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Potassium Silicate Modulates Leaf Water Relations and Membrane Integrity in Cotton (Gossypium hirsutum L.)

Author: J. Annie Sheeba1*, Kanjana D.2 and Prakash A.H.1

Address:

1Department of Plant Physiology,

ICAR- Central Institute for Cotton Research, Regional Station, Coimbatore (TN), India.

2Department of Soil Science,

ICAR- Central Institute for Cotton Research, Regional Station, Coimbatore (TN), India.

 (Corresponding author: J. Annie Sheeba* anniephysiology@gmail.com)

DOI: https://doi.org/10.65041/BF.2025.17.11.2

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Abstract

Potassium (K) and silica (SiO2) are important nutrient elements offering tolerance to various abiotic and biotic stresses faced by plants. Potassium silicate (K2SiO3) is a potential source of K and Si. A study was conducted to evaluate the effect of the application of K2SiO3 on drought tolerance in the cotton hybrid Bunny Bt 2. Foliar sprays of different concentrations of K2SiO3 (40, 60, 80 µl/l) were taken up under irrigated and water-stressed conditions. Relative water content (RWC), proline content and cell membrane stability were increased significantly, whereas lipid peroxidation and per cent membrane injury decreased with the application of K2SiO3 when compared with control. Under water stress conditions, 40µl of potassium silicate treated plants recorded higher K contents over control plants. This study suggests the positive effect of K2SiO3 on water relations and membrane integrity which can help alleviate the negative effects of water stress in cotton plants.

Introduction

Climate change, with rising temperatures and fluctuating weather patterns, increases the frequency of droughts, floods, and salinity which affects the productivity of commercially important crops like cotton. When exposed to stress, plants close their stomata slowing down metabolism and enhancing senescence and cell death. Potassium (K) and silica (SiO2) are important nutrient elements offering tolerance to various abiotic stresses faced by plants. K is essential for maintaining turgidity of plant cells, especially guard cells of stomata, thus regulating opening and closure of stomata (Qi et al., 2019). Under ideal conditions, plants can grow even without silicon as it is considered to be a beneficial element and not an essential one. However, silicon was found to enhance plants' tolerance to various abiotic stresses by modulating water relations, cell-wall flexibility and membrane stability (Rehman et al., 2019; Tuladhar et al., 2021). Silicon is absorbed by plants in the form of silicic acid. This compound forms an amorphous gellike physical barrier between cuticle and cell wall and cell wall and plasma membrane thus reducing evaporation loss of water. Potassium silicate (K2SiO3) is a potential source of K and Si. Spraying potassium silicate eliminated the adverse effects of drought stress on crops (Zahedi et al., 2020). Potassium silicate was found to positively influence the quantitative and qualitative performance of potato plants (Talebi et al., 2015). Application of potassium silicate was found to improve drought tolerance in sweet corn (Karvar et al., 2023). Exogenous application of potassium silicate was found to improve drought tolerance in cotton genotypes (Nazim et al., 2024). This study was aimed at investigating whether potassium silicate will alleviate the negative effects caused by drought stress by modulating leaf water relations and membrane integrity in cotton plants.

Material & Methods

The experiment was conducted at the Central Institute for Cotton Research, Nagpur at Plant Physiology glass house during 2016-2017 in a factorial completely randomised design. Bunny Bt 2 plants were raised in cement tanks with dimensions of 258 × 88 cm with a spacing of 60 × 30 cm. The cement tanks were filled with farm soil (fine smectitic hyperthermic typic haplustert) with pH 7.9 and field capacity of 42.4%. Plants were irrigated up to 40 DAS and irrigation was withheld for 10 days during flowering. Experimental plants were subjected to foliar spray of 40, 60 and 80 µl/l of potassium silicate {Agrisil (L)} 60 DAS (10 days after imposing stress); control plants were sprayed water. Six plants were tagged per treatment, and morphological and yield parameters recorded. Relative water content (RWC) and proline content were estimated by following the methodology of Barrs and Weatherley (1962) and Bates (1973), respectively. Lipid peroxidation assay was performed according to the methodology of Velikova et al. (2000). Cell membrane stability was determined by the methodology of Deshmukh et al. (1991). Percent membrane injury was quantified by following the methodology of Sullivan et al. (1972). Potassium content was estimated by the flame photometric method given by Johnston et al., 1952. Statistical Analysis is done using standard Analysis of Variance.

Results & Discussion

Under stressed conditions, plants that received foliar spray of 40 µl/l of potassium silicate exhibited high relative water content (RWC) (98%) [60 µl/l (89.4%) and 80 µl/l (80.4%)] as against control (73%). Under irrigated conditions, RWC was higher in plants treated with 60 µl/l of potassium silicate (83.3%) relative to control (76.4%). Under drought conditions leaf RWC tends to decrease, which is influenced by stomatal responses and carbon economy (Rad et al., 2023). However, potassium silicate-applied cotton plants were able to maintain higher RWC (Fig. 1). This is in accordance with the findings of Eyni-Nargeseh et al. (2022), Rad et al. (2023) and Nazim et al. (2024). The increase in leaf RWC after the application of potassium silicate might be due to the silicon deposition on the leaf cuticle layer which might have increased leaf thickness and hence reduced the leaf transpiration under water-stress conditions (Ma and Yamaji 2006). Leaf water potential is closely related to the RWC of leaves (O'Neill et al., 2006) and indicates the plant water content status and drought tolerance (Sairam and Srivastava 2001). In the present study, plants treated with 80 µl/l of potassium silicate recorded higher leaf water potential under irrigated (-12.0 bars) and stressed conditions (-21.3 bars) when compared with control plants under irrigated (-16.8 bars) and stressed conditions (-23.0 bars) (Fig. 2). 

Fig. 1.  Relative Water Content as influenced by foliar application of potassium silicate.

Fig. 2.  Leaf Water Potential as influenced by foliar application of potassium silicate




The RWC and leaf water potential were found to be enhanced with the application of potassium silicate. Plants with relatively higher water content towards the terminal stress period are considered to be more drought-tolerant (Basu, 2004). Hence the role of increasing RWC in improving drought tolerance could be validated. Potassium silicate-treated plants recorded higher proline content than control plants both under irrigated and stressed conditions. Plants sprayed with 40 µl/l potassium silicate recorded higher proline content of 654.8 µmol/g FW under water-stressed conditions as against water-sprayed control (553.8 µmol/g FW) (Fig. 3). This result is concordant with the findings of Hajiboland et al. (2017), who observed that the concentration of osmotic regulators like proline increased significantly when potassium silicate was applied under water-deficit conditions. The increase in proline content might be attributed to the silicon-induced activity of pyrroline-5-carboxylate synthetase (P5 CS) and glutamate dehydrogenase (GDH), the precursors of proline biosynthesis as reported by Garg and Sing (2018). Liu et al., 2015 and Coskun et al., 2016 found that silicon could improve the osmotic adjustment in plants by promoting the accumulation of proline and sugars. Potassium silicate concentrations above 40 µl/l decreased the proline accumulation probably because of the stress-mitigating effects of potassium. Potassium-applied plants were found to maintain higher leaf water potential, turgor potential and RWC and lower osmotic potential when compared with untreated plants of Vigna radiata (Nandwal et al., 1998) grown under water-stress conditions. Since potassium content is higher in higher doses of potassium silicate and as it helps maintain the higher water potential by itself, plants might not have the need to invest in biosynthesis of proline to maintain the turgidity of leaves. Under irrigated conditions, control plants recorded higher K % than potassium silicate-treated plants. Under stress conditions, plants treated with 40 µl/l of potassium silicate recorded higher K (1.17%) content when compared with control plants (0.9%). (Fig. 4). 

Fig. 3.  Proline content as influenced by foliar application of potassium silicate.

Fig. 4.  Potassium content as influenced by foliar application of potassium silicate.




This is similar to the findings of Oraee and Tehranifar (2023) where application of K2SiO3 were found to enhance the accumulation of silicon (Si) and potassium (K) in daisy plants. Lipid peroxidation was lower in all the potassium silicate-treated plants when compared with the control plants after the second spray. While control plants recorded higher lipid peroxidation (5.9 µmol MDA/g FW), plants treated with 80 µl/l potassium silicate recorded lower lipid peroxidation (0.7 µmol MDA/g FW) under stressed conditions (Fig. 5). Cell membrane integrity was higher in plants subjected to potassium silicate treatments when compared with control plants and hence membrane injury was lower in plants treated with potassium silicate both under irrigated and stressed conditions (Fig. 6 and 7). The decreased lipid peroxidation and percent membrane injury and increased membrane integrity might be attributed to the increase in proline content (Garg and Sing 2018). Moreover, lower lipid peroxidation might be attributed to higher K content due to potassium silicate application (Fang et al., 2022). Hence the significance of potassium and silicon in protecting cell membranes and maintaining RWC under water-stressed conditions has been demonstrated in the present study.


Fig. 5.  Lipid Peroxidation  as influenced by foliar application of potassium silicate.

Fig. 6.  Cell Membrane Integrity  as influenced by foliar application of potassium silicate.


Fig. 7. Per cent Membrane injury  as influenced by foliar application of potassium.

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How to cite this article

J. Annie Sheeba, Kanjana D. and Prakash A.H. (2025). Potassium Silicate Modulates Leaf Water Relations and Membrane Integrity in Cotton (Gossypium hirsutum L.). Biological Forum, 17(11): 05-10.