γ-Aminobutyric acid (GABA) and ectoine (ECT) impacts with and without AMF on antioxidants, gas exchange attributes and nutrients of cotton cultivated in salt affected soil

Abstract

Salinity stress is one of the major hurdles in agriculture which adversely affects crop production. It can cause osmotic imbalance, ion toxicity that disrupts essential nutrient balance, impaired nutrient uptake, stunted growth, increased oxidative stress, altered metabolism, and diminished crop yield and quality. However, foliar application of osmoprotectant is becoming popular to resolve this issue in crops. These osmoprotectants regulate the cellular osmotic balance and protect plants from the detrimental effects of high salt concentrations. Furthermore, the role of arbuscular mycorrhizae (AMF) is also established in this regard. These AMF effectively reduce the salinity negative effects by improving the essential nutrient balance via the promotion of root growth. That's why keeping in mind the effectiveness of osmoprotectants current study was conducted on cotton. Total of six levels of γ-Aminobutyric acid (GABA = 0 mM, 0. 5 mM, and 1 mM) and ectoine (ECT = 0 mM, 0.25 mM, and 0.5 mM) were applied as treatments in 3 replications. Results showed that 0.5 mM γ-Aminobutyric acid and ectoine performed significantly best for the improvement in cotton growth attributes. It also caused significant enhancement in K and Ca contents of the leaf, stem, bur, and seeds compared to the control. Furthermore, 0.5 mM γ-Aminobutyric acid and ectoine also caused a significant decline in Cl and Na contents of leaf, stem, bur, and seeds of cotton compared to control under salinity stress. A significant enhancement in chlorophyll contents, gas exchange attributes, and decline in electrolyte leakage validated the effectiveness of 0.5 mM γ-Aminobutyric acid and ectoine over control. In conclusion, 0.5 mM γ-Aminobutyric acid and ectoine have the potential to mitigate the salinity stress in cotton.

Keywords: Chlorophyll contents; Cotton; Growth attributes; Osmoprotectants; Salinity stress.

Fig. 1

Effect of osmoprotectants γ-Aminobutyric acid (GABA) and ectoine (ECT) different foliar application rates with and with AMF on germination (A) and plant height (B) of cotton cultivated in salinity stress (soil EC = 5.64 dS/m). Bars are means of 3 replicates ± SE. Different letters on bars showed significant changes at p ≤ 0.05; Fisher’s LSD

Fig. 2

Effect of osmoprotectants γ-Aminobutyric acid (GABA) and ectoine (ECT) different foliar application rates with and with AMF on leaf dry biomass (A), stem dry biomass (B), bur dry biomass (C) and seed dry biomass (D) of cotton cultivated in salinity stress (soil EC = 5.64 dS/m). Bars are means of 3 replicates ± SE. Different letters on bars showed significant changes at p ≤ 0.05; Fisher’s LSD

Fig. 3

Effect of osmoprotectants γ-Aminobutyric acid (GABA) and ectoine (ECT) different foliar application rates with and with AMF on shed dry biomass (A) and root dry biomass (B) of cotton cultivated in salinity stress (soil EC = 5.64 dS/m). Bars are means of 3 replicates ± SE. Different letters on bars showed significant changes at p ≤ 0.05; Fisher’s LSD

Fig. 4

Effect of osmoprotectants γ-Aminobutyric acid (GABA) and ectoine (ECT) different foliar application rates with and with AMF on leaf K (A), leaf Ca (B), leaf Cl (C) and leaf Na (D) of cotton cultivated in salinity stress (soil EC = 5.64 dS/m). Bars are means of 3 replicates ± SE. Different letters on bars showed significant changes at p ≤ 0.05; Fisher’s LSD

Fig. 5

Effect of osmoprotectants γ-Aminobutyric acid (GABA) and ectoine (ECT) different foliar application rates with and with AMF on stem K (A), stem Ca (B), stem Cl (C) and stem Na (D) of cotton cultivated in salinity stress (soil EC = 5.64 dS/m). Bars are means of 3 replicates ± SE. Different letters on bars showed significant changes at p ≤ 0.05; Fisher’s LSD

Fig. 6

Effect of osmoprotectants γ-Aminobutyric acid (GABA) and ectoine (ECT) different foliar application rates with and with AMF on bur K (A), bur Ca (B), bur Cl (C) and bur Na (D) of cotton cultivated in salinity stress (soil EC = 5.64 dS/m). Bars are means of 3 replicates ± SE. Different letters on bars showed significant changes at p ≤ 0.05; Fisher’s LSD

Fig. 7

Effect of osmoprotectants γ-Aminobutyric acid (GABA) and ectoine (ECT) different foliar application rates with and with AMF on seed K (A), seed Ca (B), seed Cl (C) and seed Na (D) of cotton cultivated in salinity stress (soil EC = 5.64 dS/m). Bars are means of 3 replicates ± SE. Different letters on bars showed significant changes at p ≤ 0.05; Fisher’s LSD

Fig. 8

Effect of osmoprotectants γ-Aminobutyric acid (GABA) and ectoine (ECT) different foliar application rates with and with AMF on chlorophyll a (A), chlorophyll b (B), total chlorophyll (C) and electrolyte leakage (D) of cotton cultivated in salinity stress (soil EC = 5.64 dS/m). Bars are means of 3 replicates ± SE. Different letters on bars showed significant changes at p ≤ 0.05; Fisher’s LSD

Fig. 9

Effect of osmoprotectants γ-Aminobutyric acid (GABA) and ectoine (ECT) different foliar application rates with and with AMF on photosynthetic rate (A), transpiration rate (B) and stomatal conductance (C) of cotton cultivated in salinity stress (soil EC = 5.64 dS/m). Bars are means of 3 replicates ± SE. Different letters on bars showed significant changes at p ≤ 0.05; Fisher’s LSD

Fig. 10

Effect of osmoprotectants γ-Aminobutyric acid (GABA) and ectoine (ECT) different foliar application rates with and with AMF on SOD (A), POD (B), CAT (C) and APX (D) of cotton cultivated in salinity stress (soil EC = 5.64 dS/m). Bars are means of 3 replicates ± SE. Different letters on bars showed significant changes at p ≤ 0.05; Fisher’s LSD

Fig. 11

Cluster plot convex hull for treatments (A), AMF levels (B), and hierarchical cluster plot (C) for studied attributes