Seed priming is a state-of-the-art, low-cost, and environment-friendly strategy to improve seed germination, seed vigor, abiotic and biotic stress tolerance, and the yield of field and horticultural crops. Seed priming involves imbibing the seeds in a priming solution under a desired set of environmental conditions for a period followed by drying before the radicle protrusion. Several seed priming approaches including hydropriming, osmopriming, bio-priming, hormonal priming, nutrient priming, nanoparticle priming, and electropriming can be effectively employed under different environmental conditions to improve crop growth and stress resilience. Seed priming is known to trigger enzymatic, hormonal, physiological, transcriptomic, metabolomic, and proteomic regulations in seed embryos during seed germination and plant growth, which leads to faster and synchronized seed germination and higher abiotic and biotic stress tolerance in crop plants. Furthermore, seed priming can induce cross-tolerance between abiotic and biotic stressors and induce stress memory for higher resilience of the next generation to environmental stresses. The present review paper discusses the applications of seed priming in biotic and abiotic stress tolerance and the underlying abiotic and biotic stress tolerance physiological, biochemical, and molecular mechanisms of seed priming. Furthermore, we discuss the current challenges/bottlenecks in the widespread application of seed priming in crop production.

SUMMARY: Rhizobiome confer stress tolerance to ruderal plants, yet their ability to alleviate stress in crops is widely debated, and the associated mechanisms are poorly understood. We monitored the drought tolerance of maize (Zea mays) as influenced by the cross‐inoculation of rhizobiota from a congeneric ruderal grassAndropogon virginicus(andropogon‐inoculum), and rhizobiota from organic farm maintained under mesic condition (organic‐inoculum). Across drought treatments (40% field capacity), maize that receivedandropogon‐inoculumproduced two‐fold greater biomass. This drought tolerance translated to a similar leaf metabolomic composition as that of the well‐watered control (80% field capacity) and reduced oxidative damage, despite a lower activity of antioxidant enzymes. At a morphological‐level, drought tolerance was associated with an increase in specific root length and surface area facilitated by the homeostasis of phytohormones promoting root branching. At a proteome‐level, the drought tolerance was associated with upregulation of proteins related to glutathione metabolism and endoplasmic reticulum‐associated degradation process. Fungal taxa belonging to Ascomycota, Mortierellomycota, Archaeorhizomycetes, Dothideomycetes, and Agaricomycetes inandropogon‐inoculumwere identified as potential indicators of drought tolerance. Our study provides a mechanistic understanding of the rhizobiome‐facilitated drought tolerance and demonstrates a better path to utilize plant–rhizobiome associations to enhance drought tolerance in crops.

Temperature rise in March induces forced maturity in wheat (Triticum aestivum L.), which generally reduces the grain-filling period under North Indian conditions. A field experiment was conducted at the Punjab Agricultural University, Ludhiana, India, during 2015–16 and 2016–17 to evaluate the effect of salicylic acid on plant growth, physiological parameters, and grain yield of two wheat cultivars sown at different dates. A split-split-plot design was used, with sowing dates (November 5, November 20, and December 5) as main plots, wheat cultivars (WH1105, PBW677) as sub-plots, and salicylic acid foliar treatments (control, water spray, salicylic acid 75 and 100 mg l⁻¹) as sub-sub plots. The highest tiller count, atLEAF-chlorophyll index, pollen viability, number of grains ear⁻¹, 1000-grain weight, biological and grain yield were recorded for the November 5 sowing date. Salicylic acid foliar application at 75 and 100 mg l⁻¹ increased the grain-filling period, improved the normalized difference vegetative index (NDVI), pollen viability, number of grains ear⁻¹, proline content, 1000-grain weight, and grain yield. We concluded that wheat cultivars WH1105 and PBW677 can be grown successfully by sowing early (November 5) and that foliar application of salicylic acid at 75 mg l⁻¹ can improve the wheat grain yield under north Indian conditions.