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.

中文翻译：

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镉胁迫下耐镉根瘤菌对苦瓜生长特性和叶绿素含量的影响

镉（Cd）是对植物生长产生负面影响的重金属之一。水中的高溶解度使镉很容易进入植物，从而减少了种子发芽，光合作用和蒸腾作用。它还显示出对许多植物营养素（如锰，钙，钾，镁和铁）的拮抗作用。如今，用ACC脱氨酶（ACCD）根瘤菌接种植物以减轻Cd的不利影响引起了环境微生物学家的注意。根瘤菌分泌可以将Cd固定在土壤中的有机化合物。因此，本研究完成以研究ACCD植物促生根瘤菌（PGPR）对镉胁迫下苦瓜的影响。有六种治疗方法，包括两种ACCD PGPR（嗜麦芽窄食单胞菌和 农杆菌fabrum）菌株和无机肥料在两个层次的Cd，即，2（CD2）和5mg千克^-1土壤（CD5）。结果表明：A. fabrum与推荐氮磷钾肥（RNPKF）显著增加蔓长（48和55％），鲜重（24和22％），和叶绿素a（79和50％），叶绿素b的内容（ 30和33％）和总叶绿素（61和36％），分别超过两个Cd水平即Cd2和Cd5。总之，推荐的NPK肥料+ A. fabrum 组合是一种非常有效的处理方法，可将Cd固定在土壤中以改善苦瓜的生长。