Effect of Azotobacter chroococcum and Rhizophagus irregularis on morphological and biochemical traits of bitter gourd under saline conditions

Abstract

Bitter gourd (Momordica charantia L.) is produced and consumed worldwide due to its numerous health benefits. The quantity of salt in the soil has an influence on a plant's roots' ability to absorb water and critical nutrients from the environment. The present study investigates the impact of inoculating bitter gourd plants with plant growth-promoting rhizobacteria (PGPR) Azotobacter chroococcum and arbuscular mycorrhizal fungi (AMF) Rhizophagus irregularis on fruit morphometric traits, chemical properties, and fruit yield under saline conditions. A total of 32 traits were assessed, including 9 phenotypic, 2 biochemical, and 21 fruit morphometric characteristics. Bitter gourd plants were treated with A. chroococcum, R. irregularis, or a consortium of both under saline and normal watering conditions. Biochemical traits, including ascorbic acid and beta-carotene content were analyzed, and fruit yield per plant was recorded. Additionally, the AM spore number and root colonization percentage were measured. The results revealed that the consortium treatment of A. chroococcum and R. irregularis under saline stress significantly improved fruit morphometric traits compared with individual treatments. The biochemical features ascorbic acid and beta-carotene showed a 49.43 and 75.95% increase, respectively, under normal watering conditions. The fruit yield per plant exhibited a significant increase only with the AS + Ri treatment (315.56%) with respect to control under saline conditions. Other treatments showed increases (71.11% with A. chroococcum, 188.89% with normal package, and 202.22% with R. irregularis) but these were not statistically significant with respect to the control under saline conditions. The highest AM spore number (113) and root colonization (71.54%) were observed in the consortium treatment. The study concludes that the combined inoculation of A. chroococcum and R. irregularis under saline stress significantly enhanced plant growth, biochemical content, and fruit yield, surpassing the effects of individual treatments. The consortium treatment provided a protective effect under salt stress, enabling the plants to perform as if grown under normal conditions. This indicates the potential of using PGPR and AMF consortia to improve agricultural productivity in saline-affected soils.

Keywords: Azotobacter; Bitter gourd; Mycorrhizal fungi; Rhizophagus; Salinity.

Fig. 1

Variation recorded for the (1) No. of fruits/plant and fruit weight (g), (2) fruit yield/plant (kg), and (3) AM spore No. and root colonization (%) in 5 treatments studied for bitter gourd under salinity stress conditions.

Fig. 2

Variation recorded for (1) ascorbic acid content (mg/ 100 g) and (2) B-carotene content (mg/100 g) in 5 treatments studied for bitter gourd under salinity stress conditions.