Combined Use of Sewage Sludge and Plant Growth-Promoting Rhizobia Improves Germination, Biochemical Response and Yield of Ridge Gourd (Luffa acutangula (L.) Roxb.) under Field Conditions

Vinod Kumar,Ivan Širić,Archana Bachheti,Željko Andabaka,Jogendra Singh,Sonika Kumari,Ashish Kumar Arya,Kyung-Sook Choi,Ebrahem M Eid,Pankaj Kumar,Dhafer A Al-Bakre,Madhumita Goala,Bashir Adelodun,Samy M Abdallah

doi:10.3390/agriculture12020173

Abstract

This research investigated the combined use of sewage sludge (SS) and plant growth-promoting rhizobia (PGPR) for Ridge gourd (Luffa acutangula (L.) Roxb.) cultivated under field conditions. The different treatments of SS and PGPR such as 0% (soil as control), 5% SS, 5% SS + PGPR, 10% SS, and 10% SS + PGPR were applied to assess their impacts on seedling growth, biochemical response, and yield performance of Ridge gourd. The results showed that the highest seedling emergence (92.3 ± 2.1%), fresh biomass (9.6 ± 0.3 g), growth rate (1.4 ± 0.1 g/day), seedling length (15.5 ± 0.3 cm), root length (10.4 ± 0.3 cm), total chlorophyll (3.2 ± 0.1 mg/g), crop yield (13.8 ± 0.1 kg/plant), and average crop yield per harvest (2.8 ± 0.1 kg/plant) were observed in 10% SS + PGPR treatment. The enzyme activities of superoxide dismutase (SOD; µg/g) and catalase (CAT: µg/g) were significantly lowered after PGPR inoculation in higher SS treatments. The results of principal component (PC) and Euclidian clustered distance analyses showed a positive influence of SS dose on soil nutrient availability and Ridge gourd’s growth, biochemical responses, and yield performance. Moreover, the elemental analysis showed that the bioaccumulation factor (BAF < 0.90) and health risk index (HRI < 0.40) of selected metal elements (Cd, Cr, Cu, Fe, Mn, and Zn) were within the permissible limits, indicating consumption of Ridge gourd fruits was safe. The outcomes of this study suggest the potential use of SS and PGPR for improved Ridge gourd production and contribution towards sustainable development goal (SDG) 12 on responsible consumption and production of vegetable crops.

Highlights

The rate of domestic waste discharges has recently grown dramatically as a result of an uncontrolled increase in the human population [1]
Post-digested sewage sludge (SS) was obtained from 27 MLD Sewage Treatment Plant (STP) of Jagjeetpur, Haridwar, India (29◦54 02.5 N 78◦08 26.6 E), which is operated under the Clean Ganga Mission of Namami Gange Project, Government of India
principal component analysis (PCA) results showed that SS dose had a significant effect on increased nutrient availability (Table 2)

Summary

Introduction

The rate of domestic waste discharges has recently grown dramatically as a result of an uncontrolled increase in the human population [1]. Sewage wastewater is amongst the top contributor of domestic wastes, which has become a difficult to manage problem globally [2]. It is estimated that nearly 359 billion cubic meters of wastewater are generated globally, with only 52% being sufficiently or partially treated while the remaining is disposed of without any treatment [3]. Sewage sludge (SS) is a solid or semi-solid substance generated from the different steps of sewage treatment plants (STPs). The management of SS occurs at different stages such as production (minimization), collection, treatment, and reuse [6]. Being rich in various organic and nutrient substances, SS is widely utilized for secondary purposes such as biogas, biochar, syngas, biofertilizer production, composting, building materials, among many others [7,8]

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