Effect of Cadmium-Tolerant Rhizobacteria on Growth Attributes and Chlorophyll Contents of Bitter Gourd under Cadmium Toxicity

Abstract

Cadmium (Cd) is one of the heavy metals that negatively affects the growth of plants. High solubilization in water leads Cd to enter into plants quite easily, thus decreasing seed germination, photosynthesis, and transpiration. It also shows an antagonistic effect with many of the plants’ nutrients like Mn, Ca, K, Mg and Fe. Nowadays, inoculation of plants with ACC deaminase (ACCD) rhizobacteria to mitigate Cd’s adverse effects has drawn the attention of environmental microbiologists. The rhizobacteria secrete organic compounds that can immobilize Cd in soil. Therefore, this study was accomplished to investigate the effect of ACCD plant growth promoting rhizobacteria (PGPR) on the bitter gourd under Cd stress. There were six treatments consisting of two ACCD PGPR (Stenotrophomonas maltophilia and Agrobacterium fabrum) strains and inorganic fertilizers at two levels of Cd, i.e., 2 (Cd2) and 5 mg kg−1 soil (Cd5). The results showed A. fabrum with the recommended NPK fertilizer (RNPKF) significantly increased the vine length (48 and 55%), fresh weight (24 and 22%), and contents of chlorophyll a (79 and 50%), chlorophyll b (30 and 33%) and total chlorophyll (61 and 36%), over control at the two Cd levels i.e., Cd2 and Cd5, respectively. In conclusion, the recommended NPK fertilizer + A. fabrum combination is a very effective treatment with which to immobilize Cd in soil for the improvement of bitter gourd growth.

Ameliorative Effects of Exogenous Proline on Photosynthetic Attributes, Nutrients Uptake, and Oxidative Stresses under Cadmium in Pigeon Pea (Cajanus cajan L.)

“…Cadmium stress-induced oxidative stress in pigeon pea was measured by the elevated contents of hydrogen peroxide, thiobarbituric acid reactive substances, and electrolyte leakage (Figure 2). Our findings are consistent with previous studies, where similar oxidative damage under cadmium exposure in other plant species has been reported [14][15][16].…”

“…These growth-inhibiting effects of Cd on pigeon pea may be attributed to the significant decrease in photosynthetic activities, nutrient deficiency, and excessive ROS production (Tables 1 and 2; Figure 1). Previous studies have reported similar reduced growth attributes in other plant species due to cadmium stress [14,15,52,53]. Photosynthesis is plants' life-sustaining process and is often sensitive to metal stresses.…”

“…Its existence in agricultural soil poses a severe threat due to its entry into the food chain, thus damaging animal and human health [11][12][13]. Elevated cadmium quantities in plants delay seed germination, induce growth inhibition, and reduce productivity [14][15][16]. It plays an influential role in the uptake, transport, and distribution of nutrients [17][18][19][20].…”

Role of Bacillus cereus in Improving the Growth and Phytoextractability of Brassica nigra (L.) K. Koch in Chromium Contaminated Soil

“…PGPR release essential substances and increase nutrients availability which plays an important role in the synthesis of photosynthetic pigments which were required for the process of photosynthesis [ 44 ]. Zafar-ul-Hye et al [ 45 ] research show that Stemtrophomonas maltaphilia and Agrobacterium fabrum inoculation increased chlorophyll a chlorophyll b and total chlorophyll content in the bitter gourd in Cd contaminated soil. Plants facing heavy metal stress have reduced water uptake which decreases the photosynthetic capacity of plants and results in a reduced growth rate [ 46 ].…”

Peptone-Induced Physio-Biochemical Modulations Reduce Cadmium Toxicity and Accumulation in Spinach (Spinacia oleracea L.)

“…These results were in agreement with that previously reported [ 35 ]. Previous reports have revealed that the environmental stresses considerably induce oxidative stress as well as the levels of electrolyte leakage (EL) and malondialdehyde (MDA) in different plant species, causing damages in plant tissues [ 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 ]. Similarly, in the current study, spinach plants also exhibited higher levels of EL and MDA in the absence of peptone treatment.…”