Responses of three cowpea cultivars to planting date and foliar fertilization

Aziz Mahdi Abd Al-Shammari [Department of Horticulture and Landscape, College of Agriculture, University of Diyala, Baqubah (Iraq)]
Nadir F. Almubarak [Department of Field Crop Sciences, College of Agriculture, University of Diyala, Baqubah, Iraq]
Ghassan Jaafar Hamdi [Department of Horticulture and Landscape, College of Agriculture, University of Diyala, Baqubah, Iraq]
Rana Kareem Saeed [Department of Horticulture and Landscape, College of Agriculture, University of Diyala, Baqubah, Iraq]

The interaction between the genotype and the planting date can affect the performance of cowpea [vigna unguiculata (L.) Walp.] plants. This study was undertaken to evaluate the influence of planting date, 15 July and 1 August 2019, and foliar application of a commercial fertilizer (Grow more® 20.20.20 + Micro) at 0, 50, 100 or 150 mL L-1 on the performances of cowpea cvs. Blackeye, Kafr Al-Sheikh, and Ramshorn. The experiment was arranged in a split–split plot design, with a completely randomized distribution with three replications. The cultivar Kafr Al-Sheikh treated with 150 mL L-1 of the fertilizer produced the tallest plants (103.8 cm). The cultivars Kafr Al-Sheikh and Ramshorn had the highest leaf phosphorus content (an average of 0.074%) when sprayed with 150 mL L-1 of the fertilizer. The cv. Blackeye, planted on 15 July, and treated with 150 mL L-1 of Grow more® had the highest relative chlorophyll content (SPAD index = 125.8). The largest leaf area was measured in Blackeye plants treated with 100 mL L-1 of the fertilizer (812 dm2/plant). The cv. Kafr Al-Sheikh, planted on 15 July, and treated with 100 mL L-1 of the fertilizer had the highest leaf nitrogen content in leaves and the highest yield (3.73%, 88.91 Mg ha-1, respectively). The highest leaf potassium content was measured in the ‘Ramshorn’ cultivar planted on 15 July, and treated with 100 or 150 mL L-1 of the fertilizer (1.92 and 1.96%, respectively). The use of Grow more®, as a foliar fertilizer, appears to be suitable for the cultivation of cowpea plants to increase green pods yield.

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