Effect of seaweed extract of Solieria chordalis-Gracileria edulis and Sargassum sap on the performance of potato in the Laterite soil of West Bengal

Introduction

Potato [Solanum tuberosum L.] is one of the most important tuber crops ensuring global food and nutritional security. Potato is fourth in production and consumption after rice,wheat and maize. It is recognized as the "King of Vegetables" due to its high productivity per unit area and time, wider adaptability and high nutritional value. Globally, it is cultivated in over 20.32 million ha with a production of 376 million tonnes. India is the second largest producer of potato in the world after China, contributing about 15% to the world production. West Bengal is the leading state in potato production, contributing about 26% of total area and 28% of production with an average productivity of 24.18 t/ ha Potato is largely concentrated in the alluvial zones of West Bengal. However, there is considerable scope to expand and intensify its cultivation in the Red and Lateritic Zone comprising districts of Purulia, Bankura, Birbhum, Jhargram and western part of Paschim Medinipur. This zone covers about 23.5% of the total geographical area of the state and is characterized by undulating topography, compact and shallow soils with poor water holding capacity. The soils are typically acidic in reaction [pH 4.8-6.2], low in organic carbon [0.31-0.50% ], low in available nitrogen, phosphorus and potassium, poor in cation exchange capacity and suffer from Fe and Al toxicity and P-fixation problems. Consequently, the productivity of potato in this zone [18-20 t/ha]is considerably lower than the state average. The yield gap is attributed to poor crop growth, restricted root development and inefficient nutrient utilization under moisture stress and acidic soil conditions. Potato is a heavy feeder and highly responsive to nutrient management. The indiscriminate use of chemical fertilizers to achieve higher yields in these fragile soils has led to deterioration of soil health, nutrient imbalance and escalating cost of cultivation for small and marginal farmers. Therefore, there is an urgent need for sustainable and eco-friendly approaches to improve growth and productivity without degrading the resource base. The use of biostimulants of natural origin has emerged as a promising strategy in this context. Among various biostimulants, seaweed extracts are gaining considerable attention these days. Seaweed extracts are derived from marine macro-algae such as Kappaphycus alvarezii, Sargassum wightii, Gracilaria edulis and Ascophyllum nodosum [Khan et al., 2009]. Commercial formulations like Sagarika [K sap + G sap] developed by IFFCO and CSIR-CSMCRI are now widely available in India. These extracts are rich sources of macro and micronutrients, amino acids, vitamins, and diverse range of plant growth promoting substances like auxins, cytokinins, gibberellins, betaines and abscisic acid. They also contain complex polysaccharides such as alginates, laminarins, fucoidans and carrageenans which improve soil physical condition and microbial activity (Bhattacharyya et al., 2015) [2] . Seaweed extracts applied as foliar spray or as granules in soil influence various physiological and biochemical processes. They enhance chlorophyll content, photosynthetic rate, delay leaf senescence, promote root proliferation and improve nutrient uptake and fertilizer use efficiency. The presence of betaines and cytokinins helps in mitigating abiotic stresses like drought and acidity, which are common constraints in lateritic soils. Enhanced root growth and early vigour are particularly important for tuber crops as they determine the source-sink relationship and tuber bulking. Several studies have reported positive effects of seaweed application on potato. Pramanick et al. [2013] [4] observed significant increase in plant height, leaf area index, dry matter accumulation and tuber yield with application of seaweed extract @ 2.5-5.0 ml. Pramanick et al. [2017] [5] reported 12-18% increase in potato tuber yield with foliar application of Kappaphycus and Gracilaria sap in the Indo-Gangetic plains. Similarly, application of seaweed extract improved number of tubers per plant, average tuber weight and quality parameters like starch and ascorbic acid content. However, most of the studies were conducted in alluvial or black soils and information on the efficacy of seaweed biostimulant on growth and tuber productivity of potato under the specific edapho-climatic condition of red and lateritic soils of West Bengal is meagre. Keeping in view the above facts and the need for productivity enhancement in red and lateritic belt, the present investigation was undertaken with the objective to assess the effect of different doses and time of application of seaweed extract on growth attributes, yield components and productivity of potato and to evaluate its potentiality to improve fertilizer use efficiency and soil health in the red and lateritic soils of West Bengal.

Materials and Methods

Experimental site

The field experiment was conducted at the P.S.B. Agricultural Farm, Palli Siksha Bhavana, Visva-Bharati, Sriniketan, Birbhum, West Bengal, situated in the Lateritic Agro-climatic Zone of West Bengal during the rabi season of 2021-22. The soil of the experimental plot was found to be sandy loam in nature.

Experimental details

The present investigation was conducted to evaluate the effect of foliar application of seaweed extracts of Solieria chordalis-Gracilaria edulis and Sargassum sap on the growth, yield parameters and yield, of potato. The experiment was done in Randomised block design with 14 treatments and 3 replications. The treatments are depicted in table 1. The seaweed saps were sourced from CSIR-CSMCRI, Bhavanagar, Gujrat. The seaweed saps were applied as foliar sprays using a knapsack sprayer fitted with a hollow-cone nozzle to ensure uniform coverage of the plant canopy. The required concentrations of Solieria chordalis-Gracilaria edulis (SG) sap and Sargassum (S) sap were prepared by diluting the stock solution with clean water immediately before spraying. In potato, three foliar sprays were applied at 40, 55 and 70 days after planting (DAP). Potato variety Kufri Jyoti was cultivated with all the standard package of practices

Observations Recorded

The observations were recorded at various successive growth stages for plant height, leaf area, leaf area index, dry matter accumulation, tuber growth rate and tuber yield. For each observation, five tagged plants were chosen from each plot. The dry matter accumulation was determined by oven drying method. From the sample rows in each plot, two plants were randomly selected and stored separately. After the tubers and shoots were thoroughly cleaned of any debris or dust, they were measured using a physical balance. The materials were dried at 70 O C in an electric oven till they reached a consistent weight. Once more, the dry matter was determined by weight and expressed in grams. Similarly, leaf area was measured with the help of leaf area meter and was expressed sq.cm. The data were subjected to statistical analysis using analysis of variance (ANOVA) for a randomized block design, and treatment means were compared at the 5% level of significance following the procedure.

Results and Discussion

Effect of seaweed sap on growth attributes

During 2021-22, significant differences among treatments were observed at all growth stages. The maximum plant height at 30 and 45 DAP was recorded under T 6 (10% SG sap + 75% RDF), giving 35.77 and 57.47 cm, respectively, whereas at 60 DAP the highest plant height was recorded under T 12 (10% S sap + 75% RDF) (79.62 cm) and at 75 DAP under T 5 (7.5% SG sap + 75% RDF) (82.50 cm). These treatments were statistically at par with each other at most of the stages. The minimum plant height at 30 and 45 DAP was recorded under T 1 (0.5% SG sap + 75% RDF) (23.32 and 40.08 cm, respectively), whereas T 13 (75% RDF + water spray) recorded the lowest values at 60 and 75 DAP (53.33 and 59.44 cm, respectively). The findings are depicted in the Table 2. The significant increase in the height of the plant under higher dose of seaweed sap concentration can be due to the presence of phytohormones. They induce or rather stimulate the necessary meristematic activities and results in better height of the plant (Bhattacharyya et al., 2015) [2] . The maximum leaf area was consistently recorded under T 6 (10% SG sap + 75% RDF), registering 210.14, 503.80, 731.54 and 590.00 cm² at 30, 45, 60 and 75 DAP, respectively, which was statistically at par with T 12 (10% S sap + 75% RDF) (192.20, 470.67, 639.34 and 530.00 cm²) and T 5 (7.5% SG sap + 75% RDF) (185.91, 450.00, 660.00 and 540.00 cm²) at all the stages. The minimum leaf area was recorded under T 13 (75% RDF + water spray), registering 102.47, 204.64, 343.03 and 300.00 cm² at 30, 45, 60 and 75DAP, respectively. The observations of leaf area are given in the Table 3 [3] . The findings are depicted in the Table 5.

Effect of seaweed sap on yield parameter and yield-

Tuber Growth Rate (TGR) represents the rate of increase in tuber weight per plant per unit time and reflects the efficiency of assimilate translocation towards developing tubers. TGR increased up to 60-75 DAP and declined thereafter during 75-90 DAP. The highest TGR values were recorded under T 6 (10% SG sap + 75% RDF), registering 8.69, 10.49 and 5.50 g plant⁻¹ day⁻¹ during 45-60, 60-75 and 75-90 DAP, respectively, which was statistically at par with T 12 (10% S sap + 75% RDF) (8.06, 13.38 and 5.20 g plant⁻¹ day⁻¹) and T 5 (7.5% SG sap + 75% RDF) (7.20, 9.03 and 5.00 g plant⁻¹ day⁻¹) at all the growth intervals. The lowest TGR was recorded under T 13 (75% RDF + water spray), registering 3.80, 5.00 and 2.70 g plant⁻¹ day⁻¹ at 45-60, 60-75 and 75-90 DAP, respectively. Seaweed sap increase the activities of invertase and sucrose synthase, increasing the hexose availability in sink tissues and thus resulting in higher TGR (Ali et al.,2021) [1] . The findings are depicted in the table 6. Yield per hectare represents the final economic yield and overall treatment efficiency under field conditions. During 2021-22, the highest yield per hectare was recorded under T 6 (10% SG sap + 75% RDF) (34.00 t ha⁻¹), which was statistically at par with T 12 (10% S sap + 75% RDF) (33.16 t ha⁻¹) and T 11 (7.5% S sap + 75% RDF) (32.96 t ha⁻¹). The lowest yield per hectare was recorded under T 13 (75% RDF + water spray) (19.04 t ha⁻¹). The findings are depicted in the Table 7.

Conclusion

It can be well concluded from the conducted experiment that the treatment T 6 (10% SG sap + 75% RDF) is the best performing treatment in the red-laterite zone of Birbhum district and can be recommended to the farmers of this region. The superior response of this particular treatment was attributed to the presence of naturally occurring plant growth regulators, amino acids, micronutrients and other bioactive compounds in seaweed extracts, which enhanced the process of photosynthesis, nutrient absorption and assimilate translocation.

Acknowledgement

AcknowledgementsThe author is thankful to CSIR-CSMCRI for their constant technological support and chemical analysis in their laboratory.

References

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