Seed priming with plant gum biopolymers enhances efficacy of metalaxyl 35 SD against pearl millet downy mildew

Abstract

Priming' the plant and seed induces a physiological state in which plants are able to activate defense responses. Plant-based exudates are excellent gum biopolymers which contain plant growth-regulating hormones with priming potential without any side effects. In this study, gum exudates of Acacia arabica, Moringa oleifera, Carica papaya and Azadirachta indica were evaluated for synergistic effects of seed priming with exuded gum biopolymer combined with metalaxyl (Apron 35 SD) on pearl millet seed quality, growth parameters, and resistance to Sclerospora graminicola. Seeds of 7042S were primed with gum biopolymers and metalaxyl 35 SD and evaluated under laboratory and greenhouse conditions. Seed germination and vigor were synergistically enhanced using gum biopolymers solution (1:2 w/v) with 3 g kg −1 metalaxyl 35 SD. A. arabica and A. indica gum biopolymers alone or with 3 g kg −1 of metalaxyl 35 SD resulted in seed germination of >91%. Seed priming with 6 g kg −1 of metalaxyl 35 SD gave 89% seed germination and was not significantly different from control. A similar trend in vigor was observed among treatments. Seed priming with gum biopolymers alone provided varied disease protection levels when compared with the control. A. arabica or A. indica gum with 3 g kg −1 of metalaxyl 35 SD was the superior treatment, offering significant 86% disease reduction while exhibiting a growth-promoting effect. Synergistic use of gum biopolymers and metalaxyl 35 SD by seed priming is highly effective in growth promotion and management of pearl millet downy mildew disease.

Isolation and evaluation of proteolytic actinomycete isolates as novel inducers of pearl millet downy mildew disease protection

“…Among the various methods tested, seed treatment is the only effective and economical method for downy mildew control 13 , because pearl millet is cultivated by most economically backward farmers across the globe. Because of various market factors and low profit return, these farmers cannot afford expensive and repeated control measures 13 14 20 . Thus, there is not only the need for finding newer and more effective inducers of resistance against downy mildew disease, but also for optimizing the method(s) by which new inducers of resistance are made viable, durable, robust and economical.…”

“…It is estimated that 50% of the world millets is occupied by pearl millet crop, and India alone accounts for more than 50% of the global output 13 . Successful control of the downy mildew disease is dependent on expensive chemicals and host resistance 14 . Due to the distinct physiological and phylogenetic niches that these organisms occupy, most of the control measures have failed 15 .…”

“…Various types of induced resistance have been reported to control crop diseases 14 16 17 . Advantages of such methods include broad spectrum resistance, thereby enhancing the crop yield in an eco-friendly and feasible manner.…”

Exogenous Trehalose Treatment Enhances the Activities of Defense-Related Enzymes and Triggers Resistance against Downy Mildew Disease of Pearl Millet

“…Two-day-old seedlings were inoculated with SDW or zoospores of S. graminicola at a concentration of 4 × 10 4 zoospores mL -1 according to Jogaiah et al (2014). Apron 35SD (6 g Kg -1 seeds) was used as a standard chemical for positive control (Sudisha et al, 2009). The disease severity percentage was recorded after 30 days after treatments.…”

“…The experiments were conducted in four replicates with 100 seedlings each, and repeated twice. Apron 35SD (6 g Kg -1 seeds) was used as a standard chemical for positive control in the field experiment (Sudisha et al, 2009). …”