3 combination. Akther et al. (2016) [1] and Bhatt et al. (2019) [2] reported similar results.

Conclusion

In view of the findings and results presented above, it may be concluded that the treatments F 2 [125% of recommended dose of NPK (100:75:75 kg/ha) and S 2 (60 cm x 60 cm)] found significantly superior over all other treatments which was found to be statistically at par with treatments F 1 [100% recommended dose of NPK (80:60:60 kg/ha) and S 1 (60 cm x 45 cm). In relation to the combined effect, treatment F 2 S 2 found to be superior for all growth parameters under Marathwada conditions.

References

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