Abstract
Sunflower (Helianthus annuus L.), a member of the Asteraceae, is one of the major oilseed crops around the world. Charcoal rot caused by Macrophomina phaseolina (Tassi) Goid is the most damaging disease of sunflowers globally. Fungicides are mostly used to control charcoal rot; however, these cause environmental pollution and pose adverse effects on the ecosystem. Therefore, ecofriendly management options are inevitable for the management of charcoal rot disease. Plant mineral nutrition, the use of plant growth-promoting rhizobacteria and biochar have recently been manipulated for the management of different plant diseases. However, the interactive effects of all these treatments have rarely been tested on charcoal rot suppression in sunflowers. This study assessed the influence of sulfur (0 and 2.25 mg/kg) combined with farmyard manure biochar (2%), NPK (20:20:20 mg/kg) and three different plant growth-promoting rhizobacteria (PGPR) strains on the charcoal rot suppression growth, yield, biochemistry and physiology of sunflower. The PGPR strains included in the study were Bacillus sp. strain MR-1/2 (regarded as PGPR1), Achromobacter sp. strain FB-14 (regarded as PGPR2) and Planomicrobium sp. strain MSSA-10 (regarded as PGPR3). The charcoal rot infestation was induced by inoculating the soil with M. phaseolina, and the impacts of the different treatments were studied on the disease infestation, growth, yield, biochemistry and physiology of sunflowers under 0 and 2.25-mg/kg S application. The results revealed that farmyard manure biochar and Planomicrobium sp. strain MSSA-10 in combination with 2.25-mg/kg S proved effective for the management of charcoal rot disease through regulating the antioxidant enzymes’ activities and strengthening the immune system of sunflower plants. The studied health markers (total chlorophyll content and carotenoids) and stress markers (total protein content, catalase and peroxidase) were significantly altered by the applied treatments under 0 and 2.25-mg/kg S applications. The findings of the experiment indicated that both farmyard manure biochar and Planomicrobium sp. strain MSSA-10, combined with 2.25-mg/kg S, could be used to enhance the crop yield and manage charcoal rot disease in sunflowers. Farmyard manure biochar and Planomicrobium sp. strain MSSA-10 are an easy-to-apply, cost-effective, ecofriendly and sustainable option for the management of charcoal rot disease in sunflowers.
Highlights
Sunflower (Helianthus annuus L.) belongs to the family Asteraceae and genus Helianthus, which consists of sixty-five species [1]
The pure culture of Macrophomina phaseolina was obtained from the Fungal Culture Bank of Pakistan (FCBP), Institute of Agricultural Sciences, University of Punjab, Lahore, Pakistan and multiplied in the laboratory
The inoculation of M. phaseolina without S application resulted in the highest disease infestation and plant mortality, whereas NPK without S application recorded the similar disease incidence and plant mortality
Summary
Sunflower (Helianthus annuus L.) belongs to the family Asteraceae and genus Helianthus, which consists of sixty-five species [1]. It is third-most important oilseed crop and mostly cultivated in temperate and subtropical zones of the world [2]. During 2019 to 2020, sunflowers were cultivated on 219,000 hectares, which produced 105,000 tons of seeds and. Sunflower production is negatively affected by several biotic and abiotic factors, including disease infestation. Charcoal rot caused by Macrophomina phaseolina (Tassi) Goid is a significant threat to sunflower production around the world [7,8,9]. A total of 67 host species for M. phaseolina have been reported from
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