The Role of Spent Oyster Substrate Supplemented with Biological Factors and spraying with Spent substrate extract on some Vegetative Growth Characteristics of Cowpea (Vigna unguiculata L.)

• Miaad Ibrahim Turki 1*, Faris Mohammed Suhail 2, and Ahmed Kareem Abdulrazzaq

  Author

The experiment was conducted in pots at the research station of the Department of Soil Science and Water Resources - College of Agriculture / University of Diyala during the period from March to May 2025 to evaluate the effect of  spent oyster substrates treated with bacteria and yeast  on the growth of cowpea plants. The experiment was performed  using a completely randomized design (CRD). The experiment included 14 treatments resulting from the interaction of two factors: The first factor was the  incorporation  of spent oyster substrates with  the soil at a ratio of 25%, comprising seven levels: wheat straw treated with Azotobacter chroococcum (WSA), wheat straw treated with yeast(WSY), Suaeda aegyptiaca treated with Azotobacter chroococcum (SAA), Suaeda aegyptiaca treated with yeast(SAY), Phragmites australis treated with Azotobacter chroococcum (PAA), Phragmites australis treated with yeast(PAY), and the control (soil only), The second factor involves two levels of spent oyster substrate extract application (Spraying with spent substrate extract S1 and no spraying S2). The data were statistically analyzed and the means of the treatments were compared according to Duncan's multiple coefficient test at a probability level of 0.05. The results showed that the treatment of Phragmites australiss substrate with yeast  (PAY)and spraying with the spent substrate extract(S1) achieved the highest plant length and Dry Weight of the Shoots system, reaching 43.00 cm plant^-1and 12.43 g plant^-1 respectively. The wheat straw substrate with Azotobacter chroococcum(WSA ) and spraying with the extract(S1) recorded the Dry Weight of Root system and number of active nodules, reaching 1.81 g plant^-1 and 20.66 nodules plant^-1 respectively. All treatments using spent biological substrates (wheat straw, Phragmites australis , and Suaeda aegyptiaca). showed a significant advantage in increasing cowpea plant growth compared to the control treatment.

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