Agronomy

Industrial hemp (Cannabis sativa subsp. sativa L.) is an emerging crop in Florida, generating $445 million in 2024. However, it is highly susceptible to acarine pests, including spider mites (Tetranychidae), broad mites (Tarsonemidae), and russet mites (Eriophyidae). Management options are limited due to a few federally registered products approved by the Florida Department of Agriculture and Consumer Services (FDACS-DPI). Laboratory bioassays were conducted on hemp leaf discs infested with Tetranychus urticae, T. gloveri, Polyphagotarsonemus latus, or Aculops cannabicola, and treated with biorational pesticides (citric acid, rosemary, thyme, sesame, garlic, and mineral oil) at maximum label rates. Citric acid and garlic oil were most efficacious against T. urticae, while garlic and thyme oils were most efficacious against the other species, causing over 80% mortality. Greenhouse trials confirmed the efficacy of citric acid and garlic oil against T. urticae, achieving 60–80% mortality within 24 h. Predatory mites (Amblyseius swirskii, A. andersoni, Neoseiulus californicus, Galendromus occidentalis) were evaluated against A. cannabicola, with A. swirskii showing the highest predation (≈20 adults/24 h) and reproduction. Compatibility tests indicated thyme and garlic oils did not significantly affect A. swirskii survival (>70% alive after 24 h). These findings support integrated pest management strategies for hemp acarine pests.

Light intensity strongly influences the morphological development and photoprotective responses of in vitro plantlets, yet the optimal conditions for hydrangea remain undefined. This study investigated the effects of five light intensity gradients (TrA: 80–120 lux, TrB: 380–480 lux, TrC: 1500–1800 lux, TrD: 3800–4000 lux, TrE: 6000–6400 lux) on Hydrangea macrophylla ‘Qingtian’ plantlets. Plantlets exhibited optimal growth at TrB, showing maximal biomass, leaf expansion, chlorophyll content, and root activity, accompanied by low antioxidant enzyme activities and soluble sugar levels. Nutrient accumulation was greater under low light than under high light conditions. Transcriptome analysis of treatments (TrB and TrE) with marked phenotypic differences revealed 7119 differentially expressed genes (DEGs). Of these, 4582 genes were up-regulated and 2537 were down-regulated. The up-regulated genes were significantly enriched in pathways related to cell walls, the microtubule cytoskeleton, and developmental processes, which are involved in the plant growth and development process, such as photosynthesis, nutrient ion transport and regulation, as well as plant hormone responses and transport; whereas the down-regulated genes were significantly enriched in pathways related to carbohydrate metabolism, oxidoreductase activity, and glutathione metabolism, suggesting that high light stress impairs growth by disrupting carbon and antioxidant processes. These results demonstrated that 380–480 lux is the optimal light intensity for ‘Qingtian’ Hydrangea macrophylla in vitro plantlets. This study provides a foundation for optimizing culture conditions and offers new insights into the molecular regulation of light-responsive genes.

Australia’s southern cropping systems have limited plant diversity, dominated by cultivation of small grain winter cereals, mainly wheat (Triticum aestivum L) and barley (Hordeum vulgare L.), with a smaller proportion of break crops including canola (Brassica napus L.) and pulse legumes. Synchronous intercropping, where two cash crops are sown and grown together, and harvested simultaneously, could increase plant diversity but adds additional complexities in these highly mechanised farming systems. Temporary intercropping involves multiple plant species being sown together, with all but one species (the cash crop) terminated prior to harvest. This perspective explores temporary intercropping as a management practice to integrate a greater diversity of plant species into the cropping system. The impacts of temporary intercropping on cash crop growth, grain yields, soil health, and nitrogen cycling are reviewed. The ease with which temporary intercropping trials can be implemented through participatory farmer research is demonstrated via two case studies. We conclude that temporary intercropping holds promise as a means by which to introduce greater plant species diversity into Australian southern farming systems, but further research is needed to optimise intercrop species and seeding rates, fertiliser practices, and the timing of intercrop termination before economic assessments can be made.