Effect of seed soaking and growing media on germination and survivability of acid lime (Citrus aurantifolia Swingle) under shade net condition

Introduction

Acid lime (Citrus aurantifolia Swingle) is an important fruit crop belonging to the family Rutaceae and is widely cultivated in tropical and subtropical regions of India. It is valued for its tart flavour, aromatic properties, nutritional importance and high vitamin C content. Acid lime is commercially cultivated in several states of India including Andhra Pradesh, Gujarat, Maharashtra, Karnataka, Bihar, Madhya Pradesh, Assam and Chhattisgarh. Chhattisgarh is also an important acid lime growing region. Acid lime is mainly propagated through seeds because of its high degree of nucellar embryony, which contributes to the production of true-to-type seedlings. However, acid lime seeds are recalcitrant in nature and are sensitive to drying and chilling. The crop also exhibits relatively slow and irregular germination, which can result in poor seedling establishment and increased mortality under nursery conditions. Seed germination and subsequent seedling establishment are influenced by several factors including seed quality, pre-sowing seed treatment, growing media, moisture availability, aeration and nutrient supply. Seed soaking treatments can help modify the seed coat, remove inhibitory substances and activate metabolic processes required for germination. Organic substances such as cow urine and vermiwash have also been reported to contain nutrients and growth-promoting substances that may enhance germination and seedling vigour.

Growing media play an important role in providing physical support, moisture, aeration and nutrients to developing seedlings. Sand improves drainage and aeration, cocopeat provides good pore space and moisture retention, while FYM and vermicompost contribute nutrients and improve the physical and biological properties of the growing medium. Keeping these aspects in view, the present investigation was undertaken to identify a suitable combination of seed soaking treatment and growing media for improving germination, survivability and seedling growth of acid lime under shade net conditions.

Materials and Methods

The present investigation was carried out in a shade net house at the Horticulture Nursery, Department of Fruit Science, College of Agriculture, Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh, during the winter season of 2025-26. Raipur is situated in the central Chhattisgarh plain at 298.15 m above mean sea level (21.25° N latitude, 81.62° E longitude) and comes under the seventh agro-climatic zone of India (Eastern Plateau and Hills region), characterized by a sub-humid climate with hot summers and cold winters and an average annual rainfall of 1200-1400 mm. The experiment was laid out in a Completely Randomized Design (CRD) comprising fifteen treatment combinations, each replicated thrice, with 20 seedlings per treatment (900 seedlings in total). Three seed soaking treatments Water @ 24 hours, Vermiwash @ 25% for 12 hours and Cow urine @ 25% for 12 hours were combined with growing media prepared from sand, soil, farmyard manure (FYM), cocopeat and vermicompost either singly or in combination, to constitute the fifteen treatments (T 0 -T 14 ) as detailed in Table 1.

Notation

Water @ 24 hrs + Sand + Soil (Control) T1

Water @ 24 hrs + Sand + Soil + FYM T2

Water @ 24 hrs + Sand + Soil + Vermicompost T3

Water @ 24 hrs + Sand + Soil + Cocopeat T4

Water @ 24 hrs + Sand + Soil + FYM + Cocopeat + Vermicompost T5 Vermiwash @ 25% for 12 hrs + Sand + Soil T6 Vermiwash @ 25% for 12 hrs + Sand + Soil + FYM T7 Vermiwash @ 25% for 12 hrs + Sand + Soil + Vermicompost T8 Vermiwash @ 25% for 12 hrs + Sand + Soil + Cocopeat T9 Vermiwash @ 25% for 12 hrs + Sand + Soil + FYM + Cocopeat + Vermicompost T10

Cow urine @ 25% for 12 hrs + Sand + Soil T11

Cow urine @ 25% for 12 hrs + Sand + Soil + FYM T12

Cow urine @ 25% for 12 hrs + Sand + Soil + Vermicompost T13

Cow urine @ 25% for 12 hrs + Sand + Soil + Cocopeat T14

Cow urine @ 25% for 12 hrs + Sand + Soil + FYM + Cocopeat + Vermicompost Data on days taken for initiation of germination, germination percentage, survival percentage, germination index, average number of seedlings per seed (polyembryony), seedling height, seedling diameter, number of leaves, fresh and dry weight of shoot and root, tap root length, seedling vigour indices, success percentage and economics of seedling production were recorded at appropriate intervals up to 120 days after sowing (DAS). The data were statistically analyzed following the analysis of variance (ANOVA) technique for CRD (Fisher and Yates, 1963) and treatment means were compared using the critical difference (CD) at 5% level of significance. The superior performance of T 9 may be attributed to the presence of plant growth-promoting substances, essential nutrients, enzymes and beneficial microorganisms in vermiwash, which enhance physiological and biochemical activity within the seed, while the enriched medium (FYM, cocopeat and vermicompost) improved aeration, moisture retention and nutrient availability favouring rapid imbibition, embryo development and multiple embryo emergence. These findings are in close agreement with Yadav et al. (2012) [19] and Kiran Sagar et al. (2024) [12] in acid lime, Bhutiya (2017) [3] in Kagzi lime and with the reports of Panda et al. (2018) [16] and Jadhav et al. (2019) [6] , who observed enhanced germination and polyembryony with organic seed treatments and nutrient-rich growing media.

Results and discussion

Seedling growth parameters

The height of seedling, seedling diameter and number of leaves per seedling were recorded at 30, 60, 90 and 120 DAS (Table 3), while fresh and dry weight of shoot, their ratio and success percentage were recorded at 120 DAS (Table 4). At every stage of observation, T 9 recorded significantly superior seedling height, diameter and number of leaves followed by T 14 and T 4 , while the control (T 0 ) remained the lowest throughout the observation. At 120 DAS, maximum seedling height was 20.98 cm in T 9 and minimum was 9.44 cm in T 0 . Similarly the maximum diameter was 2.96 mm in T 9 and minimum was 1.88 mm in T 0 .The maximum number of leaves observed in T 9 (22.53) and minimum in T 0 (11.49). Fresh weight of shoot recorded maximum in T 9 (4.35 g) and minimum in T 0 (1.41 g).

Similarly the dry weight of shoot recorded maximum in T 9 (2.02 g)) and minimum in T 0 (0.49 g). The fresh-to-dry weight ratio was recorded maximum in the water-soaked treatments T 10 (2.90) and T 0 (2.87), whereas the minimum was recorded in T [7] and Meshram et al. (2015) [14] in acid lime/Kagzi lime, and Dhaka and Pal (2009) [4] and Kherdekar (2003) [10] , who reported similar improvement in seedling growth and vigour with organic seed treatments and nutrient-enriched media.

Root parameters

Data on length of tap root, fresh and dry weight of root and dry shoot: root ratios at 120 DAS are presented in Table 5.

The maximum tap root length (19.98 cm) was recorded in T 9 and minimum in (8.76 cm).The maximum fresh root weight (2.54 g) and dry root weight (1.46 g) were recorded in T 9 , followed by T 14 and T 4 , while the minimum fresh root weight (0.63 g) and dry root weight (0.17 g) were recorded in T 0 . The dry shoot: root ratio was minimum in T 9 (1.38) and maximum in T 11 (3.15), indicating that T 9 produced a proportionately larger and more efficient root system relative to shoot growth. The enhanced root growth under T 9 and T 14 may be ascribed to improved nutrient availability, microbial activity and moisture retention in the enriched growing medium together with the growth-promoting effect of vermiwash/cow urine. The similar findings with Vishwakarma and Sharma (2020) [18] in acid lime, Sindhe et al. (2008) [17] in Rangpur lime, and Lunagariya et al. (2022) [13] and Kiran Sagar et al. (2024) [12] in acid lime.

Seedling vigour index

Seedling vigour index-I and vigour index-II at 120 DAS, computed from germination percentage and total seedling length are presented in Table 6. The maximum vigour index-I (4125.51) and vigour index-II (299.34) were recorded in T 9 , followed by T 14 , while the minimum vigour index-I (843.76) and vigour index-II (30.59) were recorded in T 0 . The maximum vigour indices in T 9 reflect the cumulative benefit of rapid, uniform germination combined with vigorous shoot and root growth, consistent with the reports of Atiyeh et al. (2000) [2] and Arancon et al. (2004) [1] on vermicompost-based media, and Kiran Sagar et al.

Economic efficiency

The economics of acid lime seedling production under different treatments, computed on the basis of total cost, gross returns, net returns and benefit: cost (B:C) ratio, are presented in Table 7. Treatment T 9 recorded the maximum B:C ratio (3.80), followed by T 14 (3.60) and T4 (3.39). The minimum B:C ratio was recorded in control T 0 (2.01). The higher profitability recorded under T 9 was mainly due to better germination, survival and seedling growth resulting from vermiwash seed soaking along with the nutrientenriched growing medium.

Conclusion

The present investigation revealed that acid lime seeds treated with vermiwash at 25% concentration for 12 hours and sown in a growing medium enriched with Sand + Soil + FYM + Cocopeat + Vermicompost (T 9 ) consistently outperformed all other treatments with respect to germination parameters, shoot and root growth, seedling vigour, survival, polyembryony and economic returns, recording the highest net return (₹1068) and B:C ratio (3.80). Cow urine at 25% for 12 hours combined with the same enriched medium (T 14 ) proved to be the second-best treatment and a viable alternative to vermiwash. The control treatment (Water @ 24 hours + Sand + Soil), lacking both a bio-stimulant seed soaking treatment and organic media amendments, recorded the poorest performance across all parameters studied. Seed soaking with vermiwash @ 25% for 12 hours combined with an enriched sand-soil-FYMcocopeat-vermicompost medium can therefore be recommended for improving germination, survivability, seedling vigour and overall nursery performance of acid lime under shade net conditions.

Acknowledgement

References

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