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• Yield and fruit quality response to foliar application of biostimulants in an apple orchard

  17-23.

  Adam Csihon

  Marianna Sipos

  Imre Holb

  Views:

  540

  Nutrient supply plays an important role in fruit production technology. Among the methods of nutrient management, the application of foliar fertilization has become an essential tool to harmonize the vegetative and generative performance of fruit trees. This study was conducted to determine the effect of four foliar fertilizers (Bistep, brown juice, Trichoderma harzianum, Clonostachys rosea) on yield and fruit quality in an apple orchard with the cultivar ‘Pinova’, at the University of Debrecen in Hungary. Trees were trained to a slender spindle canopy with a spacing of 4 × 1 m. Treatments were applied five times during different phenological phases in 2021 and 2022. Based on our results, biostimulants had a positive effect on fruit yield and fruit quality, but extreme weather events also influenced the data. In 2021, the effect of the treatments on yield data could not be observed (10.1–13.5 kg/tree; 0.16–0.24 kg/cm²). However, in 2022, plants sprayed with Bistep, T. harzianum, and C. rosea reached 28.7–31.2 kg/tree (0.33–0.46 kg/cm²), while control trees produced only 19.8 kg/tree (0.20 kg/cm²). Fruit size development improved with an increase of 2–6 mm over the two years. Among the treatments, Bistep was able to enhance fruit surface coloration to a greater extent in 2021, as red skin color reached 44% for this foliar fertilizer, while control trees presented only 27%.

• Age-dependent physiological responses of Corchorus olitorius to aqueous extracts of Murraya koenigii and Tithonia rotundifolia

  61-66.

  A. A. Ogunwole

  Views:

  62

  Sustainable crop production increasingly utilizes allelopathic plants as sources of bioactive compounds, yet their bimodal inhibitory–stimulatory effects and oxidative mechanisms require further elucidation. This study investigated the concentration-, tissue-, and stage-dependent effects of aqueous shoot extracts from Murraya koenigii and Tithonia rotundifolia on the germination, growth, and oxidative defense of Corchorus olitorius. Seed emergence and elongation of radicles and plumules were monitored in the laboratory using 50% and 100% aqueous extracts, while potted seedlings were treated separately with 100% extracts. Laboratory bioassays demonstrated a dose-dependent response: a 50% M. koenigii extract transiently increased germination by 4%, while higher concentrations of both species inhibited germination by 7–25%. Juvenile growth inhibition was tissue-specific, with 100% M. koenigii primarily suppressing plumule elongation and 100% T. rotundifolia significantly reducing radicle growth. Conversely, pot experiments using 100% extract concentrations of both plants significantly enhanced vegetative growth, physiological traits, and biochemical constituents, including protein and ascorbic acid. These extracts bolstered the antioxidant defense system—increasing superoxide dismutase, catalase, and peroxidase activities—while markedly reducing malondialdehyde levels. These findings provide evidence of allelopathic hormesis, where initial inhibitory effects transition into growth stimulation and oxidative stress mitigation during later developmental stages. The results suggest that M. koenigii and T. rotundifolia shoot extracts serve as effective eco-friendly biostimulants that improve crop performance by modulating antioxidant responses.