Effect of reclaimed water and dehydrated sludge on the morpho-physiology and yield of sorghum

ABSTRACT

The effect on the morpho-physiological parameters and yield of sorghum cultivated in a greenhouse with reclaimed water (RW) and (dehydrated sludge (DS) obtained in a sewage treatment plant, was evaluated. Six treatments (T), with five repetitions each, were carried out in entirely randomized blocks. Water (W) was used in T1 (W) (control), T2 (W + NPK), and T3 (W + DS); RW was used in T4 (RW), T5 (RW + P), and T6 (RW + DS). The results showed that irrigation with only RW (T4), or W + DS (T3) was very suitable for the cultivation since an adequate nutritional supply was provided. The positive effects on the morpho-physiological parameters, plant height, stem diameter and stem length (in cm), were: T3 – 148.8, 1.50, and 103, respectively; T4 – 154, 1.70, and 107, respectively; and on the grain production in weight of 1000 seeds (g), and productivity in grains per plant: T3 – 6.97 and 1453, respectively; T4 – 6.81 and 1636, respectively. Both treatments showed for most of the parameters, no significant differences compared with those of T2 or T5 with supplementary fertilizers. A high production of metabolites (mg g^–1) like free amino acids was also shown: T3 – 6.45; T4 – 8.43 and proline: T3 – 1.86; T4 – 1.77, known to be a good indication of a plant natural defence against stress conditions, and in soluble protein: T3 – 11.20; T4 – 13.51. Therefore, since the production of such grains with RW or DS can be environmentally and economically beneficial, their use is recommended for small and medium farmers in semiarid regions.

GRAPHICAL ABSTRACT

KEYWORDS:

• Amino acids
• proline
• reuse
• semiarid
• sludge

Acknowledgements

The authors would like to thank to CNPq (Brazilian National Council for the Scientific Development) and FACEPE (Foundation for the Science and Technology Development of Pernambuco State), for financial support to project PRONEX NUTREL-3/APQ-0603-3.07/14 and project Water Resources and Reuse/APQ 0298-3.07/17); and INCT (Brazilian National Institute for Science and Technology), also for financial support to project Sustainable STPs/CNPq/FAPEMIG). Also, to COMPESA (Pernambuco Sanitation Company), BRK Ambiental Ltd. and Fibra Ambiental Engenharia Ltd. for the field support and help in sampling treated wastewater and sludge; Department of Nuclear Energy (DEN-UFPE), for the kind permission to use its greenhouse for the experiments; Agronomic Institute of Pernambuco (IPA), for the sorghum seeds and soil analysis; Laboratory of Plant Biochemistry (UFRPE), for the plant chemical analysis; and the students and technical staff from the Laboratory of Environmental Sanitation (LSA-UFPE) and Laboratory of Environmental Engineering (LEA-CAA-UFPE).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All authors state that the data and materials that support the results or analyses presented in the present paper are freely available upon request.

Additional information

Funding

CNPq (Brazilian National Council for the Scientific Development) and FACEPE (Foundation for the Science and Technology Development of Pernambuco State), for financial support to project PRONEX NUTREL-3: Process APQ-0603-3.07/14; FACEPE for the project Water Resources and Reuse: Process APQ 0298-3.07/17; INCT (Brazilian National Institute for Science and Technology)/CNPq for financial support to project Sustainable STPs/CNPq/FAPEMIG: Process 400324/2022-9 .