DefinePK

Research Objective

To investigate the allelopathic interactions between Ailanthus altissima (tree of heaven) extracts and rhizosphere soil on the germination and various growth parameters of two important crops: Pennisetum glaucum (pearl millet) and Brassica nigra (black mustard).

Methodology

Plant material (Ailanthus altissima leaves) was collected, shade dried, and powdered. Aqueous (cold and hot water) and methanol extracts were prepared. Treatments included applying these extracts at 5gm and 10gm concentrations to seeds, a litter bed bioassay using crushed leaves, and testing the effect of rhizosphere soil collected from Ailanthus altissima roots versus control soil. Parameters measured after 72 hours (extracts) or 7 days (rhizosphere) included germination percentage, plumule length, radicle length, fresh weight, dry weight, and moisture content. Statistical analysis involved ANOVA and LSD for post-hoc analysis, and Student's t-Test for rhizosphere data, using Excel software.

Methodology Flowchart

                        graph TD;
A[Collect A. altissima parts] --> B[Prepare Powder];
B --> C[Prepare Extracts: Cold Water, Hot Water, Methanol];
C --> D[Apply Extracts to Seeds P. glaucum & B. nigra];
D --> E[Measure Germination & Growth Parameters 72h];
B --> F[Collect Rhizosphere Soil];
F --> G[Plant Seeds in Rhizosphere Soil vs. Control];
G --> H[Measure Growth Parameters 7 days];
E --> I[Statistical Analysis: ANOVA, LSD];
H --> J[Statistical Analysis: t-Test];
I & J --> K[Key Findings & Conclusion];                    

Discussion

The study confirms concentration-dependent allelopathic responses. Cold water extracts showed stimulation for millet, consistent with some prior research, while methanol extracts were generally inhibitory. The rhizosphere soil demonstrated complex, multifaceted effects: inhibitory on millet germination but stimulatory on shoot length, echoing the complexity documented in literature regarding plant-soil interactions. The lack of significant effects on Brassica nigra parameters in rhizosphere soil suggests resilience or adaptation, highlighting the need to consider specific plant species and soil composition in such studies.

Key Findings

Pearl Millet (Pennisetum glaucum*): The 5gm cold water extract showed significant stimulatory effects on germination (100%), plumule length (1.054cm), radicle length (0.728cm), and fresh weight (0.3g). Conversely, methanol extracts generally exhibited inhibitory effects.
* Rhizosphere Soil (Millet): Rhizosphere soil had a slight inhibitory effect on germination (30% vs. 32% control) but significantly increased shoot length compared to the control. Dry weight showed no significant difference.
Black Mustard (Brassica nigra*): Different concentrations of cold water, hot water, methanol extracts, and litter bed bioassay significantly influenced germination, plumule length, and radicle length.
* Rhizosphere Soil (Mustard): Statistical analysis indicated no significant differences (p > 0.05) between control and rhizosphere soil treatments for mustard's fresh weight, dry weight, or moisture content, although trends in shoot length were observed.

Conclusion

Ailanthus altissima exhibits complex allelopathic effects on P. glaucum and B. nigra, dependent on the extract type and concentration. Cold water extracts stimulated pearl millet growth, while methanol extracts were inhibitory. Rhizosphere soil interactions are nuanced, showing differential impacts on growth parameters between the two crop species, underscoring the intricate nature of plant-soil relationships relevant to sustainable agriculture.

Fact Check

1. The highest germination rate for pearl millet was observed in the 5gm cold water Ailanthus altissima extract (100%).
2. Methanol extracts at 10g concentration resulted in the lowest germination rate for pearl millet (10%).
3. The study was published in Pure and Applied Biology, Vol. 13, Issue 4, in December, 2024.

Mind Map