BackgroundLow soil temperature and its fluctuation can negatively impact the growth of seedlings. The district of Cooch Behar (India), belonging to the Cwa zone (according to Koppen's classification), receives several cold waves during winter. Our previous study demonstrated that a constant temperature of 20 degrees C (chilling but not freezing) can cause a loss in the vigor of tomatoes. Since the temperature of the soil is not uniform throughout the day, we hypothesized that the duration of cold exposure can have variable effects on seed vigor.ResultsIt was observed that increasing the duration of cold stress can slow down the germination process and reduce vigor. This was due to the cold-mediated damage to cell membranes (due to dehydration) which caused electrolyte leakage and reduced levels of glutathione reductase. In this regard, biopriming seeds with microbes that produce exopolysaccharide (EPS) can be useful as it can form a protective layer on the seeds. Indigenous EPS-producing bacteria, Bacillus, Phytobacter and Priestia sp., were used for biopriming. Priestia and Phytobacter sp. not only reduced the electrolyte leakage but also increased the levels of antioxidant genes. This improved the germination speed and vigor. In a field trial, the rhizosphere of the seedlings pretreated with bioinoculants displayed a reduced thermal fluctuation compared with the untreated seeds.ConclusionThe seedlings treated with bioinoculants grew faster in soil in spite of low soil temperature. This can reduce the nursery time of seedlings. (c) 2025 Society of Chemical Industry.

Unlike the Himalayas, the sub-Himalayan zones did not experience snowfall and thus suitable for growing solanaceous vegetables. However, several cold waves have been reported to affect the district of Coochbehar (West Bengal, India), which belongs to the Cwa zone (as per Koppen's classification). Variable duration of sub-optimal soil temperature can have a detrimental effect on the growth of seedlings. Our previous study demonstrates that a constant temperature of 20 degrees C (6 degrees below the optimal soil temperature) causes a 71% loss of vigor in seeds of solanaceous plants. Since the soil temperature is not constant diurnally, it was hypothesized that the duration of cold stress can have variable effects on vigor of Capsicum annuum L. It was observed that increasing the duration of cold stress (18 degrees C) up to 2 hours/day can improve the vigor but after 6 hours/day, a significant drop in vigor was observed. This was because of the cold-associated membrane damage leading to the leakage of electrolytes. To date, this stress existing in these regions has gone unnoticed. In this regard, biopriming the seeds with exopolysaccharide (EPS)-producing microbes can be useful as the EPS can form a protective layer on the seeds. Two lesser-known bacteria namely, Phytobacter and Priestia sp. were evaluated for their vigor-recovering ability. Treatment of seed with these microbes reduced the electrolyte leakage which improved the vigor under sub-optimal stress. This was also validated by fluorescent microscopy. Both these strains displayed an enhanced EPS-producing ability at 18 degrees C which correlated with the reduced electrolyte leakage and enhanced stability of cell membrane. Such bacteria can help in promoting seed vigor under sub-optimal temperature stress. Bacterial inoculation prevents cold-induced membrane damage in seedlings.

Fall armyworm (FAW), Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), invasion in Africa has threatened food security. Optimization of plant tolerance and post-infestation recovery are among the management tactics that are being promoted for the integrated management of this pest, but these techniques are poorly studied in sub-Saharan Africa. Our study examined the efficacy of enriched compost, split-NPK fertilization, conventional fertilization, and bioinsecticides on FAW infestation rates, maize plant resilience, natural enemy presence, and grain yield. We found that split-NPK fertilization significantly improved maize plant robustness and reduced FAW incidence and leaf damage in a phenology-dependent manner, leading to higher grain yields. A synergistic effect was observed when split-NPK was coupled with bioinsecticides, resulting in increased populations of natural predators, and specifically the egg endoparasitoid, Telenomus remus (Nixon) (Hymenoptera: Scelionidae). Multivariate analyses confirmed that factors like split-NPK fertilization, bioinsecticide usage, stem circumference, and overall plant robustness are major determinants of maize grain yield. Our results endorse soil fertility management via split-NPK fertilization as an effective cultural control measure against FAW, providing an alternative to synthetic insecticides. These insights set the stage for future research focused on assessing the economic viability of this integrated approach, exploring the integration of split-NPK with alternative insecticides, evaluating environmental impacts, and examining the underlying resilience mechanisms to FAW, among other avenues.